| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a circuit board which ensures high reliability in the connection between a wiring conductor and a through hole conductor in a condition where a heat load is repeatedly impressed thereon for a long period of time. <P>SOLUTION: The circuit board has such an arrangement in which; a plurality of insulating layers 1 of heat resistant textile base impregnated with thermosetting resin and a plurality of wiring conductors 2 each consisting of a copper foil are alternately stacked; and the wiring conductors 2, which are disposed above and below the insulating layer 1, are electrically connected through a through conductor 4 obtained by filling a through hole 3 provided in the insulating layer 1 with a conductive material that comprises metal powder 5 whose main component is tin and a thermosetting resin. Each wiring conductor 2 is formed so that a diffusion layer 6 formed by the diffusion of tin on the surface of a copper foil for establishing connection with the through conductor 4, extends outward, in terms of an opening 8 of the through hole 3, from the end thereof to the extent of 1 to 30% of the diameter of the opening 8. <P>COPYRIGHT: (C)2004,JPO |
