First, the flexible circuit board flexibility and reliability
Currently four kinds of flexible circuit boards: single-sided, double-sided, multi-layer and just - torsion combination type. "The cost of a single-sided flexible board is the lowest," says Friedman. "When the electrical performance is not high,
When wiring, you should use single-sided flexible board. "This most common form has been commercially available, such as the printer's inkjet cartridges and the computer's memory. Flex PCB The single-sided flexible board has a layer of chemical corrosion
The conductive pattern on the surface of the flexible insulating substrate is a rolled copper foil. The insulating substrate used as the flexible assembly may be polyimide (Kapton), Flex PCB polyethylene terephthalate Ester (PET), aramid fiber paper (Nomex) and polyvinyl chloride (PVC).
The double-sided flexible plate is a conductive pattern formed by etching a two-sided surface of the base film. The metal hole connects the two sides of the insulating material to form a conductive path to meet the flexibility.
And the use of functions. Flex PCB 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 to form a metal hole, Flex PCB formed in different layers of conductive path. This eliminates the need for complex welding processes. Although the number of conductive layers designed for such flexible types may be infinite, in designing the layout, in order to ensure easy assembly
When considering the size of the assembly, the interaction between the number of layers and flexibility.
The conventional rigid-flexible plates are composed of rigid and flexible substrates that are selectively laminated together. The structure is compact and forms a conductive connection with a metallized hole. Flex PCB Taking into account the reliability and price factors, production The plant should try to keep as few layers as possible.
Flexible circuit board industry is in small scale but rapid development. Polymeric thick film method (PTF) is a highly efficient and low cost process for producing circuit boards. Flex PCB The process is inexpensive for the flexible base Material, the selective printing of conductive polymer ink. Its representative flexible substrate is PET. PTF conductors include screened metal fillers or toner fillers. PTF itself is very clean, use lead-free SMT sticky Adhesive, do not have to be etched.
There is also a mixed structure of the flexible circuit board, it is also a multi-layer board, but the multilayer conductive layer by the composition of different metals. Flex PCB This hybrid structure is mostly used in electrical signal conversion and heat conversion The relationship between the electrical properties and 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 overall way is not the same, Mobile phone is a block layout form; portable computer is X-Y direction can be positioned layout; printer is just - scratch PCB form. These products are made of different materials of different prices to reduce each lead within the lead cost of. Each design has to undergo a typological assessment to achieve the best cost performance. "
Second, the flexibility of flexible circuit boards
If the circuit design is relatively simple, the total volume is not large, and the space is appropriate, the traditional way to connect most of the more cost-effective. Flex PCB If the lines are complex, handle many signals, or have special ones Electrical or mechanical performance requirements, Flex PCB flexible circuit board is a better design choice. Flexible materials have a potential cost savings compared to rigid materials, eliminating the need for plug-ins.
High cost of raw materials is the main reason for the high price of flexible circuit boards. Despite the fact that its raw materials are more expensive and creating trouble, DiPalermo still believes that folding, bendable and multi- Can reduce the overall component size, the material used to reduce the total cost of assembly to reduce.
Third, the cost of flexible circuit boards is further reduced Despite the above-mentioned cost factors, the price of flexible assembly is declining and becoming close to the traditional PCB. Flex PCB This is mainly the introduction of updated materials, improved production processes as well Changed the reason for the structure. With such an example, the use of acrylic adhesives has been eliminated on rigid-flexible panels with many layers.
Now some of the updated materials because the copper layer is thinner and can make more fine lines. The thinner copper layer makes the assembly lighter and lighter, and the lighter and thinner assembly makes the flexible components more suitable Load a smaller space. In the past, Flex PCB we used the roll process to adhere the copper foil to the adhesive-coated medium. Today, copper foils can be formed directly on the media without the use of adhesives. These techniques Can get a few microns of copper layer, so that the industry can get 3 mil or even narrower narrow lines. "After removing the adhesive from the flexible circuit board, the flexible circuit board has flame retardant properties.
This will speed up the UL certification process and further reduce costs. When the flexible circuit board continues to rapidly from the initial military industrial applications to the development of civilian and consumer applications, to obtain UL certification More important. The flexible board solder mask and other surface coatings further reduce the cost of flexible assembly. Over the past decade, Flex PCB some of these new materials and new processes have greatly reduced costs
The At the same time, it is precisely because the products have been widely recognized and demand, the cost of flexible materials is also declining.
In the next few years, more filial piety and complexity and assembly of higher cost flexible circuit boards will require assembly to be more innovative and require additional flexible flexible circuit boards. The challenge for the flexible circuit board industry is Strengthen its technological advantages, Flex PCB and keep pace with the computer, telematics, consumer demand and active market. In addition, flexible circuit boards will play an important role in lead-free operations.