Flexible circuits Single-sided

Roll forming is a process used to manufacture flexible circuits in very large quantities. This is the lowest-cost method for the manufacture of flexible circuits. However, it involves substantial tooling, so it is apphcable only for very high volume products. Examples of PCBs manufactured using this method are printer head connections, disk drive head connections, and the circuits used in cameras and camcorders. The PCBs can be single- or double-sided. 

The same process is repeated for double-sided copper-clad laminates. (Some laminate manufacturers, however, have developed simplified manufacturing processes that can make the double-sided laminate in one single process to reduce manufacturing cost.) A well-conditioned aging process is important to achieving reliable bond strength and flexible characteristics of the laminates as the raw material of flexible circuits. 

FIGURE 62.3 Basic structure of single-sided flexible circuit... 

FIGURE 62.5 Cross section of a single-sided flexible circuit showing (a) adhesives-based laminate and film overlay (b) adhesiveless laminate with liquid coverlay. 

Basically, the same construction systems of coverlay, stiffeners, and surface treatments as single-side flexible circuits could be available for double-side flexible circuits. 

Figure 66.1 indicates two basic structures of dual-access conductors, in both the single sided and double-sided types of flexible circuits. Figure 66.2 shows actual examples of the fine flying leads built on the single side circuits and double side circuits. Basically, a coverlayer is applied to the side of the conductive layer opposite the substrate.The coverlayer can be processed easily to create the top-side exposure. The flying lead is created when the base substrate is also removed in the same area. 

TAB S manufacturing capabilities are very different from traditional flexible circuits and they cover different apphcation area as shown in Fig. 66.10.TAB has been focusing single side fine traces with flying lead constructions. It has advantages for the volume productions of the small size circuitries because of special reel-to-reel manufacturing. 

JPCA-FC 01 Single-sided flexible printed circuits JPCA-FC 02 Double-sided flexible printed circuits JPCA-FC 03 Visual defect criteria for flexible printed circuits... 

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