Technical points in FPC design

FPC Effective design needs to take into account the overall effect.

1. Shape:

First design the basic route, and then design the shape of FPC. use FPC The main reason is only for miniaturization, so it is often necessary to determine the size and shape of the machine first. The position of important parts in the machine should be given priority. If so, even if some changes may be required, no substantive changes are required. After determining the location of the main components, determine the shape of the wiring. First, decide to use the curved part before and after. However, in addition to software, FPC must have a certain stiffness, so it can not really approach the internal edge of the machine, so it needs to be designed to respond to the gap approved.

2. Tour:

There are many restrictions on line wiring, especially the front and rear bending parts. If the design is improper, the service life will be greatly shortened. Some need to be used back and forth fpc In principle, a unilateral mechanism is needed. If double-sided FPC must be used due to the complexity of the line, the following points should be noted:

(1) See if you can stop punching (not one). Because perforation plating will have a negative impact on the folding resistance.

(2) If perforation is not used, the perforation of the serrated part does not need copper plating.

(3) Make single sawtooth part with single board FPC, and then connect double-sided FPC.

3. Line pattern design:

We already know how to use FPC Therefore, the machine and electrical characteristics should be considered in the design.

(1) Current capacity and thermal design: the thickness of copper foil used in the conductor part is related to the current capacity and thermal design of the circuit. The thicker the copper foil of the conductor, the smaller the resistance, which is inversely proportional. Once heated, the resistance of the wire increases. In the double-sided through-hole structure, the thickness of copper coating can also reduce the resistance value. It is designed to be 20 ≤ 30% higher than the allowable current. But in fact, thermal design is not only related to attraction factors, but also related to circuit density, ambient temperature, heat dissipation characteristics and other factors.

(2) Insulation: there are many factors affecting the insulation characteristics, which are not as stable as the resistance of the conductor. The general insulation resistance value determines whether there are pre drying conditions, but it must contain considerable moisture when actually using electronic equipment and drying performance. The moisture absorption of polyvinyl alcohol (PET) is much lower than polyimid, and the insulation characteristics are very stable. As a maintenance film and welding resistance printing, the insulation characteristics after moisture drop are much higher than PI.