Energetic material initiation device having integrated low-energy exploding foil initiator header

An initiator that includes a header body, an insulating spacer, an initiator chip, a plurality of terminals and a plurality of contacts. The insulating spacer is coupled to the header body. The initiator chip that forms at least a portion of an exploding foil initiator and includes a plurality of electric interfaces. The initiator chip is secured to a side of the insulating spacer opposite the header body. The terminals extend through the header body. The contacts electrically couple the electric interfaces to the terminals. The cover is coupled to the header body and cooperates with the header body to house the insulating spacer, the initiator chip and the contacts. A method for forming an initiator is also provided.

The present invention generally relates to devices for initiating combustion, deflagration and detonation events and methods for their construction.

Modern initiators, such as detonators, commonly employ materials including ceramics and stainless steels in their construction. These materials are typically selected to provide the initiator with a degree of robustness that permits the initiator to withstand extreme changes in temperature and humidity, as well as to resist oxidization. While modern initiator configurations are generally satisfactory for their intended purposes, they are nonetheless susceptible to improvement.

For example, many of these initiators, particularly those that employ exploding foil initiators, are relatively difficult and labor-intensive to fabricate. Consequently, they are relatively expensive and are not employed in many applications due to considerations for cost. One proposed solution is a plastic encapsulated energetic material initiation device of the type that is disclosed in U.S. Patent Application Publication No. 2005/0235858A1, the disclosure of which is hereby incorporated by reference as if fully set forth in detail herein. This energetic material initiation device, however, may not be suited for some applications, such as in devices that experience relatively high shock loads and/or require a very strong and durable hermetic seal.

SUMMARY

In one form, the present teachings provide a method for forming an initiator that includes: providing a header body; inserting a plurality of terminals through the header body; securing an insulating spacer to the header body, the plurality of terminals extending through the insulating spacer; coupling an initiator chip to the insulating spacer, the initiator chip including a plurality of electric interfaces; providing a lead frame having a plurality of contacts; orienting the lead frame to at least one of the header body, the terminals and the initiator chip; fixedly and electrically coupling the contacts to the terminals and the electric interfaces; and shearing the contacts from a remainder of the lead frame.

In another form, the present teachings provide an initiator that includes a header body, an insulating spacer, an initiator chip, a plurality of terminals and a plurality of contacts. The insulating spacer is coupled to the header body. The initiator chip that forms at least a portion of an exploding foil initiator and includes a plurality of electric interfaces. The initiator chip is secured to a side of the insulating spacer opposite the header body. The terminals extend through the header body. The contacts electrically couple the electric interfaces to the terminals. The cover is coupled to the header body and cooperates with the header body to house the insulating spacer, the initiator chip and the contacts.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

With reference toFIGS. 1 and 2of the drawings, an initiator constructed in accordance with the teachings of the present invention is generally indicated by reference numeral10. While the initiator10is illustrated as being a detonator-type initiator, the initiator10may be any type of initiator and may be configured to initiate a combustion event, a deflagration event and/or a detonation event. The initiator10can include a header assembly20, an insulator barrel22, an input sleeve24, an input charge26, a barrier28, an output charge30and a cover32.

With reference toFIGS. 3 and 4, the header assembly20can include a header40, an insulating spacer42, a frame member44, an initiator chip46and a plurality of contacts48. The header40can include a header body50, a plurality of terminals52, and a plurality of seal members54.

The header body50can be formed of an appropriate material, such as KOVAR®, and can be shaped in a desired manner. The header body50can define first and second end faces60and62, respectively, a shoulder64, a plurality of first terminal apertures66and a second terminal aperture68. The shoulder64can include an abutting face70, which can be generally parallel to the first and second end faces60and62, and a shoulder wall72that is generally perpendicular to the abutting face70. The first terminal apertures66can be formed through the header body50generally perpendicular to the first and second end faces60and62. The second terminal aperture68can be a blind hole that is formed in the header body50through the first end face60.

With additional reference toFIG. 1, a first quantity of the terminals52(e.g., terminals52athrough52d) can be received in respective ones of the first terminal apertures66and can extend outwardly from the first and second end faces60and62. A remaining one of the terminals52ecan be received in the second terminal aperture68and can be fixedly electrically coupled to the header body50. In the particular example provided, the terminal52eis soldered to the header body50and can serves as a means for electrically coupling the header body50to an electric ground (not shown). It will be appreciated that the terminals52can be arranged in a non-symmetrical manner to thereby key the header40in a particular orientation relative to the device (not shown) to which the initiator10is to be coupled. It will also be appreciated that a keying feature, such as a tab (not shown) or a recess (not shown), can be incorporated into a portion of the header40(e.g., the header body50) to key the header40in a particular orientation.

Returning toFIGS. 3 and 4, the seal members54can be formed of a suitable material, such as glass conforming to 2304 Natural or another dielectric material, and can be received into an associated one of the first terminal apertures66. The seal members54sealingly engage the header body50as well as an associated one of the terminals52. The seal members54can form a relatively strong seal, such as a seal that will leak at a rate less than about 1×10−5or 1×10−6units when one side of the header body50is exposed to helium gas at a gauge pressure of about 1 atmosphere while the other side of the header body50is exposed to atmospheric pressure.

The insulating spacer42can be formed of a suitable dielectric material, such as polycarbonate, synthetic resin bonded paper (SRBP) or epoxy resin bonded glass fabric (ERBGF), and can define a body80having a plurality of clearance apertures82that are sized to receive the terminals52athrough52d(FIG. 1) there through. The body80can be received onto the second end face62and within a volume that is defined by the shoulder wall72.

The frame member44can include a body44aand a plurality of electrical conductors44b. The body44acan be formed of an appropriate dielectric material, such as synthetic resin bonded paper (SRBP) or epoxy resin bonded glass fabric (ERBGF). The conductors44bcan be arranged about the body44ain a predetermined manner and can comprise one or more conductive layers of material, such as gold, silver, copper, nickel and alloys thereof. The conductors44bcan be formed onto the body44ain any desired manner, such as through metallization of the entire surface of the body44aand acid-etch removal of portions of the metallization that are not desired. The frame member44can be sized and shaped to closely conform to the size and shape of the insulating spacer42and can include a plurality of terminal apertures90and an interior aperture92that is sized to receive the initiator chip46. The terminal apertures90can be sized to receive a corresponding one of the terminals52(e.g., terminals52athrough52dinFIG. 1) therein.

In the particular example provided, the initiator chip46is constructed in a manner that is disclosed in co-pending U.S. patent application Ser. Nos. 11/431,111 and 11/430,944 entitled “Full Function Initiator With Integrated Planar Switch” the disclosures of which are hereby incorporated by reference as if fully set forth in detail herein. Briefly, the initiator chip46includes at least a portion of an exploding foil initiator100(FIG. 1), a first switch102and a second switch104.

With reference toFIG. 6, the portion of the exploding foil initiator100(FIG. 1) can conventionally include a substrate120, a bridge122, first and second bridge contacts124and126, respectively, and a flyer128. The substrate120can be formed of an appropriate structural material, such as a ceramic. The bridge122and the first and second bridge contacts124and126can be coupled to the substrate120and can be formed of an appropriate conductive material, such as gold, silver, copper, nickel and alloys thereof. The bridge122and the first and second bridge contacts124and126can be formed in one or more layers that can be deposited onto the substrate120in an appropriate manner, such as by vapor deposition. The first switch102can include a first switch pad130that can be coupled to the substrate120and offset from the first bridge contact126by a first gap132. The second switch104can include a second switch pad136that can be coupled to the substrate and offset from the second bridge contact124by a second gap138. While the initiator chip46has been illustrated and described as including an exploding foil initiator and one or more switches that provide the initiator chip46with integrated switching capabilities, those of ordinary skill in the art will appreciate that any appropriate initiator chip (e.g., an initiator chip without integrated switching capabilities) may be employed. The flyer128can be formed of an appropriate material, such as polyamide.

With additional reference toFIGS. 3 and 4, the initiator chip46can be received in the interior aperture92that is formed by the frame member44. In the particular example provided, an adhesive, such as SCOTCH-WELD™ EC-2216 Grey epoxy marketed by Minnesota Mining and Manufacturing Company of St. Paul, Minn., is employed to bond the frame member44and the initiator chip46to the insulating spacer42as well as to bond the insulating spacer42to the header body50. It will be appreciated that the surface A (FIG. 6) of the initiator chip46and the surface B (FIG. 6) of the frame44can be abutted against a flat surface so that the surfaces A and B will be substantially parallel and co-planar. With reference toFIG. 6A, the epoxy E can be applied to the surfaces of the initiator chip46and the frame member44opposite the surfaces A and B, respectively. The epoxy E can be employed to secure the frame member44and the initiator chip46to one another, as well as to provide a bottom surface X of the assembly that is generally parallel to the surfaces A and B. In this way, the top and bottom surfaces of the assembly (i.e., the frame member44, the initiator chip46and the epoxy E) can be flat and parallel within a desired tolerance, such as 0.001 inch. The terminal apertures90can be formed via a suitable process, such as drilling.

With reference toFIGS. 3 and 7, the contacts48can be formed of a suitable electrically conductive material, such as KOVAR® having a thickness of about 0.003 inch, and can include a terminal aperture150that can receive an associated one of the terminals52(e.g., the terminals52athrough52dinFIG. 1) and a plurality of solder apertures152. The contacts46can be shaped to engage an associated electric interface (e.g., the first bridge contact124, the second bridge contact126, the first switch pad130and the second switch pad136). In the particular example provided, the contacts48are soldered to an associated one of the terminals52and an associated one of the electric interfaces with an appropriate solder S (FIG. 3), such as a F540SN62-86D4 solder paste marketed by Heraeus Inc., Circuit Materials Division of Scottsville, Ariz. The solder apertures152permit solder to flow through the contacts48in predetermined areas, such as locations in-line with the associated electric interfaces and in-line with the conductors44b(FIG. 6) of the frame member44. Accordingly, it is possible to visually-inspect the solder joints associated with each contact48through the solder apertures152and the terminal aperture150.

We have found it to be desirable to form the contacts48such that they are connected to one another and form a lead frame160. The terminals52can be received in a high-tolerance fixture (not shown), insulating spacer42, and the frame44can be placed onto the terminals52using the terminals52as guide pins. The lead frame160can be oriented to the header body50and thereafter the lead frame160and the header body50can be clamped together via an assembly fixture (not shown). The header body50and the lead frame160can be processed through a reflow oven to solder the contacts48to the terminals52, the conductors44b(FIG. 6) and the associated electric interfaces in a single soldering operation. The header assembly20can thereafter be separated from the lead frame160by shearing the contacts48from the lead frame160. The insulating spacer42can prevent the contacts48from shorting to the header body50. Moreover, the contacts48can be sheared from the lead frame in a direction that drives the sharp edges of the contacts48into the frame member44. It will be appreciated that as a force is applied to assembly prior to the soldering of the contacts48, the terminals52, the solder and the contacts48will cooperate to apply maintain this force on the frame member44and the initiator chip46.

With reference toFIGS. 2 and 8, the insulator barrel22can be formed of a suitable electrically insulating material, such as polyamide. The insulator barrel22can cover the frame member44and the contacts48to electrically isolate these elements from the input sleeve24. Additionally, the insulator barrel22can define a barrel aperture170through which the flyer128(FIG. 6) may be expelled when the initiator chip46is activated. In this regard, it will be appreciated that the barrel aperture170, the flyer128(FIG. 6) and the bridge122(FIG. 6) are disposed in-line with one another.

It will be appreciated that the thicknesses of the insulator barrel22, the contacts48and the solder that couples the contacts48to the terminals52and the electric interfaces is selected to space the bridge122(FIG. 6) apart from the input charge26by a predetermined spacing, such as about 0.004 inch to about 0.008 inch. It will be also appreciated that it can be important in some situations that the contacts48be relatively flat so as not to affect the spacing between the bridge122(FIG. 6) and the input charge26.

The input sleeve24can be configured to support the input charge26and direct energy from the input charge26in a desired direction. In the particular example provided, the input sleeve24is formed of a suitable steel and defines a cavity180that can be located in-line with the bridge122(FIG. 6). The input charge26can be formed of a suitable energetic material, such as RSI-007, which is available from Reynolds Systems, Inc. of Middletown, Calif. The input charge26can be received in the cavity180in the input sleeve24and compacted to a desired density. It will be appreciated that in some applications, the input charge26may fill the entire volume of the cavity180. It will also be appreciated that in some applications the input sleeve24may be deleted.

The barrier28can be employed to separate the input charge26from the output charge30. In the particular example provided, the barrier28includes a first barrier member200, a second barrier member202and a resilient member204. The first barrier member200, which can be abutted against the input sleeve24, can be a formed of a reactive material, which may be a metal, such as titanium, or another suitably reactive material that is inert under normal circumstances. The second barrier member202, which can be abutted against the first barrier member200, can be formed of an oxidizable material, such as polytetrafluoroethylene. The resilient member204can be an annular silicone rubber element and can be disposed between the second barrier member202and the output charge30. The barrier28can be tailored to a desired application to permit a desired amount of energy to be transmitted to the output charge30in a desired amount of time. In the particular example provided, the barrier28is employed to somewhat attenuate the energy that is released by the input charge26, as well as to employ a portion of the energy that is released from the input charge26to initiate a reaction between the first and second barrier members200and202that generates additional heat.

The output charge30can be formed of a suitable energetic material, such as a secondary explosive and can be abutted against a side of the barrier28opposite the input sleeve24. In the particular example provided, the output charge30is abutted against a side of the resilient member204opposite the second barrier member202.

The cover32can be formed of a suitable material, such as KOVAR®, and can include a cover body220and a rim222. The cover body220can be a cup-line structure that can receive the portion of the initiator10outwardly of the abutting face70. The rim222can extend radially outwardly from the cover body220and can matingly engage the abutting face70. The rim222and the shoulder64(FIG. 4) can be welded in an appropriate manner (e.g., laser welded) to fixedly and sealingly couple the cover32to the header body50. It will be appreciated that a preload force can be applied to the cover32to seat the cover32to the header body50and as such, various components of the initiator10, such as the output charge30, the barrier28, the frame44and the initiator chip46can be maintained in a state of compression.

While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims.