Flexibility and reliability of flexible circuit boards?
Visit:3690 Date:2017-07-25
Currently four kinds of flexible circuit boards: single-sided, double-sided, multi-layer and just - screw combination type. "The cost of a single-sided flexible board is the lowest," says Friedman, "the single-sided flexible board should be used when the electrical performance is not high and the single-sided wiring can be used." This most common form has been used for commercial applications such as printers Inkjet cartridges and computer memory. The single-sided flexible plate has a layer of chemically etched conductive pattern, and the conductive pattern layer on the surface of the flexible insulating substrate is a rolled copper foil. Insulating substrates for flexible assembly may be polyimide (Kapton), polyethylene terephthalate (PET), aramid fiber paper (Nomex) and polyvinyl chloride (PVC).
The double-sided flexible plate is a conductive pattern formed by etching on both sides of the base film. The metal hole connects the two sides of the insulating material to form a conductive path to meet the flexibility of the design and use of the function. The cover film protects the single and double sided wires and indicates the position where the components are placed.
Multi-layer flexible board is three or more layers of single-sided flexible circuit board or double-sided flexible circuit board laminated together, through the drilling, plating the formation of metal holes in the formation of conductive between the different layers. This eliminates the need for complex welding processes. Although the number of conductive layers designed for this type of flexible type may be infinite, in the design of the layout, the assembly size, the number of layers and the interaction of the flexibility should be taken into account in order to ensure easy assembly.
The conventional rigid-flexible plates are composed of rigid and flexible substrates that are selectively laminated together. The structure is tight, forming a conductive connection with a metal hole. Taking into account the reliability and price factors, the manufacturer should try to keep as few layers as possible.
Flexible circuit board industry is in small scale but rapid development. Polymer Thick Film Act (PTF) is an efficient, low-cost process for producing circuit boards. The process is on an inexpensive flexible substrate, selectively screening conductive polymer inks. Its representative flexible substrate is PET. PTF conductors include screened metal fillers or toner fillers. The PTF itself is clean and uses lead-free SMT adhesives without etching.
There is also a mixed structure of the flexible circuit board, it is also a multi-layer board, but the multilayer conductive layer is made of different metals. This hybrid structure is mostly used in the relationship between electrical signal conversion and heat conversion and electrical performance of relatively harsh low temperature conditions. In this case, flexible hybrid circuits are the only viable solution.
Whether these flexible circuit boards are cost-effective and whether they are optimally utilized can be evaluated by the convenience of the interconnection design and the total cost. The mainframe is not the same, the phone is in the form of a block layout; the portable computer is the XY orientation to locate the layout; the printer is in the form of a rigid-scratch PCB. These products are made of different materials of different prices to reduce each The cost of the root lead. Each design must undergo a typological assessment to achieve the best cost performance.