In today's electronics the steady tendency to more condensed mounting is noted that became the reason of emergence of the BGA body. What is represented by BGA soldering of the body in house conditions and in what its feature?
Initially directly under chip and its body large number of points of conclusion was placed, and it was to rebolling of bga-chips. Thanks to this feature all conclusions could be placed in the minimum square that allows to save considerably time and to be engaged in creation of small devices.
However availability of similar approach during equipment manufacturing can turn back some inconveniences at repair of the equipment. Moreover, in case of repair of ration has to be exact and it is accurate, otherwise it is possible to damage the equipment.
What equipment is necessary for work
- the soldering station with the thermohair dryer;
- tweezers;
- soldering paste;
- insulating tape;
- the braid necessary to remove solder;
- gumboil (it is the best of all pine);
- cliches or palettes for putting soldering paste on chips.
Soldering of the BGA body is not the most complex business, but in order that process took place successfully, it is necessary to be prepared correctly for this process.
The most important feature which needs to be noted is that it is important to note conditions and possibility of full repetition. For example, it is possible to use cliches from the Chinese producers. The feature of the Chinese models is that here 2-3 or the bigger number of chips can be assembled on certain big preparation.
Thanks to this feature the cliche will heat up and be bent. And because of the big size of the panel the cliche will take away a lot of heat when heating (or, otherwise, the effect of radiator appears). All this brings that the person needs to spend more time for warming up of the chip that has an adverse effect on operability of the chip in general.
The products created with application of laser cutting differ in enhanced accuracy (deviation no more than 5 microns) that allows are more practical to use any created designs for their direct designated purpose.
Before starting unsoldering of the scheme, it is important to put several strokes passing directly at the edges. It is important to make it if there will be no silk-screen printing demonstrating provisions of electronic components. And it, in turn, considerably will facilitate installation of the chip on payment.
The hair dryer in the course of work has to create air with temperature of 320-350 degrees Celsius (here important accounting temperature monitoring), and its speed has to be the smallest (otherwise the person risks to melt and spoil other parts and contacts.
The hair dryer when soldering needs to be held so that air flow moved not in parallel, and perpendicular to payment, and it is necessary to warm payment within one minute, directing air to edges of payment. Importance of this technologists is in to allowing overheating of crystals of the processor.
After that it is necessary to hook chip for any of edges and to lift it over payment (you should not tear off it from all – best of all to warm up a little more and to achieve that solder has melted completely). In certain cases on time of drawing gumboil and during its warming up, solder can begin to gather in Razna by the size balls. Then soldering of chip in the BGA body can be unsuccessful.
In order that work was qualitative, and soldering kept very long, it is necessary not to forget about such important process as cleaning. To clean working surface, it is necessary to put spirtokanifol, to properly warm up it and to receive the garbage collected as a result of it. Here it is important to pay attention that such mechanism cannot be used during operating time with soldering. It is connected with rather small specific coefficient.
The following obligatory step is thorough washing of working area. After that the person will also receive perfectly prepared working area.
The following that needs to be made is to examine conclusions and their state. It is important to define, it is only possible to establish them on the former place. If it is possible – it is necessary to put and if is not present – to replace that.
For replacement it is necessary to clean chips and payments from former solder. At the same time always is probability that the nickel on payment can be torn off (especially in case the person uses braid). And in that case the best option will use the simplest and most standard soldering iron. Though some people use for the same purpose also the hair dryer.
During commission of manipulations it is necessary to watch closely integrity of soldering mask. That is, if it is damaged, solder will just spread on several paths, and BGA soldering just will not turn out such what it has to be.
In case of need it is possible to use the preparations which are already prepared earlier. In this case it is necessary to spread out simply preparations on several contact pads, and after that to melt them. However such option approaches only in case of small amount of conclusions.
If simpler option is necessary, it is possible to use pattern technology. Thanks to this technology it is possible not only not to lose in quality, but also to make all work much quicker.
At this stage important point is to use quality soldering paste. It will be able to turn into smooth brilliant ball most quicker. Low-quality paste simply will break up to slightly small, but same round splinters.
For bigger convenience it is possible to fix chip on cliche, and after that, using the palette, to apply soldering paste and to melt it. At the same time temperature should not be higher, than 30 degree centigrades.
The cliche needs to be supported until solder stiffens completely. And only after it it is possible to remove fixing insulating tape and, using the hair dryer, to heat gumboil until its melting. Only after it it will be possible to disconnect chip from cliche.
The final result of all made actions is receiving equal balls both ready to work and further use of chip.
If the user decides not to do strokes, then it is possible to carry out positioning in the following way:
- To invert chip so that it stood conclusions up.
- To put edges to nickels so that they completely approach under balls.
- To record, edges of chip have to be located where exactly (as option, it is possible to make several scratches).
- To fix for a start one party, and after that that that it was perpendicular to the first.
- To put chip on the existing designations.
- To catch nickels at the biggest height.
At the same time it is necessary to warm up properly working area up to that moment until solder melts and will become more liquid. In case all clauses described above have been implemented precisely according to the instruction and with respect for all norms, the chip will have to rise after that on the place with hardly any trouble at all. In process will not prevent to cause number of gumboil also.
Everything that has been described above, and carries the name of soldering of the BGA body in house conditions. It is also important to note also that here not the usual soldering iron, but the hair dryer is used. However, even taking into account it, soldering of BGA shows excellent result