PCB surface treatment oxidation resistance manufacturing process
Add time:2020/11/6 9:54:05 From: Hits:2633

Degreasing → micro erosion overflow water washing 1 → overflow water washing 2 → acid pickling → pressurized water washing 1 → pressurized water washing → clean water washing → pressurized water 3 → DI water washing → air knife flushing → anti oxidation washing → air knife flushing → overflow water washing 3 → overflow water washing 4 → Di washing → strong wind drying → hot air drying

Oil removal and micro corrosion: remove the residue, grease and copper oxide layer, and activate the copper surface.

Pickling: further remove the copper powder on the plate surface and prevent the re oxidation of the activated copper surface.

Anti oxidation immersion: in order to form an anti-oxidation film on the plate surface and in the hole, the immersion type is better than the spray type, and the anti-oxidation film with thickness of 0.15-0.25um can be obtained by soaking at 40 ℃ for 60-90s. If the concentration, pH, temperature, washing time and other parameters are within the normal range, but the film thickness is not enough, supplement solution A should be added to adjust, and F2 solution can be used without dilution. The transfer shaft shall be made of lightweight material.

Anti oxidation process control

1. The pH value is the most important factor to maintain the film thickness, so it should be measured every day. With the increase of pH value, the film thickness becomes thicker, and with the decrease of pH value, the film thickness becomes biased. If the pH value is too high, crystallization will occur. Due to the volatilization of acetic acid and the introduction of water, the pH value tends to rise, so it is necessary to add acetic acid for adjustment, and the pH value should be controlled between 3.80-4.20.

2. In order to keep the film thickness in the optimal range, the concentration of active components should be maintained between 90-110%. If it is too high, crystallization will occur.

3. The film thickness should be kept between 0.15-0.25um as much as possible. If the film thickness is less than 0.12um, the copper surface will not be oxidized during storage and thermal cycling. However, if the film thickness is more than 0.3um, it is not easy to be washed away by flux and affect the tin loading performance.

4. Under normal conditions of various parameters, if the film thickness is too thin, make-up liquid a can be added appropriately. When adding supplement liquid a, it should be added slowly, otherwise star like oil spots will appear on the liquid surface, which is the precursor of solution crystallization. Other reasons may also cause crystallization, such as high pH and high concentration. Therefore, it is necessary to observe regularly and take measures to avoid it.

5. When the roller is not working for a long time, the suction roller behind the antioxidant cylinder is easy to crystallize. Therefore, a small amount of water should be used to spray the suction roller to remove the residue of F2 liquid medicine after shutdown. In addition, extra row rollers should be prepared for replacement. Otherwise, the existing roller will be easily printed on the board due to the long service time of the roller.

6. Since acetic acid is used in F2 liquid medicine, it is necessary to equip with air exhausting device. However, excessive ventilation will cause excessive evaporation and high concentration of liquid medicine. Therefore, when the system stops working, the exhaust air should be turned to the minimum and the sealing between the gaps should be ensured.

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