Patent Number: 7,131,566

Title: Packaging method using lead-free solder

Abstract: This invention relates to a packaging method using lead-free solder, characterized by including a reflow-soldering step in which a surface mount device is soldered to a circuit board with a lead-free solder paste; an inserting step in which the lead or terminal of a insertion mount device is inserted into the circuit board; a step in which a warp preventing jig is attached to the circuit board; a flux applying step in which flux is applied to the foregoing circuit board; a preheating step in which, after applying flux, the lower surface of the circuit board is preheated; a flow-soldering step in which the upper surface of the circuit board the lower surface of which was preheated in the preheating step is heated, and by applying lead-free solder paste to the lower surface of the circuit board, the lead or terminal of the insertion mount device is flow-soldered to the circuit board; and a temperature controlling step where temperatures of both surfaces of a circuit board are adjusted, the upper surface of the circuit board is cooled or heated and the lower surface of the said circuit board is cooled, immediately after soldering in the flow-soldering step.

Inventors: Nakatsuka; Tetsuya (Tokyo, JP), Okamoto; Masahide (Tokyo, JP), Ohmura; Tomoyuki (Tokyo, JP)

Assignee: Hitachi, Ltd.

International Classification: H05K 3/34 (20060101)

Expiration Date: 2019-11-07 0:00:00