| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 96 === Traditionally, gold is the preferred material to connect IC chips to lead frames or the bond pads by a thermosonic process. The inherent properties, such as higher electrical and thermal conductivity, of copper as well as its cost effectiveness, when compared to gold, have made it a preferred alternative. But the shortcoming for copper bond arises from the stand point of oxidation and the lower ductility, which might cause poor bondability.
This thesis reports investigation of EFO (electric flame-off) characteristics of continually annealed copper wire with different diameters, it has been reported that the wire size has no effects on the properties of the HAZ (heat affected zone) when the wire diameter ranges from 20 to 25μm.
On the next part, the effects of annealing and EFO process on the 20μm copper wire have been simultaneously studied. On the whole, the annealing process improves the ductility of the wire, while EFO weakens the strength of as-drawn samples, and lowers the elongation of annealed ones. And it is worth noting that the HAZ dimensions of wires with two different annealing conditions (610℃/0.02sec and 510℃/0.4sec) are quite identical.
In this study, the 20μm-diameter copper wire are bonded to aluminum film, which has been deposited onto quartz-glass substrates, by a thermosonic process. It is discovered that the pull strength of bonded samples are varied with the film thickness, which ranges from 76 to 800nm. On the other hand, the oxidized balls are also found to form bonds with the substrates, and the structures in the balls are mainly dendrite, which could cause the lower bondability.
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