Multilayer Printed Circuit Board Immersion Gold Process Control Brief - PCB, PCB-screen special printing industry

I. Introduction Process The purpose of Immersion Gold Process is deposited on the surface of the printed circuit color stability, good brightness, coating formation, good solderability of nickel gold plating. Basic can be divided into four phases: pre-treatment (degreasing, micro-etching, activation, after the dip), Nickel, Immersion Gold, post-treatment (scrap washed, DI water washing and drying).

Immersion Gold PCB ( HC screen Special Indian network With map) 2, pretreatment Immersion Gold pre-treatment are generally the following steps: degreasing (30% AD-482), micro-etching (60g/InaPS, 2% H2SO4), activation (10% Act-354-2), after the dip ( 1% H2S04). To remove surface oxides of copper and copper surface in the Journal of palladium for nickel activation center. One of these links are not properly handled, will affect the subsequent Nickel and Immersion Gold, and lead to volume of scrap. The production process, and all kinds of medicine to be regular analysis of additional control at the required range. More important such as: micro-erosion rate should be controlled in "25U? 40U", the activation solution of copper content more than 800PPM must open a new cylinder, tank cleaning and maintenance drug couplet influence the quality of PCB is larger, fuel tanks, micro-etching cylinder, for a week after the dip tank should tank, the wash tank should be cleaned every week.

Three nickel Nickel solution of the main components of Ni ² + (5.1-5.8g / 1) and reducing agent sodium hypophosphite (25-30g / 1) and the stabilizer, due to the chemical composition range of nickel on the strict requirement of medicine, in class analysis of the production process must test twice, and according to the production of bare copper board area or the experience of additional Ni ² reducing agent, charging up when

Should follow the small, scattered many times the principle of feeding to prevent severe local reaction bath, resulting in accelerated aging bath, PH value, the bath temperature had great influence on the thickness of nickel, nickel syrup temperature is controlled at 85 Plagiarism -90 . PH at 5.3-5.7, nickel cylinder does not produce, should be reduced to nickel-cylinder temperature is 70 , in order to slow down the aging plating, chemical nickel-plating solution is sensitive to impurities, many harmful chemical composition of the nickel, can be divided into the following categories: inhibitors: including Pb.Sn.. Hg.Ti.Bi (low melting point metal),

Organic impurities, including S ², nitric acid and anionic wetting agent. All of these substances will reduce activity, resulting in reduced plating speed and leakage-plated, punish, it will lead to a complete cessation of Electroless Nickel Plating.

Organic impurities: include: in addition to the above mentioned organic stabilizer, there are Plastic Agents and devices and solder from impurities. Despite the clear coated by a continuous part of impurities, but not completely removed.

Unstable agents: including Pd and a small amount of copper, these two ingredients create instability in the chemistry of nickel, the coating roughness, and over-plating in the tank wall and heater. Solid impurities: include calcium sulfate or calcium phosphate and other insoluble substances sink or into the solution. Filter can remove solids.

In short: in the production process to take effective measures to reduce such impurities mixed in the bath.

4, Immersion Gold Immersion Gold process is a leaching process, the main component of Shen gold cylinder; Au (1.5-3.5g / l), binding agent for the (Ec0.06-0.16mol / L), nickel-phosphorus alloy layer in replacement of the gold plating on the strange, making a smooth coating, fine crystal, bath PH value is usually between 4-5, control temperature 85 -90 .

Five post-treatment Immersion Gold is also an important part of post-processing of printed circuit boards, the general include: scrap washed, DI water washing, drying and other steps, able to do so can be integrated with standard washer further on Immersion Gold board washer, dryer. Horizontal plate washer can be washed drugs (10% sulfuric acid, hydrogen peroxide 30g / L), high-pressure DI water washing (30 ~ 50PSI), DI water washing, drying, drying in order to set process to completely remove the PCB holes and the surface of syrup and water stains, and be uniform coating, good brightness Immersion Gold board.

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