What are the factors affecting reflow quality?

1. it shall have the function of temperature curve test. If the equipment does not have this configuration, the temperature curve collector shall be purchased.

PCB design and processing quality, components and solder paste quality are the basis to ensure reflow quality. As long as the PCB design is correct and the quality of PCB, components and solder paste is qualified, the quality of reflow soldering can be controlled through the process of printing, mounting and reflow soldering.

2. the longer the heating zone is, the more the heating zone is, the easier it is to adjust and control the temperature curve. Generally, 5-6 temperature zones are selected for medium and small batch production, and the reflux furnace with a heating zone length of about 1.8m can meet the requirements. For standard lead-free production, there are usually 8 temperature zones. In terms of control, there are touch type, computer type and button type. In addition, the heater shall control the temperature independently to facilitate the adjustment and control of the temperature curve.

3. the conveyor belt shall be stable during operation. For medium and low grade reflow soldering, the transmission mechanism is relatively simple and has little vibration. Vibration of the conveyor belt can cause welding defects, such as displacement, suspension bridge, cold welding, etc.

4. different reflow soldering has different insulation properties. The insulation layer of low-grade products is usually not enough, and the maximum temperature is usually lower than 300 ℃. The maximum heating temperature is generally 300 ~ 350 ℃. If it is lead-free solder or metal substrate, it should be higher than 350 ℃.

5. heating mode and heat transfer mode of reflow soldering:

The heating wire heater has high exchange rate and long service life. The heating efficiency of the heat pipe type heat generator is low. If there is no hot air, the uniformity of the heating surface is not good. The infrared tube heater has good radiation uniformity, but will produce color temperature difference. It is mainly used in the thermal compensation area, not in the welding area.

6. the width of the conveyor belt must meet the maximum PCB size requirements. The larger the width, the greater the reflow power. Therefore, it is very important to select the appropriate solder.

7. save electricity. Reflow soldering consumes an astonishing amount of power in SMT equipment. Therefore, when selecting reflow soldering equipment, please pay attention to the quality of its insulation materials. If the insulation materials are used well and the heat loss is small, reflow soldering will save power.