Wave soldering process is also a matter of concern for SMT patch processing plant, the temperature and time of blending will affect the wave soldering connection. Today, we will briefly understand the relationship between the two.
First, the peak soldering temperature:
1 Due to the structure, size and packaging of the components on the PCB (Printed Circuit Board) are different, we can not describe the temperature change by a single curve, but choose a set of temperature distribution curve. As a result, there is a range of peak soldering temperatures, including maximum and minimum peak temperatures.
2. When designing the temperature profile, it is necessary to ensure that the peak soldering temperature of each component is neither higher than the highest heat-resistant temperature of the component nor lower than the lowest soldering temperature. Typically, this temperature should be 15°C above the melting point of the solder paste, but below 260°C (for lead-free soldering).
3. It is worth noting that components with lower heat capacities have higher temperatures, while components with higher heat capacities have relatively lower temperatures. Why should the minimum temperature for soldering be 15°C higher than the melting point of the solder paste? This is because this temperature difference ensures that the BGA (Ball Grid Array) encapsulation technology completes the secondary collapse of the concrete and calibrates itself to the working position. It also ensures that all BGA solder joints meet the ±4°C peak soldering temperature tolerance, thus reducing the ball and socket phenomenon.
Second, the welding time
1. The soldering time mainly depends on the thermal characteristics of the PCB and the packaging of components. As long as the solder joints can reach the appropriate soldering temperature, BGA solder balls and melted solder paste mixed evenly to achieve thermal balance, the welding can be completed.
2. For ordinary solder joints, 3-5 seconds of soldering time is usually sufficient. However, in PCBA (Printed Circuit Board Assembly) processing, it is necessary to consider all the soldering points to meet the requirements, and reduce the temperature difference between different parts to reduce thermal deformation. Therefore, PCBA soldering and single-point soldering will be different, and can be considered that they are not comfortable a system.
According to the above, we can understand that in the SMT SMD processing staff through reasonable control of temperature and time, is to ensure the welding quality and product performance of the key.
