ALUMINA CERAMIC LID

PROBLEM TO BE SOLVED: To enhance the folding strength of an alumina ceramic lid which seals the cavity of a ceramic package. SOLUTION: An alumina ceramic lid 14 is bonded with solder 15 to the top face of a ceramic package 11 to seal its cavity 12. Primary grain of alumina, the raw material of the lid 14, is pulverized into a fine grain of 1-2 microns in a mean grain size and press-formed (after decay) to increase the contact points of the primary grain, thereby improving the sintering property. It is more treated to provide a sharp grain size distribution having D10-D90 (accumulated 10% and 90% grain sizes from the fine grain side) within ±70% of the mean grain size. Owing to this, the primary grain is roughly charged in the granular material before press-forming, thereby increasing the porosity to lower the granular material strength and improve the decay property (collapsing property) of the material. Thus, a compact and high-strength alumina sintered compact.