Rigid-Flex Board Cable Connectors I/O Connectors

What is rigid flex circuit?

1. Substrate: FCCL (flexible copper clad laminate)
Polyamide: Kapton (12.5um/20um/25um/50um/75um), the belt has good flexibility, high temperature resistance (long-term use temperature of 260 ℃, short-term resistance to 400 ℃), high moisture absorption, good electrical and mechanical properties , Good tear resistance. Good weather resistance and chemical resistance, good flame retardancy. Polyesteramine (PI) is the most widely used. 80% of them are produced by DuPont.
Polyester (25um/50um/75um), low price, has good flexibility and tear resistance. Good mechanical and electrical properties such as tensile strength, good water resistance and moisture absorption. However, the shrinkage rate after heating is large, and the high temperature resistance is poor. Not suitable for high temperature welding, melting point is 250°C, and it is relatively rarely used now.
Application of Rigid-Flex Board and Rigid-Flex PCB Production Process
2. Coverlay
The main function of the cover layer is to protect the circuit, prevent the circuit from moisture, pollution and anti-soldering.
The thickness of the cover layer ranges from 1/2 mil to 5 mils (12.7 to 127um). The conductive layer (conductive layer) is divided into rolling copper (rolling and annealing copper), electrolytic copper (electrodeposited copper) and silver sputtering/spraying (silver ink). The structure of the electrolytic copper crystal is rough, which is not conducive to the yield of fine wires. The crystal structure of rolled copper is smooth, but the bonding force with the base film is poor. You can distinguish dots and rolled copper foil from the outside.
Electrolytic copper foil is copper red, and rolled copper foil is off-white. Auxiliary materials and reinforcement plates (additional materials and reinforcements). A hard material partially pressed on a soft board to weld parts or increase installation strength.
Reinforced film can be used for FR4, resin, pressure sensitive adhesive, steel and aluminum reinforcement, etc. Semi-cured sheet (low fluidity PP), does not contain fluid/non-fluid glue. Used for lamination of flexible and rigid adhesive plates (rigid and flexible connection), the production process is similar to high frequency mixing pressure plate, usually very thin PP.
Usually use 2mil, 1080 (3.0mil/3.5mil), 2116 (5.6mil)
3. The structure of rigid and flexible PCB
Rigid and flexible PCBs are again glued to one or more rigid layers on the flexible board. The rigid layer of the circuit and the flexible layer on the circuit are connected to each other through metallization. A new Rigid-Flex Board is formed, each rigid and flexible adhesive board has one or more rigid areas and flexible areas. Shown below is a combination of simple rigid and flexible boards with multiple layers.
The application of rigid-flex PCB and the production process of rigid-flex PCB

In addition, a flexible board and several rigid boards are combined, and several flexible boards and several rigid boards are combined, using drilling, coating holes, and laminating processes to achieve electrical interconnection. According to the design needs, the design concept is more suitable for the installation and debugging of the equipment and PCBA Manufacturing. Ensure better use of the advantages and flexibility of rigid and flexible bonding panels. This situation is more complicated, with more than two layers of wires. as follows:
The composite is a composite material of copper foil, p-sheet, memory flexible wire, and external rigid pressure to synthesize a multilayer board. The lamination of a rigid adhesive board is different from the lamination of only a soft board or the lamination of a rigid board. It is not only necessary to consider the deformation of the flexible board during the lamination process, but also the surface smoothness of the rigid board. Therefore, in addition to material selection, the appropriate thickness of the rigid board needs to be considered in the design process to ensure that the rigid part shrinks uniformly and does not warp. Experiments prove that a thickness of 0.8~1.0mm is more appropriate.
At the same time, it is important to note that the rigid board and the flexible board are placed a certain distance away from the junction, so that it will not affect the rigid joint part.
4. Rigid and flexible PCB production process
The soft and hard bond board is a combination of FPC and PCB. The production of soft and hard bond board should have both FPC production equipment and PCB processing equipment. First, the electronic engineer will send it to the factory that produces the soft and hard bonding board according to the line and shape of the soft bonding board, and the cam engineer will process the relevant documents, make a plan, and then arrange the FPC production line to produce the required FPC , PCB production line produces PCB, these two soft boards and hard boards come out,
According to the electronic planning requirements, the FPC and PCB are seamlessly compacted by the compressor, and then through a series of details, the soft and hard boards are finally processed. Consider the Microwave radio frequency board, a 4-layer board (two-layer hard board and two-layer soft board). The board production requires HDI PCB design, Surface-Mount (SMT) &BGA Assembly spacing 0.5mm. The thickness of the soft board is 25um with ivh (clearance through hole local interlayer guide hole) hole design. The thickness of the whole board: 0.295 +/- 0.052mm. The inner lw/sp is 3/3mil.