Title: Stress Relaxation in Accelerated Testing of Adhesively Bonded Stacks

Authors: Curtis M. Bartosz, Felix C. Chen

DOI: 10.33599/nasampe/s.24.0053

Abstract: Composite structures consisting of multiple polymeric layers adhered with pressure sensitive adhesive (PSA) are common in electronics packaging and structural applications. Our general experience with such adhesive stacks has been that thermal cycling confirms robustness to debonding. However, we recently encountered failures of adhesive bonds at high temperature that previously passed thermal cycling. After further analysis we discovered that under elevated temperature static exposure, viscoelastic behavior of the adhesive created failures unseen during thermal cycling. We subsequently determined this was due to time at temperature as distinct from straight thermal expansion coefficient differences. From this we developed an analytical model that incorporates the differing extents of viscoelastic relaxation with temperature. Superimposing this response upon real temperature data throughout the world then enabled us to predict that average field failure rates associated with this construction still fall within acceptable bounds. Understanding the nature of this failure is also guiding us in improving this design through adhesive selection and more targeted thermomechanical testing.

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Conference: SAMPE 2024

Publication Date: 2024/05/20

SKU: TP24-0000000053

Pages: 11

Price: $22.00