Chemical durability of anorthite-based low temperature co-fired ceramics

The chemical durability of a typical low k LTCC material consisting of zinc calcium aluminoborosilicate glass and alumina filler was studied. Leaching experiments were performed by measuring weight loss of the samples in selected acid and base aqueous solutions of HCl, H₂SO₄ and KOH at two different temperatures of 25° and 80°C. The leaching performance was found to depend strongly on the type of leaching solution, duration and temperature. The LTCC sample was most stable in 10 vol% KOH with a minimal weight loss of ̃0.43% even after 300 min at 80°C. At the same condition, both cases of 10 vol% HCl and 10 vol% H₂SO₄ exhibited serious weight losses greater than 30%. It was interesting to observe that the high capability of leaching in the acid solutions originated significantly from the leaching of crystalline anorthite (CaAl ₂Si₂O₈) phase.