How the Right Cored Wire Can Optimize Automated Soldering

Jen Fijalkowski, Westin Bent, Geoffrey Post
MacDermid Alpha Electronic Solutions
NJ, USA

Ken Takahashi
JAPAN UNIX Co.,Ltd.
Tokyo, Japan

Automated soldering is becoming increasingly popular because it reduces assembly variation and cycle times. To optimize an automated point-to-point process, one must select a cored wire which wets rapidly, minimizes defects, and leaves minimal, electrochemically safe post-soldering residues.

This study investigates the impact cored wire flux activity and flux core percentage has on soldering performance and speed. Additionally, this research aims to identify optimal soldering parameters by varying preheat time, feed rate, tip temperature, dwell time. Cored wires used in this study are SAC305 No Cleans with ROL0 and ROL1 flux classifications with 2.2wt%, 3.3wt%, 4.4wt% and 6.0% flux cores.

Measurement methods include visual post-soldering inspection and x-ray analysis of barrel-fill to assess solder joint and flux residue quality. The goal of this paper is to inform users of practical strategies for improving automated wire soldering efficiency and quality in electronics assembly.

Data collected in this study shows that using higher flux content wires, such as P4 and P6, with Low heating time settings, results in soldering performance that is equal to or better than the lower flux content wires, P2 and P3, no matter heating time settings.

Additionally, findings indicate that using higher flux content wires with automated point-to-point soldering systems could result in reduced cycle times as compared to lower flux content wires which increases productivity and profitability of an assembler while maintaining or potentially improving board level reliability.

Finally, use of this ROL1 wire (CW3) produced more consistently high-quality joints no matter the flux content or heat time settings compared the ROL0 formulations (CW1 and CW2) and is therefore recommended when appropriate.