This time let’s talk about more details about the structure of FPC(flexible circuits). Normally, according to the layer of conductive copper, FPC is divided into single-sided, double-sided, multilayer, dual access, etc.
The structure of single-sided FPC is the most simple. Based material FCCL: PI + adhesive + copper and adhesive + coverlay top layer. Firstly, the copper needs to be etched to get the traces, while the coverlay needs to be drilled to expose corresponding soldering pad. Make the plating for the exposed soldering pads to protect from oxidization. At last, FPC is punched into corresponding outline by required.
The structure of mulilayer FPC: The most typical difference between multilayer and single layer FPC is that the multilayer FPC is added with plated through holes to connect the copper on every layer. The first workmanship of Based material FCCL: PI + adhesive + copper is to make plated through holes(PTH). Later the technique is almost the same with single layer FPC.
The structure of dual access FPC: dual access FPC has soldering pads on its two sides, mainly used to connect with other circuit boards. Although it has similar structure with single layer FPC, its technique has great difference.