Patent ES-8306922-A1 (ES)
Title: Semiconductor power device assembly
IPC: H01L21/50
Filed: 1981-06-19
Abstract: EP--42693 A The assembly includes a heat spreader (12) of e.g. copper with a thin gold or nickel layer (13) plated on its upper surface. A semiconductor power transistor chip (10) is soldered to the heat spreader. A chamfered lower surface of the spreader has a layer (14) of a ceramic such as aluminium oxide, sprayed on it, as by a plasma spraying operation. The ceramic layer is bonded to a copper base providing a heat sink (15) by a layer (16) of epoxy resin loaded with particles of silver to render the layer thermally inductive. - In a second form the heat spreader has no chamfered edge and so the layer of ceramic is flat. On the other hand, the base is provided with a central raised portion by coining. This portion has an upper surface of smaller cross-sectional area than that of the heat spreader. Other ceramics which may be used are oxides of zirconium, titanium or magnesium, or nitride ceramics such as silicon nitride may be used. The preferred particle size for the sprayed ceramic is in the range of five to forty-five micrometres. EPAB- EP--42693 B The assembly includes a heat spreader (12) of e.g. copper with a thin gold or nickel layer (13) plated on its upper surface. A semiconductor power transistor chip (10) is soldered to the heat spreader. A chanfered lower surface of the spreader has a layer (14) of a ceramic such as aluminium oxide, sprayed on it, as by a plasma spraying operation. The ceramic layer is bonded to a copper base providing a heat sink (15) by a layer (16) of epoxy resin loaded with particles of silver to render the layer thermally inductive. - In a second form the heat spreader has no chamfered edge and so the layer of ceramic is flat. On the other hand, the base is provided with a central raised portion by coining. This portion has an upper surface of smaller cross-sectional area than that of the heat spreader. Other ceramics which may be used are oxides of zirconium, titanium or magnesium, or nitride ceramics such as silicon nitride may be used. The preferred particle size for the sprayed ceramic is in the range of five to forty-five micrometres.  (11pp Dwg. No.1) - EP--42693 B The assembly includes a heat spreader (12) of e.g. copper with a thin gold or nickel layer (13) plated on its upper surface. A semiconductor power transistor chip (10) is soldered to the heat spreader. A chamfered lower surface of the spreader has a layer (14) of a ceramic such as aluminium oxide, sprayed on it, as by a plasma spraying operation. The ceramic layer is bonded to a copper base providing a heat sink (15) by a layer (16) of epoxy resin loaded with particles of silver to render the layer thermally inductive. - In a second form the heat spreader has no chamfered edge and so the layer of ceramic is flat. On the other hand, the base is provided with a central raised portion by coining. This portion has an upper surface of smaller cross-sectional area than that of the heat spreader. Other ceramics which may be used are oxides of zirconium, titanium or magnesium, or nitride ceramics such as silicon nitride may be used. The preferred particle size for the sprayed ceramic is in the range of five to forty-five micrometres. (Dwg.1) - EP--42693 B A semi-conductor power device assembly comprising  a semi-conductor power device (10,110), a heat spreader (12,112) to which the semi-conductor power device is secured, a base material (15,115), and means disposed between the heat spreader and the base material for securing the heat spreader and the base material together and for electrically insulating the heat spreader from the base material, characterised in that said means comprises a ceramic layer (14,114) which has been sprayed onto the heat spreader (12,112) and means (16,116) bonding the ceramic layer (14,114) to the base material (15,115).  (6pp) USAB- US4450471 A The heat spreader has a thin ceramic layer plasma sprayed onto its lower surface which may be chamfered. The upper surface of the spreader is then plated with a thin nickel or gold layer and a semi-conductor power device is soldered to the latter. The spreader is then secured via the ceramic layer to a base material serving as a heat sink by a layer of epoxy resin loaded with silver particles. - The thin ceramic layer electrically insulates the spreader from the base material but enables heat conduction inbetween. The application of the plasma sprayed ceramic layer to the spreader is easy and economical to effect. Pref. the silver particles range in size from 5 to 45 microns.  (5pp)h