Soldering temperature for electronics PCB

The process of soldering with a manual soldering iron connects 3 bodies with lead solder. All 3 bodies - the electronic component, the printed circuit board and the solder alloy have different heat capacity. Sometimes this is complicated by large polygons of copper metallization on the printed circuit board. The heat capacity parameter is very important. In order to quickly heat all three bodies to the melting temperature of the lead solder alloy, this heat must be accumulated on the soldering iron tip, and it must be large enough to heat all three bodies to the melting temperature, or have a type of soldering iron that can instantly compensate for the heat lost to the printed circuit board. Many resort to an unjustified increase in the temperature on the soldering iron tip, which has a negative effect on the mask of the PCB, on the component, on the rapid burnout of the soldering flux. Understanding heat capacity and using the right temperature reduces component stress, ensures better solder fillets, and improves the reliability of your PCB assembly.

The melting temperature of lead solder is in the range of 183-190°C. In order to solder all 3 bodies, they must all be heated to at least this temperature. But there is one problem - heat loss and its rapid distribution across the printed circuit board, which will negate the heating of the soldering point at 190°C. That is, heat loss through the PCB occurs many times faster than the heating of the connection we need. At the moment the soldering iron tip with molten solder touches the pad, the soldering iron tip instantly gives off all the heat to the printed circuit board, the temperature drops below the melting point of the solder and the soldering iron tip sticks. Therefore, we need to make a temperature reserve so that we have enough temperature to heat the connection. At the moment of touching the PCB pad, the temperature drops sharply and in 1-2 seconds we need to melt the solder and not allow the temperature to drop below 190°C. The drop in temperature of the soldering iron tip is equivalent to an increase in temperature on the PCB pad. This is an energy exchange. The most modern soldering stations can compensate for the lost heat in real time. Therefore, the ideal solution in the electronics industry for soldering lead solders with soldering iron is considered to be a temperature of 320°C. For oven with adjusted soldering profile is 205°C The temperature reserve of 140°C allows the spent heat to be spent on the primary heating of three bodies. In the same seconds, the coil of the soldering iron tip should begin to compensate for the spent heat. Thus, you can solder at a comfortable speed without being distracted by delays in cooling the tip and causing minimal damage.

Optimal Soldering Temperatures for Leaded and Lead-Free Alloys

What is wrong with raising the temperature to 350°C or higher? Destruction of the structure of components, delamination of the upper layer of the PCB, peeling off of the mask. Of course, when soldering lead-free solders alloy, we raise the temperature by 30°C and this is a forced measure. The risk of thermal shock is always bad and it is necessary to minimize this phenomenon. Soldering of electronics in furnaces occurs at a temperature of 210°C - this is the usual soldering temperature with lead solder alloy and solder pastes. For PbFree soldering in oven, the temperature varies from 230°C to 240°C. For soldering iron the practice has shown that 300°C is not enough for high-speed comfortable work, and at 350°C - problems with carbon deposits on the soldering iron tip begin. By the way, for soldering lead-free alloy's, some manufacturers of soldering stations have a series of soldering iron tips for high temperatures. Manufacturers of lead-free soldering wire have alloys with additives that extend the service life of tips for high temperatures. When soldering large components, there are cases when soldering irons as a class are insufficient, and bottom preheating hot plate come to the rescue. Preheating hot plate - excellent solution for soldering individual components, include microcircuits. It is important to understand what you are doing and do it correctly. Choosing the right temperature and tools for lead and lead-free soldering ensures less tip wear and reduses defects.

By mastering proper soldering temperatures, you enhance solder quality, reduce rework, and boost the reliability of your electronic projects.

Thank you for reading!