The electroplating process of the PCB board can be roughly classified into acid bright copper electroplating, nickel/gold electroplating, and electroplating.
Process flow:
1. Pickling → full-board copper plating → pattern transfer → acid degreasing → secondary countercurrent rinsing → micro-etching → secondary countercurrent rinsing → pickling → tin plating → secondary countercurrent rinsing → countercurrent rinsing → pickling → pattern copper plating → secondary 1st stage countercurrent rinsing → nickel plating → 2nd stage water washing → dipping in citric acid → gold plating → recycling → 2-3 stage pure water washing → drying
Process description:
2.1 Pickling
Function and purpose: To remove oxide from the board surface and activate it. The general concentration is 5%, with some at about 10%, mainly to prevent water from entering the tank and causing instability in sulfuric acid content. The acid leaching time should not be too long to prevent surface oxidation, and the acid solution should be replaced when turbid or copper content is too high to prevent contamination. C.P grade sulfuric acid should be used.
2.2 Full PCB Board Copper Electroplating
Function and purpose: To protect the thin chemical copper and prevent it from being etched by acid after oxidation. The main components are copper sulfate and sulfuric acid. High acid and low copper formula is used for uniformity and deep plating ability. Parameters include sulfuric acid content of 180-240 g/L, copper sulfate content of about 75 g/L, and trace amounts of chloride ions for gloss effect. Copper light agent is added at 3-5ml/L, and current calculation is 2A/square decimeter. Temperature is controlled at room temperature, not exceeding 32 degrees.
Process maintenance includes replenishing copper light agent daily, checking filter pump, wiping cathode conductive rod, and analyzing copper sulfate, sulfuric acid, and chloride ions weekly. Anode conductive rod should be cleaned weekly, and anode copper balls should be replenished. Anode titanium basket should be checked for damage and anode sludge accumulation.
Major treatment procedures involve cleaning anode, soaking in lye and acid, transferring tank liquid, adding hydrogen peroxide, dissolving activated carbon powder, filtering, and electrolysis. Regular maintenance and analysis are crucial.
2.3 Acid Degreasing
Purpose: To remove oxides and residual glue from the copper surface and ensure bonding force. Acid degreaser is used due to graphic ink sensitivity to alkali. Concentration should be about 10% for 6 minutes.
2.4 Micro-Etching
Purpose: To clean and roughen copper surface for bonding. Sodium persulfate is commonly used at 60 g/L for about 20 seconds. Copper content should be below 20 g/L.
2.5 Pickling
Function and purpose: To remove oxides and activate the board surface.
2.6 Pattern Copper Plating
Purpose: To thicken hole and line copper for current load requirements.
2.7 Electroplating Tin
Purpose: To protect circuit etching. Parameters include stannous sulfate and sulfuric acid content, temperature control, and maintenance procedures.
2.8 Nickel Plating
Purpose: To prevent diffusion of gold and copper, increase strength, and improve solderability. Process parameters, maintenance, and treatment procedures are outlined.
2.9 Gold Plating
Purpose: To provide excellent characteristics like weldability and corrosion resistance. Citric acid gold bath is commonly used, with specific parameters and maintenance practices detailed. Platinum-plated titanium mesh is recommended as the anode material. Continuous filtration and maintenance are essential for quality plating.
Process flow:
1. Pickling → full-board copper plating → pattern transfer → acid degreasing → secondary countercurrent rinsing → micro-etching → secondary countercurrent rinsing → pickling → tin plating → secondary countercurrent rinsing → countercurrent rinsing → pickling → pattern copper plating → secondary 1st stage countercurrent rinsing → nickel plating → 2nd stage water washing → dipping in citric acid → gold plating → recycling → 2-3 stage pure water washing → drying
Process description:
2.1 Pickling
Function and purpose: To remove oxide from the board surface and activate it. The general concentration is 5%, with some at about 10%, mainly to prevent water from entering the tank and causing instability in sulfuric acid content. The acid leaching time should not be too long to prevent surface oxidation, and the acid solution should be replaced when turbid or copper content is too high to prevent contamination. C.P grade sulfuric acid should be used.
2.2 Full PCB Board Copper Electroplating
Function and purpose: To protect the thin chemical copper and prevent it from being etched by acid after oxidation. The main components are copper sulfate and sulfuric acid. High acid and low copper formula is used for uniformity and deep plating ability. Parameters include sulfuric acid content of 180-240 g/L, copper sulfate content of about 75 g/L, and trace amounts of chloride ions for gloss effect. Copper light agent is added at 3-5ml/L, and current calculation is 2A/square decimeter. Temperature is controlled at room temperature, not exceeding 32 degrees.
Process maintenance includes replenishing copper light agent daily, checking filter pump, wiping cathode conductive rod, and analyzing copper sulfate, sulfuric acid, and chloride ions weekly. Anode conductive rod should be cleaned weekly, and anode copper balls should be replenished. Anode titanium basket should be checked for damage and anode sludge accumulation.
Major treatment procedures involve cleaning anode, soaking in lye and acid, transferring tank liquid, adding hydrogen peroxide, dissolving activated carbon powder, filtering, and electrolysis. Regular maintenance and analysis are crucial.
2.3 Acid Degreasing
Purpose: To remove oxides and residual glue from the copper surface and ensure bonding force. Acid degreaser is used due to graphic ink sensitivity to alkali. Concentration should be about 10% for 6 minutes.
2.4 Micro-Etching
Purpose: To clean and roughen copper surface for bonding. Sodium persulfate is commonly used at 60 g/L for about 20 seconds. Copper content should be below 20 g/L.
2.5 Pickling
Function and purpose: To remove oxides and activate the board surface.
2.6 Pattern Copper Plating
Purpose: To thicken hole and line copper for current load requirements.
2.7 Electroplating Tin
Purpose: To protect circuit etching. Parameters include stannous sulfate and sulfuric acid content, temperature control, and maintenance procedures.
2.8 Nickel Plating
Purpose: To prevent diffusion of gold and copper, increase strength, and improve solderability. Process parameters, maintenance, and treatment procedures are outlined.
2.9 Gold Plating
Purpose: To provide excellent characteristics like weldability and corrosion resistance. Citric acid gold bath is commonly used, with specific parameters and maintenance practices detailed. Platinum-plated titanium mesh is recommended as the anode material. Continuous filtration and maintenance are essential for quality plating.