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Common problems and defects analysis of pcb chemical nickel gold

o-lead o-leading.com 2018-07-09 20:01:40
Common problems and defects analysis of pcb chemical nickel gold

First, plating

Analysis of the cause of the problem:

1. The nickel cylinder is too active;

2. Pretreatment activated palladium has a high concentration or is contaminated (metal iron, copper ion contamination or high local temperature will accelerate the aging of the syrup), long time for soaking the plate, too high temperature or insufficient water washing after the activation cylinder (ie before the nickel is deposited);

3. The pre-processed grinding plate is too deep and even the substrate is easy to adsorb palladium. The roller on the equipment is not thoroughly cleaned before the grinding plate, and the water pressure is insufficient to rinse the residual copper powder on the edge of the wire (not completely etched away), etching After the residual copper and nickel are deposited, it is easy to produce electroplating; 
4. The copper PTH pretreatment colloid has a high concentration of activated palladium.

Corresponding improvement measures:

1. Strictly control the nickel cylinder load at 0.3~0.8dm2/L and appropriate stabilizer. When the anode protection current is 0.8A, the cylinder needs to be inverted;

2. Strictly control the concentration of the activation bath, the dipping time, the working temperature, the washing time, the board is fully washed after activation and the tank liquid contamination is avoided as much as possible;

3. Strengthen the nickel before QC board inspection After etching, ensure no residual copper, cleaning equipment cleaning, micro-etching depth, grinding depth and water pressure must be sufficient (normal soft board brushing selection 1000~1500', hard board brushing 800~ 1000', now often uses a jet brush to maintain the same color quality as the appearance quality);

4. The concentration of palladium on the pre-treated colloid of copper PTH should be appropriately controlled to be lower.

Second, leakage plating

Analysis of the cause of the problem:

1. Nickel pretreatment The concentration of activated palladium is too low, the immersion activation time, the temperature is insufficient, the plate before activation or the nickel is retained in the water tank for too long (passivation);

2. There is residual glue on the copper surface or the copper surface is not clean (the tin is not clean, the external pollution or the pollution of the pre-process);

3. Shen nickel tank Chinese medicine water stabilizer excessive, low temperature, insufficient activity (the nickel layer is dark, the gold surface is dark red after sinking gold), the load is insufficient, metal or organic pollution or stirring is too intense and easy to produce "leakage" plating". The copper surface is seriously oxidized or poorly washed after development, and the nickel bath PH and copper surface are contaminated by sulfide or improperly added.(Printed Circuit Board PCB Manufacturing Company)

Corresponding improvement measures:

1. Control the palladium concentration of the activation bath, dipping time, working temperature, reduce copper ion pollution (replacement when activated copper ions are greater than 100PPM), and ensure that the board time before sinking nickel stays in the sink for too long;

2. When pre-treatment of nickel, ensure that the copper surface of the board has no residual glue and the copper surface is clean;

3. Control the operating parameters of the nickel tank, ensure the activity before nickel, increase the auxiliary copper plate in the tank to increase the load, avoid metal or organic pollution and control the mixing should not be too intense.
Third, the nickel layer is “whitened” (the thickness of the nickel layer and the nickel layer is insufficient)

Analysis of the cause of the problem:

The nickel bath metal nickel ion is too low or too high, the temperature is low, the pH is low, the activity is not enough, the time is not enough, the load is large, the phosphorus content is high (the line or the edge of the hole is white) or the nickel bath is 34MTO.

Corresponding improvement measures:

Metal nickel ions are adjusted to the range, control temperature, pH value, increase activity, reduce load, reduce consumption of phosphorus content to the allowable range value or nickel to reach 34MTO.