The conductive foam has a low compression set rate, ensuring good long - term performance of the gasket. - The recommended working compression of the conductive foam electromagnetic interference gasket varies according to the gasket size. Generally, the gasket should be compressed to 30% - 60% of its original height. Mechanical and Electrical Conductivity Detection of Conductive Foam Gasket: Combine with the detection of the resistance change of the conductive foam gasket under different compression percentages to dynamically detect the compression characteristics of the conductive foam gasket in real - time.

When the conductive foam gasket is compressed, the relationship between the dynamic change of resistance and the compression percentage is a complex process. The following is an analysis of the mechanism of the dynamic detection curve of the compression percentage and resistance of the conductive foam gasket: 1. Basic Structure and Characteristics of Conductive Foam Gasket Conductive foam usually consists of a foam matrix with conductive particles (such as carbon black, metal powder, etc.). When it is uncompressed, it has a high porosity and a relatively low resistance. When compressed, the porosity decreases, and the deformation of the material and the change of conductive paths will cause the resistance to change. 2. Relationship between Compression Percentage and Resistance Change - Initial State: When the conductive foam is uncompressed, the foam has a high porosity, the path for current flow is relatively long, and the resistance is high. - Compression Process: As the foam is compressed, the porosity gradually decreases, the contact between the conductive particles in the foam structure increases, and the path for current flow becomes shorter, resulting in a decrease in resistance. - After Compression to a Certain Percentage: When the foam is highly compressed, the pores almost disappear completely. The structure of the foam may collapse or become compact, and the change in resistance gradually stabilizes. At this time, the change in resistance usually levels off, or the resistance may increase sharply due to irreversible damage to the material. 3. Mechanism of the Dynamic Resistance Change Curve The resistance change of the conductive foam gasket during the compression process usually shows the following stages: - Stage 1: Low Compression Rate Stage (Initial Stage):    - In this stage, the resistance gradually decreases as the compression increases. As the foam structure is gradually compressed, the contact area between the conductive particles increases, and the path for current to pass through becomes shorter, leading to a decrease in resistance. The change in resistance in this stage is relatively gentle. - Stage 2: Medium Compression Rate Stage:    - When entering the medium compression stage, the pores of the foam begin to decrease significantly. The geometric shape of the foam and the arrangement of conductive particles may change, and the change in resistance becomes more obvious, and the rate of resistance decrease may accelerate. - Stage 3: High Compression Rate Stage (Compression Limit Stage):    - When the compression rate approaches the limit, the pores of the foam basically disappear, and the change in resistance tends to be stable. In this stage, if the foam undergoes plastic deformation or damage, the resistance may suddenly increase, showing a sharp rise in resistance. - Stage 4: Irreversible Deformation Stage (if present):    - If the foam undergoes permanent deformation under high compression (such as material rupture, conductive particle shedding, etc.), the resistance will increase sharply. This phenomenon usually occurs after the compression reaches a certain limit. 4. Factors Affecting Resistance Change - Distribution of Conductive Particles: The resistance change of conductive foam is affected by the uniformity of the distribution of conductive particles. If the conductive particles are more evenly distributed in the foam, the resistance change will be smoother. - Elasticity and Plasticity of the Material: The differences in the elasticity and plasticity of different conductive foams will affect the change in resistance. In softer foams, the resistance changes more significantly during compression, while in harder foams, the resistance change may be smaller. - Compression Rate: The speed of compression also affects the dynamic change of resistance. Rapid compression may lead to a larger range of local stress concentration, resulting in a sharp change in resistance. 5. Experimental Detection of Resistance and Compression Percentage In the experiment, the following steps are usually taken to detect the dynamic change of resistance during compression: - Use a pressure sensor to record the compression percentage of the foam. - Use the four - probe method or a resistance strain gauge to monitor the resistance change of the foam gasket in real - time. - Compare the compression percentage with the resistance value to obtain the resistance - compression percentage curve. 6. Summary There is a complex relationship between the dynamic resistance change and the compression percentage of the conductive foam gasket. In the initial compression process, the resistance usually decreases because the foam structure becomes more compact and the contact between conductive particles increases. However, as the compression continues, the resistance change gradually levels off, and may change sharply due to irreversible deformation or material damage after reaching a certain compression percentage.