Before wave soldering, PCBA usually needs to be preheated. This step is essential to ensure the quality of soldering and the reliability of the final product. It is especially necessary in automated production and mass production. So, how important is preheating before PCBA soldering?

What is wave soldering?

Wave soldering is a soldering process that forms a specific solder wave by forming molten liquid solder, inserting components into the PCB manufacturing and passing them through the solder wave to achieve solder joint soldering. Wave soldering is often used in mass production because it can solder a large number of components quickly and efficiently.

Importance of preheating before PCBA wave soldering

1. Prevent thermal shock

During the wave soldering process, circuit boards and components are suddenly exposed to high-temperature solder. This instantaneous temperature change may cause thermal shock, damage components or cause circuit boards to deform. By preheating, the temperature of the PCBA can be gradually increased, thereby reducing the risk of thermal shock.

2. Remove moisture

Circuit boards and components may absorb moisture from the air during storage and operation. If these moisture evaporates quickly during the soldering process, it will cause the solder joint to swell, bubbles or holes, affecting the quality of soldering. Preheating can help remove moisture from the PCBA and ensure the integrity and reliability of the solder joint.

3. Increase the wettability of the pad

The wettability of solder refers to the ability of solder liquid to expand on the metal surface. Preheating can increase the temperature of the circuit board and component pins, making it easier for the solder to wet and flow, thereby forming a reliable solder joint. Good wettability helps the solder to evenly cover the contact surface, ensuring a strong mechanical connection and reliable electrical connection.

4. Reduce temperature gradient

The temperature gradient in wave soldering refers to the temperature difference between different areas on the circuit board. Excessive temperature gradients may cause soldering defects such as cold soldering or cracking of solder joints. Preheating can make the temperature of the circuit board more uniform, reduce temperature gradients, and thus improve soldering quality.

5. Remove harmful impurities

During the preheating process, some harmful impurities in the circuit board and solder can be removed, reducing defects and failures during the soldering process.

Preheating process

Preheating equipment

In the wave soldering production line, preheating is usually done by a preheater. The preheater can be an infrared heater, a hot air heater, or a contact heater. Different types of preheaters have different heating methods and efficiencies, but the goal is to gradually increase the temperature of the PCBA.

Preheating temperature and time

The preheating temperature and time need to be determined according to the specific PCBA design and soldering process requirements. Generally speaking, the preheating temperature is usually between 100°C and 150°C, and the preheating time ranges from tens of seconds to several minutes. The preheating process must be properly controlled to avoid overheating and damage to components or deformation of the circuit board.

Effect of preheating on welding quality

Solder joint quality

Preheating can significantly improve the quality of solder joints. By reducing thermal shock and moisture and improving solder wettability, preheating helps to form smooth, uniform and strong solder joints and reduce the occurrence of solder joint defects.

Electrical performance

Good solder joints are not only mechanically strong, but also more reliable in electrical performance. Preheating ensures a good bond between the solder and the metal contact surface, reduces the resistance of the electrical connection, and improves the overall performance and reliability of the circuit board.

Long-term reliability

Preheating can also improve the long-term reliability of the PCBA. By reducing soldering defects and improving solder joint quality, preheating helps avoid potential failure problems and extend the service life of electronic products.

Preheating for wave soldering is to improve soldering quality, avoid soldering defects, and ensure the stability and reliability of the soldering process. Therefore, in actual operation, preheating is an indispensable and important step in wave soldering.

PCBAMake has the latest wave soldering equipment, which can provide efficient and precise soldering quality. During the PCBA assembly process, we strictly follow every step, from preheating to soldering to final inspection, to ensure that every detail is perfectly handled. Our equipment and rigorous process flow ensure the high reliability and excellent performance of each circuit board.