Abstract
In this study, the stress in an integrated circuit (IC) package caused by flip-chip bonding (FCB) is evaluated using 9 × 9 mm2 and 550 μm thick piezoresistive sensor embedded test element group (TEG) chips. After capillary underfill (CUF) or non-conductive film (NCF) coating, the TEG chip is connected to the substrate by FCB. The stress inside the TEG chip is obtained at each process during FCB by measuring the change in resistance at the piezoresistive sensor. After FCB, the compressive stress is high in the center of TEG chips but lower toward the corners. The real compressive stress in the flip-chip package decreases with increasing temperature up to 120°C. After the stress test, moisture sensitivity level (MSL) and reflow tests are performed at elevated temperatures. NCF and CUF are compared through the same process and the stress at the delaminated position between the CUF and substrate is higher than that in the CUF after MSL and reflow tests.
