PURPOSE: To eliminate warpage, peeling of a surface-mount circuit board, breakage, damage, etc., of a mounting component and to enhance quality, reliability by sequentially using a preliminarily heating hot air nozzle and a solder melting hot nozzle. ;CONSTITUTION: Time up to a point C of curve A of the case of a part to be soldered and a curve B of the case of a surface-mount circuit board of a temperature profile at the time of mounting and soldering is located at a preliminarily heating step by a first hot air nozzle, and time after the point C is located at a heating step for raising the part to be soldered to 23°C of a necessary temperature. The difference of the temperature rises of the board 2 and the part to be soldered, i.e., in this case, a connecting lead la and a connecting pad 2a is not almost recognized, and since both are heated to be raised at temperatures, overheating of the board 2 and a mounting PGA type semiconductor device 1 while the parts to be soldered are heated to a predetermined temperature is entirely eliminated.;COPYRIGHT: (C)1993,JPO&Japio
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