SEMICONDUCTOR DEVICE PACKAGES

Abstract: An igniter device for use in automotiver airbags includes two pins (16, 17) used as male connecting elements to a firing system. One pin (16) is directly connected to an electrically conductive header (18) and the other pin (17) extends through the header (18) and is insulated therefrom by means of a glass seal (20) which provides full hermeticity to the device. A semiconductor igniter die (21) is bonded on its underside to the conductive surface of the header (18) and is connected to the pin (17) via a wire (22) connected to a bond pad on the top side of the die. The semiconductor die (21) has a bottom surface of the die which provides a contact so that only one wire bond is needed on the top surface. A can body (23), of relatively thin wall thickness and made of nickel, iron or other ferromagnetic material has a flange (25) which is hermetically sealed to the header (18). A cavity is therefore created that is filled with a predetermined amount of pyrotechnic material (24).

Description: SEMICONDUCTOR DEVICE PACKAGES FIELD OF THE INVENTION This invention relates to semiconductor device packages. BACKGROUND OF THE INVENTION The use of semiconductor fuse elements in igniter devices for automobile applications where the igniter element explodes so as to inflate airbags or tighten seatbelt retractors has been suggested. Such igniter devices would include a semiconductor fuse device mounted in a package formed of a header having two terminals extending therefrom for receiving current from control circuitry to actuate the fuse device and an enclosure member (hereinafter referred to as a "can body") denning a cavity within which is placed a predetermined amount of pyrotechnic material provided in close proximity to the semiconductor fuse device so as to be ignited thereby. One problem of using semiconductor fuse devices in known igniter devices is the making of safe connection of the igniter devices to other systems with which they must interact. This is especially so in vehicular applications. A second problem is that known igniter devices can be unreliable in certain climatic conditions or after prolonged periods. BRIEF SUMMARY OF THE INVEN ION Accordingly, in one aspect, the invention provides a two terminal semiconductor package comprising a header having an electrically conductive mounting surface for receiving a semiconductor device thereon and two pins extending externally from the header to provide two external terminals, a first one of said pins extending through said header and being insulated therefrom to provide an internal terminal for coupling to the semiconductor device, a second one of the pins being electrically coupled to the mounting surface of the header, said header being provided with a flange for receiving a can body, wherein said pins are sufficiently thick and rigid to make a mechanical non- soldered electrical connection with a connector adapted to receive the terminals of the package. In a second aspect, the invention provides a semiconductor package comprising a two terminal semiconductor device having one terminal formed by a surface of the device and a second terminal provided by a contact on the device, a header having an electrically conductive mounting surface on an internal side of the header and a flange around the periphery of the header for receiving a can body extending over said device and being attached to the flange of said header, the semiconductor device being mounted with its said surface in electrical contact with said mounting surface, and a pair of terminals extending from an external side of the header, one of said terminals being in electrical contact with said mounting surface and the other of said terminals being insulated from the header and passing through said header to the internal side thereof and being electrically coupled to said contact of said device. In another aspect, the invention provides a semiconductor igniter device for automotive airbag or seatbelt retractor ignition, the device comprising a header having mounted thereon an igniter element and having a flange therearaound for mating with a can body which extends over the igniter element and is hermetically sealed to the flange. BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be more fully described, by way of example, with reference to the drawings, of which: FIG. 1 shows a schematic cross-section through a known igniter device; FIG. 2 shows a schematic cross-section through a second known igniter device; and FIG. 3 shows a schematic cross-section through an igniter device according to the invention. DETAILED DESCRIPTION Thus, as shown in FIG. 1, a known igniter device comprises two pins 1 extending through a header 2 compressed in a metal envelope 3. A resistive wire 4 is electrically connected between the ends of the pins 1 . The two pins 1 are used as male connecting elements to the firing system. .An epoxy moulded can body structure 5 is attached to the metal envelope 3 and a predetermined amount of pyrotechnic material 6 is compressed within the cavity between the header 2 and the can body structure 5 against the resistive wire 4. The igniter device is then usually surrounded by more pyrotechnic material surrounded by gas-producing material so as to inflate automotive airbags. When the pyrotechnic material 6 is to be ignited, a current is driven through the wire 4 via the pins 1 so as to heat up the wire 4 and thus ignite the pyrotechnic material 6. Such a device, however, cannot provide full hermeticity in the cavity, because the epoxy can body structure 5 cannot be hermetically sealed to the metal envelope 3 and there is no structure present to provide such sealing. Thus, humiditu or other contaminants can penetrate between the can body structure and the metal envelope and degrade the pyrotechnic material. Furthermore, this type of igniter device, which uses a current-passing wire to ignite the pyrotechnic material is not particularly suitable for use with modern semiconductor type fuse devices. FIG. 2 shows a cross section of a second known igniter device used in military applications. The device includes a header 9 having an electrically conductive mounting surface for receiving a semiconductor chip 11 of a type having two wire bond pads and a fuse section between them. One pin 8 extends through the header 9 and insulated therefrom by an insulating layer 10, for example of glass. The other pin 7 is electrically attached to the header 9. Both pins 7 and 8 are used to electrically link the device to a firing system. Electrical connection of the semiconductor chip 11 to pin 8 is made by direct connection with a wire 13 bonded to a pad on the chip 11 and to the end of pin 8. Electrical connection to pin 7 is made by bonding a wire 12 between a pad on the chip 11 and the header 9. A can body 14 is glued to the header 9, thus creating a cavity that is filled with pyrotechnic material 15. Since the device is used in military applications, it is generally required that the pyrotechnic material 15 explode in one preferred direction. Therefore, the can body 14 has a relatively large wall thickness and is made of brass. This means that the can body 14 cannot be hermetically sealed, for example by welding, to the header, which is generally made of gold-plated Kovar alloy material. This device actually uses a modified standard semiconductor package, e.g. a T046 package, which is designed for connection with a printed circuit board connector and the pins are therefore too thin for direct insertion into automotive female connectors and their spacing is not correct for standard female automotive connectors which are widely used throughout the automotive industry. Accordingly, complicated additional mechanical structural modifications would be required to enable the device to connect with automotive connectors. As shown in FIG.3, in an igniter device according to one embodiment of the present invention, two pins 16, 17 are used as male connecting elements to a firing system. Pin 16 is directly connected to an electrically conductive header 18. Pin 17 extends through the header 18 and is insulated therefrom by means of a glass seal 20 which provides full hermeticity to the device . A semiconductor die 21 is bonded on its underside to the conductive surface of the header 18 and is connected to the pin 17 via a wire 22 connected to a bond pad on the top side of the die. The bottom surface of the semiconductor die 21 provides a contact so that only one wire bond is needed on the top surface. A can body 23, of relatively thin wall thickness and made of nickel, iron or other ferromagnetic material has a flange 25 which is hermetically sealed, for instance by electric welding, to a flange 19 of the header 18. A cavity is therefore created that is filled with a predetermined amount of pyrotechnic material 24. This structure provides full hermeticity in the cavity and provides a direct connection to the firing system. Because the semiconductor die 21 only has one wire bond from its top surface, there is sufficient area on the header for the two pins to be of a sufficient thickness and therefore strength for direct insertion into standard female automotive connectors to make a mechanical non-soldered electrical connection. The pins 16 and 17 are each provided with a bend 26 to provide the appropriate spacing at their ends for insertion into the standard female automotive connector. .Although the described embodiment of the invention uses two pins for connection to a firing control system, it will be appreciated that the package could include three or more pins, in order to allow for more complex semiconductor igniting devices. This could be of particular interest in the event of igniter devices actuated by more complex firing signals, so as to increase the level of security, for instance in automobile applications.

Claims: CLAIMS 1. A semiconductor igniter device comprising: an igniter element; a header having an electrically conductive mounting surface for receiving the igniter element thereon; at least two pins extending externally from the header to provide two external terminals, a first one of said pins extending through said header and being insulated therefrom to provide an internal terminal for coupling to the igniter element, a second one of the pins being electrically coupled to the mounting surface of the header; a can body extending over the igniter element and being hermetically sealed to the header, said header having a flange for mating with a co¬ operating flange of the can body; and pyrotechnic material within the can body in close proximity to the igniter element. 2. A semiconductor igniter device according to claim 1 wherein said pins are sufficiently thick and rigid to make a mechanical non-soldered electrical connection with a female connector adapted to receive the terminals of the package. 3. A semiconductor igniter device according to claim 1 or 2 wherein at least one of said pins is provided with a bend so as to produce a predetermined spacing of the exterior ends of the pins suitable for connecting with a standard female automotive connector. 4. A semiconductor igniter device according to claims 1, 2 or 3, wherein at least one of said pins is hermetically sealed to the header.

Inventors: ALLIER JEAN-FRANCOIS, CAILLABA JEAN, ALLIER, JEAN-FRANCOIS, CAILLABA, JEAN
Applicants: ALLIER JEAN FRANCOIS, CAILLABA JEAN, MOTOROLA SEMICONDUCTEURS, ALLIER, JEAN-FRANCOIS, CAILLABA, JEAN, MOTOROLA SEMICONDUCTEURS S.A.
Application year: 1995
Main classification: F42B3
IPC codes: F42B3