Understanding the importance and application of Flex PCBs

Flex PCB is a printed circuit board made of bendable material. Compared with traditional rigid PCBs, Flex PCBs have foldable and bendable characteristics, and are suitable for a variety of electronic devices that require a high degree of reliability and flexibility. As an indispensable part of modern electronic devices, PCBs flexible PCB plays an important role in various fields. In this article, we will introduce the PCB color, characteristics, production process, and its practical applications.

Colorful Rigid PCBs can often be seen, in green, red, blue, purple, yellow, black, matte red matte green, and so on. However, in Flex PCBs, the main colors are yellow and black, and transparent flex PCBs can be produced as well. In Rigid PCBs, colors are called ink colors/solder resist colors, but in flexible PCBs, they are often called overlay colors instead of solder resist colors.

Advantages of Flex PCB
(1) Kneadability
It is more convenient to route and connect in three-dimensional space, and can be curled and folded up for use. It can be curled within the allowable radius of curvature and can withstand thousands to tens of thousands of uses without damage. to tens of thousands of times without damage.
(2) Reduced size
Compared to the use of wire and cable in component assembly, flex PCB has a thin and flat conductor cross-section, which reduces the size of the conductor and allows it to be shaped along the chassis, making the structure of the equipment more compact and rational. This makes the structure of the equipment more compact and reasonable and reduces the volume of the assembly. Compared with rigid PCBs, space savings of 60 to 90% can be achieved.
(3) Weight reduction
In the same volume, flex PCB and wire and cable than the same load capacity, their weight can be reduced by about 70%, compared with rigid PCB, the weight is reduced by about 90%. Compared with rigid PCB, the weight can be reduced by about 90%.

(4) Consistency of mounting
The flex PCB eliminates the errors associated with wire and cable wiring. As long as the processing drawings are proofread and passed, all the winding circuits produced in the future are the same. There is no misconnection when installing wires.

(5) Selectable materials
Flex PCBs can be manufactured with different base materials according to different usage requirements. For example, polyester film can be used for low-cost mounting applications. In demanding applications that require excellent performance, polyimide film can be used.

Precautions for Flex PCB placement
(1) Pre-treatment of Flex PCB
FPC board is softer, the factory is generally not vacuum packaging, it is easy to absorb moisture in the air during transportation and storage, needs to be in the SMT cast line before the pre-baking process, and the moisture is slowly forced out. Otherwise, under the impact of the high temperature of reflow soldering, FPC absorbed moisture quickly vaporizes into water vapor protruding FPC, easily causing FPC delamination, blistering, and other bad.

Pre-baking conditions are generally a temperature of 80-100 ℃ time of 4-8 hours, under special circumstances, the temperature can be raised to 125 ℃ or more, but need to shorten the baking time accordingly. Before baking, be sure to make a small sample test to determine whether the FPC can withstand the set baking temperature, but also to the FPC manufacturer to consult the appropriate baking conditions. Baking, FPC stacking can not be too much, 10-20PNL is more appropriate, some FPC manufacturers will put a piece of paper between each PNL isolation, need to confirm that this isolation with the paper can withstand the set baking temperature, if not need to isolate the piece of paper to be withdrawn after the baking. After baking the FPC should have no obvious discoloration, deformation, warping, or other defects, and need to be qualified by the IPQC sampling before casting. pcb flex

(2) The production of special carrier board
According to the circuit board CAD files, read the FPC hole positioning data to manufacture high-precision FPC positioning template and special carrier board, so that the positioning template on the diameter of the positioning pins and the carrier board on the positioning holes, FPC positioning holes on the aperture to match. Many FPCs because of the need to protect part of the line or design reasons are not the same thickness, some places thick and some places to be thinner, and some have to strengthen the metal plate, so the carrier plate and FPC need to be processed by the actual situation of the combination of grinding and grooving, the role is to ensure that the FPC in the printing and mounting is flat. The material of the carrier plate is light and thin, High strength, low heat absorption, fast heat dissipation, and after several thermal shock warping deformation is small. Commonly used carrier plate materials are synthetic stone, aluminum, silicone plate, and Special high-temperature resistant magnetized steel plate.

Flex PCB has a wide range of applications, especially in the fields of cell phones, computers, and consumer electronics. The main products in the field of cell phones are smart phones The main products in the mobile phone field are smartphones, the PC field are computers, the main products in the consumer electronics field are tablet PCs and wearable devices, etc., and the main products in the automotive field are LEDs, instruments, ADAS, automotive, and other devices. The main products in the automotive field are LED, instruments, ADAS, entertainment control systems, etc.; the main products in the server/data memory field are server/data memory, and the main products in the military aerospace field are artificial satellites. The main products in the field of military aviation are artificial satellites, detection instruments, radar systems, etc. The main products in the field of industrial control are laser measurement and control, sensors, heating coils, etc. The main products in the field of medical care are LEDs and wearable devices. The main products in the field of industrial control include laser measurement and control, sensors, heating coils, etc. The main products in the field of medical care include psychotherapeutic devices, pacemakers, endoscopes, and probes. pcb flex

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