Heated Gas Jet Reflow: An Alternative Reflow Solder Assembly Process Technology*

Abstract

A new product design required the addition of a second layer of electronics to control a base module. This product was designed with significant overhangs of heavy leads and components which presented a significant challenge to many different solder assembly processes. Only the heated gas jet process was able to solder the product successfully without damaging the printed wiring boards.

To answer the challenge, a new machine was developed, combining dispensing of solder paste with hot gas jet reflow technology. This provided a combination of capabilities resulting in a flexible process which was significantly superior to alternative technologies.

Other soldering processes such as laser, focused xenon lamp, robotic soldering iron, and focused IR soldering technologies were evaluated. Each of these technologies causes some damage or defect to the assembly due to the heat sinking aspect of the circuit assembled. These alternative processes would create damage or defects to the assemblies by burning the laminate, delaminating the pads on the printed wiring board, or not soldering the pads.

Proof of concept tests before machine designs were initiated demonstrated the potential and capabilities of this technology for automated assembly soldering. Testing indicated that the heated gas jet processing would provide a means of soldering the assemblies at a controllable rate without damaging the circuit boards.

While evaluating the machine ion its design phase, a designed experiment was initiated to help understand the relationships between head temperature settings versus gas flow rates, the measurable output was time to reflow.

The process meets all expectations in terms of solder fillet appearance, volume, and overall visual quality while maintaining process cycle time requirements.

Citation

Lichtenberg, L.R. and Gillespie, P.J. (1997), "Heated Gas Jet Reflow: An Alternative Reflow Solder Assembly Process Technology*", Soldering & Surface Mount Technology, Vol. 9 No. 1, pp. 13-16. https://doi.org/10.1108/09540919710777770