Causes and solutions of insufficient solder joints in PCBA processing BGA

Shenzhen Viasion Electronic Technology Co., Ltd. specializes in providing integrated PCBA electronic manufacturing services, including one-stop services from upstream electronic component procurement to PCB production and processing, SMT patch, DIP plug-in, PCBA testing, and finished product assembly. Next, I will introduce the reasons and solutions for the insufficient solder joints of PCBA processing BGA.

What is PCBA processing BGA solder joints are not full?

For PCBA processing, the underfilled solder joints in BGA rework refers to the insufficient volume of the solder joints, and the BGA solder joints that cannot be reliably connected in BGA soldering. The characteristic of underfilled solder joints is that the appearance of the solder joints will be obvious during AXI inspection. Smaller than other solder joints.

Causes of insufficient solder joints in PCBA processing BGA For this BGA problem, the root cause is insufficient solder paste. Another common cause of insufficient solder joints encountered in PCBA processing BGA rework is the wicking phenomenon of the solder. BGA solder flows into the through hole due to the capillary effect to form information. SMD deviation or print tin deviation and BGA pads and betrayal vias without solder mask isolation may cause wicking, resulting in insufficient BGA solder joints. Special attention should be paid to the fact that if the solder mask is damaged during the rework process of BGA devices, the wicking phenomenon will be aggravated, leading to the formation of underfilled solder joints. Incorrect PCB design can also lead to insufficient solder joints. If a hole in the disk is designed on the BGA pad, a large part of the solder will flow into the hole. If the amount of solder paste provided at this time is insufficient, a low Standoff solder joint will be formed. The way to make up is to increase the amount of solder paste printed. When designing the stencil, consider the amount of solder paste absorbed by the holes in the plate, and increase the thickness of the stencil or increase the opening size of the stencil to ensure sufficient solder paste; One solution is to use micro-via technology to replace the hole-in-disk design, thereby reducing the loss of solder. Another factor that produces underfilled solder joints is the poor coplanarity between the device and the PCB. If the amount of solder paste printing is sufficient. However, the gap between BGA and PCB is inconsistent, that is, poor coplanarity will cause insufficient solder joints.

PCBA processing BGA solder joints are not full solutions

1. Print enough solder paste;

2. Cover the vias with solder mask to avoid solder loss;

3. Avoid damaging the solder mask during the rework stage of PCBA processing BGA;

4. Accurate alignment when printing solder paste;

5. The accuracy of BGA placement;

6. Correctly operate BGA components during the repair phase;

7. Meet the coplanarity requirements of PCB and BGA to avoid warpage. For example, proper preheating can be adopted in the rework stage;

8. Use micro-hole technology to replace the hole-in-the-panel design to reduce solder loss.