Hi all. In this video, we will try a new format. Its essence lies in the fact
that I will review videos on Youtube and comment on errors in them.
In this case, we will consider a video on replacing BGA microcircuit balls by one of the authors, who has collected
a fairly large number of views. Let's get started!
Hi all. Today I will tell you how to roll this dull shit called Mediatek mt6322. This is a power controller
that is found in various Chinese scrap metal. To do this, we need a universal stencil.
I take a soldering iron, I need to tin the conclusions, hold it, smear it with flux.
We take the POS-61 alloy on the soldering iron, so that there are uniform areas. Here is our stencil. We take solvent 646.
Attention. A solvent is used to clean the flux. For me, to be honest,
this is nonsense, because the solvent is not compatible with many metals. The solvent causes the metals to oxidize.
Or mixed with acetone. Let's see how it looks now - here is our controller.
It works without gloves, that is, the fats that remain on the microcircuit contribute to the quality of work.
Tinning is normal, nothing sticks out. The pins are all in place. Here is our solder paste, it's a bit dry.
Remember this moment - the solder paste is a little dried up.
If there is a lot of flux in the solder paste and it is very liquid, then it begins to spread. When boiling, if you start frying very quickly, the flux boils.
In this case, a person does not exactly understand how solder paste works and his main task is to heat it
so that it melts, and naturally, from this erroneous approach, he again draws false conclusions.
If it is strongly heated, then the solder paste begins to splatter. There is a thermal profile for this. In order for the solder paste not to splash
, it must go through some procedures, operations - heating, stabilization.
Remember - I told you in many videos that during the stabilization phase, the flux begins to actively evaporate.
and during reflow there, in principle, there is nothing to splash. The second point - what does a lot of flux in solder paste mean?
It comes with a certain proportion of flux. So that the flux is sufficient
for both melting and wetting. So that during the passage of the thermal profile, the flux is enough for everything.
Solder paste cannot be liquid or non-liquid. It is the way it was released from the factory according to the standards for solder pastes.
If your solder paste is dry, then you store it incorrectly. Or you bought it with an expired expiration date.
The person in this case shows his knowledge. And we can see his knowledge.
He brings the hot air gun very close to the solder paste, which is already applied to the stencil,
and it starts to splash and spread, because the temperature is very high and the soldering thermal profile is not observed.
The balls just jump out of the stencil.
And his balls just jump out of the stencil! Yes, how is that? Of course they will take off at this temperature!
We take a mega stencil, which are usually crooked after mega masters. I don't know what will or won't work.
Here is a very interesting point - the person says that the stencils are crooked after the masters.
Honestly, from my own experience, I have never taken stencils from someone, I bought all the stencils
and used them myself, that is, if they become crooked, then this is solely my fault.
And then a man says that someone ruined his stencil and gave it back to him, this is strange of course.
We press, do not press this tweezers.
In this episode, a person does not exactly understand what a chip reballing tool is. Doesn't know what stencil holders are.
While using such a stencil, your microcircuit lies, you install a stencil on it
and press the stencil on top with tweezers and the stencil begins to sag. And it turns out here is such a picture
. The main thing is to just hold on.
The main thing is to just hold on! That is, something like barely touching.
you need to fix the center of the stencil so that it does not move. An interesting approach.
If your hands are shaking, then you need to get drunk.
If your hands are shaking, then maybe you shouldn't take on this business at all ....
We take our solder paste. It's like dumplings, it's quite liquid.
Another misconception is that solder paste is quite liquid. By what criteria does he evaluate it? I do not understand.
Soldering paste is in principle liquid, it cannot be liquid, because then it cannot be used.
It is not necessary to press hard, because the stencil is usually curved.
It is not necessary to press hard - what does this mean? This means that he is afraid to push in a lot of solder paste. And since his stencil is bent,
he also holds it with tweezers, then all the solder paste will fall under the stencil and jumpers may appear there.
And when you use a snap-in stencil holder, then you need to put the solder paste in there a little by pressing it in
to fill all the apertures more or less evenly.
From afar, 330 degrees, the main thing is that your left hand, which you hold, does not shake. We look, it starts to smell, gurgles,
This flux gurgles. It is clear that the flux will flow out under the stencil.
The flux will flow out over the stencil. This once again proves that a person does not understand what a thermal profile is.
During the reflow of the flux solder paste, there is already a minimum left if the solder paste has correctly passed the technical process - heating, stabilization, reflow.
And when the process of reflow is in progress, there is practically no flux left and
flux residues play a key role in terms of wettability. Everything. And his flux has not evaporated yet.
The flux did not activate. Naturally, the flux scatters in all directions. It doesn't even splatter, it spreads.
Everything must work the first time, otherwise you will not earn anything.
You won't earn anything. That is, how to do something, give it to a person and if only the device worked for the first time, and then,
after the first fall of the device, all the soldering will fall off. That says a lot about the quality of the repair.
Illiterate and fast repair.
The stencil has already warmed up. It probably won't bend anymore.
Most likely, he will not bend, but the fact that he was already bent when he pressed him with tweezers does not bother him at all.
Small balls begin to combine into large ones, that is, the flux protects the solder itself.
The flux protects the solder itself! What???
Gradually small balls become large. If your left hand begins to shake, then you forget about it, as if it were not yours.
If your hand is tired, forget it, everything is fine!
We see that the balls begin to stick out, which means we take the hot air gun to the side. Flip it over and see what happens. Cake.
Guys tell me what do you think about it? Around the microcircuit is a cake made of tin, lead and flux.
The stencil is slightly off.
The stencil went aside, because it is physically impossible to keep it with such methods of work.
We take the flux, it is necessary to warm it up a little, if some balls do not stick, then they will start to roll.
If the balls are not stuck, then they will begin to roll. In principle, he should not have succeeded with such an approach.
We look. All the balls, if everything went well, should sit down in their places and align.
We see that everything went great. We see how the solvent escapes. I will show that all the balls are in place.
I think that Chinese rubbish will work with this power controller. MTK platform.
If we look closely at the melted balls, we will notice
that they are all uneven. With such an inspection - a top view - we will not see their height and diameter.
When this microcircuit starts to be melted down on the donor - on the phone where it is planned to be installed,
then there is a high probability that one of the small balls will not reach its place on the printed circuit board.
Because the rest of the balls turned out to be very large. Visually, everything seems to be fine,
but in fact there are some balls that turned out to be very small and this can cause poor soldering.
Knowing the level of professionalism of this person, I would never give him my phone.
From you I want to know how you like this video format? How do you like my comment?
Please write in the comments. Please like this video if you liked it. Bye Bye