| Microstructure of direct bonded copper-alumina substrate has been investigated using SEM, EDX, and EPMA. Its interfacial strength was also evaluated by peel test. When the alumina bonded at 1337 K for 0.3 ks under 4.4 Pa in contact with the copper which preoxidized at 1273 K for 0.3 ks under the oxygen partial pressure of 10 Pa, the substrates had the highest interfacial (peel) strength of 8.2㎏/㎝. Microstructural investigation demonstrated that its bonding resulted from the formation of the layer consisting of copper and Cu₂O at the interface between copper and alumina. When the density of Cu₂O particles was higher along the grain boundaries than in the grain of the copper, the substrates had the higher peel strength. In addition, the substrate had the higher strength when the shape of Cu₂O particles was spherical, not nodular. |
|
