PCB circuit board electroplating process description

At present, there are two ways for us to electroplate PCB Circuit Board: full plate arc plating and graphic plating. Graphic electroplating is a process in which a Printed Circuit Board undergoes graphic transfer to protect the copper part of the conductor that does not require copper plating with a dry film. The wires and connecting plates that require copper plating are then selectively electroplated with copper, followed by electroplating with Sn (or Sn/Pb) corrosion inhibitors. After electroplating, the Pcba Circuit Board can be coated, etched, and the anti-corrosion agent removed to obtain the outer circuit.

The overall process of electroplating technology

1. Pickling → Copper plating on the entire board → Pattern transfer → Acid degreasing → Secondary countercurrent rinsing → Micro etching → Secondary → Pickling → Tin plating → Secondary countercurrent rinsing

2. Countercurrent rinsing → pickling → graphic copper plating → secondary countercurrent rinsing → nickel plating → secondary water washing → citric acid immersion → gold plating → recycling → 2-3 levels of pure water washing → drying

Important steps in graphic electroplating

Inspection: The circuit board factory (Shenzhen circuit board) mainly checks whether there is excess dry film, whether the lines are complete, and whether there are dry film residues in the holes during inspection.

Oil removal: During the image transfer process, after film application, exposure, development, inspection, and other operations, there may be fingerprints, dust, oil stains, and residual film on the board. If not handled properly, it can cause weak bonding between the copper coating and the substrate copper. During the operation, we suggest that the operator wear gloves with their full name. Similarly, printed circuit boards are made of dry film and bare copper. To remove oil, it is necessary to remove oil stains from the copper surface without damaging the organic dry film. Therefore, acidic oil removal is chosen. The main components of the degreasing solution are sulfuric acid and phosphoric acid. Our circuit board manufacturers are particularly careful and cautious during wake-up operations, as they involve chemical substances.

Micro etching: Remove the copper oxide layer in the circuit and hole, increase surface roughness, and thus improve the bonding between the coating and the substrate copper. There are two commonly used types of micro etching solutions: persulfate type and sulfuric acid hydrogen peroxide type, with sodium persulfate and ammonium persulfate as the main types. Ammonium persulfate micro etching solution is prone to decomposition, and the decomposed ammonia gas affects the environment and is not conducive to environmental protection. At the same time, the micro etching rate is also unstable. Sodium persulfate micro etching solution is stable, easy to control, and has a longer service life. The sulfuric acid hydrogen peroxide system is unstable, prone to decomposition and volatilization, and has a large fluctuation in micro etching rate. However, its wastewater is easy to treat, which is beneficial for environmental protection.

Acid leaching: Circuit board factories (Shenzhen circuit boards) generally conduct copper plating or tin plating in acidic environments. In order to prevent water from entering, acid leaching treatment is required before electroplating.