smta-gdl_smta-gdl_DFM_presentation_2012-07

7/30/2019 smta-gdl_smta-gdl_DFM_presentation_2012-07

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Design for Manufacturability

(DFM)Design for Assembly (DFA)

SMTA

Guadalajara Mexico

July 12, 2012


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Welcome!!!

Joe [email protected]

ITM ConsultingDurham, New Hampshire

USA


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Joe Belmonte Motorola Information System Group

Mansfield Massachusetts (MA), USA

1978 to 1995

Manger of Advanced Manufacturing Engineering

Speedline Technologies

(MPM, Camalot, Electrovert)

Franklin MA, USA

1995 to 2007

Director of Applications Engineer and

Principal Consultant


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Joe Belmonte Bose Corporation

Framingham MA, USA

2007 to 2009Director of Advanced Manufacturing Engineering

ITM ConsultingDurham New Hampshire, USA

2009 to PresentPrincipal Consultant


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Whatever comes out of thesegates, we've got a better

chance of survival if we worktogether. Do you understand?If we stay together, we survive.

Gladiator Movie Quotes by Author Unknown


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Seminar Agenda Definition of DFM

Customer Satisfaction Requirements

Functional Responsibilities of DFM

Concurrent Engineering

Early Supplier Involvement Well Defined Development Process

Defining a Process

Six Sigma and Statistical Thinking

Understanding and Controlling Process

Variation


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Seminar Agenda

Inspection and Test Planning

Process Characterization Concepts

Stencil Design

Evaluating Printed Circuit Board Designs

Software


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The significant problems we

face cannot be solved at thesame level of thinking we were

at when we created them-- Albert Einstein


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We are what we repeatedly do.Excellence, then,

is not an act, but a habit.

-- Aristotle


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Ultimate Purpose of DFM/DFA is

Customer Satisfaction!!!!!

Quality Reliability

Cost

Delivery

Features


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Design for Manufacturability must includea detailed understanding of the processes

that will be used to build the product, howthe processes are developed, how theprocesses are controlled, and howcontinuous improvement is accomplished.


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DFM&DFA GuidelinesThe two most important documents the

electronic assembler should have are:

Workmanship Standards

Design for Manufacturability andAssembly (DFMA) Guidelines


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Design forManufacturability

Definitions


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Design for Manufacturability is the process bywhich every aspect of the product and

process design is formally evaluated to insurethe lowest possible product cost, the fastestpossible process cycle time, and the highestpossible first pass yield.


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Designing a product to be produced in themost efficient manner possible (in terms of

cost, resources, and time) taking intoconsideration how the product will beprocessed, utilizing the existing skill base

(and avoiding the learning curve) to achievethe highest yields possible

Phil Zarrow


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Design for ManufacturabilityDesign for Manufacturability is the method for creating

robust product designs that will be insensitive tolong-term dynamic variation in the processes andmaterials used in the manufacturing and will beimmune to foreseeable misuse of the product in theenvironment in which it is used. -- Motorola

DFM is the process whereby manufacturing and testengineers influence the product design to make itas manufacturable and testable as possible by

minimizing cycle time, reducing parts, usingstandard processes and maximizing test coverage.-- Dave Reed, 3COM


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What is DFM&DFA ?

Design for Assembly (DFA) - is a technique which willminimize total product cost by targeting: (this is the processside of product transformation process)

Parts Count (This is the major cost driver in Mfg.)

Assembly Time Part Cost

The Assembly Process

Design for Manufacturing (DFM) - is a technique forminimizing fabricated part cost: (this is the material and toolingside of the product development process)

Optimizing the Fabrication Process Material Selection

Part Cost

Tooling Strategies to reduce cost

Tooling Cost Estimates


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Customer SatisfactionRequirements


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A customer has a right to expect the productto be delivered without defects

A defect is any variation of a requiredcharacteristic of the product or its parts, which isfar enough removed from its target value to

prevent the product from fulfilling the physicaland functional requirements of the customer


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A customer has a right to expect the productto be delivered when promised

Every occurrence of a defect within themanufacturing process requires time to analyze,repair, and test.


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A customer has a right to expect the productnot to experience early life failure

Early life failures are the result of latent defects,or abnormalities, which will cause failure at somefuture time, depending on the degree of

abnormality and amount of applied stress. Latentdefects are not detectable by normal test orinspections.


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A customer has a right to expect the productnot to fail excessively in service

If the product design is robust, it will beinsensitive to long-term dynamic variation in theprocess and materials used in manufacturing

and will be immune to foreseeable misuse of theproduct in the environment in which it is used.


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Delivered defects are directly proportional tothe total number of defects found in the entire

manufacturing process. Average cycle time per unit is directly

proportional to the total number of defects perunit.

Latent defects are directly proportional to the

total number of defects found in the entiremanufacturing process.


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Reducing the total number of defects per unitin the entire manufacturing process will:

Reduce delivered defects

Reduce the cycle time per unit

Reduce early life failure rate


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Reduced total defects per unit will result in:

Increased customer satisfaction

Reduced warranty cost

Reduced manufacturing cost


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FunctionalResponsibilities of DFM


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Functional Responsibilities:Development Engineering (Product Design)

Using supplied capability studies for suppliers andinternal processes, design for 6 sigma performance

for both supplier and internal processes Set supplier piece part specifications at 4.5 sigma

based on supplier capabilities.

Calculate sub-assembly tolerances statistically, thencheck the prototypes against the calculations. Whenchanges are made in components, maintain up-to-

date assembly output calculations.Supply calculations to assist in new product start upsManufacturing provides performance data to development

for use in next product design


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Design for Assembly DFA

Reduced part count is the MAJORadvantage to practicing design for

assembly DFA

Part count drives/touches every aspectof an organization


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Design for Assembly DFA

Are all parts of the

assembly REQUIRED tomeet the function of thedesign?

Are these parts required toMOVE relative to each

other?

Yes - this partmay berequired

No

Yes - this partmay berequiredNo


No


No

Must this part be made ofDIFFERENT MATERIALthan other parts in theassembly?

Is this part NECESSARYfor disassembly or serviceof this assembly?

Unnecessary Parts Test

Part is a candidate for elimination


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Building better products requires a goodcomparative perspective about othercompanies to gain insight into othersources of outstanding performance

Product Development Performance

Kim Clark & Takahiro Fujimoto


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Definitions

Benchmarking Is the continuous process of measuring products,

services and practices against the toughest competitorsor those recognized as industry leaders.

Competitive Intelligence Is the process of gleaming and combining disparate

information about a competitor in order to deduce itsobjectives.

Reverse Engineering Is the systematic dismantling of a product to understand

its technology with the purpose of replication.


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B th d D h t DFMA


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Boothroyd Dewhurst DFMA

Software Tools and Services Founded in 1985 in Wakefield Rhode Island

USA

Provides product design and productmanufacturability software tools and

consulting services

F i l R ibili i


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Functional Responsibilities:Component Engineering

At the time of component qualification, display in thecomponent qualification report the actual data on

each critical parameter. Show any corrective actionrequired by the supplier so that all parties are awareof what must be done to finish qualification of the

part to make it acceptable. Mechanical dimensions must be qualified to the

same design margins as those of electrical

parameters. This will be done when supplier data forthe first piece parts is scrutinized.

F i l R ibili i


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Functional Responsibilities:New Product Introduction Engineering

Work as closely as possible, as early as possible,with the product development team to insure all

aspects of manufacturability and testability are builtinto the product design from its inception. Work as amember of the product development team.

Coordinate and communicate with all concernedgroups (manufacturing, sustaining engineering,development, purchasing, component engineering,

quality, marketing, sales, etc.) the productdevelopment status at each step of the process.

F ti l R ibiliti


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Functional Responsibilities:Process/Manufacturing Engineering

Perform process capability studies on allexisting processes and place under statisticalcontrol. Supply current capability to productdevelopment engineers.

Start a procedure of process improvementthat brings performance of each process tosix sigma levels. As processes improve,

update development engineering on the newcapabilities.

F ti l R ibiliti


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During the prototype and pilot runs, every failuremust be treated as either a parametric or catastrophic

failure, and its source must be corrected by design orprocess improvements. This applies both to internalfailures and supplier failures.

At prototype and pilot runs, and in conjunction withproduction personnel, re-check the process capabilitydata to ensure nothing has changed. Maintain

statistical control and statistically analyze for designmargins to six sigma. Identify each failure and treat

as described.

Functional Responsibilities:Process/Manufacturing Engineering

F ti l R ibiliti


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Perform specification compliance evaluations

Perform accelerated life/reliability evaluations

and statistical analysis on all criticalparameters. Report the actual designmargins found in the finished product toproduct design and manufacturing.

Functional Responsibilities:Product Quality Engineering

F nctional Responsibilities


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Calculate process capabilities (Cp/Cpk) oneach new piece of equipment or new processbefore turning them over to manufacturing.

The manufacturing engineer responsible for

the new equipment or process will verify it inproduction mode and establish thecapabilities and statistical controls (SPC) for

ongoing manufacturing.

Functional Responsibilities:Advanced Manufacturing Technology

Functional Responsibilities:


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Develop supplier process capabilities andfurnish them to development engineering.

Work with suppliers to improve processcapabilities when the design cannot tolerate

variation in the suppliers existing processes. Ensure supplier compliance to SPC

requirements and require that proof of control

is supplied with each lot of material.

Functional Responsibilities:Supplier Component Engineer and Purchasing


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ConcurrentEngineering

N P d t D l t P


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New Product Development Process

P d t D l t P


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Product Development Process

DFMA process and tools can be applied throughoutthe product development cycle

The Cost of Making Changes


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According to President Hiroshi Hamada, Ricoh did not detect aproblem with one of its copiers until the machines were shipped tocustomers.Had the problem been corrected earlier, before the start ofproduction, he estimated the cost of correcting the problem atvarious stages as follows:

At the design phase: $ 35

Before procuring parts: $177Before start of production: $368

Instead, the cost of correcting this problem was:

$590,000.00

The Cost of Making Changes

Wh C t th Bi t Sh d ?


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Who Casts the Biggest Shadow?

Design 5%

70% 20%

Material50%

5%

Labor15%

5%

Overhead30%

Influence

Product Cost

Adapted from Ford Motor Co.

D i f M f t bilit


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75 to 90% of project/product costs

are determined during the first

7 to 8% of development time.

-- Paul Collins Ph.D., University ofWashington and Strategy ResearchApplications

C t E i i


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Concurrent Engineering is a competitive strategyattempting to simultaneously achieve a portfolio of

benefits in time, money, and novelty (features). Concurrent Engineering involves multiple functions

involved in decision-making on product design so

that downstream issues such as manufacturability,marketability, serviceability, and total life cycleproblems are anticipated at very early productdesign stages.

-- Paul Collins Ph.D. University of Washington and Strategy ResearchApplications

C t E i i


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Product Development Time Reductions:

40% to 67%

Product Development Costs reductions:16% to 46% for Telecommunications

55% to 95% for Aerospace

Engineering Rework Reductions:

50% to 54%

-- Paul Collins Ph.D. University of Washington and Strategy Research Applications


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Early SupplierInvolvement

Early Supplier Involvement


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Capture the vendors know how and experienceearly.

Share a commitment to the product by workingtogether from the start.

Optimize the part design to take advantage of the

vendors capabilities and processes. Optimize the part design for ease of manufacture

with input from the vendor on the emerging design.

Set target cost for tooling and parts using costmodels to support the products cost goals. Usethis data to open communications with vendors.



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Our customers teach us to be good suppliers;perhaps our suppliers could teach us to be good

customers. We realize that we are not taking full advantage of

the benefits of supplier design expertise early

enough in our design process. Many of ourcustomers have enjoyed these benefits for years.They know the value of supplier-customer designteams.

Suppliers can help design in quality from thebeginning, and shorten the product developmentcycle time -- Gary Tooker, Motorola



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The early supplier involvement processrequires the trust and openness to share

critical information between the customer andchosen supplier.

A supplier must be prepared with personalcapable of responding to the customersrequirements.



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These questions should be asked:Do you have a standard item that can be

substituted?What are the available manufacturing

alternatives?

Can you suggest a material alternative?

Do you have any suggestions that would

reduce processing?Are there any product design alternatives that

can be made to assist you?



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These questions should be asked:Can you evaluate cost versus precision?

Can you suggest procedures to detect andremedy deviations?

Does your company have the technicalexpertise available in a time frame appropriateto the customer requirements?

Do you have any further suggestions thatmight reduce lead time, simplify the part,and/or reduce cost?



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What are ways to insure 100% usablepurchased parts and materials?

Cpk equal to or greater than 1.5

Supplier specifications that reflect true critical

valuesThe specs supplied by the customer mustallow the supplier to use the most efficient

manufacturing process.Internal policies and procedures must conform

to the above.

Benefits of Early Supplier Involvement


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Lower development and part cost

Optimized manufacturability

Improved part quality

Improved delivery schedules

Improved communications Optimized product design



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Minimized design changes

Reduced product development time

Optimized material selection

Utilized supplier technology

Standardized parts Calculated Six Sigma design


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Well DefinedDevelopment Process

Well Defined Development Process


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Be documented, graphically and textually

Key terms are defined

Documentation is distributed to and understoodby all involved parties

Be detailed and specific enough to serve as a

working development blueprint; yet flexibleenough to accommodate products of varyingcomplexity

Minimize all opportunities for paralleldevelopment



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Define the items listed for each phase:

Required inputs and sources

Constituent steps and tasksPer step/task, roles and responsibilities

Outputs, including documentation specifications

Phase entry and exit criteria

Necessary functional involvement

Be enforced and monitored



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A formal review should occur at the end ofeach development phase in order to:

Detect problems (potential defects) as close aspossible to their point of origin.

Track and document sources of error and defects.

Uncover errors, but NOT to fix them (during thereview)

Confirm outputs that do not require

improvements.

Make projects more manageable.

Characteristics of Formal Phase Reviews


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Cross functional representation, includingcustomers

Material disseminated in advance Scope of material covers wide spectrum

May need to occur over several meetings Coordinated by project leader

Sign-off and follow-up report required


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Defining a Process

Define the Process


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e e t e ocess The term process means different things to

different people. So, it is important to clearlydefine what we mean by process.

A process can be defined as the logicalorganization of people, materials,

environment, equipment, and procedures intowork activities designed to produce aspecified end result.

Elements of a Process


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Materials

Equipment

Procedures

PeopleCustomer

RequirementsProducts &Services

Environment

WorkActivities

A key/critical process is basically a "valued-added" process in the Macro Map whichinhibits achieving 6 sigma quality in our products or services.

Defining Process Parameters


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g

Process

Material

Design Defects

OutputParameter(s)

InputParameter(s)

ProcessParameters

Variable

Characteristics

Defining Process Parameters


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Input ParametersA measurement system or a parameter in a process that is

used in the creation of process output.

Input parameters are materials, methods, measurements,machines, people, and environment.

Process Parameters

Steps or activities completed using the input parametersto generate a product or service.

Output Parameters

The end result of a process. It may include as little as onlyone specific output on only one product or it my include asmuch as all products and all outputs produced by themachine(s) and/or operation(s) included in the process.

Identifying Parameters


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y g

Choosing those parameters that will be the leadingindicators to the quality level being produced by the

process.

Those parameters that have the most

significant impact to the next process,clients or our customer.

Process

Material

Design Defects

OutputParameter(s)

InputParameter(s)

ProcessParameters

VariableCharacteristics

Process Mapping


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Understanding the flow of the process, allinputs, outputs, of each process steps.

Macro-Map : Macro-Mapping is the process ofcharting the coarse flow of an operation (such asa manufacturing line).

Micro-Map : Micro-Mapping breaks down aprocess in the Macro-Map into severalconsecutive sub-steps (identifying all inputs andoutputs).

ProcessA

ProcessB

ProcessC

OutputProduct or

Service

InputParameter(s)

Methods Used to Identify Parameters


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Brainstorming Techniques

Prioritization Matrix

Cause and Effect Diagrams (Fishbone)

Modified Cause and Effect Diagrams

Weighted Voting Affinity Diagrams


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Six Sigmaand

Statistical Thinking

ConditionConditionConditionCondition

CapabilityCapabilityCapabilityCapability 1111 2222

AAAA

Condition 2Condition 2Condition 2Condition 2:

Distribution AverageDistribution AverageDistribution AverageDistribution Average


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CCCC

AAAA

BBBB

-6s -5s -4s -3s -2s -1s 1s 2s 3s 4s 5s 6s

LSLLSLLSLLSL USLUSLUSLUSLNominalNominalNominalNominal

CCCC pppp ==== ==== 2.02.02.02.0 2.02.02.02.0

AAAA

BBBB

CCCC pkpkpkpk ==== ==== 2.02.02.02.0 1.51.51.51.5CCCC

0.5 B0.5 B0.5 B0.5 B

Condition 1: DistributionCondition 1: DistributionCondition 1: DistributionCondition 1: DistributionAverage Centered onAverage Centered onAverage Centered onAverage Centered on

Normal SpecificationNormal SpecificationNormal SpecificationNormal Specification

Distribution AverageDistribution AverageDistribution AverageDistribution Average

Shifted 1.5s from theShifted 1.5s from theShifted 1.5s from theShifted 1.5s from theNominal SpecificationNominal SpecificationNominal SpecificationNominal Specification

LCLLCLLCLLCLLCLLCLLCLLCL UCLUCLUCLUCLUCLUCLUCLUCL

LSLLSLLSLLSLLSLLSLLSLLSL

USLUSLUSLUSLUSLUSLUSLUSL

What is Six Sigma?


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A discipline of continuous improvement toachieve Total Customer Satisfaction.

Implement Permanent Corrective Actions

Prevent Recurrence Control the Process Standardization Redesign

4 - Action

Define Goals and Targets

Recognize Parameters Identify Key Opportunities Identify Key Processes

Improvement Plan Select Project/Team1 - Plan

Measure Improvement Assess Effectiveness Review Projects

3 - Check Education and Training Implementation

2 - Do

Key Factors for Success


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Management LeadershipTop down

Committed

Clear & Aggressive Goals

Breakthrough Thinking Training (Black Belt Program)

Reinforcing Successes

Drive Six Sigma Quality through StatisticalThinking and Analytical Problem Solving

Six Sigma Key Initiative Challenges


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The achievement of Error Free Performance inProducts, Processes and Services

Six Sigma Quality - 3.4 defects per million opportunities

Total Cycle Time Reduction - 10x improvement every 2years

Six Sigma Designs

Process and Supplier CharacterizationVariation Reduction in Processes and Designs

Cp/Cpk > 1.5

Total Customer Satisfaction

Software Quality - SEI

Six Sigma is a highly disciplined and quantitative

approach to improvements

Five Myths of Statistical Thinking &


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Analytical Problem Solving Only works in manufacturing

Is added effort, takes too long

Requires large teams

Creates a lot of bureaucracy

Just another quality program

The Role of Continuous


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Improvement To achieve consistency in our processes, we

need to reduce variation. But, how do we:

Measure the current levels of variation?

Decide what to work on next?

Know we have improved? To answer these questions, we must have a

process and associated tools. It is here thatstatistics and statistical thinking play a majorrole.

The Role of Statistical Thinking


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in Continuous Improvement Statistics: The science of turning data into information formaking business or engineering decisions in the presence ofuncertainty. The electronics business is a data-drivenindustry. We apply statistical methods to enable us to makequantitative statements in the presence of variability.

Statistical methods are like a microscope is to a scientist.

They help us focus our expertise on the solution of theproblem at hand.

Why Does Statistical Thinking Work?


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Creates Bottom Line Results ($)

Uses a Disciplined Approach

Managed by Data Approach Sound Statistical & Problem Solving

Approach

Creates Proficient Quality Professionals

Standardized Approach that works Across

Processes, Products and Organizations.

Statistical Thinking is


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Different and it Works Focused ApproachPhased Improvement Methodology

Define, Measure, Analyze, Improve and Control

Understanding and reducing variation are keys tosuccess.

Statistical Thinking is a way of thinking, athought process, rather than a method ofcalculating.


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Process Variation

Components of Variation


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ProcessProcessProcessProcess

MaterialMaterialMaterialMaterial

OperatorOperatorOperatorOperator

EnvironmentalEnvironmentalEnvironmentalEnvironmental

MeasurementMeasurementMeasurementMeasurement

In all aspects of theprocessunderstand and control

What Is Variation?


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Common CauseNatural, expected variation

Difficult to identifyCannot be eliminated

DOE can reduce Controllable Ex: Solder Paste Parameters,Temp, R/H, Lead Co-planar.

Special CauseUnnatural, not expected

Easily IdentifiedCan be eliminated Ex: Paste dried out onstencil, machine fail, settingchanged w/o OKNever change operatingparameters for special cause

variation (do not tweak!!!)

Types of DefectsSpecial & Common Causes


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SPECIALCAUSE!!

COMMON

CAUSES!!

SPECIALCAUSE!!

UCL

LCL

Identification of Special


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and Common CausesCorrective Action : SPC rule violations

"Special Cause - changes, anomalies, unusual events

"Common Cause - shift in mean, trend in mean,increased variability "

Implement contaminate plan, and monitor for repeat

occurrences.-Stop defects from escaping to next process-Keep process in operation while permanent corrective action isimplemented

For repeat occurrences tie specific cause to corrective actionusing problem solving methods.

Never change operating parameters

for Special Cause Variations

Process TweakingThe definition that best describes tweaking in the

f


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electronics manufacturing industry is: To touch something up, fiddle with the finishing touches

or make tiny little changes. In our industry, tweak is

usually used in sentences such as I just have to tweak alittle bit here and there and it will be perfect.

That usually leads to a statement such as "I just tweakedthis and THIS AND THIS AND THIS and this and OH NO

now this...

If we have done our formal process developmentand optimization, we are monitoring the process

using statistical process control (SPC), andunderstand the concepts of common cause andspecial cause variation, we should be adamantabout NEVER tweaking the process.

Process Tweaking What operating parameters should I allow my

dj ?


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operators to adjust?NONE!!!!

But my operators are very well trained andhave all worked with the process for manyyears. With their knowledge and experienceshouldnt they be given the authority to change

operating parameters to optimizeperformance?

NO

No process operator, no matter howknowledgeable or how experienced, shouldever be allowed to adjust ANY operating

parameter under ANY circumstances.

The Funnel Experiment

Th i ti f


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IndividualsIndividualsIndividualsIndividuals X CHARTX CHARTX CHARTX CHART

8

8.59

7.5

7

0

1

2

RANGE CHARTRANGE CHARTRANGE CHARTRANGE CHART

Showing the spread of individualsShowing the spread of individualsShowing the spread of individualsShowing the spread of individualson and Xbar and R chart.on and Xbar and R chart.on and Xbar and R chart.on and Xbar and R chart.

The variation of a processreacts to adjustmentsmade to improve the

process.

Dr. Deming discusses 4different methods thathave been commonly

used to adjust processes.

Rule 1

L th f l fi d


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XXXX

Rule 1Rule 1Rule 1Rule 1

Leave the funnel fixed,aimed at the target, noadjustment.

Results: this is by far thebest choice. Rule 1 will

produce a stabledistribution of points. Itproduces minimumvariance on any diameter

drawn through the target

Rule 2

Adj st for the error b


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XXXX


Adjust for the error bymoving the target theerror distance in the

opposite direction of itslast position.

Tweaking! Never do it.Produces a stableprocess, but higher

variance than rule 1.

Rule 3

Adjust for the error


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XXXX


Adjust for the errorby moving the targetthe error distance in

the oppositedirection of thetarget

Worse than tweakingexplodes.

Rule 4


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XXXX


Set the funnel at eachdrop right over where

it last hit.

Explodes

Relate to Traveling to Work:

Goal 7 00 AM Arrival


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Goal 7:00 AM Arrival

XXXX


Rule 1: Choose a reasonable routeand consistently follow the route

leaving your home at the same timeeach day.

Day Departure Arrival

1 6:30 a.m. 7:05 a.m.2 6:30 a.m. 6:58 a.m.3 6:30 a.m. 6:55 a.m.4 6:30 a.m. 7:00 a.m.

5 6:30 a.m. 7:02 a.m.

Rule 2

Compensate the amount of time you


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XXXX


Compensate the amount of time youarrived at work early or late byleaving your home that much earlieror later, and continue

adjusting youre departure each daybased on the previous daysdeparture.

Day Departure Arrival1 6:30 a.m. 7:05 a.m.2 6:25 a.m. 6:50 a.m.3 6:35 a.m. 7:15 a.m.4 6:20 a.m. 7:00 a.m.

5 6:20 a.m. 6:50 a.m.

Rule 3

Compensate the amount of time you arrivedt k l l t b l i h


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XXXX


Compensate the amount of time you arrivedat work early or late by leaving your homethat much earlier or later than the originaldeparture time, and continue adjusting your

original departure time each day based onhow early or late you were the previous day.

Day Departure Arrival

1 6:30 a.m. 7:05 a.m.2 6:25 a.m. 6:50 a.m.3 6:40 a.m. 7:15 a.m.4 6:15 a.m. 6:40 a.m.5 6:50 a.m. 7:25 a.m.

Rule 4

Compensate the amount of time you arrived at


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XXXX


Compensate the amount of time you arrived atwork early or late by leaving your homeat the previous days arrival time, and continueadjusting your departure time each day based on

the time you arrived the previous day.

Day Departure Arrival1 6:30 a.m. 7:05 a.m.

2 7:05 a.m. 7:30 a.m.3 7:30 a.m. 8:15 a.m.4 8:15 a.m. 8:45 a.m.5 8:45 a.m. 9:20 a.m.

What Process PerformanceMetric is Important


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The bottom line the only metric that measureshow well a process line is performing is how

many good products are built each day.How many of what we build today can we ship toour customers?

Good product is one built in an acceptable time thatpasses all required testing the first time without anyinspection, touch-up, or repair.

Cycle Time/Throughput Balance

There is a definite balance between product cycle


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There is a definite balance between product cycletime (how long it takes a product to get frombeginning to end of the manufacturing process) and

the quality of that product.Producing defective product just to achieve somerequired cycle time is certainly not acceptable; nor is

slowing the process unduly to minimize everypossible defect.

We must understand and optimize this balance.

I ti


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Inspection

andTest

Planning

Inspection & Test Planning

All inspection and test processes are NON


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All inspection and test processes are NONVALUE ADDED functions.

Inspection and test processes should be keptto a minimum.

Focus on capable, stable processes to

produce products that will minimizes therequirement for inspection and test.


Inspection and test planning is the activity of:


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Inspection and test planning is the activity of:

Designating the stations at which inspection ortest should be performed.

Establishing the effectiveness of each inspectionand test process.

Identifying which process contributes the mostdefects.


How can Inspection & Test Planning assist in


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How can Inspection & Test Planning assist inQuality Planning ?

Knowing the observed defect level, inspectionand test effectiveness, we can estimate thesubmitted defects and escaping defects.


For example:


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For example:

Observed Defects = 0.25 dpu

Insp. Or Test Effectiveness = 0.8Submitted Defects = 0.31 dpu (0.25/.8)

Escaping Defects = 0.06 dpu (0.31 - 0.25)

Inspection

or Test

Process

Submitted Escaping

Observed

How can Defect Level Constraints be

used in Process Design?C t t t d fl di m f th


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used in Process Design? Create a structured process flow diagram for theentire set of assembly operations for the product,

identifying:All inspection/test points.

Include the nonconforming product found at eachinspection/test point.

Establish maximum defect/unit level for the deliveredproduct.

Working from the start of the process to the end,estimate the defect/unit entering, escaping eachprocess step using actual factory data and theeffectiveness of the inspection or test process.

How can Defect Level Constraintsbe used in Process Design?

If th ti t d d li d f t/ it i


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If the estimated process delivery defect/unit isgreater than the maximum allowed:

Revise the process flow where necessary by: Redesigning the operations for increased process

capability to produce fewer defects.

Implement Statistical Process Control and Design ofExperiments (DOE) to reduce process variation.

Inspection or Test

Process Effectiveness


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Inspection

or TestProcess

SubmittedDefects

Escaping

Defects

Observed

Defects

Submitted Observed Escapes

1,487 152 1,335

0.1375 0.014 0.1235

10.22 % = (152/1,487) * 100

Defectsdpu

Effectiveness

Process Effectiveness



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Stencil Printing& Placement

Process

d0 Pre-ReflowInspection

Reflow Process Post-ReflowInspection

TestProcess

d1 d2 d3 d4 d5

dnSupplier0.030dpu

0.1075dpu

0.014dpu

0.0528dpu

0.029dpu

0.1159dpu

0.1375dpu

0.1235dpu

0.1763dpu

0.1473dpu

0.0314dpu

Observed Escapes

152 1,335

0.014 0.1235

10.22 %

Defectsdpu

Effectiveness

Observed Escapes

317 1,588

0.029 0.1473

16.64 %

Observed Escapes

1,251 340

0.1159 0.0314

78.62 %

Pre-IR Inspection Post-IR Inspection Test Process

Inspection & Test Planning:

Summary Eliminating defects is the most important key


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Summary Eliminating defects is the most important keyto achieving a World - Class Manufacturing

Operation. Defects per unit is the best measure of actual

total product quality because it allowsprediction, analysis, planning andbenchmarking by product / process

development teams


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Process

Characterization

Concepts

Process Characterization

Process Characterization is a technique to


111/263

Definition

Process Monitoring

Process Stability

Process Output

1

2

45

identify and minimize sources of variation inour processes and to obtain an understandingof the quantitative effects of the processinputs on the process outputs.

Statistical methods are employed throughoutthe process characterization program toisolate sources of variation to meet stability

and capability requirements.

1

Eight Steps to Process

Characterization


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ProcessDefinitionProcessMonitoring

Institutionalize andDocumentation

Process Capability

ProcessStability

Measurement EquipmentAssessment

Selection of

Process Outputs

1

2

3

4

5

6

8

7

Machine Acceptance

Characterization

Prevention vs. Reaction

Machine Acceptance Studies


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Statistically confirms machine operation

Reduces special cause variation due tomachine operation

Minimizes loss of production time

Minimizes machine down time

Defect ReductionMethodology Process

Characterization Approach


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Process

MaterialDesign

Defects

OutputParameters

1. Identified, Cpk=1.5

2. Identified, Cant Measure

3. Have Not Identified

InputParameters

DOEs;Optimization,

Control

Defects Are Caused ByMany Parameters

Evidence of ProcessCharacterization Methodology

Process Focus


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Attribute and Variable Data

Terminology of Cp/Cpks

Identifying Process Parameter to Study

Performing Capability Studies

Optimizing the Process

Implementing Process Controls

Identifying Additional Critical Parameters Reuse Of Other Facilities Findings

Use of DOEs & Statistical Methods Apparent

Correlating Parameters to Actual Process Improvement


Methodology Is a way of understanding controlling and coping with


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gy Is a way of understanding, controlling and coping with

variability - that is managing variability.

Management Commitment to Statistical Data Analysis andProblem Solving

Implement Statistical Process Control (SPC) to monitor keyprocess parameters

Daily Quality Meetings

Root Cause Corrective Actions

Measurement Systems Analysis

Design of Experiments

Continuous Process Improvements

SPC Audits


Methodology Results:


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gy Results:

Reducing Defect Rate (dpu), Cycle Time, Repair

costs, and increasing Productivity.

Increasing the time the process is in an ideal state.

Decreasing the process variability.

Increasing the time that the process characteristicsmean remains at its target value or remainsconstant at acceptable level.

Reducing the number of out of control conditions onSPC .

Intent and ExpectationQuality Goals

Material Defects


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Process

Material

Design

Defects

OutputParameters

1. Identified, Cpk=1.5

2. Identified, Cant Measure3. Have Not Identified

InputParameters

DOEs;

Optimization;Control

2

3

1

2

1. Institutionalize statistical methods based problem solving techniques

2. It is more important to identify (and control) additional parameters that have an impact on actualprocess performance than to pursue parameters that have a low impact on actual process performance .

3. Quality reviews should address the impact of process characterization efforts on reducing DPU. Thisis expected to be qualitative at first and should become quantitative as time progresses.

Evolution of Continuous Improvementin the Reduction of Variation

Before Using

Statistical Methods

SPC

Implementation

Utilizing Design

of Experiments


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LSL USL

The Process is not incontrol, not predictable.

USLLSL

Using SPC, the process is in

control, but its capability is poor.

USLLSL

Using DOE & problem

Solving techniques, theprocess capability has improved.

Link Process Characterizationto DPHU Efforts


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DPHU

Initial CharacterizationActivity

Additional Parameter(Identified, Optimized, Controlled)

Additional Parameter

Time

Continuous ImprovementActivity in a Process

Characterization Environment Involves:


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Involves:Reducing the number of out of control

conditions.

Increasing the time the process is in an ideal

state.Decreasing the process variability.

Increasing the time that the process

characteristics mean remains at its targetvalue or remains constant at some acceptablelevel.

Operations Macro Map Develop Required Process

Procedures

Define Statistical/Engineering objectives Identify Machine Response Parameter(s) Define Measurement Tech./Equipment Define Response Parameter(s) Tolerance Measurement R&R Studies Machine Capability , R&R studies, etc.

MachineAcceptance Studies

Define Response Parameter(s) Define Measurement Tech. / Equipment Define Response Parameter(s)

Process

Definition

Selection ofProcess Output(s)

Process

CharacterizationProcess


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Repeatability andReproducibility

Study

ImproveTechnique

orInvestigate

ImprovedMeasurementDevice

Fails

p ( )Tolerance

In Control

Identify Potential Causes Develop Process Micromap Develop Cause & Effect Diagram Test each cause/solution through

experimentation and statisticaldata analysis or pattern analysis.

Develop / Revise Problem & Solutionmatrix to Out of Control

Out of Control

Identify Common&Special Causes

Process Capability

Cp & Cpk > 1.5Process 1.5.

Process Stability

Data Collectionfor SPC

Establish "Best" operatingtarget and range for allcritical input parameters.

Implement Control Strategyfor all Critical (input)

Parameters and set totheir optimal levels.

Achieve Quality Levelsthrough Improvement /

Optimization Studies. Define Critical Process( input) Parameter(s)

Process Monitoring(Documentation)

Long Term Process Monitoring Process Capability Studies Document Process

Characterization studies.

Develop SPC Quality Plan

Process Output(s)

Set InputControls

ProcessImprovement /

Optimization Study

Passes

Passes

Fails

Requirement

MeetsCapability

Process

To support the Process Characterization initiative, the following matrix of important characteristics should

Printing Positrol Diagram


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o suppo t t e ocess C a acte at o t at e, t e o o g at o po ta t c a acte st cs s ou dbe available to process engineers for use in their respective processes as required to achieve defect reductions.

Impor tant Character ist ic Process ToleranceSuggested Measurement

Equipment

Suggested Process

Control

Solder Paste Viscosity By paste type Viscometer X bar, R control charts

Stencil Aperture WidthDependent upon Stencil

Mfgr.Micro view system X bar, R control charts

Facility Temperature & Humidity By paste type Temp./Humidity gage X bar, R control charts

Time solder paste sits on stencil10 to 15 min.'s (Paste

Dependent)

Equipment's paste knead or

double print next board

Equipment's process

software

Stencil Wash: IPA - % flux on Board From supplier Omega Meter Process Log

Stencil Wash: Saponifier - Tr itat ion From supplier Tr itat ion kit from supplier Process Log

Stencil Quality (Dents, cleanliness, wear &

tear)

Not Applicable Visual Inspection Process Log & Audits

Suppor t Tooling (Placement, Cleanliness,

Wear & Tear)Not Applicable Visual Inspection Process Log & Audits

INPUT CHARACTERISTICS

Supplier materials, methods, machine parameters and environment


OUTPUT CHARACTERISTICS

Produced by machine or operation


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Equipment

Suggested Process

Control

Solder Paste Height 8 mil +/- 2 mils

6 mil -1,+2 mils

Solder Paste Coverage +/- 10% Target Equipment 2D systemEquipments 2D error

detection system

Process Defects & Errors Not ApplicableFactory Reporting System,

Trend Charts

U-Control chart by process,

Pareto Charts,

Solder Paste Volume +/- 30 % of Target CyberSentry or SVS system X bar, R control charts

CyberSentry or SVS system X bar, R control charts


Equipment

Suggested Process

Control

Frequency of stencil wipingEvery 6 to 8 boards (Paste

Dependent)Not Applicable

Process audits or automatic

wiping

Solder Paste Handling from refr igerat ion Ambient for 24 hrs Not Applicable

Process Log, date / t ime

stamp paste container

OPERATOR DEPENDENT CHARACTERISTICS


Impor tant Character ist ic Process ToleranceSuggested Measurement Suggested Process

PREVENTATIVE MAINTENANCE CHARACTERISTICS


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Impor tant Character ist ic Process ToleranceEquipment Control

Height of Support nest plate to base Screen printer mfgr. Height Gage PM Logs & Audits

Stencil holder to base parallelism Screen printer mfgr. Height Gage PM Logs & Audits

Blade Angle Screen printer mfgr. Calib. to 90 degrees PM Logs & AuditsForce applied to right/left side of print

headScreen printer mfgr. Calibration on control cards PM Logs & Audits

Printer Cleanliness (Nest, Stencil, base,

height sensor, etc.)Not Applicable Visual Inspection PM Logs & Audits

Squeegee Blade ( Dents and angle ) Not Applicable Visual Inspection Process Log & Audits


Equipment

Suggested Process

Control

Operator Certification Program Not Applicable Not ApplicableWrit ten and/or observation

tests

OTHER CHARACTERISTICS

Stencil Design


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Ste c es g

Paste Flow in Apertures


127/263

OMNIX 5000 Poly Blade

Type III Powder 25 mil Width

1.5 in/sec Print Speed 1.5 lb/in Squeegee Pressure

Solder Paste Release Performance


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10 mil Diameter Aperture

0.1 in/sec Stencil Release Velocity

Design Rules For Stencils

There are two rules used in Stencil Design

Aspect Ratio Rule

The aspect ratio rule has been used for a great deal


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The aspect ratio rule has been used for a great dealof time in determining how well solder paste will

transfer from the aperture to the surface of the printedcircuit board

Area Ratio Rule

As smaller components have been used inelectronics products requiring smaller stencilapertures the area of the opening of the aperture and

the area of the walls of the aperture have becomecloser requiring the use of the area ratio rule in stencildesign

Aspect Ratio RuleFor Optimal Transfer Efficiency

Aspect Ratio Ensures that the aperture will allow the printed material to


130/263

release onto the substrate.

Aspect Ratio - W / t > 1.5 (chem-etch) For Example: 9 mil. aperture min. use 6 mil foil.

Width > 1.5 x t

Violation of Aspect Ratio Correct Aspect Ratio

Reduce aperture size by 20% to your pad size,maintain a minimum of 1.5 aspect ratio of aperturewidth to stencil thickness (25mil pitch and Below)

Stencils - Aperture DesignTypical Fine Pitch Apertures


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width to stencil thickness. (25mil pitch and Below).

Minimum Aperture Design Guidelines:

w

t

Aspect Ratio = W / t >1.5

Width >= 4-5 Particle Diameters

Design Rules For Stencils Aspect Ratio

For Fine Pitch QFPs, Aspect Ratio Was The Limiting

Factor for Printing:

A t R ti i A t idth (W )


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Aspect Ratio is .. Aperture width (WA)

Stencil Thickness (TS)A Typical 0.4mm (16mils) Pitch QFP Aspect Ratio is 9 = 1.8

5

However as the apertures have become smaller, thearea of the opening of the aperture and the area of theaperture walls have become very much the same.

Aspect Ratio alone is not the only stencil designcalculation that must be used to insure an optimumstencil design. The Area Ratio must also be used.

Area Ratio

Design Rules For Stencils Area Ratio

Area of the opening


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Area of the aperture walls

The holding force of the solder paste to the

printed circuit board pad must be greater thanthe holding force of the solder paste to the

stencil aperture for the solder paste to release

from the aperture and attach to the printed

circuit board pad

Area Ratio RuleFor Optimal Transfer Efficiency

Area Ratio Ensures that the forces pulling a material onto the pad

t th th f h ldi it i th t


134/263

are greater than the forces holding it in the aperture.

w

TW

L

Pad Pulling Tension (P) Aperture (Length (L) Width (W))

= 0.6Retaining Wall Tension (R) Stencil Thickness (T) Aperture Perimeter (2 (L+ W))

Area Ratio for Square andRectangular Apertures


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Area Ratio for Circular Apertures


136/263

Why is Wall/Pad Ratio Important?Area Ratio

Key process feature for successful fine pitchprinting is paste release from stencil


137/263

printing is paste release from stencil.

1

2

Violation ofArea RatioRule

Correct

Area Ratio

Comparing Aspect Ratio and Area Ratio

1 mm


138/263

0.25mm

0.15 mm Stencil

0.2 mm .(008)

Circle

Aperture Wall Area = 0.118 mm2

Pad Surface Area = 0.049 mm2

Aspect Ratio = 1.67

Surface Area Ratio = 0.42

Rectangle

Aperture Wall Area = 0.36 mm2

Pad Surface Area = 0.2 mm2

Aspect Ratio = 1.34

Surface Area Ratio = 0.56

The circle is more difficult to print because of the lowerSurface Area Ratio.

The aspect ratio is no longer a good indicator as here itsuggests that the circle would be easier to print - it isnt

Sample Area Ratio Chart


139/263

Relationship:

Transfer EfficiencyArea Ratio

Standard Deviation

100.00%

120.00%

200.00

250.00


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The higher the relative AR,

the higher the relative FT,the lower the absolute SD

0.00%

20.00%

40.00%

60.00%

80.00%

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Area Ratio (AR)

TransferEfficiency(F

0.00

50.00

100.00

150.00

200.00

StandardDeviatio

n(S

Reduction of Aperture Size

25 mil 20 mil


141/263

10 mil15 mil

Paste Release for a 15 mil (.015) Circle

Paste A SnPb Paste A Lead Free

15 mil (.38 mm) Dia. Circle (Area Ratio = 0.96)


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Paste B SnPb Paste B Lead Free

Paste Release for a 10 mil (.010) Circle

Paste A SnPb Paste A Lead Free

10 mil (.25 mm) Dia. Circle (Area Ratio = 0.64)


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Paste B SnPb Paste B Lead Free

Low Area Ratio Solder Paste Release


144/263

High Area Ratio Solder Paste Release


145/263

Print to Pad Ratio Gasketing The ratio between the aperture width and pad

should be at least 1:1.2

Often called Aperture Reduction


146/263

EXAMPLE: 20 MIL (.5mm) Pitch Component

SMT PAD

12 x 0.80 = 10 mil aperture

10 MIL

12 MIL

STENCILOPENING

SMT PAD

STENCIL

Aperture to Pad Alignment PCB Pads Over-etched

Making them smaller than the size in the Gerber data.

For boards that are over-etched, Good gasketing isensured by reducing the size of the aperture to the pad


147/263

ensured by reducing the size of the aperture to the pad

Printed Circuit Board Tolerance

Machine Alignment Tolerance Stencil to PCB

Even the most accurate printing equipment has an

alignment tolerance

Stencil Tolerance

Stencil Design

Land Pattern & Aperture Design for 2-sided components

Land Pattern

Y YA

Aperture DesignC = L(max) + 0.030

A = L(min) - 2 x T(max)


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C

B

Y Y

X

A

D

C

B

Y Y

X

A

F

Y L(max) and (min) arethe part lengthtolerances

W(max) is the partwidth tolerance

T(max) is the partthickness tolerance

The Home Plate design for chipswas created to assist in reducing theeffect of Solderballing when usingNo-Clean solder pastes, when toomuch paste is applied and too muchsolder is trapped beneath the part.

X = W(max) + 0.010

Y = (C-A) / 2D = 0.75 * Y

F = X - 0.002

B = pad pitch

Aperture Modifications (examples)

Shapes


149/263

XA

YA YP

XP

XA

YA YP

XA

YA YPSize

Exceptions

Poor Gasketing: Stencil Design

The speed at which squeeze out accumulates

is dependent on the width of aperture relativeto the pad Apertures reduced relative to the pad width will minimize


150/263

p p

squeeze out and prevent bridging.

Reduced

Not Reduced

Gasketing (Sealing)

The contact of the PWB and stencil form agasket or seal between the stencil aperture andthe printed circuit board component pad.

If the gasket is broken solder shorts will occur


151/263

If the gasket is broken, solder shorts will occur.

Stencil

Board

PadsGasketSolder Mask

Pitch Pad Width Aperture Stencil thick A.R.


Pad & Aperture Size Recommendations

English Units


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.025 .015 .012 .006 2.0

.020 .012 .009-.010 .005-.006 1.7

.016 .010 .007-.008 .005 1.4

.012 .008 .005-.006 .004-.005 1.2

.025 .015 .012 .006 2.0

.020 .012 .009-.010 .005-.006 1.7

.016 .010 .007-.008 .005 1.4

.012 .008 .005-.006 .004-.005 1.2

Pad & Aperture Size Recommendations

Metric Units


64 38 30 15 2 0


64 38 30 15 2 0


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.64 mm .38 mm .30 mm .15 mm 2.0

.51 mm .30 mm .23-.25 mm .127-.15 mm 1.7

.41 mm .25 mm .18-.20 mm .127 mm 1.4

.30 mm .20 mm .127-.15 mm .1-.127 mm 1.2

.64 mm .38 mm .30 mm .15 mm 2.0

.51 mm .30 mm .23-.25 mm .127-.15 mm 1.7

.41 mm .25 mm .18-.20 mm .127 mm 1.4

.30 mm .20 mm .127-.15 mm .1-.127 mm 1.2

Common Resistor Sizes, Land Patterns, and Stencil

Openings (from IPC-SM-782) specifications)

Stencils Passive Devices


154/263

Board / Mask Problems

Paste Bleed out


155/263

Solder Mask over Pads

Silkscreen, and labels can prop up the

stencil and prevents good gasketingwhich causes bleed out.

Board Legends Labels or legends can also cause gasket

problems


156/263

ComponentReference ID (ink)

Legend, Trace andSilkscreen is too high

Cookson Stencil Design Principles1. Keep aperture shape the same as pad shape, unless

otherwise required (by volume or process requirements) Maximized board to stencil alignment repeatability

2. Apply absolute aperture reduction relative to pad Maximized board to stencil alignment repeatability (2x -1 mil around)


157/263

Maximized board to stencil alignment repeatability (2x 1 mil around)

3. Center aperture on pad Maximized board to stencil alignment repeatability

4. When maximizing volume, use squares over circles Maximizes volume (4/ greater volume then circles) while

minimizing pitch issues

5. Area Ratio is main factor for paste release (see FIG 1) Highest Area Ratios ( 0.66) provide Lowest Standard Deviation on

Transfer Efficiency

Cookson Stencil Design Principles

6. Medium taper gives best transfer efficiency (smallest

standard deviation) Taper of 0.8 0.2 mil provide Highest Transfer Efficiency with the

Lowest Standard Deviation.

7. Aperture Design Modifications are independent from stencil


158/263

manufacturing technique Recommend thinner foil thickness (-5%) for ALPHA FORM stencilsdue to increased Transfer Efficiencies.

8. Component Technology 20 mil pitch and or StencilThickness 4 mil use ALPHA FORM Electroforming

Technology Highest volume deposits with lowest standard deviations measured

under these circumstances with POS

9. Use Custom Shapes for discrete components

A 66% home plate design to increase process window by improvingcomponent alignment & outgassing, reduce squeeze balls &tombstoning effects.

Cookson Stencil Design Principles10.Area Array type of packages require Square Apertures

Maximizes volume (4/ greater volume then circles) while minimizingpitch issues Different rules apply for fine feature BGAs

11.Solder Spreading Characteristics require different aperturedesign modifications


159/263

design modifications No aperture reductions for Lead Free Alloys and Water Soluble

Pastes: they dont spread to the edges of the pads and will leaveexposed pad finish

12.Stencil Thickness & Use of Steps will be determined by the

smallest aperture and the largest aperture Using the stencil thickness look-up tables based on pad sizes andAspect Ratio (1:1.5)

13.Large apertures require support bars to prevent scooping,squeegee damage and voids.

Apertures 150 mil in X and/or Y require support bar 20 mil in Xand/or Y.

Cookson Stencil Design Principles

14. Stepped areas required offset angle to prevent squeegee

damage Steps should be rotated using a -5angle

15. Frame less stencils should be considered Consistent tension provides improved positional accuracy and


160/263

Consistent tension provides improved positional accuracy and

reduced variation Stencil storage space reduction

16. Aperture Orientation is a factor in stencil design 45Is neutral, however, altering 0or 90apertures would be below

manufacturing tolerances and is therefore not significant

17. Squeegees and enclosed print heads is not a factor instencil design

No data (yet) to design specific design rules

18. Reversed Taper only for experimental use No data (yet) to design specific design rules

Common Stencil Types


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Electroplated Laser cut Chemical etched

Stencil aperture definition will impact paste deposition volume and defect rate

Stencil aperture (0.007 X 0.0875) at 10X

Conventional Stencil Technology

ManufacturingManufacturingManufacturingManufacturing

ProcessesProcessesProcessesProcesses

ConcernsConcernsConcernsConcerns MagnifiedMagnifiedMagnifiedMagnified

imageimageimageimage

Chemically etchedChemically etchedChemically etchedChemically etched Isotropic etching

produces

Tapered sidewalls


162/263

limiting pitch

Laser CutLaser CutLaser CutLaser Cut Sequential process

Laser-metal

Interaction hencerough aperture

sidewalls

ElectroformedElectroformedElectroformedElectroformed Aperture size and

shape varies

Stencil Release Performance


163/263

ElectroFormed Paste D

20 mil Aperture

Laser Cut Paste D

20 mil Aperture

Evaluating


164/263

Printed Circuit BoardDesigns


165/263

Classification ofElectronic Assemblies

ANSI/J-STD-001 classifies three levels ofelectronic assemblies based on end-item use.The 3 classifications were established to reflect


166/263

differences in producibility, complexity,functional performance requirements andverification frequency. They are as follows:

Class 1- General Electronic Products:Consumer products, computer and computer

peripherals, and hardware suitable forapplications where the major requirement is afunction of the completed assembly

(Source: Printed Circuits Handbook, pp 36.3, Coombs, ISBN: 0-07-012754-9)

Classification ofElectronic Assemblies

Class 2- Dedicated Service Electronic Products:Includes communication equipment, sophisticatedbusiness machines, and instruments where high


167/263

performance and extended life are required, and forwhich uninterrupted service is desired but notcritical

Class3- High Performance Electronic Products:Includes equipment for commercial and militaryproducts where continued performance or

performance on demand is critical

Standard Multi-Layer Interconnection

PTH

Blind Via

Line

BGAPGA

3. DH Dp + 4 mils, Max DH 2.5Dp

4. Max Pad D < 3 DH


168/263

PTH Land

Buried ViaBuried Line

SMT PadPassive Discrete

PTH Used as

Interconnect

1. 0.25-0.5 mm clearancepin to hole

General Requirements

PCB Should have good rigidity, minimalrouting.

PCB should have minimal warpage.


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Fiducials located on Breakaways ofpanelized boards may decrease accuracy.

If aperture is not reduced, bridging and needfor wiping will be increased.

Printed Circuit Board Size

Maximum printed circuit board size (length,width, and thickness) determined by theparticular process equipment being used.


170/263

Minimum printed circuit board size (length,width, and thickness) determined by theparticular process equipment being used.

Boards smaller than the minimum size maybe panelized (two or more individual circuits

per panel).

Printed Circuit Board Size

One factor that must be considered is the printedcircuit board fabrication vendors material usagefrom a single process sheet. Significant savings


171/263

can be obtained by increasing the number ofboards that can be fabricated from a singleprocess sheet.

It is important to understand the printed circuitboard suppliers guidelines and preferences andadhere to them in designing the board. This is

an excellent example of early supplierinvolvement.

Printed Circuit Board Shape

Rectangular shaped boards with no cut outsor breakaways are always preferred.

When breakaways are necessary, there are

i


172/263

two common options;The Route and Tab Method

The V Groove Method

Component Spacing

There is no limit on maximum interpackagespacing

Land to land spacing between adjacent

t h ld b 1 25 l


173/263

components should be 1.25 mm clear spaceall around the edges of the printed board ifboards are tested off the connector or 2.5 mmminimum if vacuum seal for testing is used.

Source: IPC-SM-782A, Section 3.6.1.1, pp 20

Component Spacing


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Source: IPC-SM-782A, page 21

Lead Protrusions

For single sided PCB Assembly, lead or wireprotrusion must be a minimum of 0.5 mm forall classes

F d bl id d d ltil PCB


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For double-sided and multilayer PCBAssembly, in all classes, the minimum leadprotrusion is that the lead end be visible in the

solder The maximum lead protrusion for Class 1 is

that there should be no danger of shorts

Lead Protrusions

For Class 2, the maximum lead protrusion is2.5 mm and for Class 3 the maximum leadprotrusion is 1.5 mm

For boards thicker than 2 3 mm the lead


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For boards thicker than 2.3 mm, the leadprotrusions may not be visible

Source: Printed Circuits Handbook, pp 36.27

Edge Clearance Example

No SMT components should be placed within0.150 (3.81 mm) from the edges of a board.

No traces or planes should be routed within

0 050 (1 27 mm) from the edge of a board


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0.050 (1.27 mm) from the edge of a board.

No via holes should be placed within 0.100

(2.54 mm) from the edge of a board. No test points (pads or via holes) should be

placed within 0.125 (3.18 mm) from the edge

of a board.

Component Hole Size

Suppliers will have recommended hole sizesfor specific components

If a hole size is not recommended; use a hole

that is 015 ( 38 mm) larger than maximum


178/263

that is .015 (.38 mm) larger than maximumlead diameter (round lead) or lead diagonal(square or rectangular lead).

If the component is being automaticallyinserted, use the hole size recommended by

the insertion equipment supplier.

Tooling Holes

Required for location and fixturing of theboards during the fabrication, assembly andtest processes.

Requirements must be specified on a board


179/263

Requirements must be specified on a boardoutline drawing.

Specific quantity, size, location, clearance,etc. will be determined by theManufacturing/Process Engineer and

specified in the printed circuit board designguidelines

Tooling HolesRequirement Example

Quantity 4

Size (diameter) 0.159 +0.002/ - 0.001

Location 4 corners


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Location 4 corners Plating Non plated

Clearance (diameter) 0.25 from edge of hole

Datum lower left corner hole

Fiducial Marks

Used by all automatic process equipment toprecisely locate each printed circuit board.

Two types of fiducial marks are used;

Board Level


181/263

Board LevelComponent Level

Board level are used on every board to adjust the

location of the stencil in the printer and to modifyprograms in the other process equipment.

Component level are used on boards with complex

components for very precise alignment. Exact shape and location determined by process

Board Level Fiducial Marks Example

Quantity: 3 (minimum) Location: Corners of the board

Size: .040 (1 mm) diameterpad


182/263

pad

Clearance: .120 (3 mm) diameter

(no soldermask, traces,via holes, andlegend/silk-screening)

Edge Distance: .250 (6.35 mm) minimum

Board Level Fiducial Marks

A test board displaying a variety of fiducial mark

geometries that can be used for stencil to boardalignment


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Courtesy or Speedline Technologies

Component Level Fiducial Marks Example

Component Local Fiducial RequiredBGA No

.025 (.65 mm) pitch or greater No


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.025 (.65 mm) pitch or greater No

.020 (.5 mm) pitch less than 120 pins No

.020 (.5 mm) pitch more than 120 pins Yes

Less than .020 (.5 mm) pitch Yes

Component Selection

Always use existing components if possibleReduce component variety

Reduce component cost

Reduce material storage and handling


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Reduce material storage and handling

Reduce feeder requirements

Minimize required feeder carriage space

Purchase larger component reels

Component Selection

Maximize use of SMT components (ABCCosting)

Minimize use of manually inserted components

Consider through hole connectors if the Pin in


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Consider through hole connectors if the Pin inPaste Process is used

Use quality and cycle time data to influencecomponent selection on new products

Understand the impact on the process of new

components prior to approving for design

Activity Based Costing Calculates the total cost of the assembly operation

Equipment

People

Overhead (lights, heat, etc.)

Calculates number of components to be inserted


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Calculates number of components to be inserted

Divides the total cost by the total components todetermine the cost to assemble a component

Automatically inserted components will have a muchlower cost than manually inserted components

Cost of assembly + material = product cost

Some operations consider the cost of test

Slow Secondary Operations

Avoid components that require slowsecondary operations that are longer than thecycle time of the SMT manufacturing process

and/or cannot be done in the in line process.


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and/or cannot be done in the in line process.Undefill

Incapsulant

Hand soldering

Wire bonding

Flip Chip, Chip on Board (COB), some ChipScale Packages (CSP), TAB

Passive Use Growth

A billion hours ago the stone age was thefuture

A billion minutes ago Caesar ruled Rome

A billion passives ago was this morning!


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A billion passives ago was this morning!

Every year enough are produced to give each

man, woman and child on the planet 160passives

Size of 01005 Component

01005 Package Size = 10 mil (.010) X 5 mil (.005)

Or

0.25 mm X 0.125 mm


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Their width (5 mils) is only slightlylarger than the thickness of a humanhair and their length about thethickness of a sheet of resume paper!

0603

0402

Imperial/Metric Component Sizes


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0201 01005

Chip Component Size& Spacing Comparisons


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Houston et al; Implementation of 01005s: a Case Study; SMTAI-08

Chip Size and Spacing Options


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Chen, et al.; ASSEMBLY PROCESS RESEARCH ON 01005 CHIP COMPONENTS IN LEAD-FREE SYSTEM; SMTAI-06

Flip Chip


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Chip on Board (COB)


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FC = SMT Process

Print Underfillor Dip Apply

Underfill

Print SolderPaste for SMT

Assembly BGA


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SimultaneousSolder Interconnect Reflow and

Underfill Cure

Chip

BGA

Bare Chip Placement piercing

underfill to form partial fillets

Chip

The Printed Circuit Design Guidelines must specifythe requirements for the placement of allcomponents used (refer to PCB Design Guidelinesfor exact values).

Board side

Component Placement


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Soldering process to be used

Spacing between components for reflow soldering

Spacing between components for wave soldering

Spacing between components and test points

Direction of travel through wave solder process

Size and location of solder thief pads for wave soldering

Component Footprints and Pads

A library of component foot prints and pads isusually specified in the Printed Circuit Board DesignGuidelines and maintained in the CAD System usedto design the boards.

There is an IPC Printed Circuit Board Design


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gSpecification (IPC781) that details componentfootprints and pad sizes.

Reduce aperture size by 20% to your pad size,maintain a minimum of 1.5 aspect ratio of aperturewidth to stencil thickness. (.025/.64 mm pitch andbelow).

Wave Soldering

Printed Circuit Board Design


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Portions

Board Design Considerationsfor Wave Soldering


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Preferred


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Not Preferred


Documents

smta-gdl_smta-gdl_DFM_presentation_2012-07