In modern electronics there is a steady tendency to the fact that the installation becomes more denser. The consequence of this was the emergence of BGA cases. Soldering of these structures at home and we will be considered in the framework of this article.
general information
Initially, there were many pins under the chip body. Due to this they were located in a small area. This allows you to save time and create more and more miniature devices. But the availability of such an approach in the manufacture turns into inconvenience during the repair of electronic equipment in the BGA package. Soldering in this case should be as accurate as possible and accurately performed using technology.
What do you need to work?
It is necessary to stock up:
- A soldering station where there is a thermofan.
- Tweezers.
- Solder paste.
- Insulating tape.
- Braid to remove solder.
- Flux (preferably pine).
- Stencil (to put the solder paste on the chip) or spatula (but stay better on the first option).
Soldering BGA packages is not a difficult task. But for it to be successfully implemented, it is necessary to prepare the working area. Also, for the possibility of repeating the actions described in the article, it is necessary to tell about the features. Then the technology of soldering chips in the BGA package will not be difficult (in the presence of understanding the process).
Features
Talking about what the BGA soldering technology is, it's necessary to note the conditions for the possibility of a full-fledged repetition. So, Chinese stencils were used. Their peculiarity is that here a few chips are assembled on one large workpiece. Due to this, when heated, the stencil begins to bend. The large size of the panel leads to the fact that it generates a significant amount of heat when heated (that is, the radiator effect appears). Because of this, more time is needed to warm up the chip (which negatively affects its performance). Also such stencils are made by chemical etching. Therefore, the paste is not applied as easily as the samples made by laser cutting. Well, if there are thermoshows. This will prevent the bending of the stencils during their heating. And finally, it should be noted that products manufactured using laser cutting, provides high accuracy (the deviation does not exceed 5 microns). And thanks to this, you can easily and conveniently use the design for the intended purpose. This concludes the introduction, and we will study what the BGA soldering technology in the home environment is.
Preparation
Before you begin to solder the chip, you need to apply strokes on the edge of its body. This should be done in the absence of silkscreen, which indicates the position of the electronic component. This is necessary to make it easier in the future to put the chip back on the board. The dye should generate air with a heat of 320-350 degrees Celsius. At the same time, the air speed should be minimal (otherwise it will be necessary to solder the small stuff placed next to it). The hairdryer should be held so that it is perpendicular to the board. We warm it up this way for about a minute. And the air should be directed not to the center, but along the perimeter (edges) of the board. This is necessary in order to avoid overheating of the crystal. Memory is especially sensitive to this. Then you have to chip the chip at one end and lift it over the board. In this case, you should not try to tear as hard as you can. After all, if the solder was not completely melted, then there is a risk to tear off the tracks. Sometimes, when the flux is applied and heated, the solder will collect in the balls. Their size will be uneven in this case. And the soldering of chips in the BGA package will be unsuccessful.
Cleaning
We put spirtoknifol, we warm it and get the collected garbage. In this case, note that this mechanism can not be used in any case when working with soldering. This is due to a low specific factor. Then you should wash the work area, and there will be a good place. Then you should examine the status of the conclusions and assess whether their installation will be possible in the old place. If the answer is negative, they should be replaced. Therefore, you should clean the boards and chips from the old solder. There is also the possibility that the "nickle" on the board (when using a braid) will be torn off. In this case, a simple soldering iron can help. Although some people use a braid and a hairdryer together. When performing manipulations, you should monitor the integrity of the solder mask. If it is damaged, the solder will dissolve along the tracks. And then BGA-soldering will not succeed.
The rolling of new balls
You can apply already prepared blanks. In such a case, they should simply be spread out over contact pads and melt. But this is only suitable for a small number of conclusions (can you imagine a microcircuit with 250 "legs"?). Therefore, screen printing is used as an easier method. Thanks to her work is faster and with the same quality. Important here is the use of quality solder paste. It will immediately turn into a brilliant smooth ball. A substandard specimen will fall into a large number of small round "splinters." And in this case, it's not even a fact that heating up to 400 degrees of heat and mixing with flux can help. For convenience of operation, the microcircuit is fixed in a stencil. Then use a spatula with solder paste (although you can use your finger). Then, supporting the stencil with tweezers, it is necessary to melt the paste. The temperature of the hair dryer should not exceed 300 degrees Celsius. In this case, the device itself should be perpendicular to the paste. The stencil should be maintained until the solder is completely solidified. After that, you can remove the fixing insulating tape and a hair dryer that will warm the air to 150 degrees Celsius, gently heat it until the flux begins to melt. After that, you can detach the chip from the stencil. In the final result, even balls will be obtained. The chip is completely ready to install it on the board. As you can see, soldering BGA-cases is not difficult at home.
Fixing
Previously, it was recommended to do the finishing touches. If this advice was not taken into account, then positioning should be performed as follows:
- Flip the microcircuit so that it is pins up.
- Attach the edge to the heels so that they coincide with the balls.
- We fix where the edges of the microcircuit should be located (for this you can apply small scratches with a needle).
- First we fix one side, then perpendicular to it. Thus, two scratches will suffice.
- We put the microcircuit on the notation and try to catch the balls to the touch with a penny at maximum height.
- It is necessary to warm up the working area until the solder is in the molten state. If the previous items were executed exactly, then the chip should be in its place without problems. It will be helped by the surface tension that solder has. In this case, it is necessary to apply very little flux.
Conclusion
This is all called "chip soldering technology in the BGA package". It should be noted that the soldering iron used here is not used by most radio amateurs, but a hair dryer. But, despite this, BGA-soldering shows a good result. Therefore, they continue to use it and do it very successfully. Although the new has always scared many, but with practical experience, this technology becomes a familiar tool.