Claims
- 1. A primer housing for a semiconductor bridge device, comprising:
- a primer cup having a base and sidewalls with an aperture formed in said base;
- a primer button located within said aperture and electrically isolated from said primer cup;
- an electrical conductive washer contacting a bonding site on said semiconductor bridge device and being in electrical contact with both said semiconductor bridge device and an interior surface of said sidewalls;
- said primer cup, primer button, and electrically conductive washer individually selected from the group consisting of copper, aluminum, copper alloys, aluminum alloys andiron-nickel alloys;
- an electrically conductive compliant die attach material both bonding and electrically interconnecting said semiconductor bridge device to said primer button; and
- a dielectric material selected from the group consisting of polymers, ceramics and glasses disposed between said primer button and said primer cup.
- 2. The primer housing of claim 1 wherein said washer is formed from a copper alloy having a spring temper and is maintained in electrical contact with said semiconductor bridge device by spring tension.
- 3. The primer housing of claim 2 wherein said semiconductor bridge device includes bumps on the bonding site which contacts said washer.
- 4. The primer housing of claim 3 wherein a gold metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 5. The primer housing of claim 3 wherein a silver metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 6. The primer housing of claim 2 wherein a gold metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 7. The primer housing of claim 2 wherein a silver metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 8. The primer housing of claim 2 wherein said copper alloy washer is selected from the group consisting of copper alloys C194, C195 and C260.
- 9. The primer housing of claim 8 wherein said washer is silver plated copper alloy C260.
- 10. The primer housing of claim 9 wherein a nickel diffusion layer is disposed between said copper alloy C260 washer and said silver plating.
- 11. The primer housing of claim 8 wherein said washer is gold plated copper alloy C260.
- 12. The primer housing of claim 11 wherein a nickel diffusion layer is disposed between said gold plating and said copper alloy C260 washer.
- 13. The primer housing of claim 1 wherein said washer is maintained in electrical contact with said semiconductor bridge device by soldering to said bonding site.
- 14. A primer housing for a semiconductor bridge device, comprising:
- a primer cup having a base and sidewalls with an aperture formed in said base;
- a primer button located within said aperture and electrically isolated from said primer cup;
- an electrical conductive washer contacting a bonding site on said semiconductor bridge device and being in electrical contact with both said semiconductor bridge device and an interior surface of said sidewalls;
- said primer cup, primer button, and electrically conductive washer individually selected from the group consisting of copper, aluminum, copper alloys, aluminum alloys and iron-nickel alloys;
- an electrically conductive buffered die attach material, both bonding and electrically interconnecting said semiconductor bridge device to said primer button; and
- a dielectric material selected from the group consisting of polymers, ceramics and glasses disposed between said primer button and said primer cup.
- 15. The primer housing of claim 14 wherein said washer is formed from a copper alloy having a spring temper and is maintained in electrical contact with said semiconductor bridge device by spring tension.
- 16. The primer housing of claim 15 wherein said semiconductor bridge device includes bumps on the bonding site which contacts said washer.
- 17. The primer housing of claim 16 wherein a gold metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 18. The primer housing of claim 16 wherein a silver metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 19. The primer housing of claim 15 wherein a gold metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 20. The primer housing of claim 15 wherein a silver metallization layer is deposited on said bonding site to reduce electrical resistivity.
- 21. The primer housing of claim 15 wherein said copper alloy washer is selected from the group consisting of copper alloys C194, C195 and C260.
- 22. The primer housing of claim 21 wherein said washer is silver plated copper alloy C260.
- 23. The primer housing of claim 22 wherein a nickel diffusion layer is disposed between said copper alloy C260 washer and said silver plating.
- 24. The primer housing of claim 21 wherein said washer is gold plated copper alloy C260.
- 25. The primer housing of claim 24 wherein a nickel diffusion layer is disposed between said gold plating and said copper alloy C260 washer.
Parent Case Info
"This application is a division of application Ser. No. 07/412,252, filed Sep. 25, 1989, now U.S. Pat. No. 5,029,529."
The present invention relates to a metal package for housing a semiconductor device. More particularly, the invention relates to a cup shaped package for housing a semiconductor bridge (SCB) initiator circuit in close proximity to an explosive medium.
Military weapon systems are typically activated by a primer system. The primer usually employs a small metal bridgewire to ignite a contained explosive mixture. An electric current typically in the range of from about 3 amps to about 5 amps is passed through the bridgewire. Internal resistance heats the bridgewire to a temperature in excess of about 900.degree. K. The hot bridgewire ignites an energetic powder,, triggering the primer which in turn ignites the primary system. The system may incorporate a pyrotechnic mixture for use as a flare or tracer, a propellant or an explosive powder.
In addition, bridgewire initiated primer systems find application outside the military. The systems are employed in the automotive industry to inflate automotive airbags upon impact.
A problem with the bridgewire type primer is a sensitivity to externally generated electric circuits. High levels of electromagnetic energy from sources such as radio waves, static electricity, lightning or radar may induce an electric current within the bridgewire sufficient to cause an undesired, premature ignition. The problem is sufficiently serious that certain radar installations must be deactivated while military aircraft land. As disclosed in the New York Times (Feb. 23, 1989), the emissions from the radar are believed capable of initiating an accidental detonation.
A solution to the induced current problem encountered in bridgewire type initiator is disclosed in U.S. Pat. No. 4,708,060 to Bickes, Jr. et al and in Sandia National Labs Report No. SAND 86-2211 edited by Bickes, Jr. Both of which are incorporated herein by reference. A semiconductor bridge circuit will initiate the explosive reaction within the primer when a current is applied. The SCB circuit is significantly less susceptible to induced electric currents and the resultant possibility of accidental or premature ignition is reduced.
A semiconductor bridge circuit comprises a circuit formed on a semiconductor material such as silicon or gallium arsenide. A heavily doped region of an n-type dopant such as phosphorous is vaporized when a current of sufficient amperage is applied. The silicon vapor is electrically heated and permeates the adjacent energetic powder mixture. Through localized convection and condensation, the energetic powder is heated to its ignition temperature leading to the desired explosive reaction being initiated.
The advantages of the SCB type initiator over the bridgewire include lower voltage requirements, less susceptibility to accidental or premature initiation and more rapid firing times. However, to the best knowledge of the inventors, there has not yet been developed a satisfactory means to house an SCB circuit.
The SCB circuit is formed on a brittle semiconductor substrate. The package housing the device must provide both mechanical and environmental protection to the device. The components making up the electronic package must also be compatible with the SCB device, the energetic powder and the remainder of the explosive system.
Presently the device is mounted on a ceramic header containing KOVAR feed through pins. Aluminum or gold wires electrically interconnect the feed throughs to bonding sites on the semiconductor device. The package is not a preferred structure. The ceramic header is brittle and may not withstand rough handling. The wire bonds have a high profile and may break due to stresses resulting from contact with the powder. Forming ceramic headers with metal feed throughs is a relatively expensive process adding to the cost of the device. Also, the profile of the feed throughs is not compatible with the wiping device used to activate the primer thereby firing the weapon.
Therefore, in accordance with the invention, there is provided an electronic package primer incorporating a semiconductor bridge type initiator circuit which does not have the disadvantages of a ceramic header type package. It is an advantage of the present advantage that the package components are manufactured from metal and may be readily formed into shape by conventional mechanical processes such as deep drawing, coining, cupping and stamping. It is another advantage of the invention that in one embodiment of the invention the leadwire lengths are reduced and in a second embodiment the leadwires are eliminated minimizing the potential for lead breakage and subsequent device failure. Yet another advantage of the electronic packages of the invention is that ductile components are employed increasing the resistance of the primer package to mechanical damage. It is a feature of the invention that the package components may be coated with a corrosion resistant material to minimize package degradation due to exposure to hostile environments or to the energetic powder.
Accordingly, there is provided a metal or metal alloy primer housing adapted to secure a semiconductor bridge circuit in close proximity to an energetic medium. The housing comprises a primer cup having an aperture in the base, a primer button is positioned within the aperture. An electrically conductive washer is electrically interconnected to an interior sidewall of the primer cup. A dielectric medium electrically isolates the primer button from both the housing and from the conductive washer. A means is provided to electrically interconnect the SCB to both the primer button and to the housing.
The above-stated objects, features and advantages of the invention as well as others will become apparent to those skilled in the art from the specification and accompanying figures which follow wherein primed reference numerals indicate components which are substantially the same as the components identified by the same unprimed reference numerals.
US Referenced Citations (14)
Foreign Referenced Citations (3)
| Number |
Date |
Country |
| 3308635 |
Mar 1983 |
DEX |
| 3537820 |
Oct 1985 |
DEX |
| 960186 |
Jun 1964 |
GBX |
Non-Patent Literature Citations (2)
| Entry |
| Bickles, Jr. "Semiconductor Bridge (SCB) Development Transfer Symposium" prepared by Sandia National Laboratories, unlimited release as SAND86-2211.UC-13 printed Jan. 1987, pp. 1-146 (Sandia Report). |
| New York Times, Feb. 12 1989 "Defense Radar must Turn Off As Planes Land". |
Divisions (1)
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Number |
Date |
Country |
| Parent |
412252 |
Sep 1989 |
|
Patent Grant
5113764
