| 摘要 |
1,258,309. Semi-conductor devices. GENERAL ELECTRIC CO. 27 March, 1969 [9 April, 1968], No. 16207/69. Heading H1K. In a semi-conductor device comprising a wafer enclosed in a sealed housing and contacted by electrodes on opposite faces mounted under pressure by means of an external thrust member acting on one of the electrodes, a strain buffer of a material having a coefficient of expansion approximately the same as that of the semi-conductor material is disposed between the thrust member and the electrode. The strain buffer prevents distortion of the wafer due to friction at the sliding pressure contacts during thermal cycling. As shown, a thyristor 12 comprising a silicon wafer (22) mounted on a tungsten or molybdenum plate (23) is disposed between two ductile dish shaped electrodes 29, 30 of copper, silver, aluminium or brass, plated with nickel, silver or gold brazed to the ends of two ceramic cylinders 34, 35. The upper face of the semi-conductor wafer is provided with a coating (25) of gold, silver, indium, rhodium or nickel, and the lower face of the carrier plate is coated with a layer (24) of gold-nickel alloy. The gate electrode (26) of the thyristor is connected to an annular plate 37 brazed to the upper end of cylinder 34 and the edge of the wafer is covered with a layer 28 of silicone rubber. The lower end of the ceramic cylinder 35 is also provided with an annular plate 36 which is welded to plate 37 in an inert atmosphere to complete the housing. The dish shaped electrodes 29, 30 are pressed into contact with the thyristor structure by means of posts 20, 21 of copper, aluminium or brass the ends of which are coated with silver, nickel or gold. A strain buffer 45 of tungsten, molybdenum or chromium or an iron-nickel or iron-nickelcobalt alloy plated with nickel, silver or gold is disposed between the upper post 21 and the upper electrode 30. The surfaces of the buffer may be lubricated with a thin film of silicone oil to reduce the friction at the sliding contact. The upper electrode 30 is shaped to clear the gate contact and its connection to the ring 37 and the post 21 and strain buffer 45 are correspondingly shaped. The strain buffer 45 may be brazed or otherwise attached to the lower end of the post 21. Resilient rings 46 are provided to support the housing between the posts. The semiconductor device may comprise a rectifying diode instead of a thyristor. |
