| Budget Amount *help |
¥7,500,000 (Direct Cost: ¥7,500,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1996: ¥6,400,000 (Direct Cost: ¥6,400,000)
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| Research Abstract |
The anodic bonding has recently absorbed considerable attention as a process by which the glass can be bonded to the metal at lower bonding temperatures with smaller deformation of the materials than other processes, but only little information has been reported about its fundamental bonding mechanism. In the present project, we have investigated the influences of the properties of metals on interfacial phenomena by anodically-bonding a glass to thin films of various metals formed on a common substrate metal, in order to obtain better insight into the bonding mechanism.
The glass specimen to be bonded was a borosilicate glass, and the metal specimen was the Kovar alloy, iron-base alloy, having a thermal expansion coefficient nearly equal to that of the glass employed. At the interface of the glass to the Kovar alloy itself, a Na depletion layr was observed, within which a K depletion layr and a following K pile-up layr were formed. In the area closer to the joint interface within these
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layrs, an amorphous layr of about 100 nm thickness consisting of a Fe-Si complex oxide was found by TEM observations. This interfacial reaction layr can be considered to be an anodically-oxidized layr which has been suggested as a binder between glass and metal by many authors.
When the glass was bonded to Si and Al that can furnish only fewer mobile cations to the glass than Fe, the enlargement of the intimately-contacted area was much accelerated as compared with the glass/Kovar alloy joint, and the growth of the Na and K depletion layrs was much restricted. In contrast to this, at the joint interface of the glass to Ag that can furnish abundant mobile cations to the glass, the Na depletion layr became very thick, and an Ag penetration layr was formed to almost the same depth as the Na depletion layr, while no K depletion or pile-up layr was observed. The bond strength of the glass/Ag joint, however, was much lower than the other joints. Analyzes of the potential distribution in the glass during the anodic bonding suggest that these results can be explained as resulting from the compensation of the negative charge accumulation in the Na depletion layr by the cation furnished by the metal. Less
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