Flexible circuit manufacturing Plating

The plastic film with interconnection layers, denoted (2) in Fig. 16.1, can be made by a process similar to that used to manufacture flexible circuit boards. First, plastic films coated with copper foil are processed by a numerically controlled (NC) drilling machine to make via holes. Plating is then used to make interconnections between top and bottom sides though via holes. Finally, the copper layers are patterned by conventional photolithography and etching. Gold plating is occasionally employed to improve electronic interconnections. 

FIGURE 43.2 Standard manufacturing process for microvia holes in double-sided flexible circuits starting with copper clad laminate (CCL). The hole is created by drilling and then copper plated. 

Manufacture of Printed Wiring Boards. Printed wiring boards, or printed circuit boards, are usually thin flat panels than contain one or multiple layers of thin copper patterns that interconnect the various electronic components (e.g. integrated circuit chips, connectors, resistors) that are attached to the boards. These panels are present in almost every consumer electronic product and automobile sold today. The various photopolymer products used to manufacture the printed wiring boards include film resists, electroless plating resists (23), liquid resists, electrodeposited resists (24), solder masks (25), laser exposed photoresists (26), flexible photoimageable permanent coatings (27) and polyimide interlayer insulator films (28). Another new use of photopolymer chemistry is the selective formation of conductive patterns in polymers (29). 

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