Flexible Multi-layer Circuit Board Hole Metallization Technology

The hole metallization which including Drill, Desmear, Nonelectrical plating,Electrical plating etc., is a key process in the manufacturing of the flexible printedcircuit (FPC). Because it is a process that is made up of many steps, if it was notwell done, the qualified rate of product will be very low. The single side and doublesides FPC are the main products in the market several years ago, the holemetallization process of the manufacturing of the single side and double sides FPCwas relatively easy to be done. The application of FPC can make electronic productssmaller, lighter, thinner, more exquisite and pocketable. In recent years, suchproductions become more and more popular, so the demand for FPC is expandingvery fast, the layers of FPC are increasing continuously, the diameter of the holebecome smaller and smaller. The hole metallization process become difficult to dealwith, it has became the bottleneck of the FPC manufacturaing.The development and prospect of FPC, the principle of the hole metallizationprocess, Influence of various process factor on product quality was introduced inthis paper. The desmear process and the nonelectrical copper plating process, whichwere the key processes, were studied and introduced in detail.Because the material of flexible printed circuit (FPC) is different from the rigidprinted circuit board(RPCB), RPCB is mainly based on materials , such as epoxyresin , glass cloth, PTFE (Polytetrafluoroethylene), etc. the smear that caused by thismaterials can be get rid of using Potassium permanganate.while FPC is mainlybased on materials, such as PI (Polyimide), polyacrylates, this material willexpansion and make the layers breakaway, So the smear caused by this materialcan't be get rid of using Potassium permanganate. There are two effective method,they are PI adjust and plasma wash method, can be used to getting rid of this smearthrough reading references and summarizing actual experience at present.Useing Uniform Design we research the plasma etch process, receive betterprocess parameter and regression curve related with each factors, prove that theresult is correct in manufacturing. Regarding the etching speed as criteria, weanalyse the influence for etching speed on PI in each factor.Using Orthogonal test we research the PI adjust process, get best matching of...