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OCTOBER 2026 I SMT007 MAGAZINE 61 So, when is laser soldering a good option? Four examples might include thermal sensitivity, joint accessibility, traceability, and any follow-on work that cannot be done via wave or reflow. Thermal Sensitivity When key components or fragile substrates cannot survive reflow or wave soldering, the more precise methods become crucial. If the board design calls for a high-energy solder joint near a temperature- sensitive component or fixture, a laser is a good option. Laser soldering also finds a place when components on the board have reached their reflow cycling limits. Another related situation occurs when work on the shop floor is high-mix, with reflow recipes rapidly swapping in and out. Switching to laser soldering may be a longer soldering process, but that might be offset by sidestepping the time it takes to stabi- lize the reflow oven to a new recipe. Inaccessible Joints While there are a variety of levels of inaccessibility, an obvious situation well suited to laser is when a joint resides inside a housing unreachable by a soldering iron. Post-reflow Follow-on Work We've already introduced the situation where components must be withheld until after reflow. Through-hole components, wires, terminals, and sensors all might create this situation. Traceability Laser soldering can be highly detailed about how and how much energy was delivered to each indi- vidual joint, making traceability much more gran- ular, a level of detail that wave or convection reflow cannot deliver. Of course, lasers aren't always the ideal soldering methodology. For example, boards built with beefy ground planes, busbars, etc., might dissipate thermal energy faster than the laser can apply it, causing cold solder joints. Copper, gold, silver, and tin absorb heat energy differently. Especially in silver's case, surface tarnish can also change the energy required. Position orientation and positional deviations can change how the laser hits the target joint, affecting energy transfer. This is also true of joints without a clear optical path. Finally, compo- nent, joint, solder, or board contamination can affect solderability. Ultimately, the laser can deliver the required heat to a solder joint; it cannot correct for poor solderability. Conclusion Perhaps above all else, laser soldering offers preci- sion soldering; it is not a universal replacement for other soldering techniques. When high production volumes and low-complexity soldering converge, wave and reflow soldering continue to deliver high- throughput, affordable solutions. But as complexi- ties increase, including higher densities and sensi- tive components, it stands to reason that laser soldering will meet the critical need for post-reflow soldering. SMT007 References 1. "Laser beam soldering with 450 nm visible wavelength" Fraunhaufer ILT.