| 摘要 |
PROBLEM TO BE SOLVED: To improve the toughness, strength and conductivity of the entire of a circuit board by arranging a high heat-conducting silicon nitride board having a specific heat conductivity and a board having a specific heat conductivity on the same plane, and jointing a metal circuit board at least to the high heat-conducting silicon nitride board having a specific heat conductivity. SOLUTION: A silicon nitride (Si3 N4 ) board 2, having a heat conductivity of 70W/m.K(60W/m.K or more) is formed, and on the other hand Al2 O3 boards 2a having heat conductivities less than 60W/m.K are formed, and they are combined on the same plane to form a composite board 10. In the circuit-layer forming regions of the surfaces of the silicon nitride board 2 and the alumina boards 2a, active metal soldering material layers 7a, 7b are formed, and they are heated in a vacuum with copper circuit boards 4 kept in touch with a metal board 5 at specified position to make a jointed substance. By arranging high heat-conducting silicon nitride boards, having sharply improved heat conductivities in addition to high strength toughness properties intrinsic in silicon nitride sintered compacts, at regions where signticntly improved strength and heat conduction are required, it becomes possible to improve the toughness, strength and conductivity for the entire of the circuit board. |
