Brief Introduction of Multilayer Printed Circuit Board Immersion Gold Process Control 1
I. Process Introduction: The purpose of the immersion process is to deposit a nickel-gold coating with stable color, good brightness, flat plating and good solderability on the printed circuit board surface. It can be basically divided into four stages: pre-treatment (de-oiling, micro-etching, activation, post-dipping), nickel sinking, immersion gold, post-treatment (waste gold washing, DI washing, drying).
Second, pre-treatment: Shenjin pre-treatment generally has the following steps: degreasing ( 30% AD-482 ), micro-etching ( 60g/InaPS, 2% H2SO4 ) , activation ( 10%Act-354-2 ), after Dip ( 1% H2S04 ). In order to remove the copper oxide, palladium is deposited on the copper surface to serve as a nickel-activated center. If one of the links is not handled well, it will affect the subsequent nickel and immersion gold, and lead to batch scrapping. During the production process, all kinds of syrup must be analyzed and supplemented regularly, and the control is within the requirements. More important, for example, the micro-etching rate should be controlled at “25U—40U†, and the activated syrup copper content must be more than 800PPM . A new cylinder must be opened. The cleaning and maintenance of the medicated water tank has a great influence on the quality of the joint PCB . In addition to the oil cylinder, micro-etching cylinder, The rear dip tank should be changed every week, and each washing tank should be cleaned weekly. Welcome to the company's official website http://
3. Nickel: The main components of the nickel syrup are Ni2+ (5.1-5.8g/1) and the reducing agent sodium hypophosphite ( 25-30g/1 ) and stabilizers. During the production process, it is necessary to analyze and test twice per shift, and add Ni2 reducing agent according to the bare copper area or experience of the production board. When supplementing the feeding, the principle of dispersing multiple feedings should be followed to prevent the local plating solution from reacting drastically. , causing accelerated aging of the plating solution, PH value, bath temperature has a greater influence on nickel thickness, and nickel syrup temperature control is controlled at 85 °C -90 °C . PH in 5.3-5.7, nickel cylinder When not in production, the temperature of the nickel cylinder should be reduced to about 70 °C to slow the aging of the plating solution. The chemical nickel plating solution is sensitive to impurities. Many chemical components are harmful to chemical nickel and can be classified into the following categories: inhibitors: including Pb .Sn..Hg.Ti.Bi ( low melting point heavy metal ) .
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