Novel Double-Layer Structure LTCC Substrate with Enhanced Flexural and Adhesions Strengths

Abstract

To enhance both adhesive strength and flexural strength, a new structure consisting of two layers with different degree of crystallization was investigated as a substrate material for low‐temperature co‐fired ceramics (LTCC). A mixture system of silica‐based glass and Al2O3 crystalline powder, which is known to be crystallized during the sintering process was used. Glasses with different compositions and various amounts of alumina filler were used for our new structure. Crystallization behavior was monitored by means of powder X‐ray diffraction. The microstructure of sintered body after electroless plating was examined by scanning electron microscopy. It was observed that the degree of crystallization was strongly affected by glass composition and amount of alumina filler but sintering behavior depended on glass composition rather than amount of alumina. The combination of layers with 40 wt% alumina and 45 wt% alumina as an inner layer and outer layer, relatively, shows 362 MPa flexural strength and 1.74 kgf adhesion strength.

INFLUENCE OF THE CaO CONTENT IN GLASS ON THE SINTERABILITY AND PROPERTIES OF A GLASS/Al₂O₃ COMPOSITE FOR LTCC APPLICATIONS

“…Shang et al [24] added a small amount of CaO to a K 2 O-B 2 O 3 -SiO 2 -Al 2 O 3 glass to improve the material densification and obtained a glass-ceramic with flexural strength of 173 MPa. For glass/ceramic system of LTCC materials, studies have shown that a CaO-B 2 O 3 -SiO 2 / Mg 2 Al 4 Si 5 O 18 [25], CaO- [26] system glass sintering will react to form a strong phase interface, which is conducive to the wettability of the glass to the ceramic filler and improves the densification of the materials, and the formed anorthite phase can also improve the flexural strength. The CaO content of the glass in these studies was generally high (> 35 wt.…”