A mixture system of MO-SiO2 (M: Ca, Sr, Ba) glass and Al2O3 crystalline powder has been investigated as a substrate material for low temperature co-fired ceramics (LTCC). This type of glass-ceramic mixture is known to be crystallized during the sintering process. We found that the adhesion strength of external electrode was strongly related with sintering condition. Crystallization behavior was monitored by means of powder X-ray diffraction (XRD). The microstructure of sintered body after electroless plating was examined by Scanning Electron Microscopy (SEM). It was observed that the degree of crystallization was strongly affected by sintering condition. We focused ourselves on elucidating the relationship between the degree of crystallization and the adhesion strength of external electrode that was made by means of electroless plating.

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.

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