Outer layer of protective material, that is, solder mask layer, there are generally three types to choose
- The first type is the traditional cover film (Coverlay), is a choice of polyimide materials and adhesives directly after etching and need to be The protection of the circuit board laminated in order to laminate, this cover film preformed before module push or Laser cutting, exposing the need to weld parts, it can not meet the more sophisticated assembly requirements,
- The second type is photosensitive development of dry film cover to film machine
- The third type is a liquid screen printing type covering material, commonly used is a thermosetting polyimide material, such as the sun PSR-4000 as well as the heat-curing type polyimide material, Sensitive development of flexible circuit board solder resist ink, such materials can better meet the fine pitch, high-density assembly of flexible board requirements.
Production process and the key part of the control
Rigid and rigid board development in the flexible board and high-density multilayer rigid pcb on the basis of the process in terms of manufacturing and rigid plate has many of the same places, but due to rigid flex pcb combination of plate materials and its structure and Application of the particularity of the decision from the design ,
the requirements to the production process are different from the ordinary rigid PCB and flexible board, almost every production process must be tested, adjusted, and ultimately optimize the entire process and parameters.
Rigid-flex PCB general process flow chart