The 12th international symposium

on east Asian resources recycling technology

Development of an Apparatus

to Disassemble Electronic Components

from Printed Circuit Board

Seungsoo Park

Ph.D. Student

Mineral and Environment Processing Lab.

Hanyang University, South Korea

Contents

Background

Lab-scale apparatus

• Experiment

• Result

Bench-scale apparatus

• Experiment

• Result

Conclusion

Terminology

Background

PCB(Printed Circuit Board) Assembly

PCB

Printed Circuit Board

ECs

Electronic Components

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Metal composition of PCBA*

Background

PCB; Printed Circuit Board

ECs; Electronic Components

PCB tracks

• Copper (99.99%)

Etch-resistant

• Nickel, tin, tin-lead, gold, silver

Semi conductor

• Ga, Se, Si, Ge, etc.

IC chip

• Ta, Ga, In, Ti, Si, Ge, As, Sb, Se, Te, etc.

Solder joint

• Pb, Cd

* Jianzhi Li, et al., 『Printed Circuit Board Recycling: A State-of-the-Art Survey』

Over 20

kinds of

metals

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Limitation of pyrometallurgy for PCBA recycling

Limited kinds of metal are recovered

• Cu, Ag, Au, Se, Te, Pd, Pt

Toxic materials are disposed without treatment

• Br, Pb, Cd, etc.

Background

PCBAPyrometallurgy process

• Only 7 kinds of metal are recovered

• Harmful to environment.

Loss of valuable metals

Such as Ta, Ga, In, etc.

Economic

lossEnviron-

mental

Problem

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PCBA recycling process with ECs disassembly

Metal composition of PCB and ECs are quite different

• PCB: base metals (copper, nickel, etc.) and precious metals (such as gold, silver).

• ECs: include base metals, rare metals (Tantalum, Indium, Selenium, etc.)

All these metals needs slightly different metallurgy process

Toxic metals need to be removed before disposed

Background

PCBA

PCB

ECs

Separation/

hydrometallurgy

Valuable metals Toxic metals

Cu Ag Au Pb

Ta Ga AsIn

Te Se

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Evacuate and sort

Without heating(mechanical)

Crushing

SolderAbrasion

With heating

Infrared heater

Liquid Medium

Gas medium

Principles of ECs disassembly

Experiment

Fig. 1. Various PCBA disassembly principles

Low cost

Simple system

Easy to scale up

High efficiency

Less residual product

Easy to automate

Fast heat transmission

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Flowchart of the experiment

Experiment

Fig. 2. Flowchart of the experiment

Development

Experiment/

Evaluation

Development

Experiment

Evaluation

Improving based on the lab-scale experiment results

: Applying heat via IR heater based on Evacuate and sort system

: Experiment and evaluate Disassembly ratio

: Scaled-up apparatus with improved components

: Experiment and evaluate Disassembly ratio

Lab

-sca

leB

ench

-sca

le

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PCBA

Feeding rod

Steel brush

IR heater

PCBA in

Lab-scale - Experiment

PCBA Disassembly apparatus (Lab-scale)

Variables

• Feeding speed (rotation speed of feeding rod)

• Heating temperature

Fig. 3. Schematic diagram of the apparatus (Lab-scale)

Heat PCBA(via IR heater)

Sweep off ECs(via steel brush)

Feed PCBA(via feeding rod)

Discharge PCBA(via feeding rod)

Fig. 4. Sequence of PCBA disassembly process

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Feed sample

Waste PCBA(printed circuit board assembly)

• Laptop printed circuit board assemblies made by various manufacturers

• Manually separated from the laptop

• Populated with many different electronic components

Lab-scale - Experiment

Fig. 5. Printed Circuit Board Assembly used in this study

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Effect of temperature and feeding speed

Disassembly ratio (%)= 𝑊1−𝑊2

𝑊1−𝑊3× 100

where, 𝑊1: mass of PCBA before passing the apparatus

𝑊2: mass of PCBA after passing the apparatus

𝑊3: mass of bared PCB (no ECs)

Max. disassembly ratio: 82.6%

• Temperature: 350℃

• Feeding speed: 1RPM

Disassembly rate increases;

• Feeding speed gets slower

• Heating temperature gets higher

Lab-scale - Result

9RPM

6RPM

3RPM

1RPM

0%

20%

40%

60%

80%

100%

300℃325℃

350℃

Dis

asse

mbly

Rat

io (

%)

Fig. 6. Disassembly ratio on various condition

Maximum

disassembly ratio

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Lab-scale - Result

The result of disassembly treatment

ECs on both sides of PCBs were disassembled well.

Most ECs (blue box) were removed,

whereas some ECs (red box) connected by TMT(through-hole mount technology) were

still remained.

Fig. 7. Photo of PCBA before/after the disassembly treatment (front side)

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Lab-scale - Result

The result of disassembly treatment

ECs on both sides of PCBs were disassembled well.

Most ECs (blue box) were removed,

whereas some ECs (red box) connected by TMT(through-hole mount technology) were

still remained.

Fig. 8. Photo of PCBA before/after the disassembly treatment (back side)

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Points to improve

Low disassembly ratio

• Maximum disassembly ratio: 82.6 %

• Place 3 disassembly modules in a row

Difficulty in disassemble of ECs connected via TMT

• Add saw-tooth on feeding rod for crushing effect on TMT

Occasional burning of PCB

• Set the heating temperature under 300℃

• Prevent the thermal losses

Lab-scale - Result

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PCBA

Feeding/

Crushing rod

Steel brush

IR heater

PCBA in

Bench-scale - Experiment

PCBA Disassembly apparatus (Bench-scale)

Fig. 9. Schematic diagram of the apparatus (Bench-scale)

Patent pending: KR10-2012-0065933

Heat PCBA(via IR heater)

Crush large ECs(via feeding/crushing rod)

Sweep off small ECs(via steel brush)

Feed PCBA(via feeding/crushing rod)

Discharge PCBA(via feeding/crushing rod)

Rep

eat 3

times

Fig. 10. Sequence of PCBA disassembly process

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Effect of temperature and feeding speed

Max. disassembly ratio: 94%

• Temperature: 250℃

• Feeding speed: 1RPM

(Capacity: 15 kg/hr)

Effect of feeding speed

• Exponentially increases

as feeding speed gets slower

Effect of heating temperature

• Stabilized around temperature range of

225℃ - 250℃

cf.> Melting point of Sn-Ag-Cu solder: 217℃

Bench-scale - Result

9RPM

6RPM

3RPM

1RPM

0%

20%

40%

60%

80%

100%

200℃225℃

250℃275℃

Dis

asse

mbly

Rat

io (

%)

Maximum

disassembly ratio

Fig.11. Disassembly ratio on various condition16/20

Bench-scale - Result

The result of disassembly treatment

ECs on both sides of PCBs were disassembled

ECs with TMT connection(Red box) are removed

as well as other kinds of ECs (Blue box)

Fig. 12. Photo of PCBA before/after the disassembly treatment (front side)

17/20

Bench-scale - Result

The result of disassembly treatment

ECs on both sides of PCBs were disassembled

ECs with TMT connection(Red box) are removed

as well as other kinds of ECs (Blue box)

Fig. 13. Photo of PCBA before/after the disassembly treatment (back side)

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Conclusion

Development of PCBA disassembly apparatus

PCBA disassembly apparatus were developed

• Consists of IR heater, Crushing/feeding rod, Steel brush

• Simultaneous disassembly on both front/back side were possible

• Small amount of residual product were generated

Maximum disassembly ratio: 94%

• Temperature: 250℃

• Feeding speed: 1RPM

• Capacity: 15 kg/hr

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Thank you!

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Appendix

Disassembly apparatus

M M

21

4

3

578

10 11

12

9

PCBA in

6

13

15

1617

18

14

PCBA in

(a) (b)

Fig. 2. Electronic components disassembly apparatus used in this study (patent pending, the application number : KR10-2012-0065933): (a)

Structure of disassembly apparatus, 1. Control Panel (controllable factors: rotating speed of feeding rod, rotating speed of steel brush,

heating temperature), 2. PCBA, 3. Feed hopper, 4. Feeding rod, 5. Steel brush, 6. IR heater, 7, 8. Trapezoidal change gear, 9. Product

hopper, 10. Basket, 11, 12. Motors. (b) detailed diagram of disassembly module. 13. PCBA, 14. Feed hopper, 15. Feeding rod, 16. Steel

brush, 17. IR heater, 18. Product hopper.

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Appendix

Disassembly apparatus

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Appendix

Feeding rod vs. Feeding/crushing rod

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Appendix

Heat transmission methods

Method Advantages Disadvantages

Infrared rays - selective and simultaneous use

- easy to automate

- no contact, no medium

- fast heat transmission possible

- not dependent on shape or position of printed circuit board

- no production facilities

- high thermal strain for devices(black ICs)

- high strain of printed circuit device

- rather high loss of energy

- slow

Laser - purposive energy transmission

- very short time needed.

- little strain for devices

- high precision

- doses good to measure

- very expensive

- not usable tor simultaneous dismantling

- very high energy consumption

- problems with rays(“J”-connections and “leadless” SMD. E.g.

PLCC)

Hot fluid - simultaneous and selective warming possible

- very fast warming because of great surface

- usable for SMD boards

- short time for desoldering

- position of printed circuit board is important(drop no components

in fluid)

- not usable for double sided THT-assembly

- components must not be fixed

Table. Connections on printed circuit boards comparison of some heat transmission methods for desoldering of electronic components

Laptop PCBA and their ECs

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Appendix

Connection Electronic components and their frequencies1

Type Figure CPU/GPU IC chip OscillatorCopper

coilCapacitor Card slot Ports

Cooling

Fan

Sub

PCB

SMT ++ +++ ++ ++ +++ ++ - - -

TMT - - - - + - ++ - -

Screw

joint- - - - - + - + -

Rivet - - - - - - + - -

Socket

pedestal- - - - - + - - +

1+++: Very frequently appeared, more than several tens per board and/or always expected to be appeared

++: Usually appeared, more or less than ten per board and/or always expected to be appeared

+: Rarely appeared, less than five per board and/or usually not appeared

-: Seldom appeared

Table. Various types of ECs on laptop PCBA and their frequencies based on connection types

“Look and picks” vs. “Evacuate and sort”

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Appendix

PCBA

PCB

“Look and picks”

IC Chip

Capacitors

MLCC

CPUPCB ECs

“Evacuate and sort”

MLCCCapacitorCPUIC chip

PCBA

Residual product generation

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Appendix

PCBA PCB ECs Powder loss

Weight (g) 193.65 87.73 99.5 4.29 2.13

wt.% 100 45.30 51.38 2.22 1.10

Table. Weight and weight fraction of disassembly process products

Residual product generation

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Appendix

Fig. Electronic components disassembly time (feeding road

rotating speed: 1RPM). Red line indicates the total removal

time and blue line indicates the average removal time to

process number of boards.