The ideal reflow soldering temperature is composed of four parts or zones, the first three zones are heated and the last zone is cooled. Regardless of the number of temperature zones of the reflow oven, the overall temperature zone composition is these four major temperature zones. The more temperature zones of the reflow oven, the more accurate and close the profile of the temperature curve can be. Guangshengde reflow soldering Let's talk about the role of the four basic temperature zones for reflow soldering.

1. reflow soldering preheating zone function

The preheating zone for reflow soldering is used to raise the temperature of the PCB from the ambient temperature to the required active temperature. Its temperature rises continuously at a rate of no more than 2~5°C per second. If the temperature rises too fast, it will cause some defects, such as micro-cracks in ceramic capacitors. If the temperature rises too slowly, the solder paste will be overheated and not enough. Time allows the PCB to reach the active temperature. The preheating zone of the furnace generally occupies 25~33% of the length of the entire heating channel.

2. The role of reflow soldering insulation zone

The reflow soldering holding area is sometimes called the drying or soaking area. This area generally occupies 33-50% of the heating channel. It has two functions. The first is to sense the temperature of the P CB at a fairly stable temperature to enable components of different quality Have the same temperature, reducing their considerable temperature difference. The second function is to allow the flux to be activated and volatile substances to volatilize from the solder paste. The general activation temperature range is 120~150°C. If the temperature of the active zone is set too high, the flux will not have enough time to activate. Therefore, the ideal curve requires a fairly stable temperature, so that the temperature of the PCB is equal at the beginning and the end of the active zone.

3. the role of reflow zone of reflow soldering

The function of the reflow zone is to increase the temperature of the PCB assembly from the active temperature to the recommended peak temperature. The typical peak temperature range is 205~230°C. Setting the temperature in this zone too high will cause excessive curling, delamination or burning of the PCB, and damage the integrity of the component.

4. the role of reflow soldering cooling zone

The ideal cooling zone curve should be a mirror image relationship with the reflux zone curve. The closer to this mirror image relationship, the closer the structure of the solder joints to solid state, the higher the quality of the solder joints, and the better the integrity of the joints.