Characterization of a laser-soldered avionic component using lead-free paste

• Published in: Optics and laser technology Vol. 41; no. 2; pp. 159 - 164
• Main Authors: Lima, M.S.F., Riva, R., Destro, M.G., Santo, A.M.E., Silva, R.A., Guimaraes, S.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2009; Elsevier
• Subjects: Biological and medical applications; Electrical contacts; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Industrial applications; Laser soldering; Lead-free soldering; Optics; Physics; Lead-free soldering; Laser soldering; Electrical contacts; Performance evaluation; Electrical properties; Industrial application; Laser assisted processing; Laser beam applications; Copper; Soldering; Avionics
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2008.05.015

Electrical cable-connector sets used in airplanes have been laser soldered using a lead-free paste. These connections are usually crimped using a hand tool, which necessarily leads to variable mechanical and electrical properties in the connection. Calorimetric studies have shown that paste melting occurs within tenths of a second at laser intensities of 400 or 500 W cm −2. However, when such laser intensities strike the connector surface, some boiling occurs. In order to avoid paste losses, a stepped heating curve is applied, which allows good weldability. It was verified that a reaction layer of 2 μm length exists between the wires and the solidified solder paste, and also that there is some diffusion of copper from the wires to the paste. The soldered joints are 38% more electrically conductible and have 113% more tensile strength resistance than crimped joints.