- Flexibility and reliability of FPC
At present, there are four kinds of FPCs: single-sided, double-sided, multi-layer and rigid flexible composite. “The cost of single-sided flexible board is the lowest. When the requirements for electrical performance are not high and single-sided wiring is possible, single-sided flexible board should be used.” This most common form has been used commercially, such as inkjet cartridges for printers and memory for computers. The single-sided flexible board has a layer of chemically etched conductive patterns, and the conductive pattern layer on the flexible insulating substrate is a calendered copper foil. The insulating substrates used for flexible assembly can be polyimide (Kapton), polyethylene terephthalate (PET), aramid fiber paper (Nomex) and polyvinyl chloride (PVC).
The double-sided flexible plate is a conductive pattern made of a layer of etching on both sides of the base film. The metallized hole connects the figures on both sides of the insulating material to form a conductive path to meet the design and use functions of flexibility. The covering film can protect the single and double sided wires and indicate the location of the components.
Multilayer flexible board is to laminate three or more layers of single-sided flexible circuit boards or double-sided flexible circuit boards together, form metallized holes through drilling and electroplating, and form conductive paths between different layers. In this way, complex welding processes are not required. Although the number of conductive layers designed as such flexible type can be unlimited, in order to ensure convenient assembly, the interaction between assembly size, number of layers and flexibility should be taken into account when designing the layout.
- Economy of FPC
If the design of the circuit is relatively simple, the total volume is small, and the space is suitable, the traditional internal connection mode is more cost-effective. If the circuit is complex, processes many signals, or has special electrical or mechanical performance requirements, FPC is a good design option. Another potential cost saving reason for flexible materials compared with rigid materials is the elimination of connectors. The cost of raw materials is the main reason for the high price of FPCs. Although its raw materials are expensive and difficult to manufacture, its foldable, bendable and multi-layer panel functions will reduce the overall component size, the materials used and the total assembly cost.
- The cost of FPC is being further reduced
In spite of the above cost factors, the price of flexible assembly is declining and becomes close to the traditional PCB. This is mainly due to the introduction of new materials, the improvement of the production process and the change of the structure. In one example, the use of acrylic adhesive was eliminated on rigid flex plate components with many layers. Now some newer materials can make finer lines because the copper layer is thinner. The thinner copper layer makes the component more and more lightweight, while the lighter and thinner assembly makes the flexible component more suitable for loading into smaller space. Today, copper foil can be directly generated on the medium without using adhesives. The copper layer of several microns that can be obtained by these technologies enables industry to obtain fine lines of 3 mils or even narrower width. “After the adhesive is removed from the flexible circuit board, the flexible circuit board has flame retardant performance. This can not only accelerate the UL certification process, but also further reduce the cost. When the flexible circuit board continues to develop rapidly from the initial military industrial applications to civil and consumer applications, it is more important to obtain the UL certification. The flexible board solder mask and other surface coatings further reduce the cost of flexible assembly. In the past decade These new materials and processes have greatly reduced the cost. At the same time, it is precisely because this type of product has been widely recognized and demanded that the cost of flexible materials is also declining.