The Effect of Argon Plasma Activation on the Die-Shear Force and Reliability of Chips and Flex Substrates Assembly Using a Non-conductive Film

• Main Authors: Jun-you Chen, 陳俊佑
• Other Authors: 莊正利
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/92477356133412461509

碩士 === 中山醫學大學 === 職業安全衛生學系碩士班 === 103 === A non-conductive film (NCF) and the thermal compression bonding process were combined to assemble chips and flex substrates. Two purposes of this study are expected to achieve chips bonded on flex substrates directly and to verify the reliability of chips and flex substrates assembly. Flex substrates subjected to argon plasma activation prior to assemble the chips and flex substrates with different activated parameters. The effects of cured parameters on the bonding strength were also investigated, cured temperature and cure durations. For flex substrates activated with argon plasma, the NCF placed on the surface of flex substrates and then chips were flip-bonded on the flex substrates using thermal compression. A subsequent die-shear test was carried out to evaluate the bonding strength of chips and flex substrates assembly. Scanning electron microscopy (SEM) was conducted to confirm the morphology and elucidate the bonding interface between chips and flex substrates. After chips bonded on flex substrates using NCF, the reliability of pressure cooker test (PCT), high temperature test (HTS) and high humidity/high temperature (HH/HT) test was evaluated according JEDEC standards. For flex substrates with argon plasma activation, the NCF can be removed away from bonding interface between gold bumps and copper electrodes during thermal compression bonding. Accordingly, gold bumps were directly bonded onto copper electrodes to form an active electrical path between chips and flex substrates. A low contact angle can be obtained for flex substrates activating with argon plasma, indicating the containments on the surface of flex substrates were removed, and a good wettability on the bonding surface can be actieved. The sound bonding interface with sufficient bonding strength was achieved, since neither delamination nor porosity was found at bonding interface between the NCF and flex substrates. The argon plasma activation has a significant improvement on bonding strength of chips and flex substrates assembly using NCF. This process was potentially to be applied to the packaging of chips and flex substrates assembly. After specimen subjected to PCT and HT/HH test, the delamination can be found due to the moisture penetrated to the bonding interface among gold bumps, NCF, and flex substrates. The die-shear force of chips and flex substrates assembly is thus degraded. Similarly, the delamination that occurred at the bonding interface between NCF and flex substrates after HTS test of 1000 hr durations, and then deteriorated the die-shear force slightly.For flex substrates subjected to argon plasma activation, the gold bumps bonded on copper electrodes directly and the metallurgical bonding was formed after HTS test. This experimental result showed that the argon plasma activation was effective scheme to improve the reliability of HTS test.