1. Gold sinking for FPC FPC
Advantages: not easy to oxidize, can be stored for a long time, the surface is smooth, suitable for welding fine gap pins and components with small solder joints, can be repeated many times over reflow welding will not reduce its weldability.
Disadvantages: high cost, poor welding strength, because the use of electroless nickel process, easy to have the problem of black disk. The nickel layer oxidizes over time, and long-term reliability is a problem.
2. Silver sinking for FPC FPC
Advantages: simple process, suitable for lead-free welding, SMT. Very smooth surface, low cost, suitable for very fine line.
Disadvantages: high requirements for storage conditions, easy to pollution. Welding strength is prone to problems (microvoids). It is easy to have electromigration and givani bite on the copper under the resistance welding film. Electrical testing is also a problem.
3. FPC FPC is plated with nickel gold
Advantages: longer storage time >12 months. Suitable for contact switch design and gold wire binding. Suitable for electrical testing
Disadvantages: high cost, gold is thicker. Electroplated fingers require additional design lines to conduct electricity. Because the thickness of gold is not always, the application in welding, the gold may be too thick to lead to embrittlement, affecting the strength. Surface uniformity of electroplating. The plated nickel gold did not cover the edge of the line.
4. Tin plating on FPC flexible circuit board
Advantages: suitable for horizontal production. Suitable for fine line processing, lead-free welding, especially for pressing technology. Very good flatness for SMT.
Disadvantages: good storage conditions are required, preferably no more than 6 months, to control the growth of tin whiskers. Not suitable for contact switch design. In the production process, the welding resistance film process requirements are relatively high, otherwise it will lead to the welding resistance film off. N2 gas protection is best for multiple welds. Electrical testing is also a problem.
5. Organic solderability protector for FPC flexible circuit board (OSP)
Advantages: simple process, very smooth surface, suitable for lead-free welding and SMT. Easy rework, easy production operation, suitable for horizontal line operation. Low cost and environmentally friendly.
Disadvantages: reflow limit, not suitable for pressing technology, wire binding. Visual and electrical testing is not convenient. N2 gas protection is required for SMT. SMT rework is not suitable. Storage requirements are high.