| 摘要 |
PURPOSE:To improve die bonding strength by forming the surface of a submount base with an Au layer, providing thereupon a barrier layer consisting of a Ti layer, a Ni layer, and an Ag layer, and forming thereupon a soldering layer. CONSTITUTION:A submount base 1 made up of an electric insulating material, the entire surface on which to bond a chip in the base 1 being made to comprise an electric wiring layer 2 which doubles as a barrier layer consisting of a Ti layer 2a, a Ni layer 2b, and Au layer 2c in this order from the side of the base 1. By forming a barrier layer 3 consisting of a Ti layer 3a, a Ni layer 3b, and an Ag layer 3c in this order from the side of the base 1 only on the part in which the chip is to be bonded on this electric wiring layer, a soldering layer 5a is formed on this barrier layer 3. Further, on the entire surface which is to be bonded to a radiating metal block in the base 1, a barrier layer 4 consisting of a Ti layer 4a, a Ni layer 4b, and an Ag layer 4c is formed, and a soldering layer 5b is formed on the entire surface of such barrier layer 4. According to the constitution, the Au layers 2a, 4a are not in direct contact with the soldering layers 5a, 5b, whereby the bonding strength can be improved.
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