Unlike standard printed circuit boards, flexible PCB circuit boards use flexible polymers instead of typical FR4 materials. The commonly deployed flexible polymers require a polyimide film substrate or a polyester substrate, which is a strong material that does not soften under heating and remains flexible when thermoset. A large number of thermosetting resins such as PI remain rigid after heating, making them ideal for flexible circuit boards.

　　Another key flex PCB material that is often used with PI includes adhesive material, which helps in the attachment of layers. However, modern trends and the need to limit the unreliability caused by adhesives have led to the development of adhesive-free PI, which allows for thinner designs but without the risk of breakage. PI has also developed cover films to protect the flexible circuits. In addition, it is also important to consider mixing rigid and flexible materials when dealing with rigid-flex PCBs. Rigid components can use glass fiber as the substrate, while flexible components use adhesive-free PI. However, it is prudent to note that in this case, signals cannot be transmitted between these flexible and rigid components. In addition, multi-layer rigid-flex PCBs will contain pre-impregnated glass fiber in the middle layer (substrate). Aside from the substrate, aspects such as the copper layer material, solder mask, and screen printing in the flex circuit remain the same. Therefore, it becomes crucial to check such flexible PCB materials before delving into the design of flexible or flex-rigid circuit boards.

　　Benefits of Polyimide: Enhanced temperature adaptability; High mechanical properties; Excellent compressive and tensile strength; Excellent chemical resistance; Radiation resistance; Transparency in a large number of microwave applications; Excellent wear resistance and bearing performance.

　　KKPCB provides global customers with one-stop services from PCB layout, prototype PCB proofing, PCB manufacturing, PCBA processing (including SMT and DIP), PCBA testing, PCBA product assembly and outbound packaging. You could provide a Gerber file or BOM list to us, we will offer the finished PCB products or PCB assembly which are satisfied with you.