EMI Gasket FAQ: Selection, Installation, and Troubleshooting Guide

In EMI shielding applications, EMI Gasket may look simple, but improper use often leads to signal interference, compliance failures, or reduced product reliability. Below are practical answers to common engineering questions.

Q: Does higher compression always mean better shielding?

Not necessarily. Excessive compression can cause lateral expansion limits or adhesive overflow, forming an insulating barrier. For PU-based foam, keep compression at 20–40%; for silicone foam, 15–30%. Always design mechanical stops to prevent permanent deformation.

Q: Why is manual installation often misaligned?

Use pre-cut EMI gasket with release liners along with alignment fixtures or semi-automatic equipment. Controlling workshop conditions (23 ± 5 °C, RH 40–60%) improves bonding consistency and stability.

Q: Why do materials with similar specs perform differently?

The key lies in the coating process. Variations in nickel-copper coating thickness, uniformity, and adhesion have significant impact. Always request XRF coating reports and verify adhesion with tape-peel testing (ASTM D3359).

Q: Why does the new batch feel harder?

This may result from high storage temperatures (e.g., summer warehouses) accelerating PU crosslinking, or from process variations during foaming. Test compression stress–strain curves and establish quick incoming inspection standards.

Q: How to locate the root cause when EMI exceeds limits?

First, use copper foil to temporarily seal gaps; if EMI improves, the problem is in the gasket seal. Next, measure seam resistance at multiple points with a micro-ohmmeter to locate high-resistance areas. Avoid relying solely on visual inspection.

Q: Is EMI performance drop after high temperature always aging?

Not always. High temperatures can temporarily reduce preload due to material softening, which recovers after cooling. Permanent degradation, however, may indicate coating oxidation or compression set. For long-term durability, see Weather Resistance and Service Life Evaluation of Conductive Thermal Foam.

Q: Can EMI gasket be reused during maintenance?

Not recommended. Removal and reinstallation often damage the conductive coating and weaken adhesives. Instead, design replaceable gasket structures, include spare parts in service kits, and record replacement intervals.

As highlighted in Konlida Conductive Foam Processing and Customization Services: From Material Selection to Closed-Loop Delivery, prototyping is not just about samples—it requires a complete testing plan. Konlida provides full-cycle support from material selection to failure analysis, helping ensure first-pass success.