Hermetic Package Sealing
MCL’s resistance joining process development provides hermetic package seals with highest yields and lowest costs. Leak rates below the updated MIL-STD-883 Test Method 1014 Seal will be realized while processing with existing equipment. Services include materials design and selection; problem resolution; application-specific tooling; and engineering of internal microcircuit environment with inert gases.
Parallel Seam Sealing (PSS) is the most common hermetic encapsulation process that maintains an internal device below temperature specifications for all materials including die attach, coatings and device specifications. Joining processes of the cover and package are commonly referred to as either Weld Seal or Solder Seal.
Weld Seal processes are the direct joining of plated covers and seal rings. Standard joining materials are fabricated from KovarTM, 29=Ni/17-Co/Bal Fe alloy. The most common plating is Au over Ni for a corrosion-resistant joint that will pass the salt spray test per MIL-STD-883 TM 1009.
Solder Seal processes with eutectic 80Au20Sn solder wet the mating surfaces of the covers and seal rings. PSS, compared to conventional furnace sealing, maintains peak temperatures below specifications for all device and adhesives. Solder seal joint must meet MIL-STD-883 TM 2012 radiography for a continuous joint.
Both cover seal processes enable a variety of feedthroughs for both the cover and package with exposure temperature significantly lower than specification.
One-shot welding processing for hermetic package joining is standard for TO packages, where leads are in the bottom of the package. In addition to the leak rate requirements of MIL-STD-883 TM 1014 Seal, the sealed devices must also pass MIL-STD-883 TM 2020 Particle Impact Noise Detection testing.