1. IT 318: M13
PWB Assembly
IT M13

2. PWB Assembly Industry $1 Trillion (2013)
(Printed Circuit Design & Fab/Circuits Assembly, Dec 2013, p. 26)
(Compared to $280 Billion IC manufacturing industry)
PWBs PWB Assemblies
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3. Soldering Through-hole SMT (Surface-Mount Technology)
Place components, then wave solder
Screen-print solder paste, then place components, then reflow
SMT (Surface-Mount Technology)
For 2-sided:
Glue bottom side components, then wave solder
Top side = screen print solder paste, place components, reflow
And variations of the above
Most common solder material today: SAC 305
3% Ag, .5% Cu, 96.5% Sn
IT M13

4. IT M13

5. IT M13

6. IT M13

7. Intermetallics
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8. Hand Soldering
Essentials for good solder joints: 1. Clean (no oils, oxides, dirt); rosin 2. Mechanically stable Steps for good solder joints: 1. Clean tip of soldering iron 2. Make sure component is mechanically stable 3. Apply tip to joint; use a bit of solder for heat transfer 4. Apply solder to other side of joint 5. Continue adding solder until fillets full 6. Remove solder, then remove iron 7. Let cool naturally – do not blow 8. About 5 seconds/joint
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9. PWB Assembly Challenges
Fine-pitch parts
Screen-printing solder paste
Lead-free solder
Faster pick-&-place
Lower cost
ESD (Electro-Static Discharge) protection
Higher quality
IT M13