| 摘要 |
PROBLEM TO BE SOLVED: To improve splittability of a substrate by forming cleavage grooves and hollows on respective surfaces of front-back both sides different from each other, setting the point angle of each cleavage groove to be not larger than a specific value and forming the hollows on the underside between cleavage grooves. SOLUTION: A point angle is set to be <=20 deg.. A greensheet 1 is formed by a doctor blade process from a slurry obtained by mixing raw material powder where Al2O3 powder, MgO powder, CaCO3 powder and SiO2 powder are mixed with a butyral resin, a plasticizer and a solvent, and dispersing them. Cleavage grooves 2 are formed on the greensheet 1 by a metallic mold where blades having an edge angle of 30-45 deg. are built in e.g. at an interval of 360 μm. The hollows 3 having e.g. a width of 240 μm and a depth of 10-40 μm are formed by a metallic mold on the underside between cleavage grooves 2 of the greensheet 1 and are baked at 1,600 deg.C. Splittability does not depend on the composition of a ceramics substrate but is influenced by the form of cleavage grooves. Deeper the depth of the hollows 3, the smaller the edge angle of the cleavage grooves, which 1eads to improvement in a cleavage yield. |
