Patent ID: 6115913
Filing Date: 2000-09-12
Classification: H01R,H05K,Y02P,Y10T

Abstract:
A method of making a connecting board to be disposed between a base plate having a plurality of surface-bonding pads and a mounting board having a plurality of surface-bonding and mounting pads at corresponding positions to the surface-bonding and mounting pads of the base plate, for connection of the base plate and the mounting board through connection at the surface-bonding pads on a first surface side of the connecting board and at the surface-bonding and mounting pads on a second surface side of the connecting board, the connecting board including a substrate in the form of a flat plate, having the first surface side and the second surface side and a plurality of through holes extending between the first and second surface sides, a plurality of soft metal bodies mounted in the through holes, respectively, each of the soft metal bodies having at least one of a first protruded portion protruding from the first surface side and a second protruded portion protruding from the second surface side, a plurality of first surface side solder layers, each of which is disposed on a surface portion of each of the soft metal bodies, which is located on the first surface side, and a plurality of second surface side solder layers, each of which is disposed on a surface portion of each of the soft metal bodies, which is located on the second surface side, wherein the soft metal bodies and the first and second solder layers are made of solders of the same kind but different in melting points, the method comprising the steps of:metallizing an inner circumferential wall of each of said through holes of said connecting board substrate;preparing a plurality of solder balls for forming said respective soft metal bodies, said solder balls being larger in diameter than said through holes;mounting said solder balls on said connecting board substrate in such a manner that each of said solder balls partly gets into each of said through holes and is thereby held in place;heating and melting said solder balls and allowing said solder balls to be embedded in said through holes and partly protrude downward from said through holes; andcooling and solidifying said solder balls.