Patent ID: 6585149
Filing Date: 2003-07-01
Classification: B23K,H05K,Y02P

Abstract:
A mixed packaging method using lead-free solder comprising:a reflow-soldering step of reflow-soldering a surface mount device to an upper surface and/or a lower surface of a circuit board with a lead-free solder paste; an inserting step of inserting a lead or a terminal of an insertion mount device into a through hole drilled in said circuit board from an upper surface side of said circuit board; a flux applying step of applying flux to said circuit board after the lead or the terminal of said insertion mount device is inserted into the through hole in said inserting step; a preheating step of preheating the lower surface of said circuit board by a preheating system in order to shorten a time required for connecting the lead or the terminal of said insertion mount device to the circuit board in a flow-soldering step after the flux is applied to said circuit board in said flux applying step; the flow-soldering step including flow-soldering the lead or the terminal of said insertion mount device to the circuit board by applying a lead-free solder jet to the lower surface of said circuit board, which had been preheated in said preheating step, the lead-free solder jet being applied while cooling the upper surface of said circuit board with a board cooling system which blows fluid having a temperature not more than 50Â° C. in order to prevent a peel off effect that would result from re-melting of a portion of the solder paste connecting the surface mount device to the upper surface and/or the lower surface of the circuit board, a temperature of said lead-free solder jet applied to the lower surface of said circuit board being within a range of 170Â° C. to 260Â° C.; and a circuit board-double-side temperature control step of cooling the upper surface and the lower surface of said circuit board, immediately after the soldering in said flow-soldering step.