Patent ID: 7943001
Filing Date: 2011-05-17
Classification: H05K,Y10T

Abstract:
1. A process for producing a multilayer board including a first substrate having a terminal which is coated with a protective plating film formed of a gold plating film on an underlying nickel film, a second substrate having a terminal which is coated with a protective plating film formed of a gold plating film on an underlying nickel film, an insulating layer, and a conductive member, the first substrate being bonded to the second substrate with the insulating layer provided therebetween, the terminals being opposite each other and being electrically connected with the conductive member, the process comprising: applying a bonding ink to the terminal of the first substrate, the bonding ink including a thermosetting resin containing a filler and a curing agent, the filler being formed of copper particles each of which is plated with tin-bismuth solder, the copper particles each having a first melting point, and the tin-bismuth solder having a second melting point lower than the first melting point; preparing a bonding sheet on which a through hole has been formed; bonding the bonding sheet to the second substrate in such a manner that the terminal of the second substrate is located in the through hole, the through hole of the bonding sheet having a greater width than the terminal of the second substrate; positioning the first substrate and the second substrate in such a manner that the terminals thereof are opposite each other and laminating the first substrate and the second substrate with the bonding sheet provided therebetween; and heating and pressuring the resulting laminate to effect curing of the bonding sheet and the bonding ink to form an integral structure, whereby gold in the protective plating films diffuses and nickel in the underlying nickel films is alloyed with the filler to form strong bonding.