FPC not only has electrical functions, but also the mechanism must be balanced by overall consideration and effective design.
　　◇ Shape:

　　 First, the basic route must be designed, and then the shape of the FPC must be designed. The main reason for adopting FPC is nothing more than the desire to miniaturize. Therefore, it is often necessary to determine the size and shape of the machine first. Of course, the position of important components in the machine must be specified in priority (for example: the shutter of the camera, the head of the tape recorder…), if it is set, even if it is possible to make some changes, it does not need to be changed significantly. After determining the location of the main parts, the next step is to determine the wiring form. First of all, it is necessary to determine the part that needs to be used tortuously. However, in addition to the software, the FPC should have some rigidity, so it cannot really fit the inner edge of the machine. Therefore, it needs to be designed to correspond to the clearance that has been sold.

　　◇ Circuit:

　　 There are more restrictions on circuit wiring, especially the parts that need to be bent back and forth. Improper design will greatly reduce their life.

　　 The part that needs to be zigzag used in principle requires a single-sided FPC. If you have to use a double-sided FPC due to the complexity of the circuit, you should pay attention to the following points:

　　 1. See if the through hole can be eliminated (even if there is one). Because the electroplating of the through-hole will have an adverse effect on the folding resistance.
　　2. If through holes are not used, the through holes in the zigzag part do not need to be plated with copper.

　　3. Separately make the zigzag part with a single-sided FPC, and then join the two-sided FPC.

　　◇ Circuit pattern design:

　　 We already know the purpose of using FPC, so the design should take into account the mechanical and electrical properties.

　　 1. Current capacity, thermal design: The thickness of the copper foil used in the conductor part is related to the current capacity and thermal design of the circuit. The thicker the conductor copper foil, the smaller the resistance value, which is inversely proportional. Once heating, the conductor resistance value will increase. In the double-sided through-hole structure, the thickness of copper plating can also reduce the resistance value. It is also designed to have a 20~30% margin higher than the allowable current. However, the actual thermal design is also related to circuit density, ambient temperature, and heat dissipation characteristics in addition to the appeal factors.

2. Insulation: There are many factors that affect the insulation characteristics, not as stable as the resistance of a conductor. Generally, the insulation resistance value is determined by pre-drying conditions, but it is actually used on electronic equipment and dried, so it must contain considerable moisture. Polyethylene (PET) has much lower moisture absorption than POL YIMID, so the insulation properties are very stable. If it is used as a maintenance film and solder resist printing, after the moisture is reduced, the insulation properties are much higher than PI.