Coining Cover Assemblies

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Coining Cover Assemblies offer many advantages for hermetic sealing processes of electronic packages over techniques using separate solder preforms and covers. The base material, either Kovar™ or Alloy 42, is electroplated with nickel (nickel plating) for solderability and to prevent corrosion in the future. The base is then electroplated with gold (gold plating) to provide a highly solderable surface. Finally, the base is welded to a solder preform.

Cover Assembly Base Composition

Alloy: Typically Kovar™ or Alloy 42. Aluminum alloys, Titanium and Stainless Steel are available upon request. Plating: Typically Nickel plating per QQ-N-290, 50 – 350 microinches thick followed by Gold electroplating per MIL-G-45204, Type III, Grade A, 50 microinches thick minimum. Alternate plating schemes, including four layer plating and customer specific thicknesses, are available upon request. Base will meet the requirements of MIL-M-38510. 
Tolerances: Length and width - +/- .003"; Thickness - +/- .001"
Flatness: <.001" for lids <.500" or <.002" for lids >.500"

Coining Preform Composition

Composition: 80 +/- 1% Au, balance Sn with total purity level >99.985%. Length and Width Dimension Tolerance: +/–.003". Thickness Dimension Tolerance: +/-.0003"

Tack Weld Cover Assembly: Three integral welds, Alignment +/–.005", Weld Splatter <.003"

Cover Assembly Processing Information

We recommend a typical clip force of 0.9-2 lbs. Clip force varies depending on lid cover size, preform thickness, lid flatness, and seal-ring flatness. Typical sealing profiles allow for 2-5 minutes above 280 C (melting temperature) with a peak temperature not exceeding 340 C in dry nitrogen, or hydrogen.