Compression mounted scr clamp with heat sink means

{
  "publication_number": "US3688159A",
  "country": "US",
  "kind": "A",
  "title": "Compression mounted scr clamp with heat sink means",
  "abstract": "A mounting clamp including heat sinks for a compression mounted type power semiconductor device such as an SCR, rectifier diode, or the like. Diamond shaped, tapered springs distribute the stresses equally throughout their lengths to afford greater deflection that reduces tolerances and facilitates staying within the allowable pressure range. A unitary spring subassembly also holds the pressure bearing and the load indicator. The construction is such that if the various parts become tilted on the pressure points, the line of force will still be through the center of the silicon disc inside the SCR. A pressure plate provides an enlarged base to afford low unit pressure on the insulation. Insulated parts afford the required electrical clearances. A dust-tight insulating cover or ''''boot'''' performs sealing, positioning and insulating functions during use and may also serve as a cushioned packing during shipment.",
  "claims": [
    "1. A mounting and connecting clamp for a compression mounted semiconductor device comprising: a clamping assembly including a cross bar and a pair of clamping bolts with the threaded ends of said bolts extending up from the opposite ends of the cross bar; insulating means covering said cross bar and continuing along a portion of each of said bolts; a pair of back to back heat sinks held on said bolts above said cross bar and a semiconductor device therebetween; a compression springs subassembly coupling the threaded ends of said bolts, and nuts threaded to be tightened on the latter to apply compressive force between the power terminal faces of the semiconductor device and said heat sinks, said compression springs subassembly comprising: a pressure bearing and means holding it centered against the upper heat sink; a plurality of diamond shaped compression force springs stacked on said pressure bearing, each said spring being imperforate throughout its effective length; spring guide and force applying means holding said springs in stacked relation and applying downward force on the ends of said springs as a result of said nuts having been tightened thereby causing said springs to apply force through said pressure bearing to said heat sinks and the semiconductor device therebetween; and force indicator means mounted on said spring guide and force applying means indicating when the proper force is reached as said nuts are tightened.",
    "2. The invention defined in claim 1, wherein said spring guiding and force applying means comprises: a stack of spring Guide members at each end of said springs; said guide members being alike and each having a first configuration on one side directed inwardly on a first group thereof and guiding the associated ends of said springs and a second configuration on the other side directed inwardly on a second group thereof and overlying said ends of said springs to press down thereon when said nuts are tightened; and means rigidly securing the spring guide members of each stack together so that the lower guide members in the stack forming said first group have said first configuration directed toward said springs and the upper guide members in the stack forming said second group have said second configuration directed toward said springs.",
    "3. The invention defined in claim 2, wherein said spring guiding and force applying means also comprises: a top plate bridging the tops of the two stack of said guide members and rigidly secured thereto; and a hole in said top plate through which said force indicator means projects when said nuts are tightened.",
    "4. The invention defined in claim 3, wherein said force indicator means comprises: a metal strip coextensive with said compression force springs positioned on top of the latter and having its ends bearing on said upper guide members in the two stacks thereof; a tongue formed in said strip having a free end movable upwardly when said strip bows with said compression force springs; and a tab on the end of said tongue extending through said hole in said top plate and indicating relative to said top plate when the proper force is reached.",
    "5. The invention defined in claim 1, wherein said cross bar comprises: a round pivot bar having holes through its ends through which said clamp bolts extend and undercut end portions for locating the heads of said bolts and to keep them from turning; and a flat pressure plate between the center of said pivot bar and the lower heat sink to afford low unit pressure on the insulation therebetween.",
    "6. The invention defined in claim 1, wherein said insulating means comprises: a rubber boot surrounding the semiconductor device and sealing the space around the latter between said heat sinks.",
    "7. The invention defined in claim 1, wherein said plurality of diamond shaped compression force springs comprise: one spring for each unit of force required to be applied between said heat sinks and the semiconductor device so that the desired multiple of unit force can be attained by selecting the corresponding number of compression force springs; and each said spring being flat and tapering from a relatively wide center toward the opposite ends so as to distribute the stresses equally throughout its length.",
    "8. The invention defined in claim 2, wherein said means holding said pressure bearing centered against the upper heat sink comprises: a bottom plate rigidly secured in a bridging relation to the bottoms of the two stacks of guide members; and a hole at the center of said bottom plate retaining said pressure bearing centered on the upper heat sink.",
    "9. The invention defined in claim 1, wherein said force indicator means comprises: a spring biased plunger indicating the amount of force by its position; and a mechanical motion amplifying lever system between the upper compression force spring and said plunger; and adjustable means for presetting the initial position of said plunger with respect to a reference level and for calibrating the final position of said plunger under load.",
    "10. The invention defined in claim 1, wherein said spring guiding and force applying means comprises: a spring clip having upstanding arms between which said compression force springs are stacked and held together; and the bottom of said spring clip being offset from the lowermost compression force spring to rest on said pressure bearing to take up slack in said subassembly.",
    "11. The invention defined in claim 1, wherein said insulating means compRises insulating members covering said cross bar and portions of said bolts."
  ],
  "cpc": [
    "H10W 40/611",
    "H10W 40/625",
    "H10W 72/00"
  ],
  "assignees": [
    "CUTLER HAMMER INC"
  ],
  "filing_date": "1970-10-28",
  "publication_date": "1972-08-29",
  "grant_date": "1972-08-29",
  "priority_date": "1970-10-28",
  "application_number": "US-3688159D-A",
  "family_id": "22185714",
  "citations": [
    "US3536960A",
    "US3571663A"
  ]
}