What Is BGA?

BGA is the short of ball grid array, which is a type of mounting packaging in SMT assembly. BGA packages are usually used for permanent installation equipment like microprocessors. It is a way to reduce package size and integrate more functions on a single chip module. As a high-end assembly technology, the BGA package has been applied in widely electrical industries because of its ultra-fine-pitch technologies and reliable high-density interconnection. 

The advantages and disadvantages of BGA assembly

1. High-density interconnection

BGA allows more I/O ends because the end space is very large, then a higher density of connection is available.

2. Excellent electrical characteristic

The soldering joints of BGA are smaller and with short leads, which indicates that the BGA package has low inductances. We know that inductance would produce unwanted signal distortion in high-speed PCB applications. Therefore, low lead inductances mean that BGA packages have better electrical characteristics and frequency characteristics in high-speed circuit boards.

3. High reliability

BGA package has lower welding defects and stronger solder joints. And it is capable to self-align the tension between solder joints automatically, which results in excellent self-centering effect. All these help improve assembly reliability.

4. Better thermal dissipation

The lower the resistance is, the better the thermal dissipation is. The thermal resistance is lower in BGA packages, which helps to dissipate the heat from the integrated circuits and avoid the high temperature of the chip.

5. Difficult in inspection and rework

It is hard to inspect the assembly detects through regular optical inspection due to the solder balls are under the chip. The removal and replacement of BGA components are also uneasy tasks, which need s series rework processes.

Some requirements in the BGA assembly process

1.  The standard of Optimal BGA soldering joints

The best BGA solder joints should be smooth, with clear boundaries and no gaps. The diameters, volumes, contrast, and grayscale between all solder joints should be the same and fully aligned. And no solder balls exist.  

2.  Strict inspection process

BGA assemblies may exist different detects due to the reasons of assembly equipment, environment, and soldering technology. The common detects usually include loose soldering, misalignment, bridging, open circuits, cavities, uneven sizes, and the missing of solder balls. X-ray inspection is very necessary to find out the hard-to-find detects through optical methods.