At present, there are two ways to electroplate PCB: whole plate arc and pattern electroplating. Pattern electroplating is the process of pattern transfer of printed circuit board. The copper part of conductor which does not need copper plating is protected by dry film, and the conductor and connection plate which need copper plating are exposed. The selective copper plating is carried out on this part, and then Sn (or Sn / Pb) resist is plated. After plating, the printed circuit board can get the outer circuit after removing the film, etching and removing the resist.
Overall process of electroplating process
1. Pickling → copper plating on the whole plate → pattern transfer → acid degreasing → two-stage countercurrent rinsing → micro etching → two-stage → pickling → tin plating → two-stage countercurrent rinsing
2. Countercurrent rinsing → pickling → copper pattern electroplating → two stage countercurrent rinsing → nickel plating → two stage water washing → citric acid leaching → gold plating → recovery → 2-3 stage pure water washing → drying
Important steps of pattern electroplating
Inspection: circuit board factory (Shenzhen circuit board) mainly checks whether there is redundant dry film, whether the line is complete, and whether there is residual dry film in the hole.
In the process of image transfer, there may be dust, sticking film, etc. on the copper substrate, if the exposure is not good. In the process of operation, we suggest that the operator wear gloves to operate. Similarly, dry film and bare copper coexist in the printed circuit board. Oil removal should not only remove the oil on the copper surface, but also not damage the organic dry film. "Therefore, acid oil removal is selected. The main components of deoiling fluid are sulfuric acid and phosphoric acid. Our circuit board manufacturers are very careful when they wake up, because it involves chemical substances.
Micro etching: remove the copper oxide layer in the circuit and hole, increase the surface roughness, so as to improve the combination of coating and substrate copper. Nine commonly used micro etching solutions are persulfate type and sulfuric acid hydrogen peroxide type, in which the persulfate type is mainly sodium persulfate and ammonium persulfate. Ammonium persulfate micro etching solution is easy to decompose, and the decomposed ammonia affects the environment, which is not conducive to environmental protection, and the micro etching rate is unstable. Sodium persulfate micro etching solution is stable, easy to control and has long service life. Sulfuric acid hydrogen peroxide system is unstable, easy to decompose and volatilize, and the micro etching rate fluctuates greatly, but its wastewater is easy to treat, which is conducive to environmental protection.
Acid leaching: circuit board factory (Shenzhen circuit board) whether electroplating copper or tin, is generally carried out in the acidic environment, in order to prevent water into, before electroplating need to go through acid leaching treatment.
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