With the allocation of Silman Tech’s automatic BGA rework station completed, BGA soldering and rework experiments are about to commence. Today, as a representative of Silman Tech’s BGA rework station manufacturer, based on some previous practical activities in this area, I would like to share some techniques and methods for BGA soldering with you. Your understanding and support are greatly appreciated!
- Proper Positioning of BGA Chip for Soldering
When soldering the BGA chip, it is essential to adjust its position properly, ensuring that the chip is positioned between the upper and lower air outlets. Additionally, the PCB must be securely clamped at both ends to prevent any shaking. Use the touch of your hand as a benchmark to ensure that the mainboard does not wobble. Securing the PCB ensures that it does not deform during the heating process, which is crucial for successful soldering.
- Proper Adjustment of Preheating Temperature
Before performing BGA soldering, the mainboard should undergo comprehensive preheating to ensure that it does not deform during the heating process and to provide temperature compensation for subsequent heating.
- Proper Adjustment of Soldering Curve
Taking lead-free soldering as an example: If the temperature does not reach 217 degrees after the four-stage curve, adjust the temperature of the third and fourth stages accordingly based on the temperature difference. For example, if the measured temperature is 205 degrees, increase the temperature of both upper and lower air outlets by 10 degrees. If the difference is significant, such as a measured temperature of 195 degrees, increase the temperature of the lower air outlet by 30 degrees and the upper air outlet by 20 degrees. Pay special attention not to increase the temperature of the upper end too much to avoid damaging the chip! After heating, the ideal state is a measured value of 217 degrees. If it exceeds 220 degrees, observe the highest temperature reached by the chip before the end of the fifth stage curve. Usually, try to avoid exceeding 245 degrees. If it exceeds too much, you can appropriately reduce the temperature set by the fifth stage curve.
- Accurate Alignment During Chip Soldering
Since everyone’s rework station is equipped with infrared scanning imaging to assist in alignment, there are generally no major issues. Without infrared assistance, we can also refer to the square lines around the chip for alignment. Pay special attention to placing the chip in the middle of the square lines as much as possible. Slight deviations are not a big problem because the solder balls undergo an automatic repositioning process during melting, and minor positional deviations will automatically correct themselves.
In summary, these four points are important considerations for BGA soldering. It is essential to pay attention to them during the BGA rework process to ensure the success rate of BGA chip rework.
