Thermal resistance, thermomechanical stress and thermal cycling endurance of silicon chips bonded with adhesives

The thermomechanical stress in large silicon chips bonded to rigid substrates with adhesives is caused by the mismatch in thermal expansion between the silicon chip and the substrate. The stress induced during the chip attachment process was measured using integrated piezoresistive strain gauges on test chips. The stress was different between different adhesives. The effect of temperature cycling (i.e., stress cycling) was investigated by measuring the thermal resistance between chip and substrate. An increasing thermal resistance that strongly depends on the mismatch in thermal expansion was found. The wear-out mechanisms were crack growth and detachment.<>