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How to change a surface mount integrated circuit
SMD type components are smaller and their installation or replacement
requires special care.
Here's how to change a surface integrated circuit.
Tools
The minimum tools needed to change
a surface mount component are:
Heat Gun
This tool emits air at very high temperatures
Is used to heat and melt the soldering without need for direct contact
with the printed circuit.
Soldering Iron: Power tool that generates heat on a metal tip
It is used to solder the components, or to heat the solder
when they go to remove of the PCB.
Soldering Paste
It's a greasy ointment consisting of tin powder mixed with flux.
Is used as a flux.
Flux
A chemical compound task of cleaning oxide from surfaces to be welded
and welding helps to more easily reach
its melting point.
Welding
soft alloy of tin and lead rosin core.
It is used for soldering electronic component terminal to the PCB.
Desoldering wick
It is a copper mesh with very fine threads that when placed on the solder melts,
easily absorbed without leaving a trace.
Precision Screwdriver: Used as leverage to push
or lift the SMD component.
Can be replaced by thin tongs.
magnifying glass
optical tool that helps shorten the focal length
allowing you to see an enlarged image of the object
It is used to check welds have been well made
and no short between the terminals of the component.
Toothbrush
With this tool we clean the card and components.
Thinner o solvent
Used to clean the PCB or the recycled component
Scissors
Used to cut leftover desoldering wick
when welding are already saturated.
Brush
Use to evenly apply the flux
Pin or needle
When we have welded components
pressed with this each terminal of the integrated to verify
that they were well welded.
Multimeter
Used to verify that have not fallen short circuits between terminals
or PCB tracks
procedure
The first is to apply flux on the terminals of the integrated circuit.
If you do not get the flux, you can use the soldering paste.
Be applied abundantly, so that all pins
are impregnated with flux
Now enlisted the solder station
Button opens the air,
turn on the solder station
And raise the heat to more than 400 degrees centigrade
When the heat gun is well hot,
We heat the terminals of the integrated circuit
Circles are made on the integrated
to ensure that all the pins are heated evenly.
He very gently pushes integrated with the screwdriver
until you feel that you have already released
and lifting of the site
Another way to remove an embedded SMD is using the soldering iron.
It's a bit more time-consuming and delicate, but is possible.
With a soldering iron of at least 40 Watts, add plenty of solder
on the pins of the IC, flooding the entire area.
welding must keep it liquid and we keep the soldering iron all the time
going around the integrated circuit.
When the weld is fully melted on all sides of the integrated circuit
you will see how it will release easily.
Remove it with the screwdriver or tongs.
Recovery of an integrated circuit
When removing an integrated circuit, which we want to recycle, it will come out very dirty
and with its terminals united by the welding.
We must clean it in order to use it again.
The first step is to spread the IC with soldering paste
Then we are going to remove the welding leftovers using the soldering iron
at regular temperature.
Having the integrated fully release from the weld
wash with brush and solvent
to remove the shrapnel and the grease that could be still
Then we dry it well with the help of a cloth or napkin.
With a needle we separate the pins that may have been joined.
We also verify that there is no seam between them.
Now we proceed to clean the card.
Submerge the soldering wick in the paste.
Now place the wick on the tracks where
the IC is welded
and creeps using the hot soldering iron.
When the wick is saturated of welding, cutting the piece already used.
The procedure is repeated over and over again
until the tracks are free of weld.
Then wash the board with the toothbrush and thinner.
We dry well the card and verify that there are no welding
or grease particles, due to the solder paste.
Placing the IC
The integrated specific brands bring determining their position or direction
it should be placed.
Welding the integrated circuit
After that we have place it into the correct position
we must fix with a pair of spot welds at two of its opposite ends.
Then, with a screwdriver blade, we verified
that none of the terminals have been built up.
We do this by pressing down on each pin.
Now, we can apply abundant welding on one side
that was not welded
Heat the solder
and spread to the opposite corner
being careful not to leave lumps.
Sometimes it is necessary to tilt the card slightly
and help spread the solder quickly, before they crystallize.
The idea is that the terminals are bath in welding
at the same time that the tracks were are going to be glued.
Then we will turn on all sides of the chip.
When finished soldering
must wash the IC very well built
using thinner and toothbrush.
There should be no splinters, no excess solder
It should dry pretty good the card.
Then verify that none of the integrated terminals
is raised or detached from the card.
is done by doing pressing with a pin or needle
on each pin of the IC.
Then we check with magnifying glass. There should be no shorts between
tracks or integrated terminals
We can compare with another integrated that has not been changed.
Another way to be sure that the component was welded
is to measured with the multimeter between adjacent pins.
That is, we measured two by two pins.
There should not be short unless two pins that go to the same track or ground.
We hope this tutorial will help supplement your knowledge in electronics
and also serves the time to fix the motherboard
of your computer
or some other card with surface components
Successes!