I/O terminals of BGA (ball grid array package) are distributed under the package in the form of circular or columnar solder joints. The advantage of BGA technology is that although the number of I/O pins has increased, the pin spacing has not decreased, thus improving the assembly yield. Although the power consumption is increased, BGA can be welded by controlled chipping method to improve its electrothermal performance. The thickness and weight are lower than those of the previous packaging technology; The parasitic parameters are reduced, the signal transmission delay is small, and the use frequency is greatly improved; * * * It can be assembled by surface welding with high reliability.