| Summary: | 碩士 === 國立中正大學 === 機械系 === 88 === Wire bonding, mainly responsible for electricity and signal delivery among devices, is a critical process in electronic package. Depending on the materials to be connected, the three often-used boding techniques are the thermocompression, ultrasonic, and thermosonic wire bondings. Although these techniques have been used for years, the detailed bonding mechanism is still unclear. Some researchers believed that the boding is due to re-solidification of melting that is induced by heat generation from friction caused by the fast relative motion between wire and metal surface. Others, however, thought the metallic bonding was formed due to free electrons exchanged during fast friction process and no melting occurred. So far no direct experimental evidence is obtainable for the bonding mechanism. The time history of contact temperature is a good indicator for this understanding. During the bonding process, if the contact temperature was higher than the melting temperature, the melting and re-solidification should be a reasonable mechanism. Otherwise, the mechanism could be the latter.
From the literature, the available experimental study showed that the contact surface temperature was about 80oC. This low temperature might be due to using an oversized and insensible temperature sensor. In the present study a thin-film, K-type thermocouple, 80m in width, fabricated by sputtering deposition is used to measure the transient temperature during the bonding process. Result shows that the contact temperature was up to 170oC. Thus it is reasonable to conjecture that contact temperature can be even higher if a more smaller temperature sensor is used.
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