Wiring board and method of producing the same
First Claim
1. A method of producing a wiring board comprising a wiring laminated layer portion having a dielectric layer comprised of a polymer material and an alternately laminated conductive layer, a plurality of metal pads disposed on a major surface of the dielectric layer of the wiring laminated layer portion, and a solder resist layer disposed on the major surface of the wiring laminated layer portion and having openings therein exposing the metal pads, wherein each of the metal pads comprises a main layer, comprised of a Cu plated layer, and a Sn solder covering layer, comprised of high temperature Sn solder essentially comprised of Sn and having a liquid phase line temperature of between 185°
- C. and 232°
C., the Sn solder covering layer covering the surface of the main layer located in each of the openings of the solder resist layer at an area covering ratio of at least about 81% so as to be in contact with the main layer and having a protuberant surface with a maximum thickness at a central position of the opening and a minimum thickness at an inner peripheral edge position thereof, and the thickness of the protuberant surface at the central position being smaller than the depth of the corresponding opening, the method comprising the following steps executed in the following order;
a preliminary plating step of forming the solder resist layer such that a surface of the main layer of each metal pad is exposed in a corresponding opening, and covering the exposed surface of the main layer with a preliminary Sn plated layer;
a solder paste application step of applying a solder paste, containing solder powder comprised of the high temperature Sn solder and thicker than the preliminary Sn plated layer, on the preliminary Sn plated layer; and
a solder melting step of forming the Sn solder covering layer by melting the applied solder paste together with the preliminary Sn plated layer, by heating the applied solder paste to a temperature higher than the liquid phase line temperature of the high temperature Sn solder, and thereby wettingly extending the Sn solder covering layer over the surface of the main layer.
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Accused Products
Abstract
A method of producing a wiring board includes a preliminary plating step of forming a solder resist layer such that the main layer of each metal pad of the board is exposed in each corresponding opening and covering the surface of the exposed main layer with a preliminary Sn plated layer. A solder paste application step involves applying a solder paste, containing solder powder comprised of the high temperature Sn solder and thicker than the preliminary Sn plated layer, on the preliminary Sn plated layer. A subsequent solder melting step involves forming the Sn solder covering layer by melting the solder paste layer together with the preliminary Sn plated layer by heating the solder paste layer to a temperature higher than the liquid phase line temperature of the high temperature Sn solder. This wettingly extends the melted layers over the surface of the main layer.
16 Citations
13 Claims
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1. A method of producing a wiring board comprising a wiring laminated layer portion having a dielectric layer comprised of a polymer material and an alternately laminated conductive layer, a plurality of metal pads disposed on a major surface of the dielectric layer of the wiring laminated layer portion, and a solder resist layer disposed on the major surface of the wiring laminated layer portion and having openings therein exposing the metal pads, wherein each of the metal pads comprises a main layer, comprised of a Cu plated layer, and a Sn solder covering layer, comprised of high temperature Sn solder essentially comprised of Sn and having a liquid phase line temperature of between 185°
- C. and 232°
C., the Sn solder covering layer covering the surface of the main layer located in each of the openings of the solder resist layer at an area covering ratio of at least about 81% so as to be in contact with the main layer and having a protuberant surface with a maximum thickness at a central position of the opening and a minimum thickness at an inner peripheral edge position thereof, and the thickness of the protuberant surface at the central position being smaller than the depth of the corresponding opening, the method comprising the following steps executed in the following order;a preliminary plating step of forming the solder resist layer such that a surface of the main layer of each metal pad is exposed in a corresponding opening, and covering the exposed surface of the main layer with a preliminary Sn plated layer; a solder paste application step of applying a solder paste, containing solder powder comprised of the high temperature Sn solder and thicker than the preliminary Sn plated layer, on the preliminary Sn plated layer; and a solder melting step of forming the Sn solder covering layer by melting the applied solder paste together with the preliminary Sn plated layer, by heating the applied solder paste to a temperature higher than the liquid phase line temperature of the high temperature Sn solder, and thereby wettingly extending the Sn solder covering layer over the surface of the main layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- C. and 232°
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8. A wiring board comprising a wiring laminated layer portion having a dielectric layer comprised of a polymer material and an alternately laminated conductive layer, a plurality of metal pads disposed on a major surface formed of the dielectric layer of the wiring laminated layer portion, and a solder resist layer disposed on the major surface of the wiring laminated layer portion and having openings for exposing the metal pads,
each of the metal pads comprising a main layer, comprised of a Cu plated layer, and a Sn solder covering layer comprised of a high temperature Sn solder principally comprised of Sn and having a liquid phase line temperature of between about 185° - C. and 232°
C., the Sn solder covering layer covering a surface of the main layer located in each of the openings of the solder resist layer with an area covering ratio of at least 81% so as to be in contact with the main layer and having a protuberant shape having a maximum thickness at a central position of the opening and a minimum thickness at an inner peripheral edge position thereof, the thickness of the Sn covering layer at the central position being smaller than the depth of the corresponding opening. - View Dependent Claims (9, 10, 11, 12, 13)
- C. and 232°
Specification