Abstract:
One embodiment of the present subject matter includes an apparatus which includes an implantable case including a first opening shaped for passage of electronics, a seal connecting the cover and the first opening, the seal including a weld, electronics disposed in the case, and a foil strip backed with adhesive, oriented lengthwise with respect to the weld and disposed between the case and the electronics to reduce damage to the electronics from welding. In some embodiments, the adhesive holds the foil to a subcomponent.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to the following commonly assigned U.S. Patent Publication which is incorporated by reference in its entirety: “Batteries Including a Flat Plate Design,” U.S. Patent Publication No. 2004/0127952, filed Feb. 7, 2003, which claims the benefit under 35 U.S.C 119(e) of U.S. Provisional Application Ser. No. 60/437,537 filed Dec. 31, 2002. 
     
     TECHNICAL FIELD 
       [0002]    This disclosure relates generally to packaging for implantable medical devices, and more particularly to a method and apparatus to control heat flow from welding a device case. 
       BACKGROUND 
       [0003]    Devices which include a welded case contain devices in that case which can be exposed to an unfavorably high amount of heat if they are disposed in the case near an area where the case is welded. This is true for a welded case of an overall device, as well as for a case of a device packaged inside the overall device. This heating is problematic for implantable devices, which are often sealed with a weld. Implantable devices include, but are not limited to, pacemakers, and defibrillators. Devices inside devices include batteries and capacitors. These devices provide little extra space to thermally insulate devices. In implantable devices, space is at a premium due, as space efficiency is required to improve patient comfort. 
         [0004]    If a device is sensitive to heat, it is preferable to reduce the heat which is transmitted to that device during a welding process. What is needed is a method and apparatus which reduces heat transmitted to heat sensitive parts. 
       SUMMARY 
       [0005]    The above-mentioned problems and others not expressly discussed herein are addressed by the present subject matter and will be understood by reading and studying this specification. 
         [0006]    One embodiment of the present subject matter includes an apparatus which includes an electronics case including a first portion and a second portion, a weld connecting the first portion of the electronics case and the second portion of the electronics case, electronics disposed in the electronics case and a foil backed with adhesive and disposed between the case and the devices, the foil positioned to reduce damage to the electronics from welding. 
         [0007]    Another embodiment of the present subject matter includes a method which includes disposing devices in a device case including a first portion with a first opening defined by an edge, positioning a foil strip backed with foil adhesive between the edge and the devices and welding a second portion of the device case to the first portion along the edge, wherein the foil strip reduces damage caused by welding the second portion of the power source case to the first portion of the power source case. 
         [0008]    A further embodiment of the present subject matter includes an apparatus which includes a device case, subcomponents disposed in the device case and heat resistant means for reducing damage to the subcomponents from welding, wherein the heat resistant means are disposed between the device case and the subcomponents. 
         [0009]    Optional features within the scope of the present subject matter include a polyimide film disposed between foil and a device or subcomponent. Some embodiments use a pressure sensitive adhesive. Some embodiments partially apply an adhesive to a substrate. Some embodiments include a feedthrough as part of a seal sealing a case. Some embodiments includes a case including a butt joint. Some embodiments include a hermetic seal. 
         [0010]    This Summary is an overview of some of the teachings of the present application and not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description and appended claims. Other aspects will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which are not to be taken in a limiting sense. The scope of the present invention is defined by the appended claims and their legal equivalents. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a perspective view of a device showing a partial cut away, according to one embodiment of the present subject matter. 
           [0012]      FIG. 1B  is a cross section taken at line  1 B- 1 B in  FIG. 1A . 
           [0013]      FIG. 2  is a partial cross section of an device which includes a foil which controls heat flowing to the device, according to one embodiment of the present subject matter. 
           [0014]      FIG. 3  is a partial cross section of an device which includes a foil which controls heat flowing to the device, according to one embodiment of the present subject matter. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    The following detailed description of the present subject matter refers to subject matter in the accompanying drawings which show, by way of illustration, specific aspects and embodiments in which the present subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present subject matter. References to “an”, “one”, or “various” embodiments in this disclosure are not necessarily to the same embodiment, and such references contemplate more than one embodiment. The following detailed description is demonstrative and not to be taken in a limiting sense. The scope of the present subject matter is defined by the appended claims, along with the full scope of legal equivalents to which such claims are entitled. 
         [0016]    Many devices include an outer case. For example, implantable electronic devices often include an outer case which is compatible with implantation and which houses additional devices. Implantable devices which fall within the scope of the present subject matter include cardiac rhythm management devices, such as pacemakers and defibrillators. Various additional implantable devices also fall within the present scope. Such additional implantable devices include devices which stimulate the body during the administration of therapy, in various embodiments. 
         [0017]    Packaged within such an outer case are additional devices, in various embodiments. Such additional devices include, in various embodiments, batteries, capacitors, electrical circuits and electromechanical sensors. Additional devices not listed herein also are used with the present subject matter, in various embodiments. 
         [0018]    In some embodiments, the present subject matter includes batteries. Batteries, in various embodiments, include electrodes, such as anodes and cathodes, which are packaged in a battery case. Further discussion of batteries is included in paragraphs 98, 165-7, and 247 of United States Patent Publication 2004/0127952, which was filed Feb. 7, 2003, which has a common assignee and which is incorporated by reference. 
         [0019]    In some embodiments, the present subject matter includes capacitors. Capacitors include electrodes, such as anodes and cathodes, which are packaged in a capacitor case, in various embodiments. 
         [0020]    In some embodiments, the present subject matter includes electrical circuits packaged in an electrical circuit housing. An electrical circuit housing, in various embodiments, is polymeric. Electrical circuits include flex circuitry, in various embodiments. Other types of electrical circuitry additionally are used with the present subject matter, in various embodiments. 
         [0021]    In various embodiments of the present subject matter, the outer case of a device also houses devices which do not have their own respective case. In some of these embodiments, a support structure is housed in an overall device. In various embodiments, a support structure includes polymers. In various embodiments, a support structure is used to support electronics. One embodiment uses a support structure to support flex circuitry. Additional insulative plastic structures are also used with the present subject matter. 
         [0022]    The present subject matter includes casings which are sealed with a weld. A weld can be used to seal a first case portion to a second case portion, in various embodiments. In some embodiments, a weld seals a feedthrough to a case portion. In various embodiments, the present subject matter reduces heat which flows from a weld area to a packaged device. By reducing the heat which flows from a weld area to a packaged device, the present subject matter allows for better packaging efficiency. In embodiments which use an air gap to provide thermal insulation, the present subject matter allows for a reduction in the size of the air gap, which in turn improves packaging efficiency. As such, various embodiments provide for a smaller implantable device. 
         [0023]    Welding is used in various embodiments because it is an efficient and cost effective way to join one case portion to another. A weld provides a hermetic seal, in some embodiments. Some embodiments of the present subject matter use a laser to weld. In addition to the welding disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 213, 215-224 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. 
         [0024]      FIG. 1A  is a perspective view of a device  100  showing a partial cut away, according to one embodiment of the present subject matter.  FIG. 1B  is a cross section taken at line  1 B- 1 B in  FIG. 1A . The pictured embodiment includes subcomponent  106 . 
         [0025]    In various embodiments, subcomponent  106  is a stack of electrodes, such as anodes and cathodes. Such a stack exists in some battery embodiments. The present subject matter is not limited to batteries. Some embodiments include capacitors. The present subject matter includes any subcomponent  106  which is sensitive to heat. This includes, but is not limited to, cardiac rhythm management circuitry, in some embodiments. In addition to battery stacks disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 135-6, 138, 154-7, 170-1, 191-6 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. 
         [0026]    In addition to stack embodiments, various embodiments include electrodes which are in a jelly-roll configuration. The present subject matter is not limited to these electrode configurations, and other configurations fall within the present scope, in various embodiments. 
         [0027]    Surrounding the subcomponent  106  is a foil  104 , in various embodiments. In various embodiments, foil  104  reduces heat flow to the subcomponent  106  by isolating the subcomponent  106  from a heat source such as a weld along seam  110 . In various embodiments, the foil  104  is disposed along the surface of subcomponent  106  such that the foil  104  is disposed between the seam  110  and the subcomponent  106 . In various embodiments, the foil  104  extends along subcomponent  106 , and away from seam  110 , such that heat conducted to case portions  102 ,  108 , does not flow in excess to subcomponent  106 . 
         [0028]    Seam  110  may include different joints, in various embodiments. Various embodiments include lip joints, step joints, lap joints, and butt joints. This list of possible joints is not exhaustive or exclusive, and other joints not listed herein additionally fall within the present scope. In various embodiments, seam  110  provides a hermetic seal. 
         [0029]    In various embodiments, the foil  104  is a metallic foil. In various embodiments, the foil  104  includes, but is not limited to, thicknesses of from approximately 0.0005 inches thick to approximately 0.005 inches thick. In additional embodiments, the foil  104  is less than 0.0005 inches. The present subject matter additionally includes foils which are thicker than 0.005 inches. 
         [0030]    In various embodiments, the device  100  is configured such that the foil  104  abuts one or more case portions. In additional embodiments, the foil  104  does not abut any case portions. Various embodiments use foil  104  to reduce heat transmitted to subcomponent  106  due to the creation of a weld along seam  110 . 
         [0031]    Various embodiments include adhesive  112 . Foil  104 , in various embodiments, is adhered to the surface of subcomponent  106 . In additional embodiments, adhesive is used to adhere foil  104  to a case portion, such as case portion  108 . For example, some embodiments first adhere a foil  104  to subcomponent  106 , and then dispose subcomponent  106  in case portion  108 . But some embodiments first adhere foil  104  to case portion  108 , and then dispose subcomponent  106  into case portion  108 . 
         [0032]    The present subject matter is useful with foils which tend to distort during manufacturing. Thin foils are susceptible to crumpling. The present subject matter provides for using a foil such that the foil does not crumple. In various embodiments, the foil resists peeling. Adhesives disclosed herein provide respective resistances to peeling. Additionally, in various embodiments, the thickness of the foil  104  is selected based on the distance of the foil  104  from a weld. 
         [0033]    In various embodiments, the foil  104  is strip shaped. In some embodiments, the foil  104  is longer than the seam  110 . Some embodiments use a foil  104  which is not as long as the seal. In some embodiments, the foil  104  is a tape-like elongate strip which meets itself end to end. In various embodiments, the foil  104  is a continuous piece. In some embodiments, the foil  104  does not fully circumscribe the subcomponent  106 . 
         [0034]    In embodiments in which an adhesive is applied to a case portion which is welded to another case portion, the adhesive is applied so it does not break down due to the welding. For example, in some embodiments, the adhesive is applied to the strip along the edges of the strip so that the strip straddles a weld, with adhesive positioned away from a high heat area. In some of these embodiments, the adhesive will straddle the weld. In additional embodiments, the adhesive will straddle an area which is larger than the weld. It should be noted that the present subject matter is not limited to embodiments using one or more cup shaped case portions. 
         [0035]    Various adhesives fall within the present scope. Adhesives which are resistant to electrolyte are used in various embodiments. Some of these embodiments dispose foil  104 , adhesive  112  and subcomponent  106  in case portions  102 ,  108 , which are then sealed together and filled with electrolyte. Pressure sensitive adhesives are used, in various embodiments. Some embodiments an adhesive which includes 467MP, which is a 3M product. 3M is a registered trademark of the 3M Company, which is incorporated in Delaware and is headquartered at 3M Center, 2501 Hudson Road St. Paul Minn. 55144. 467 MP is one example of an adhesive which falls within the present scope. 
         [0036]    In some of these embodiments, subcomponent  106  includes a stack which is retained in alignment. In some embodiments of the present subject matter, foil  104  is used to retain the stack in alignment. In addition to stack embodiments in alignment as disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 112, 117 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. 
         [0037]    In some embodiments, there exist terminal features which are connected to the subcomponent  106 . In some of these embodiments, the foil  104  circumscribes the subcomponent  106  but for the area including a terminal feature. 
         [0038]    Various embodiments include a feedthrough attached to a stack of electrodes. Such a stack exists in some battery embodiments. Such a stack also exists in some capacitor embodiments. In various embodiments, a seal is formed in the case at the joint of two case parts. In some of these embodiments, a feedthrough is sealed between the two case parts. In some of these embodiments, the feedthrough is welded to the case. In additional embodiments, the feedthrough is disposed through a single case part. In various embodiments, the feedthrough is not welded to the case. In some embodiments, the foil  104  is disposed along the battery stack edge face in areas where the feedthrough is not connected to the battery stack edge face. In some embodiments where a feedthrough is welded to an aperture in a case, a washer shaped foil is used to insulate a device from the weld used to weld the feedthrough to the aperture. In addition to the feedthrough embodiments disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 161-3 and 208 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. 
         [0039]      FIG. 2  is a partial cross section of a device which includes a foil which controls heat flowing to a device, according to one embodiment of the present subject matter. The pictured embodiment includes device  208 . The pictured embodiment additionally includes case  202 . Additionally, various embodiments include adhesive  206 . Foil  204  is disposed along a surface of device  208 , in various embodiments. Foil  204 , in various embodiments, is adhered to the surface of device  208 . As mentioned above, device  208  can be a battery, capacitor, electrical circuits, structure holding other devices, or any other heat sensitive object. 
         [0040]    In various embodiments, adhesive  206  is applied to foil  204  prior to the application of foil  204  to device  208 . But in various embodiments, the adhesive  206  is first applied to device  208 , and then foil  204  is applied to adhesive  208 . In some of these embodiments, the adhesive  206  is part of a tape film which has adhesive on both sides, and which is applied to device  208 . In some embodiments, adhesive  206  is not part of such a tape film. In addition to the manufacturing processes disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 125 and 225 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. The application of a foil to device  208  can occur at different stages of these manufacturing processes, depending on the heat sensitivity of device  208  during assembly. 
         [0041]    In some embodiments, adhesive  206  is applied to foil  204  intermittently along the surface of device  208 . Such a design avoids using adhesive on the foil where there is no device  208  for the adhesive to stick to. An aperture extending through the device  208  at the area where the foil  204  covers the device  208  is one example of a use for such a design. Some embodiments of the present subject matter do not use adhesive near such features when applied to the device  208 . 
         [0042]      FIG. 3  is a partial cross section of a device which includes a foil which controls heat flowing to the device, according to one embodiment of the present subject matter. Various embodiments include a case  302 . Various case  302  embodiments include, but are not limited to, one or more of aluminum, stainless steel, titanium or alloys thereof. Materials not listed expressly herein are additionally used with the present subject matter, in various embodiments. Various foil  304  embodiments include, but are not limited to, one or more of aluminum, stainless steel, titanium or alloys thereof. Materials not listed expressly herein are additionally used with the present subject matter, in various embodiments. 
         [0043]    An adhesive  306  is included in various embodiments. Adhesive  306  is a pressure sensitive adhesive, as is discussed herein, in various embodiments. Also, various embodiments include a substrate  308 . Substrate  308 , in various embodiments, is polyimide. In some embodiments, the substrate  308  is an elongate strip. In addition to the substrate embodiments disclosed herein, the present application incorporates by reference the subject matter disclosed in paragraphs 172-3 of United States Patent Publication 2004/0127952, which has a common assignee and which was filed Feb. 7, 2003. 
         [0044]    Polyimide resists breakdown under unfavorable heat, in various embodiments. Including a substrate  308  which is resistant to heat flow allows for laser welding of the case  302  while protecting device  310  from heat excessive heat flow, in various embodiments. A substrate  308  is additionally useful to provide rigidity to an assembly including adhesive, a substrate, and a foil. Such an assembly is easier for an operator to handle, in various embodiments. 
         [0045]    In some embodiments, foil  304  is laminated to substrate  308 . In some embodiments, a structure including a foil  304 , adhesive  306 , and a substrate  308  is adhered to device  310  with optional adhesive  312 . Optional adhesive  312  is a pressure sensitive adhesive, in various embodiments, however the present subject matter includes additional adhesives. 
         [0046]    Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover adaptations or variations of the present subject matter. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the present subject matter should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.