A novel evaluation of shock absorption and adhesive strength under shear impact loading

ABSTRACT

The authors study shock absorption characteristics and their measurement methods because test standards and specifications for shock absorbing adhesives are not clearly established. Especially, microscale shock absorbing adhesive characteristics are important for mechanical properties of small-sized mobile electronics with slim, bezel-less design. For this purpose, a piezoelectric force sensor is utilized to evaluate impact response of various adhesives under ball drop impact due to high-frequency data acquisition. Next, the evaluated impact responses are compared with dynamic mechanical analysis results to confirm the viscoelastic material behavior of adhesives. In addition, the impact response is proportionally correlated with the damping factor. In order to characterize both shock absorption and adhesive strength simultaneously, a novel test apparatus for shear impact is devised based on the previous test. The correlation between two mechanical properties is determined by analyzing the change of the impact force transmitted through the adhesive. The degradation of the adhesion strength is described by the damage model, which estimates its change before detachment. The proposed experimental mechanics not only enables a concurrent evaluation of adhesion strength and shock absorption but also assesses required adhesive materials for delicate electronic components.

KEYWORDS:

• Mobile electronics
• bezel-less design
• shock absorption adhesives
• shear impact loading