接合界面におけるめっき層の存在と接合性への影響 マイクロパラレルシーム接合法及び接合機器の開発 １

Abstract

Among several hermetically sealing methods, we studied experimentally on Micro-Parallel Seam Joining (MPSJ) used for hermetic seal of high reliable ceramic package for semiconductor devices, particularly paying attention to the relationship between plated materials on the package and lid and its seam joining characteristics to verify the MPSJ phenomena.Results obtained are summarized as follows.(1) Cracks were observed on the ceramic substrate immediately after seam joining, that was considered to be caused by the difference in thermal expansion coefficient in the case where austenitic stainless steel, SUS-316 lid was used. Therefore, it will be required to use Fe-Ni-Co Alloy, KOVAR as a lid material which has a similar thermal expansion coefficient with the ceramic substrate (Al2O3).(2) Seam joined area was consisted of both a mutually diffused layer at the joining boundary formed by plating material for the lid and seal frame and the fillet formed around the circumferential edge of the lid. No molten layer of both base materials existed.(3) The main reason for the paragraph (2) is the fact that density of heat generation at the joining boundary will decrease because of current path area expands due to softening and fusion of plating material concurrent with the current flow. Therefore, both the contact resistance between the lid and roller electrodes and inherent resistance of the lid will be the majority for heat generation source. Consequently, lid and seal frame will be joined in the form of brazing under pressure of plating material.(4) From the above results, it has been verified that plating material for the lid and seal frame plays an important role to secure specified hermeticity in the case of hermetic sealing of ceramic packages by MPSJ.