PCBA Tech - smt patch processing: PBGA advantages and disadvantages

With the rapid development of electronic technology, electronic components are developing in the direction of miniaturization and high integration. BGA components have been more and more widely used in SMT assembly technology, and with the emergence of BGA and CSP, the difficulty of SMT assembly has become more and more difficult, and the process requirements have become higher and higher. Due to the difficulty of repairing BGA and the high cost of repairing, improving the quality of the BGA process is a new issue in the SMT process.

There are different types of BGAs, and different types of BGAs have different characteristics. Only by deeply understanding the advantages and disadvantages of different types of BGAs can we better formulate a process that meets the requirements of the BGA process, better achieve good BGA assembly, and reduce the BGA process. cost. BGA is usually divided into three categories, each type of BGA has its own unique characteristics, advantages and disadvantages:

1, PBGA (PLASTIC BALL GRID ARRAY) plastic package BGA

Its advantages are:

1. Thermally matched with epoxy resin PCB circuit board.

2. The solder balls participate in the formation of solder joints during reflow soldering, and the requirements for solder balls are loose.

3. Can be centered by the edge of the package body during placement.

4. Low cost.

5. Good electrical performance.

The disadvantages are: sensitive to moisture and the density of the solder ball array is lower than that of CBGA

2, CBGA (CERAMIC BGA) ceramic package BGA

Its advantages are:

1. The reliability of packaged components is high.

2. Good coplanarity and easy solder joint formation, but the solder joints are not parallel.

3. Insensitive to moisture.

4. High packaging density.

The disadvantages of are:

1. Due to the difference in thermal expansion coefficient and poor thermal matching with epoxy board, solder joint fatigue is the main failure mode.

2. The solder balls are difficult to align on the edge of the package.

3. The packaging cost is high.

3, TBGA (TAPE BGA) with load BGA

Its advantages are:

1. Although there are local stresses in the chip connection, the overall thermal matching with the epoxy board is better.

2. Mounting can be aligned by the edge of the package body.

3. is the most economical packaging form.

The disadvantages of are:

1. Sensitive to moisture.

2. Sensitive to heat.

3. Multiple rounds of different materials adversely affect reliability.

BGA has been widely used in electronic PCB products, but in actual production applications, PBGA is the majority. The biggest disadvantage of PBGA is that it is sensitive to moisture. If PBGA absorbs moisture, PBGA is prone to "popcorn" during welding, which will cause PBGA to fail. There are many articles on improving the quality of the BGA process in many literatures. This article only addresses the shortcomings of PBGA's sensitivity to moisture and discusses methods to prevent PBGA from failing due to moisture absorption in the relevant process links of the actual production process.