Patent Publication Number: US-8113117-B2

Title: Energetic material initiation device

Description:
This application is a continuation of U.S. application Ser. No. 12/497,171 filed Jul. 2, 2009 (now U.S. Pat. No. 7,866,264), which is a division of U.S. patent application Ser. No. 11/541,998 filed Sep. 29, 2006 (now U.S. Pat. No. 7,571,679). The disclosure of the above-referenced applications are hereby incorporated by reference as if fully set forth in detail herein. 
    
    
     INTRODUCTION 
     The present invention generally relates to devices for initiating an event involving combustion, deflagration and/or detonation in an energetic material. 
     Modern initiator assemblies, such as detonators, commonly employ materials including ceramics and stainless steels in their construction. These materials are typically selected to provide the initiator assembly with a degree of robustness that permits the initiator assembly to withstand extreme changes in temperature and humidity, as well as to resist oxidization. While modern initiator assembly configurations are generally satisfactory for their intended purposes, they are nonetheless susceptible to improvement. 
     For example, many of these initiator assemblies, 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 an initiator assembly having a header body, a plurality of seal members, an insulating spacer, a frame member, an initiator, a plurality of terminals and a plurality of terminal-to-initiator contacts. The header body has a plurality of first terminal apertures formed there through. Each seal member is received in an associated one of the first terminal apertures. The insulating spacer is received over the header body. The frame member overlies the insulating spacer and defines an interior aperture. The initiator is received in the interior aperture and abutted against the insulating spacer on a side opposite the header body. The initiator includes a plurality of initiator contacts and is configured to initiate an energetic material such that the energetic material is at least partly consumed in an event involving one or more of combustion, deflagration and detonation. Each of the terminals is received through the insulating spacer and an associated one of the seals. Each of the terminals is received in the frame member at a location that is outward of the interior aperture. Each terminal-to-initiator contact is electrically coupled to an associated one of the terminals and an associated one of the initiator contacts. 
     In another form, the present teachings provide an initiator assembly that includes a header body, a plurality of terminals, a plurality of seal members, an insulating spacer, a frame member, an initiator chip and a plurality of contacts. The header body has a plurality of first terminal apertures formed there through. The terminals extend through the first terminal apertures in the header body. Each seal member is received in an associated one of the first terminal apertures and is sealingly engaged to the header body and an associated one of the terminals. The insulating spacer is coupled to the header body. The frame member is received over the insulating spacer. The frame member includes a frame body, which defines a frame aperture, and a plurality of frame contacts that are coupled to the frame body. Each of the frame contacts is electrically coupled to a corresponding one of the terminals. The initiator chip forms at least a portion of an exploding foil initiator and includes a plurality of electric interfaces. The initiator chip is received in the frame aperture and secured to a side of the insulating spacer opposite the header body. The contacts electrically couple the electric interfaces to the frame contacts. 
     In yet another form, the present disclosure provides an initiator assembly that includes a header body, a plurality of seal members, an insulating spacer, a structure and a plurality of terminals. The header body has a plurality of first terminal apertures formed there through. Each seal member is received in an associated one of the first terminal apertures. The insulating spacer is received over the header body. The structure has an insulating body, which overlies the insulating spacer, a plurality of initiator contacts and a bridge that is configured to form a plasma to initiate an event involving one or more of combustion, deflagration and detonation. The initiator contacts and the bridge are coupled to the insulating body. Each of the terminals is received through the insulating spacer and an associated one of the seals and is electrically coupled to an associated one of the initiator contacts. 
     In a further form, the present disclosure provides an initiator assembly that includes a header body, a plurality of seal members, an insulating spacer, a frame member, an initiator and a plurality of terminals. The header body has a plurality of first terminal apertures formed there through into which an associated one of the seal members is received. The insulating spacer is received over the header body. The frame member overlies the insulating spacer and defines an interior aperture. The initiator is received in the interior aperture and is abutted against the insulating spacer on a side opposite the header body. The initiator includes a plurality of initiator contacts and is configured to initiate an energetic material such that the energetic material is at least partly consumed in an event involving one or more of combustion, deflagration and detonation. Each of the terminals is received through the insulating spacer and an associated one of the seals. Each of the terminals is disposed outwardly of the interior aperture and electrically coupled to an associated one of the initiator contacts. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a rear perspective view of an energetic material initiation device constructed in accordance with the teachings of the present disclosure; 
         FIG. 2  is a longitudinal section view of the energetic material initiation device of  FIG. 1 ; 
         FIG. 3  is a front perspective view of a portion of the energetic material initiation device of  FIG. 1 , illustrating the header assembly in more detail; 
         FIG. 4  is a longitudinal section view of the header assembly; 
         FIG. 5  is a bottom view of the header assembly; 
         FIG. 6  is a top plan view of a portion of the header assembly illustrating the frame member and the initiator chip in more detail; 
         FIG. 6A  is a section view taken along the line  6 A- 6 A of  FIG. 6 ; 
         FIG. 7  is a top plan view of a portion of the header assembly illustrating the contacts as coupled to a lead frame; and 
         FIG. 8  is a top plan view of a portion of the header assembly illustrating the insulator barrel. 
     
    
    
     DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS 
     With reference to  FIGS. 1 and 2  of the drawings, an initiator constructed in accordance with the teachings of the present invention is generally indicated by reference numeral  10 . While the initiator  10  is illustrated as being a detonator-type initiator, the initiator  10  may be any type of initiator and may be configured to initiate a combustion event, a deflagration event and/or a detonation event. The initiator  10  can include a header assembly  20 , an insulator barrel  22 , an input sleeve  24 , an input charge  26 , a barrier  28 , an output charge  30  and a cover  32 . 
     With reference to  FIGS. 3 and 4 , the header assembly  20  can include a header  40 , an insulating spacer  42 , a frame member  44 , an initiator chip  46  and a plurality of contacts  48 . The header  40  can include a header body  50 , a plurality of terminals  52 , and a plurality of seal members  54 . 
     The header body  50  can be formed of an appropriate material, such as KOVAR®, and can be shaped in a desired manner. The header body  50  can define first and second end faces  60  and  62 , respectively, a shoulder  64 , a plurality of first terminal apertures  66  and a second terminal aperture  68 . The shoulder  64  can include an abutting face  70 , which can be generally parallel to the first and second end faces  60  and  62 , and a shoulder wall  72  that is generally perpendicular to the abutting face  70 . The first terminal apertures  66  can be formed through the header body  50  generally perpendicular to the first and second end faces  60  and  62 . The second terminal aperture  68  can be a blind hole that is formed in the header body  50  through the first end face  60 . 
     With additional reference to  FIG. 1 , a first quantity of the terminals  52  (e.g., terminals  52   a  through  52   d ) can be received in respective ones of the first terminal apertures  66  and can extend outwardly from the first and second end faces  60  and  62 . A remaining one of the terminals  52   e  can be received in the second terminal aperture  68  and can be fixedly electrically coupled to the header body  50 . In the particular example provided, the terminal  52   e  is soldered to the header body  50  and can serves as a means for electrically coupling the header body  50  to an electric ground (not shown). It will be appreciated that the terminals  52  can be arranged in a non-symmetrical manner to thereby key the header  40  in a particular orientation relative to the device (not shown) to which the initiator  10  is 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 header  40  (e.g., the header body  50 ) to key the header  40  in a particular orientation. 
     Returning to  FIGS. 3 and 4 , the seal members  54  can 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 apertures  66 . The seal members  54  sealingly engage the header body  50  as well as an associated one of the terminals  52 . The seal members  54  can form a relatively strong seal, such as a seal that will leak at a rate less than about 1×10 −5  or 1×10 −6  units when one side of the header body  50  is exposed to helium gas at a gauge pressure of about 1 atmosphere while the other side of the header body  50  is exposed to atmospheric pressure. 
     The insulating spacer  42  can 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 body  80  having a plurality of clearance apertures  82  that are sized to receive the terminals  52   a  through  52   d  ( FIG. 1 ) there through. The body  80  can be received onto the second end face  62  and within a volume that is defined by the shoulder wall  72 . 
     The frame member  44  can include a body  44   a  and a plurality of electrical conductors  44   b . The body  44   a  can be formed of an appropriate dielectric material, such as synthetic resin bonded paper (SRBP) or epoxy resin bonded glass fabric (ERBGF). The conductors  44   b  can be arranged about the body  44   a  in a predetermined manner and can comprise one or more conductive layers of material, such as gold, silver, copper, nickel and alloys thereof. The conductors  44   b  can be formed onto the body  44   a  in any desired manner, such as through metallization of the entire surface of the body  44   a  and acid-etch removal of portions of the metallization that are not desired. The frame member  44  can be sized and shaped to closely conform to the size and shape of the insulating spacer  42  and can include a plurality of terminal apertures  90  and an interior aperture  92  that is sized to receive the initiator chip  46 . The terminal apertures  90  can be sized to receive a corresponding one of the terminals  52  (e.g., terminals  52   a  through  52   d  in  FIG. 1 ) therein. 
     In the particular example provided, the initiator chip  46  is 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 chip  46  includes at least a portion of an exploding foil initiator  100  ( FIG. 1 ), a first switch  102  and a second switch  104 . 
     With reference to  FIG. 6 , the portion of the exploding foil initiator  100  ( FIG. 1 ) can conventionally include a substrate  120 , a bridge  122 , first and second bridge contacts  124  and  126 , respectively, and a flyer  128 . The substrate  120  can be formed of an appropriate structural material, such as a ceramic. The bridge  122  and the first and second bridge contacts  124  and  126  can be coupled to the substrate  120  and can be formed of an appropriate conductive material, such as gold, silver, copper, nickel and alloys thereof. The bridge  122  and the first and second bridge contacts  124  and  126  can be formed in one or more layers that can be deposited onto the substrate  120  in an appropriate manner, such as by vapor deposition. The first switch  102  can include a first switch pad  130  that can be coupled to the substrate  120  and offset from the first bridge contact  126  by a first gap  132 . The second switch  104  can include a second switch pad  136  that can be coupled to the substrate and offset from the second bridge contact  124  by a second gap  138 . While the initiator chip  46  has been illustrated and described as including an exploding foil initiator and one or more switches that provide the initiator chip  46  with 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 flyer  128  can be formed of an appropriate material, such as polyamide. 
     With additional reference to  FIGS. 3 and 4 , the initiator chip  46  can be received in the interior aperture  92  that is formed by the frame member  44 . 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 member  44  and the initiator chip  46  to the insulating spacer  42  as well as to bond the insulating spacer  42  to the header body  50 . It will be appreciated that the surface A ( FIG. 6 ) of the initiator chip  46  and the surface B ( FIG. 6 ) of the frame  44  can be abutted against a flat surface so that the surfaces A and B will be substantially parallel and co-planar. With reference to  FIG. 6A , the epoxy E can be applied to the surfaces of the initiator chip  46  and the frame member  44  opposite the surfaces A and B, respectively. The epoxy E can be employed to secure the frame member  44  and the initiator chip  46  to 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 member  44 , the initiator chip  46  and the epoxy E) can be flat and parallel within a desired tolerance, such as 0.001 inch. The terminal apertures  90  can be formed via a suitable process, such as drilling. 
     With reference to  FIGS. 3 and 7 , the contacts  48  can be formed of a suitable electrically conductive material, such as KOVAR® having a thickness of about 0.003 inch, and can include a terminal aperture  150  that can receive an associated one of the terminals  52  (e.g., the terminals  52   a  through  52   d  in  FIG. 1 ) and a plurality of solder apertures  152 . The contacts  46  can be shaped to engage an associated electric interface (e.g., the first bridge contact  124 , the second bridge contact  126 , the first switch pad  130  and the second switch pad  136 ). In the particular example provided, the contacts  48  are soldered to an associated one of the terminals  52  and 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 apertures  152  permit solder to flow through the contacts  48  in predetermined areas, such as locations in-line with the associated electric interfaces and in-line with the conductors  44   b  ( FIG. 6 ) of the frame member  44 . Accordingly, it is possible to visually-inspect the solder joints associated with each contact  48  through the solder apertures  152  and the terminal aperture  150 . 
     We have found it to be desirable to form the contacts  48  such that they are connected to one another and form a lead frame  160 . The terminals  52  can be received in a high-tolerance fixture (not shown), insulating spacer  42 , and the frame  44  can be placed onto the terminals  52  using the terminals  52  as guide pins. The lead frame  160  can be oriented to the header body  50  and thereafter the lead frame  160  and the header body  50  can be clamped together via an assembly fixture (not shown). The header body  50  and the lead frame  160  can be processed through a reflow oven to solder the contacts  48  to the terminals  52 , the conductors  44   b  ( FIG. 6 ) and the associated electric interfaces in a single soldering operation. The header assembly  20  can thereafter be separated from the lead frame  160  by shearing the contacts  48  from the lead frame  160 . The insulating spacer  42  can prevent the contacts  48  from shorting to the header body  50 . Moreover, the contacts  48  can be sheared from the lead frame in a direction that drives the sharp edges of the contacts  48  into the frame member  44 . It will be appreciated that as a force is applied to assembly prior to the soldering of the contacts  48 , the terminals  52 , the solder and the contacts  48  will cooperate to apply maintain this force on the frame member  44  and the initiator chip  46 . 
     With reference to  FIGS. 2 and 8 , the insulator barrel  22  can be formed of a suitable electrically insulating material, such as polyamide. The insulator barrel  22  can cover the frame member  44  and the contacts  48  to electrically isolate these elements from the input sleeve  24 . Additionally, the insulator barrel  22  can define a barrel aperture  170  through which the flyer  128  ( FIG. 6 ) may be expelled when the initiator chip  46  is activated. In this regard, it will be appreciated that the barrel aperture  170 , the flyer  128  ( FIG. 6 ) and the bridge  122  ( FIG. 6 ) are disposed in-line with one another. 
     It will be appreciated that the thicknesses of the insulator barrel  22 , the contacts  48  and the solder that couples the contacts  48  to the terminals  52  and the electric interfaces is selected to space the bridge  122  ( FIG. 6 ) apart from the input charge  26  by 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 contacts  48  be relatively flat so as not to affect the spacing between the bridge  122  ( FIG. 6 ) and the input charge  26 . 
     The input sleeve  24  can be configured to support the input charge  26  and direct energy from the input charge  26  in a desired direction. In the particular example provided, the input sleeve  24  is formed of a suitable steel and defines a cavity  180  that can be located in-line with the bridge  122  ( FIG. 6 ). The input charge  26  can be formed of a suitable energetic material, such as RSI-007, which is available from Reynolds Systems, Inc. of Middletown, Calif. The input charge  26  can be received in the cavity  180  in the input sleeve  24  and compacted to a desired density. It will be appreciated that in some applications, the input charge  26  may fill the entire volume of the cavity  180 . It will also be appreciated that in some applications the input sleeve  24  may be deleted. 
     The barrier  28  can be employed to separate the input charge  26  from the output charge  30 . In the particular example provided, the barrier  28  includes a first barrier member  200 , a second barrier member  202  and a resilient member  204 . The first barrier member  200 , which can be abutted against the input sleeve  24 , 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 member  202 , which can be abutted against the first barrier member  200 , can be formed of an oxidizable material, such as polytetrafluoroethylene. The resilient member  204  can be an annular silicone rubber element and can be disposed between the second barrier member  202  and the output charge  30 . The barrier  28  can be tailored to a desired application to permit a desired amount of energy to be transmitted to the output charge  30  in a desired amount of time. In the particular example provided, the barrier  28  is employed to somewhat attenuate the energy that is released by the input charge  26 , as well as to employ a portion of the energy that is released from the input charge  26  to initiate a reaction between the first and second barrier members  200  and  202  that generates additional heat. 
     The output charge  30  can be formed of a suitable energetic material, such as a secondary explosive and can be abutted against a side of the barrier  28  opposite the input sleeve  24 . In the particular example provided, the output charge  30  is abutted against a side of the resilient member  204  opposite the second barrier member  202 . 
     The cover  32  can be formed of a suitable material, such as KOVAR®, and can include a cover body  220  and a rim  222 . The cover body  220  can be a cup-like structure that can receive the portion of the initiator  10  outwardly of the abutting face  70 . The rim  222  can extend radially outwardly from the cover body  220  and can matingly engage the abutting face  70 . The rim  222  and the shoulder  64  ( FIG. 4 ) can be welded in an appropriate manner (e.g., laser welded) to fixedly and sealingly couple the cover  32  to the header body  50 . It will be appreciated that a preload force can be applied to the cover  32  to seat the cover  32  to the header body  50  and as such, various components of the initiator  10 , such as the output charge  30 , the barrier  28 , the frame  44  and the initiator chip  46  can 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.