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Reasons why PCBA needs to be preheated before processing
2026/3/4
In the mass production PCBA processing and welding environment, the temperature profile is very important. Slow heating and preheating stages can help activate flux, prevent thermal shock, and improve soldering quality during SMT placement. However, when reworking, prototyping, or the first PCBA prototyping project, it’s easy to forget the importance of the warm-up phase, which can result in the device being compromised even if it’s not damaged. Therefore, for such an important step, why is it often forgotten in the actual operation of SMT processing plants? What are the consequences of ignoring this step?
1. What is PCBA preheating before welding?
When technicians and practitioners hear the word "temperature profile", they think of SMT reflow soldering. Along the large welding area, it is easy to see the 4 main temperature control zones that ultimately create the perfect welding joint. At each stage, technicians will rely on their own experience, repeated trials, strict control and improvement. Each stage can improve the quality of solder joints and reduce defects. However, other industrial soldering equipment may not have such precise temperature control, but what they have in common is a preheating stage.
II. Flux combustion in selective wave soldering
The role of the preheating stage is to steadily increase the temperature of the entire component from room temperature to a holding temperature lower than the melting point of the solder paste, which is about 150°C. Adjust the temperature change so that the slope remains at a few degrees per second. The period after the preheating stage is the soaking period, where the temperature is maintained for a period of time to ensure that the plate is heated evenly. Then enter the reflow stage and start solder joint formation. During the preheating and soaking process, the volatile solvents in the solder paste are burned off and the flux is activated.
In production practice, it has been proved that preheating before welding is very important.
1. What is PCBA preheating before welding?
When technicians and practitioners hear the word "temperature profile", they think of SMT reflow soldering. Along the large welding area, it is easy to see the 4 main temperature control zones that ultimately create the perfect welding joint. At each stage, technicians will rely on their own experience, repeated trials, strict control and improvement. Each stage can improve the quality of solder joints and reduce defects. However, other industrial soldering equipment may not have such precise temperature control, but what they have in common is a preheating stage.
II. Flux combustion in selective wave soldering
The role of the preheating stage is to steadily increase the temperature of the entire component from room temperature to a holding temperature lower than the melting point of the solder paste, which is about 150°C. Adjust the temperature change so that the slope remains at a few degrees per second. The period after the preheating stage is the soaking period, where the temperature is maintained for a period of time to ensure that the plate is heated evenly. Then enter the reflow stage and start solder joint formation. During the preheating and soaking process, the volatile solvents in the solder paste are burned off and the flux is activated.
In production practice, it has been proved that preheating before welding is very important.
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