Solder-coated printed circuit board and method of manufacturing the same

A method of manufacturing a solder-coated printed circuit board, comprising the steps of:

• preparing a printed circuit board body;
• forming a plurality of pads each satisfying a relation 2H<W, where H is a projecting height of each pad from a board body surface and W is a width of each pad, on the board body;
• and
• forming a solder layer on each pad, the solder layer being formed by a substitution between (a) one of a powder of a metal having the highest ionization tendency among metals constituting the solder layer and a powder of an alloy thereof, and (b) a salt formed by bonding another metal or metals in the solder layer to an organic acid.

A solder-coated printed circuit board comprising:

• a printed circuit board body;
• and
• a plurality of pads formed on a surface portion of the board body and each pad having a solder layer of a thickness necessary for soldering a parts lead,
• wherein the solder layer is of a type formed by a substitution reaction between (a) one of a powder of a metal having the highest ionization tendency among metals constituting the solder layer and a powder of an alloy thereof, and (b) a salt formed by bonding another metal or metals in the solder layer to an organic acid, the plurality of pads being arranged at a pitch of not more than 0.5 mm to form a pad array, and wherein a width of each of said pads located at two ends of the pad array is larger than that of a pad located therebetween.

A method of manufacturing a solder-coated printed circuit board, comprising the steps of:

• preparing a printed circuit board body;
• forming a plurality of pads on the board body to form a pad array which has a pitch of not more than 0.5 mm and in which a width of each of said pads at two ends of the pad array is larger than that of a pad located therebetween;
• and
• forming a solder layer on each of said plurality of pads, the solder layer being formed by a substitution reaction between (a) one of a powder of a metal having the highest ionization tendency among metals constituting the solder layer and a powder of an alloy thereof, and (b) a salt formed by bonding another metal or metals in the solder layer to an organic acid.

A solder-coated printed circuit board comprising:

• a printed circuit board body;
• and
• a plurality of pads formed on a surface portion of the board body and each pad having a solder layer of a thickness necessary for soldering a parts lead,
• wherein the solder layer is of a type formed by a substitution reaction between (a) one of a powder of a metal having the highest ionization tendency among metals constituting the solder layer and a powder of an alloy thereof, and (b) a salt formed by bonding another metal or metals in the solder layer to an organic acid, wherein the plurality of pads are arranged at a pitch of not more than 0.5 mm to form a pad array, and a width W of each pad and a pad-to-pad distance D satisfy a relation W>D.

A method of manufacturing a solder-coated printed circuit board, comprising the steps of:

• preparing a printed circuit board body;
• forming a plurality of pads on the board body at a pitch of not more than 0.5 mm such that a width W of each pad and a pad-to-pad distance D satisfy a relation W>D;
• and
• forming a solder layer on each pad, the solder layer being formed by a substitution reaction between a powder of a metal having the highest ionization tendency among metals constituting the solder layer or a powder of an alloy thereof and a salt formed by bonding an other metal or metals in the solder layer to an organic acid.