FPC product design of a multilayer structure

FPC sandwich plate as well as hard board is to use multilayer combination in the form of linking piece but sometimes use a vacuum tank type Autoclave press, can avoid the air bubbles and glue problem. After make the hole and the hole cleaning process, FPC sandwich plate hole cleaning more commonly used chemical, plasma, in addition to the glue residue. After a through hole wall conduction processing, can be copper plating process.

General copper ratherish higher shrinkage coefficient for 18 PPM / ℃, and the plastic material below glass can convert the thermal expansion coefficient of majority of more than 50 PPM / ℃, the difference between thermal cycle of internal pressure is produced. Is much larger than the copper elongation and plastic elongation, thus greatly to the copper material pulling force, this kind of problem especially in evident effects through hole plating copper, soft and hard.

So for the design of the sandwich plate layer, will limit in certain thickness range, especially to the conventional material layer limit is more obvious. Some specially designed for high level circuit board material, specially add filler material (filler), these materials can improve the degree of increases and circuit board, but relative to the material softness. So to flexural fatigue strength of higher product, is not suitable for using this kind of material with a large number of additives. Fortunately, most need better deflection sex products, does not need high level design, so still can maintain a certain flexibility and flexural strength.

For also need hard board and FPC laminated structure of product design, can use the so-called soft hard board (it Rigid Flex) technology, it mixes soft hard board and terminal connections, with soft board will directly associated with different hard.