Title: Reflow of lead-free solder by microwave heating

Authors: Yang Ju; Hayato Yamauchi; Hiroki Oshima; Kensuke Tanaka

Addresses: Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ' Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ' Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ' Department of Mechanical Science and Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan

Abstract: Recently, the use of solder containing lead in the interconnection between printed substrate and electric packages has been prohibited since lead may have a bad influence on humans and the environment. Today Sn-Ag-Cu alloys (SnAgCu) are used in general as a substitute of Sn-Pb alloys (SnPb). However, the melting point of SnAgCu is higher than that for SnPb which may induce damages in the substrate and packages. To solve this problem, the reflow of lead-free solder by microwave heating was studied. The microwave heating system worked at 2.45 GHz frequency on TE10 mode. The most suitable heating location in the waveguide and the most suitable microwave power were investigated by measuring the temperature of the substrate and the solder simultaneously. After the solder was heated up to the melting point of 493 K, solder-mounted was achieved. The intermetallic chemical compound between the solder and Cu was observed by SEM and it was also analysed by the cross-section of the solder using EDX.

Keywords: solder reflow; lead-free soldering; microwave heating; substrate temperature; solder temperature.

DOI: 10.1504/IJMSI.2014.064771

International Journal of Materials and Structural Integrity, 2014 Vol.8 No.1/2/3, pp.32 - 41

Published online: 21 Oct 2014 *

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