Industry news

PCB FAQs

2021-12-30

PCB FAQs

Analysis of process improvement in PCB productionPCB hole wall cannot sink copper
Causes: 1. Poor degreasing effect 2. Insufficient degreasing residue 3. Excessive degreasing residue
PCB degreasing (temperature 60-65 ℃)
1, there is a lot of bubbles: abnormal quality caused by foam: it will result in poor oil removal effect.
2. Composition of particulate matter: causes of composition of particulate matter: the filter is broken or the high-pressure water washing of the plate grinder is insufficient, and dust is brought from the outside.
3. The finger print cannot be removed: the finger print cannot be removed. Reasons: the oil removal temperature is low and the liquid medicine is wrong.
After PCB thermal shock, the hole copper is separated from the hole wall
Causes: 1. Poor rubber slag removal. 2. Poor water absorption performance of the substrate
PCB micro etching (NPs 80-120G / L H2SO4 5% temperature 25-35 ℃)
1. The copper surface of the board is slightly white: the reason is insufficient grinding, oil removal or pollution, and the concentration of liquid medicine is low.
2. The copper surface of the board is black: it is not clean after degreasing and is polluted by degreasing. If the copper surface is pink, it is the normal effect of micro etching.
PCB activation (the color of bath solution is black, the temperature shall not exceed 38 ℃, and air pumping is not allowed)
1. Sedimentation and clarification of tank liquid: causes of sedimentation:
(1) The concentration of palladium in the replenished water changes immediately and the content is at the bottom (the normal replenishment level applies the pre leaching solution)
(2) SN2 + concentration is low, Cl - content is low and temperature is too high.
(3) Too much air leads to palladium oxidation.
(4) Contaminated by Fe +.
2. A silver white film appears on the surface of the liquid medicine:
There is a silver white film on the surface of the liquid medicine. The reason is the oxide produced by the oxidation of PD.
Temperature of PCB chemical copper solution
High temperature will lead to rapid decomposition of chemical copper solution, change the composition of solution and affect the quality of electroless copper plating. High temperature will also produce a large amount of copper powder, resulting in copper particles on the plate surface and in the hole. It is generally controlled at about 25-35 ℃.
PCB speed (processing time 1-2 minutes, temperature 60-65 ℃)
1. No copper in the hole: Reason: the accelerated treatment time is too long, and PD is also removed while SN is removed.
2. PD is easy to fall off at high temperature
There are strip water marks on the PCB surface
Reasons: 1. The hanger design is not reasonable. 2. The copper sink is over stirred. 3. The water washing is insufficient after acceleration
PCB chemical copper cylinder solution contaminated
Causes of liquid medicine pollution: 1. Insufficient water washing before PTH 2. PD water brought into the copper cylinder 3. A plate fell off the cylinder 4. No cylinder explosion for a long time 5. Insufficient filtration
Cylinder washing: soak in 10% H2SO4 for 4 hours, neutralize with 10% NaOH, and finally clean with water.