| 摘要 |
<p>PURPOSE:To obtain a support electrode plate having a low thermal expansion coefficient approximate to the value of a thermal expansion coefficient of a semiconductor element and being excellent in a thermal dissipation property, inexpensive and easy to process by a construction wherein a high thermal conductivity metal layer on the side whereon the semiconductor element is superposed is made thicker than a high thermal conductivity metal layer on the side separate from the semiconductor element. CONSTITUTION:While operating as one electrode of a semiconductor element, an electrode plate 3 relaxes a thermal stress occurring between the semiconductor element 1 and a heat- radiating plate 8 which are different in a large degree in a thermal expansion coefficient from each other, and therefore it is preferable that a thermal conductivity is as high as possible. The heat transmitted to the composite metal electrode plate 3 and expands in the direction of the peripheral edge of the electrode plate 3 within a high thermal conductivity layer 4 thereof simultaneously with the conduction in the direction of the thickness of the plate, and transfers to an expansion layer 5 through the entire interface of contact with the expansion layer 5. A high thermal conductivity layer 6 separate from the semiconductor element functions to prevent the warp of the entire electrode plate 3 caused by a bimetal effect subsequent to a rise in temperature. After all, the thermal expansion coefficient of the electrode plate 3 in the direction of the peripheral edge thereof is determined on the basis of the total thickness of the two high thermal conductivity layers 4 and 6 and the thickness of the low thermal expansion layer 5, and thus the high thermal conductivity layer 6 remote from the element is thinned by an amount in which the high thermal conductivity layer 4 on the side near to the semiconductor element is thickened.</p> |
