From Raw Materials To Finished Products — The Complete Manufacturing Process of Hermetic Packaging

1. Incoming Material Inspection and Pretreatment

The quality of hermetic packaging begins with the raw materials. Inspection standards for the three core material types:

Metal housings — Kovar alloy housings require verification of chemical composition (Fe: 53%, Ni: 29%, Co: 17%), sampling of grain size and dimensional tolerances, and confirmation that there are no machining cracks.

Glass/ceramics — glass frit requires verification of the softening point and CTE; Al₂O₃ ceramics require verification of purity (≥96%) and density. Incoming materials must be cleaned and degreased, then dried for later use.

Metal pins — surface finish, straightness and diameter tolerance are checked; any surface scratch could become the starting point of a leak.

Pretreatment determines the success of all subsequent sealing — if the surface is not clean, the seal will not hold.

2. Sealing, Surface Treatment and Final Inspection

The sealing process is the core: GTMS is carried out in a sintering furnace and CTMS in a brazing furnace. After sealing comes surface treatment: nickel plating first, then gold plating, to ensure solderability and corrosion resistance.

Final inspection runs three gates in parallel:

Gate 1 — hermeticity testing.

Gate 2 — visual inspection, checking the sealing surface for cracks, bubbles and discoloration.

Gate 3 — sampling inspection of dimensions and electrical performance; pin spacing and insulation resistance must meet specifications.

Only a product that passes all three gates is a qualified product. From raw material to finished product, every step has standards, records and traceability.

[Next Article Preview] Next article: typical applications of hermetic packaging in the sensor field.

[Glossary]

1. Kovar Alloy: an iron-nickel-cobalt alloy (Fe:53%/Ni:29%/Co:17%) whose CTE matches borosilicate glass; the most commonly used metal in GTMS

2. Al₂O₃ Ceramic (Alumina Ceramic): aluminum oxide ceramic; at a purity of ≥96% it offers excellent insulation and mechanical strength, making it the most commonly used ceramic in CTMS

3. Insulation Resistance: the resistance between the pins and the housing — the key electrical parameter for evaluating the insulation performance of a package