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Next, we will reball the chip

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After the chip cools down, use a dustless cloth to dab some PCB cleaner on the board

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Wipe off the dirt on the chip

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After cleaning, find a paper towel and place it under the chip

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Now let's clean the stencil

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Wipe the front and back of the area that used to reball with a dustless cloth

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Check carefully to see if there is any dirt in the hole.

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For example, in this place, it is obvious that

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there is still so black residue

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This is definitely not good, let's continue to wipe it again

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Ok, now the stencil is basically clean

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Then we start to reball

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Press the two sides of the chip with a curved tweezer,

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and align the holes of the stencil with the pads at the bottom

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Apply the tin paste

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Scoop out the excess tin paste

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Find a dry, dustless cloth that has not been soaked with PCB cleaner,

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and wipe the excess tin paste on this edge

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Do not wipe with a cloth that has been soaked in PCB cleaner

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Otherwise, the PCB cleaner will dilute the tin paste,

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as a result, the tin paste will seep everywhere

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from the gap between the stencil and the chip

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And it will lead to uneven size of the pads or short circuit

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We use the rotary air gun with temperature of 230 degrees

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to blow the large area

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Blow for about 1 minute, then put the nozzle against a corner of the chip

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After the solder melts, blow for a few more seconds, and then remove the nozzle

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After removing the nozzle, wait a little longer for ten seconds,

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and then release the tweezer

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If you release the tweezer too early,

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when the solder has not yet solidified,

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the stencil is deformed a little and bounces,

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and the solder sticks together again

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Press the outside, lift the stencil from our direction, and pull out the chip

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Well, it's done

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But we missed one pad

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It may be that there is a little dirt on this pad

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Let's repair it

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Of course, you can also directly put the stencil back and blow it again

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First, a little bit of soldering oil

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Let's reheat and blow this tin bead back into place

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because it looks a little crooked

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The fourth in the second row in the lower right corner

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There is a black glue under the tin bead, so it can't be blown up

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and this tin bead is too small

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In this case, we can only take out the tin bead

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and put a new tin bead on it.

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Drag a knife on the paper towel

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blow this tin paste

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In this way, all kinds of tin beads of different sizes are made.

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Then we put the chip aside and find one that is basically the same size

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The tip of the tweezer must be clean

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This tin bead is just suitable

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When we make up this kind of tin beads,

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we still use the temperature of the air gun just now to blow it, 230 degrees

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But you have to reduce the air volume to the minimum,

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because the tin beads are loose now

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and can easily be blown away when the wind is strong

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Let's start to blow

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ok, it's glued

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In fact, if you are unstable with the tweezers,

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you will not be able to repair it after tryingmany times

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So you can directly use a soldering iron to flatten it

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and reball it again

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Okay, the chip reballing is done