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Application of Rigid-flex and flexible bonding plate

1. Base Material):FCCL(Flexible Copper Clad Laminate)

Rigid flex Printed Circuit Boards in Robot Designing

Polymide:Kapton(12.5um/20um/25um/50um/75um),with the advance of good flexibility, high temperature resistance (long-term use temperature of 260°c, short-term resistance to 400°c), high moisture absorption, good electrical and mechanical properties, good tear resistance. Good weather resistance and chemical sex, good flame retardancy. Polyester amine (PI) is the most widely used. 80% of them are made by the American DuPont Company.

Polyester(25um/50um/75um),low price with good flexibility, tear resistance. Tensile strength and other mechanical characteristics and electrical characteristics of good, 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 solder welding, melting point 250°c, relatively less used right now.

Application of Rigid-flex PCB

2. Coverlay

The main role of the coverlay is to protect the circuit, and prevent the circuit damp, pollution and anti-welding.

Coverlay thickness from1/2mil to 5 mils (12.7 to 127um). Conductive layer (Conductive Layer) is divided into several ways of calendering copper (Rolled annealed Copper), Electrolytic copper (Electrodeposited Copper) and silver sputtering/spray Plating (silver Ink). The structure of electrolytic copper crystal is rough, which is not conducive to fine line yield. The crystal structure of calendering copper is smooth, but the bonding force with the base membrane is poor. You can distinguish between points and calendering copper foil from the outside.

Electrolytic copper foil is copper red, and the calendering copper foil is grayish white. Auxiliary materials and reinforcement plates (additional material&stiffeners). A hard material that is partially pressed on a soft plate in order to weld components or increase reinforcement for installation.

Reinforcement film can be used FR4, resin plate, pressure-sensitive adhesive, steel sheet aluminum sheet reinforcement and so on. Semi-solidified sheet (low flow PP) without flow/non-flow glue. Laminated (Rigid and Flex ConnecTIon) for flex and hard bonding plates, usually very thin PP.

There are generally use in 2mil, 1080 (3.0mil/3.5mil), 2116 (5.6mil)

3. Structural form of rigid and flexible PCB

Rigid and flexible PCB  is on the flexible plate again glued one or more than two rigid layers, is that the rigid layer of the circuit and the flexible layer on the circuit connected to each other through metallization. Each rigid and flexible bonding plate has one or more rigid areas and a flexible zone. As shown below is the combination of simple rigidity and flexible plate, with more than one layer.

Rigid and flexible PCB coverlay
rigid flex pcb Laminating

In addition, a flexible plate and a few rigid plate combination, a few flexible plate and a few rigid plate combination, the use of drilling, coated hole, laminating process method to achieve electrical interconnection. According to the design needs, make the design concept more suitable for the installation and commissioning of the device and welding operations. Ensure better use of the advantages and flexibility of rigid and flexible bonding board. This situation is more complex, with more than two layers of wire. as follows:

Laminating is the composite of copper foil, p piece, memory flexible line, outer rigid line pressure synthesis Multilayer pcb board. The lamination of the rigid bonding plate is different from that of only the laminated or rigid plate of the soft plate. It is necessary to consider not only the deformation of the flexible plate in the lamination process, but also the surface smoothness of the rigid plate. Therefore, in addition to material selection, in the design process need to take into account the appropriate thickness of rigid plate, in order to ensure that the shrinkage of the rigid part of the consistent will not appear warping. Experimental proof 0. 8~ 1. 0mm thickness is more suitable.

At the same time, it is important to note that the rigid plate and the flexible plate leave the junction of a certain distance to place the hole, so that it will not have an impact on the rigid binding part.

4. Rigid and flex PCB production process

Soft and hard bonding plate is a combination of FPC and PCB, soft and hard bonding plate production should have FPC production equipment and PCB processing equipment at the same time. First of all, by the electronic engineer according to the needs of the soft bonding plate line and shape, and then, issued to the production of soft and hard bonding board factory, after the cam engineer to deal with the relevant documents, planning, and then arrange the FPC production line to produce the required FPC, PCB production line to produce PCB, these two soft board and hard plate out,

According to the planning requirements of the electronic engineer, the FPC and PCB through the compressor seamless compaction, and then through a series of details, the final process of soft and hard bonding plate. Consider Motorola 1+2F+1 Mobile display&side Keys, a 4-storey board (two-storey hard plate two-layer soft board). The plate plate making requirements are HDI pcb design, BGA spacing 0.5mm. Soft plate thickness 25um has ivh (interstitial Via hole local interlayer guide hole) hole design. Thickness of the entire plate: 0.295+/-0.052mm. The inner layer lw/sp is 3/3mil.

rigid flex circuit board
4 layer Motorola PCB

4 layer pcb Motorola 1+2F+1 Mobile Display&Side Keys