Flex PCB has the characteristics of large capacity, small volume, thin profile, lightweight and flexibility. It is widely used in various industries. It is mainly used as a carrier for electrical connections between hardware devices and signals or between some instruments transmission.
Since Flex PCB is very thin, the gold finger used to install the plug-in terminal needs to be combined with a layer of PI reinforcement to increase the thickness and strength, so it can achieve the transmission of current and signals between plug-in devices and instruments. When traditional Flex PCB is installed in car or some mechanical equipment that produces bumps and vibrations, the golden fingers and plug terminals often become loose or have instantaneous poor contact, resulting in short circuits and signal interruptions. Therefore, vibration-resistant plug was developed. Connecting circuit boards is a technical problem that needs to be solved urgently. In order to solve the above technical problems, the Flex Plus technical team developed an Vibration-resistant plug-in flex circuit board.
The specific technics of Vibration-resistant plug-in flex circuit board:
The Vibration-resistant plug-in flex circuit board includes a flexible circuit board main body. The end of the flexible circuit board main body is connected with PI reinforcement. The PI reinforcement is provided with a number of golden fingers through connecting glue. The top and bottom ends of the flexible circuit board main body are provided with a number of energy-dissipating connecting beams. When the golden finger is inserted into the connection port, the energy-dissipating connecting beam makes elastic contact with the inner wall of the connecting port. Through the energy-dissipating connecting beam, the main body of the flexible circuit board has the effect of absorbing shock and energy and fully contacting the connecting port, thereby completely solving the problem of vibration. It eliminates the problem of loosening and instantaneous poor contact between the golden fingers and the connection ports, and has stronger practicality and effect of use. Specifically the following points:
1. PI reinforcement is made of materials with an elastic modulus of 50MPa. The PI reinforced surface is roughened and micro-carbonized through laser cutting technology.
2. The connecting glue is an epoxy thermosetting glue made of H-71 epoxy resin, glycerin and 647# acid anhydride.
3. The material of the energy-dissipating connecting beam is selected as a combination of high-temperature PVC tape, and the surface of the energy-dissipating connecting beam is corrugated.
4. There are a number of through holes evenly distributed on the surface of the energy-dissipating connecting beam.
5. There are several silicone thermal pads connected to the bottom of the main body of the flexible circuit board, and several heat dissipation fins are evenly connected to the bottom of the silicone thermal pads.
6. The silicone thermal pad is in the shape of a long strip, and several silicone thermal pads and several energy-dissipating connecting beams are arranged in a staggered manner.
What are the benefits of Vibration-resistant plug-in Flex PCB technology?
The plug-in circuit board is designed to absorb and stabilize the main body of the flexible circuit board by setting energy-dissipating connecting beams next to the golden fingers at its ends. When the golden fingers are inserted into the connection port, they are located at the top and bottom of the main body of the flexible circuit board. Several energy-dissipating connecting beams at the bottom are in elastic contact with the inner top and inner bottom surfaces of the connection port. Through the energy-dissipating connecting beams, the main body of the flexible circuit board has the effect of absorbing shock and fully contacting the connection port, thereby completely solving the problem of metal damage caused by vibration. The problem of looseness and instantaneous poor contact between fingers and the plug-in spring piece in the connection port improves the stability and effect of the overall plug-in circuit board.
Flex plus’optimized processes and materials:
Regarding the existing corona roughening process and plasma roughening process used for PI reinforced surface roughening, the surface adhesion increased by this type of roughening process can only reach 1.0Kgf/cm2~2.5Kgf/cm2 Scope, in the flex plus process, the PI reinforced surface roughening is achieved through laser cutting technology. The laser cutting process of the PI reinforced surface is achieved through the existing laser cutting machine. The cutting shape is adjusted to 0.5*0.5mm rectangular grid, cutting parameter power factor is adjusted to: 90%, laser frequency:80khz, cutting speed: 600mm/s, to roughen and micro-carbonize the PI reinforced surface. Through this treatment, the PI reinforced surface can be made. The adhesion force reaches between 5Kgf/cm2 and 8Kgf/cm2, which greatly improves the bonding force between the PI reinforcement and the plug-in spring piece in the connection port.
The connecting glue is a ring made of H-71 epoxy resin, glycerin and 647# acid anhydride according to the proportion of ingredients (H-71 epoxy resin: 150g, glycerol: 6.2g, 647# acid anhydride: 123g). Oxygen thermosetting adhesive, this kind of epoxy thermosetting adhesive can be produced by using the golden finger combined hot pressing process with a pressure of 50Kgf, a laminating time of 120 seconds, and a laminating temperature parameter of 120°C. At the same time, this kind of epoxy thermosetting glue can avoid the hardening degeneration of PI reinforcement caused by high temperature and the increase of elastic modulus.
There are a number of through holes evenly distributed on the surface of the energy-dissipating coupling beam. The through-holes can be formed by drilling. By setting the through-holes, the stress-bearing elastic deformation capacity of the energy-dissipating coupling beam can be enhanced to improve the shock-absorbing effect of the energy-dissipating coupling beam.
Working principle of Vibration-resistant plug-in circuit board:
With reference to above image, the connection port is electrically connected to the external device through wires. An elastic buffer pad is provided on the inner wall of the connection port to protect the end of the golden finger. The top energy-dissipating connecting beam and the energy-dissipating connecting beam located at the bottom of the flexible circuit board main body are in elastic contact with the inner top surface and the inner bottom surface of the connection port respectively. The surface of the gold finger is in contact with the surface of the plug spring. When vibration occurs at the connection port, the waves on the main body of the flexible circuit board will disperse to the energy-dissipating connecting beams. According to the principle of wave interference, the amplitude of the vibration can be eliminated, making the link end of the main body of the flexible circuit board less likely to fall off.
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