Is preheating of assemblies unnecessary stress for components?

Every preheating process has to be physical-chemical tested in coordination with the adjacent components, soldering surfaces, heat sinks, hole fill and quality requirements for the process, since every heating process can trigger an additional aging process for the components. Therefore, it is as important to pay attention to this process as to the actual soldering process. For this reason, preheating is always part of our evaluation for customer projects.

Depending on the duration and level of the preheating, three-dimensional mechanical stress levels, oxidation surfaces and thus possible damage to the processing area may occur in the assembly. Preheating prepares the area to be soldered for the actual soldering process and thus for the temperature increase from room temperature to 120 °C and for the soldering process temperature of, for example, 300 °C.

Does too high preheating temperature affect the flux?

In order to protect the components, the typical preheating temperature gradient of approx. 3°C /sec must be maintained. Furthermore, the peaks of the preheating temperature should not destroy the flux characteristics. Only the balanced interaction of processing know-how, flux preheating-soldering processing with the component heat characteristic reduces or prevents unnecessary stress factors on the entire component.

What are the effects of a too long preheating period?

An excessively long preheating time reduces the response of the solids in the flux and thus reduces the overall effect of the flux process. Increased stress due to preheating can also occur via thermal preprocesses such as reflow soldering.

If you have further questions about preheating your assembly, please contact us and we will help you to optimize your soldering process.