PRINTED CIRCUIT UNIT AND ITS MANUFACTURE

PROBLEM TO BE SOLVED: To efficiently mount mold parts on the same board by soldering/ mounting the lead pin of a first part to the electrode of a printed circuit board with first low melting point metal, forming second low melting point metal on the electrode of the printed circuit board, jointing the electrode of a second part to second low melting point metal and mounting the second part on the printed circuit board. SOLUTION: A mask 26 having the corresponding opening part 26a of a first electrode 12 is arranged on a printed circuit board 10 and solder paste 24 is put on the mask 26. A squeegee 28 is slid along the surface of the mask 26 and the opening part 26a of the mask 26 is filled with solder paste 24. QFP 16 is positioned against the printed circuit board 10 so that the lead pins 18 of QFP 16 are out on solder paste 22 on the first electrode 12 of the circuit board 10. The lead pins 18 are tacked by solder paste 24, an infrared lamp 30 is radiated and paste is reflowed. A bear chip 20 is loaded/connected onto a second electrode 14 in connection to the first electrode 12 of the circuit board 10 with solder 24a contained in paste 24.