Abstract: The adhesion of plastic encapsulants to electrical leadframes containing substantial amounts of copper is improved by exposing the leadframes to an active oxygen ambient (e.g., 10-30% H.sub.2 O.sub.2) at temperatures below the leadframe annealing temperature (e.g., room temperature to 100.degree. C.) for a few minutes. There is no need to remove the native oxide. A preliminary degreasing step is desirable but not essential. The treatment strengthens any native oxide present on the leadframes without producing an oxide which is so thick as to interfere with subsequent bonding of electronic components or connecting wires to the leadframe. Delamination between the leadframe and the plastic encapsulant by temperture cycling from -65.degree. to 150.degree. C. is substantially reduced.

Abstract: An improved laser markable material useful for encapsulation of electroic devices is obtained by adding TiO.sub.2 or TiO.sub.2 +CrO.sub.3 to common plastic encapsulants formed from a mixture of a resin+filler+carbon black+mold release agent. When irradiated by a laser, the originally grey material turns bright gold, providing a high contrast durable mark. The material has excellent marking contrast as well as better stability with time and temperature as compared to prior art laser markable encapsulants. Desirable concentrations, in weight percent of the compound, are 1-5% TiO.sub.2 and 0-3% CrO.sub.3, with 1-3%TiO.sub.2 and 0.5-2% CrO.sub.3 being preferred. Carbon black is optional but a concentration in the range 0.1-3% by weight is desirable with 0.5-1% preferred. Improved encapsulation and marking methods and improved devices using this material are described.

Abstract: An improved laser markable material useful for encapsulation of electronic devices is obtained by adding TiO.sub.2 or TiO.sub.2 +CrO.sub.3 to common plastic encapsulants formed from a mixture of a resin+filler+carbon black+mold release agent. When irradiated by a laser, the originally grey material turns bright gold, providing a high contrast durable mark. The material has excellent marking contrast as well as better stability with time and temperature as compared to prior art laser markable encapsulants. Desirable concentrations, in weight percent of the compound, are 1-5% TiO.sub.2 and 0-3% CrO.sub.3, with 1-3% TiO.sub.2 and 0.5-2% CrO.sub.3 being preferred. Carbon black is optional but a concentration in the range 0.1-3% by weight is desirable with 0.5-1% preferred. Improved encapsulation and marking methods and improved devices using this material are described.

Abstract: A semiconductor device including a metallurgically compatible unplated package is provided. The package includes a plateless copper alloy die mount area to which a semiconductor die is attached. The semiconductor die is metallized on its mounting surface to provide electrical contact. A metallic solder which is compatible with both the copper alloy and the die metallization joins the die to the die mount area. The package further includes a plateless copper alloy lead portion which is physically joined to the die mount area. The top surface of the semiconductor die is provided with a patterned metallization making electrical contact to selected portions of the die. Electrical contact is made between the top surface die metallization and the lead portion of the package by ultrasonically bonded copper ribbon. The die and interconnecting ribbon is then enclosed by an epoxy encapsulant or by a welded metal cover.

Abstract: Passivation, alpha protection and other relatively thick, patterned layers are applied to semiconductor wafers by a screen printing method. Patterned emulsions carried on fine mesh stainless steel screens are tempered at elevated temperatures to harden the emulsion. The screens so prepared withstand many cycles of printing and cleaning with harsh solvents present in screenable polymers such as polyimide and rigid silicone.

Abstract: An improved laser markable material useful for encapsulation of electronic devices is obtained by adding TiO.sub.2 or TiO.sub.2 +CrO.sub.3 to common plastic encapsulants formed from a mixture of a resin+filler+carbon black+mold release agent. When irradiated by a laser, the originally grey material turns bright gold, providing a high contrast durable mark. The material has excellent marking contrast as well as better stability with time and temperature as compared to prior art laser markable encapsulants. Desirable concentrations, in weight percent of the compound, are 1-5% TiO.sub.2 and 0-3% CrO.sub.3, with 1-3% TiO.sub.2 and 0.5-2% CrO.sub.3 being preferred. Carbon black is optional but a concentration in the range 0.1-3% by weight is desirable with 0.5-1% preferred. Improved encapsulation and marking methods and improved devices using this material are described.

Abstract: An improved high power semiconductor device and manufacturing method are described wherein one or more die are assembled to one electrode having a heat transfer face and additional insulated electrodes, said electrode having bent up and bent over portions forming high current terminals and control terminals such that the current terminals and control terminals lie in different planes and such that terminal spacings satisfy Underwriters Laboratory recommendations. The die and electrode assembly is partly encapsulated preferably in plastic. The current terminals are diagonally located to facilitate use of standard bus bar arrangements with different device orientations. Connection nuts are movably retained to limit transfer of tightening torque to the plastic body. Choices of materials are described.

Abstract: An improved power semiconductor device and manufacturing method are described wherein the external, thermally conducting, heat transfer face of the device is electrically insulated by a glassy dielectric which is intimately bonded directly to the conductive heat spreader supporting the semiconductor die. By forming the exposed corners of the heat spreader to be substantially smooth curved surfaces having a predetermined minimum radius of curvature greater than the thickness of the glassy dielectric, formation of a ridge of glass at the corners and edges of the heat spreader is avoided. For ease of assembly the piece parts are initially substantially flat and parallel. A molding compound of controlled shrinkage is used to avoid distorting the substantially flat smooth insulated heat transfer face which remains exposed in the encapsulated device.

Abstract: A semiconductor device including a metallurgically compatible unplated package is provided. The package includes a plateless copper alloy die mount area to which a semiconductor die is attached. The semiconductor die is metallized on its mounting surface to provide electrical contact. A metallic solder which is compatible with both the copper alloy and the die metallization joins the die to the die mount area. The package further includes a plateless copper alloy lead portion which is physically joined to the die mount area. The top surface of the semiconductor die is provided with a patterned metallization making electrical contact to selected portions of the die. Electrical contact is made between the top surface die metallization and the lead portion of the package by ultrasonically bonded copper ribbon. The die and interconnecting ribbon is then enclosed by an epoxy encapsulant or by a welded metal cover.

Abstract: An improved high power semiconductor device and manufacturing method are described wherein one or more die are assembled to one electrode having a heat transfer face and additional insulated electrodes, said electrode having bent up and bent over portions forming high current terminals and control terminals such that the current terminals and control terminals lie in different planes and such that terminal spacings satisfy Underwriters Laboratory recommendations. The die and electrode assembly is partly encapsulated preferably in plastic. The current terminals are diagonally located to facilitate use of standard bus bar arrangements with different device orientations. Connection nuts are movably retained to limit transfer of tightening torque to the plastic body. Choices of materials are described.

Abstract: An improved power semiconductor device and manufacturing method are described wherein the external, thermally conducting, heat transfer face of the device is electrically insulated by a glassy dielectric which is intimately bonded directly to the conductive heat spreader supporting the semiconductor die. By forming the exposed corners of the heat spreader to be substantially smooth curved surfaces having a predetermined minimum radius of curvature greater than the thickness of the glassy dielectric, formation of a ridge of glass at the corners and edges of the heat spreader is avoided. For ease of assembly the piece parts are initially substantially flat and parallel. A molding compound of controlled shrinkage is used to avoid distorting the substantially flat smooth insulated heat transfer face which remains exposed in the encapsulated device.

Abstract: A solder system for metallurgically bonding a semiconductor die to a metal package member. The solder is based on the tin rich corner of the tin-antimony-silver ternary alloy system. The solder system has particular applicability to the bonding of power transistors.