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.
Collected Volatile Condensable Material
Condensable Residue
Mass measurement of outgassed products that deposit on a collector plate held at a specific temperature provides a baseline for evaluating material cleanliness in vacuum environments. In space qualification tests, collected volatile condensable material is expressed as a percentage of the initial specimen mass after exposure to vacuum and elevated temperature. This quantity isolates the portion of outgassed species likely to foul optical elements or thermal radiators.
Thermal Protocol
Testing relies on holding a specimen at one hundred and twenty-five degrees Celsius under a vacuum of at least twenty-five microtorr for twenty-four hours. The vaporised species from the material under test travel toward a collector plate maintained at twenty-five degrees Celsius. The difference in the mass of this plate before and after the exposure yields the collected volatile condensable material percentage.
Acceptance Boundary
Aerospace standards dictate that the maximum allowable deposition during these tests is one tenth of a percent of the total starting mass of the specimen. Material exceeding this threshold fails qualification for use near critical spacecraft payload instrumentation or high-power laser optics. Specifying lower temperatures for the collector plate can widen this boundary for terrestrial industrial applications.
Measurement Error
Condensation mass values require high-precision microbalances with microgram resolution to ensure repeatable measurements across batches. Humidity levels in the weighing room can distort results if the collector plate absorbs moisture during the post-test handling phase. Controlling the transfer environment prevents the collection of atmospheric water, securing the validity of the recorded collected volatile condensable material data.
Operators must execute the pre-weighing and post-weighing procedures within a fixed time window to avoid ambient contamination. This strict timing minimizes exposure to airborne hydrocarbons and other laboratory volatile compounds.