With the soft PCB production continues to increase and more than just the application and promotion of Flexible PCB, PCB is now more common to say, when coupled with soft, rigid or flexible to say it is just layers of the PCB. Usually, the insulating substrate made of soft flexible PCB or flexible PCB known as PCB, Rigid-flex PCB that just compound the flexible PCB. It is adapted to today's electronic products to high-density and high reliability, small size, lightweight direction of development, but also to meet the stringent economic requirements and competition in the market and technology needs.
In other countries, soft PCB in the early 1960s has been widely used. China, in the sixties began production applications. In recent years, as the global economic integration and open city to try to introduce technology to promote their use keeps growing, some small and medium rigid PCB plant hard to target this opportunity to make use of soft technology, the use of existing equipment for tooling tools and processes for improvement, transformation and adaptation of production soft soft PCB PCB consumption growing needs. To further understanding of PCB, flexible PCB assembly process here to make a study of the introduction.
First, the classification of their advantages and disadvantages of soft PCB
1. Flexible PCB classification
Flexible PCB layers and the conductor is usually based on the structure of the following categories:
1.1 soft-sided PCB
Soft-sided PCB, only one layer of conductor, the surface can cover or not cover. Substrate materials used in insulation, with the application of the product vary. Insulation materials commonly used polyester, polyimide, PTFE, soft epoxy - glass cloth and so on.
Soft-sided PCB can be further divided into the following four categories:
1) No cover side connection
PCB conductors such soft graphics on the insulating substrate, wire-free surface coating. As often as single-sided rigid PCB. These products are the cheapest kind, usually in non-critical and have environmental applications. The interconnect is soldering, welding or bonding to achieve. It is commonly used in the early telephone.
2) coating one side connected
These and the former class than just the surface of the wire according to customer requirements with a new layer coating. Required to cover the exposed pad, simply can not cover in the end zone. Required precision can be used clearance hole form. It is the single most widely used in soft PCB, the most widely used in automotive instruments, electronic instrument widely used.
3) No cover two-sided connection
Plate interface in this type of connection wires can connect the front and back. To do this, place the pad on the insulating substrate to open a pathway hole, the via hole in the insulating substrate to the desired location on the first punching, etching or other mechanical methods is made. It is used both sides of the installation element, the device and the need for soldering applications, access at the pad area without insulating substrate, such pad area is usually removed by chemical methods.
4) cover the two-sided connection
With a different type of class at the surface layer of coating. However, there is access hole cover, and allow both sides can be terminated, and still maintain cover. Such soft PCB by two layers of insulation material and a layer made of metal conductors. Was used in the devices need to cover each other and the surrounding insulation, and its also insulated from each other, they need to end the positive and negative are connected occasions.
1.2 soft-sided PCB
Soft-sided PCB, with two conductors. Such double-sided PCB application and advantages of soft-sided flexible PCB with the same, its main advantage is to increase the wiring density per unit area. It may be there, and there are no through holes, no cover is divided into: a no through holes, no cover layer; b non-metal hole, a cover layer; c a metal hole, no overlay ; d a metal hole, cover layer. No double-sided flexible PCB cover fewer applications.