The function of unidirectional conduction and gluing fixation can solve the connection problems of some tiny wires that the previous connectors could not handle.
Anisotropic conductive film (acf) is a special kind of coating and bonding between the substrate a and the substrate b, and the current can only flow through the vertical axis z direction between the substrate a and b. Coating substance.
Conduction principle: Use conductive particles to connect the electrodes between the IC chip and the substrate to make them conductive. At the same time, it can avoid the conduction and short circuit between two adjacent electrodes, and achieve the purpose of conducting only in the Z-axis direction.
Main composition: It mainly includes two parts: resin adhesive and conductive particles.
The resin adhesive functions in addition to moisture prevention, heat resistance and insulation functions, mainly to fix the relative position of the electrode between the IC chip and the substrate, and provide a pressing force to maintain the contact area between the electrode and the conductive particles.
Generally, resins are divided into two categories: thermoplastic resins and thermosetting resins. Thermoplastic materials mainly have the advantages of low temperature bonding, quick assembly and easy rework, but they also have the shortcomings of high thermal expansion and high moisture absorption, which make them prone to deterioration at high temperatures and cannot meet the requirements of reliability and reliability. Thermosetting resins such as epoxy and polyimide have the advantages of high temperature stability and low thermal expansion and hygroscopicity. However, the disadvantages of high processing temperature and difficulty in rework, but the advantages of high reliability are still present. The most widely used materials.
In terms of conductive particles, the conductive properties of anisotropic particles mainly depend on the filling rate of conductive particles. Although the conductivity of the anisotropic conductive adhesive will increase with the increase of the filling rate of the conductive particles, it will also increase the probability of the conductive particles contacting each other and causing a short circuit.
In addition, the particle size distribution and uniformity of the conductive particles will also have an impact on the conductivity characteristics of the anisotropic.