As mobile phones become more and more advanced, the degree of internal integration is also getting higher and higher, and almost all mobile phones now use ball grid array packaging modules, which is what we usually call BGA. This module is welded on the main board in the form of patch. BGA modules utilize the entire bottom of the package to interface with the circuit board. Instead of pin soldering, soldering is done with laser solder balls. And how is the BGA chip laser tin ball soldering process planted tin?

(1) cleaning

First, add an appropriate amount of solder paste on the side of the tin feet of the IC, remove the residual solder on the IC with an electric soldering iron, and then clean it with thinner.

(2) fixed

We can use the groove of the maintenance platform to locate the BGA chip, or simply use double-sided tape to stick the chip on the table to fix it.

(3) tinning

Choose a slightly dry tin paste, use a flat knife to pick an appropriate amount of tin paste onto the tin planting board, scrape it down hard, and press it while scraping, so that the tin paste is thinly and evenly filled in the small holes of the tin planting board, and tinned During the process, pay attention to pressing the tin planting plate tightly, and do not allow a gap between the tin planting plate and the chip, so as not to affect the tinning effect. as the picture shows.

(4) Blow soldering and tin planting

Fix the tin-planting plate on the IC, scrape and print the tin paste on the IC, increase the air volume of the hot air gun, adjust the temperature to about 350°C, and shake the air nozzle to heat the tin-planting plate slowly and evenly to make the solder paste slowly Slow melt. When you see that solder balls have been formed in individual small holes of the tin planting board, it means that the temperature is already in place. At this time, the nozzle of the heat gun should be raised to prevent the temperature from continuing to rise. Excessively high temperature will cause the solder paste to boil violently, resulting in the failure of tin planting, and in severe cases, the IC will be overheated and damaged. After the solder balls are cooled, separate the tin plate from the IC. The advantage of this method is that after the first tin planting, if there are missing feet, too large or too small solder balls, secondary treatment can be carried out, which is especially suitable for novices.

(5) adjustment

If after we finish blowing soldering, we find that some solder balls are uneven in size, or even some pins are not tinned, we can first use a paper knife to flatten the exposed part of the oversized solder balls along the surface of the tin planting board, and then use Use the scraper to fill the small holes where the solder balls are too small and the pins are missing, and then blow it again with a heat gun.