Polymer Die Attach Selection Criteria for Low Drift Inertial Measurement Units
Polymer die attach selection governs MEMS IMU bias drift by balancing storage modulus, glass transition temperature, and long-term viscoelastic stress relaxation.
Silicone Elastomer
Polymeric Elastomer
Synthetic polymers composed of alternating silicon and oxygen atoms with attached organic groups provide excellent flexibility and chemical stability across wide temperature ranges. In electronic and sensor packaging, silicone elastomer serves to seal sensitive enclosures and protect internal components from moisture ingress and mechanical shock. This material is selected for its stable mechanical properties under harsh environmental conditions.
Vibration Isolation
The high damping factor of these polymers makes them ideal for isolating micro-sensors from high-frequency structural noise. When a silicone elastomer mount is used, it dissipates kinetic energy as heat, reducing the transmissibility of vibration to the sensor die. This reduction is critical for maintaining high signal-to-noise ratios in inertial measurement units.
Chemical Outgassing
Standard siloxane formulations contain low-molecular-weight volatile compounds that can evaporate under vacuum and deposit on cold surfaces. To prevent this, silicone elastomer used in space flight or vacuum equipment must undergo a specialized thermal cure to drive off these volatile compounds before assembly. This step prevents the contamination of nearby lenses or sensor surfaces.
Thermal Testing
Material batches must be tested using thermogravimetric analysis to measure their outgassing behavior under vacuum and elevated temperature. This test confirms that the silicone elastomer complies with space agency outgassing limits. The measurement is repeated for each material batch to ensure that any variation in the raw polymer or cure cycle is detected before the elastomer is used in production.
This verification process ensures that the sealing materials do not compromise the integrity of the vacuum system during long missions.