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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
3/20
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
4/20
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
5/20
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
6/20
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
7/20
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
8/20
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
9/20
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
10/20
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
11/20
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)
12/20
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)
13/20
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
14/20
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
15/20
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)
18/20
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
19/20
Thank you!
21/30
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.
22/30
Appendix
Disassembly apparatus
23/30
Appendix
Feeding rod vs. Feeding/crushing rod
24/30
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
25/30
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”
26/30
Appendix
PCBA
PCB
“Look and picks”
IC Chip
Capacitors
MLCC
CPUPCB ECs
“Evacuate and sort”
MLCCCapacitorCPUIC chip
PCBA
Residual product generation
27/30
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
28/30
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.