Analysis of the Causes of "Dip Plating" on Wet Film Plate
Analysis of the Causes of "Dip Plating" on Wet Film Plate (Quality Problems of Non-Pure Tin Potion)
1. The copper surface brushed out before screen printing must be clean to ensure good adhesion between the copper surface and the wet oil film.
2. When the exposure energy of the wet film is low, it will lead to incomplete photo-curing of the wet film and poor resistance to electroplating pure tin.
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3. The wet film pre-baking parameters are unreasonable, and the local temperature difference of the oven is large.
Because the thermal curing process of the photosensitive material is relatively sensitive to temperature, it will cause incomplete thermal curing when the temperature is low, thereby reducing the anti-plating pure tin ability of the wet film.
4. No post-cure / curing treatment reduces the resistance to electroplated pure tin.
5. The boards washed by electroplated pure tin must be thoroughly cleaned. At the same time, each board must be inserted into a rack or a dry board. Stacking of boards is not allowed.
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6. Wet film quality problems.
7. Production and storage environment, time impact.Poor storage environment or long storage time will cause the wet film to swell, reducing its ability to resist pure tin plating.
8. The wet film is dissolved in the tin tank by the attack of pure tin photoagent and other organic pollution. When the anode area of the tin plating tank is insufficient, the current efficiency will inevitably be reduced. Hydrogen evolution).If the current density is too high and the sulfuric acid content is too high, the cathode hydrogen evolution will attack the wet film and lead to the occurr
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9. High concentration of stripping solution (sodium hydroxide solution), high temperature or long immersion time will produce flowing tin or dissolving tin (that is, the so-called "plating").
10. The current density of pure tin plating is too large. Generally, the best current density of wet film quality is suitable for 1.0 ~ 2.0A / dm2. Beyond this current density range, some wet film quality is prone to "plating".ence of tin infiltration (the so-called "plating").