Junction structure and junction method for conductive projection
To provide a junction structure and a junction method for conductive projection advantageous in that a required reinforcement strength can be obtained while suppressing the amount of a reinforcing resin material supplied to prevent warpage due to curing shrinkage. A conductive projection is joined to the surface of a conductor portion formed at the same level as that of the surface of the insulating layer so that a root portion of the projection is surrounded by a fillet-form resin material. The resin material contains an activator which assists in the junction between the conductive projection and the conductor portion when the resin material is in an uncured state, and is fused by heating to wet and rise the root portion of the conductive projection so as to be in a fillet form. The resin material is cured by an ultraviolet light while excluding the resin material on the conductor portion.
1. A junction structure for conductive projection, comprising:
a first insulating layer;
a conductor portion formed on a surface of the first insulating layer;
a conductive projection joined to a top surface of the conductor portion;
a second insulating layer formed on the surface of the first insulating layer such that the second insulating layer surrounds the conductor portion and is in contact with the sides of the conductor portion, but does not contact the top surface of the conductor portion, the second insulating layer having a top surface that is formed at approximately the same level as the top surface of the conductor portion; and
a resin material extending from the conductive projection to another conductive projection, a portion of the resin material surrounding a root portion of the conductive projection in a ring form, the resin material being of a different material than the second insulating material.
2. The junction structure for conductive projection according to claim 1 , wherein said resin material which surrounds said root portion of said conductive projection is in a fillet form.
3. The junction structure for conductive projection according to claim 1 , wherein said resin material contains an activator which assists the junction between said conductive projection and said conductor portion when said resin material is in an uncured state.
4. The junction structure for conductive projection according to claim 1 , wherein said resin material has photocuring property.
5. The junction structure for conductive projection according to claim 1 , wherein said conductive projection comprises a core portion and a conductive surface layer portion for covering the surface of said core portion.
6. A junction method for conductive projection, comprising the steps of:
forming a first insulating layer;
forming a conductor portion on a surface of the first insulating layer;
forming a second insulating layer on the surface of the first insulating layer such that the second insulating layer surrounds the conductor portion and is in contact with the sides of the conductor portion, but does not contact the top surface of the conductor portion, the second insulating layer having a top surface that is formed approximately the same level as the top surface of the conductor portion; and
supplying a resin material in an uncured state onto at least a junction plane of said conductor portion to which a conductive projection is joined, said resin material in an uncured state being supplied onto the entire surfaces of both of said conductor portion and said insulating layer;
curing said supplied resin except for a portion of said resin on said junction plane; disposing said conductive projection on said junction plane, on which said resin material remains uncured; and
heating said resin material and said conductive projection to join said conductive projection to said conductor portion while curing said previously uncured resin material so as that a root portion of said conductive projection is surrounded by said resin material in a ring form.