| 摘要 |
PURPOSE:To enable the improvement in durability without generating cracks even under thermal shock or thermal cycle, by a method wherein the intersection of two surfaces of an insulator substrate is curved with a radius at least double the thickness of the conductor layer. CONSTITUTION:For example, an alumina ceramic plate is chosen as the sub strate 1 made of insulator, and the intersection of the front surface 3 of the ceramic plate 1 with its side end surface 4 is cut into a curved surface R. This curved surface R can also be made when the ceramic plate 1 is molded. It is preferable that the radius of the curved surface R is molded. It is preferable that the radius of the curved surface R is at least double the thickness of a thick film metallized conductor layer 8 to be formed. The surfaces 3, 4 and the intersection curved surface R are coated with a suspension of thin film metallizing material containing no frits, which is dried and baked, and then said layer 8 is uniformly formed in continuity to the surfaces 3, 4 and the curved surface R. This process yields the title substrate having parts of the connection of the surfaces 3 and 4. |
