Cover Assemblies

CLICK HERE TO DOWNLOAD COMPLETE COVER ASSEMBLIES BROCHURE

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

Base Composition

Alloy: Typically Kovar™ or Alloy 42. Alloys of Aluminum, Titanium and Stainless Steel are available upon request. Plating: Typically Nickel electroplate per QQ-N-290, 50 – 350 microinches thick followed by Gold electroplate 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"

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 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 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.