Discussion on FPC flexible circuit board copper foil

The copper foil material for the FPC flexible circuit board is mainly divided into two types: a rolled copper and an electrolytic copper. The conductive layer is bonded to the insulating material of the cover film, and is etched into a desired pattern by processing or the like. Electrolytic copper foil is deposited on a bright stainless steel roll by an acid copper plating solution to form a uniform copper film, which is obtained by continuous stripping and winding; the rolled copper foil is made of copper ingot or copper block of a certain thickness. Repeated calendering and annealing to form the desired thickness of the copper foil.

   The copper atom structure of the calendered material is irregularly layered and strong crystal, which is recrystallized by heat treatment, so it is not easy to form cracks, and the copper foil material has good bending property; while the electrolytic copper foil material exhibits columnar crystal structure in the thickness direction, when bent In the same manner, when the cross section of the high-expansion electrolytic copper foil material subjected to special processing such as heat treatment is observed, the columnar crystal is mainly formed, but the layered crystal is formed in the copper layer, and it is not easily broken when bent.

   The bendability of the tested rolled copper foil is four times that of ordinary electrolytic copper foil, but its price is also relatively expensive. Therefore, for products with low bending requirements (such as key plates, module boards, 3D static flexible circuits, etc.), high-grade electrolytic copper foil can be used instead of rolled copper foil materials. Of course, the reliability requirements are relatively high. In the case (such as slider phone board, folding phone board, etc.), it is better to use rolled copper foil material.

   Most FPC flexible circuit board products require high bending performance, which leads to the preference of most manufacturers for calendering materials. In fact, there are many blind selection factors. The above mentioned calendering materials have their characteristics, and he also has many The shortcomings are inside and should be applied appropriately.