Desoldering device

[Mark-VA]

Anyone with experience with this tool?
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[ivconic]

I don't have it, but I've seen it with my colleagues. Correct thing.
My best experiences are with copper braid when desoldering and cleaning the pcb of excess tin.
There is no competition, especially if you work with SMD pcb and very small areas.
And lately I've been working more and more with SMD... which was not planned even in my wildest dreams.
Copper braid is definitely the best "tool" for these works. A real "vacuum cleaner" for tin and flux.

[Mark-VA]

I've been using copper braid, and it works very well but at times I'm concerned with overheating the components.

[ivconic]

I understand. Some time ago I faced (for me at that moment) an extremely difficult task.
ESP32...! Had to desolder and solder back the same chip to the main pcb multiple times!
The space around the chip was inhabited.
For someone who has avoided working with SMD for years... on the border of impossible!
But then I called for the help of a more experienced friend who visited me and showed me a couple of different methods and they were all incredibly easy!!!
And then we talked about the problem of overheating.
The PCBs I make at JLPcb (and I believe at others) are of such quality that they withstand unexpectedly high temperatures!
As for the components... that's a different matter from case to case. You should always check online.
When working with copper braid; it is crucially important that you "bath" the braid well in melted "rosin".
Very simple, you rest the braid on "rosinium" which is like a crystal and heat it from above with the tip of the soldering iron.
The braid will be drowned and watered from all sides. Then you use it on the pcb and components... with a much lower temperature (if necessary and often not).
Otherwise...just copper braid without melting in rosin...will not work! Or it will need a much higher temperature for the whole process.
When you're done; the board will be hideously ugly from the compacted layer dark brown to rosin black.
Then that part is washed with a brush and nitro thinner. Super easy and quick!
The end result is phenomenal!
As you can see it's simple and you probably knew all this. But it's the little details that make a huge difference!
Without immersing the copper braid in rosin; the story takes a completely different turn and the whole process is painful with bad results.

[ivconic]

The next "trick" is to use Kapton tape!
The standard tape is self-adhesive on one side and it is used to thermally insulate the surrounding components.
But for removing ESP32 (and similar awkward components) you need to find a slightly thicker Kapton tape that does not have self-adhesive sides.
You draw a piece of tape slowly under the row of pins on the chip, while at the same time you heat the tin on the pins from above!
"Dirty" but phenomenal trick! For which many will not reveal the secret to you!
You do this on all 3 sides of the chip's pins.
You leave tape between the row of pins and the pcb surface.
And then you heat only a small square zone from below where the "pin" for the mass and cooling of the chip is hidden!
And the chip simply "swims" and falls off!
That thicker Kapton tape without the adhesive sides is expensive and hard to find. It is used in a completely different application!
Such tape is used in ultra strong radio transmitters to "belt" and insulate the main transmitting element, be it a vacuum tube or some set of special mosfet transistors...
generally Kapton tape was originally invented for this purpose.
A square meter of such Kapton material was, if I remember correctly, about a thousand euros!
But you need 5x5cm of that material that will serve you for years as a "tool" for these purposes!
A friend gave me such a piece that withstands up to 800 degrees Celsius without any deformation.
Chips like the ESP32 "voluntarily" fall off the pcb in this way without any hassle!
There you go... a couple of pretty "dirty" little tricks that no one will ever fully reveal to you!
Why, I don't know? But the people who know these tricks jealously keep it to themselves.

[Mark-VA]

Well I can say I've never, "it is crucially important that you "bath" the braid well in melted "rosin"."


I usually brush the area with rosin before desoldering with braid, but never the braid itself.


Thanks very much for this info.

[ivconic]

Oxidation is the biggest problem with copper.
Although copper braid often looks great; be sure that a super thin layer of oxidation is already present.
However benign it may seem; such an oxidation layer greatly worsens temperature redistribution.
Rosin is a perfect "cleaner" of the copper surface and at the same time a "catalyst" in the process of bonding with tin.
Rosin has a very low melting point and it is enough to just lay the copper braid on a piece of rosin and press it from above with the tip of the soldering iron and move the tip along the length of the braid.
The copper braid will literally "suck up" the melted rosin. When you put such a braid on the pcb in the place where you have tin; move the tip of the soldering iron again slowly along the length of the braid, very slowly, you will see how the braid sucks up the tin like a "vacuum cleaner".
I have scissors ready even when the braid turns "white" from tin; I immediately cut that piece and throw it away.
Because that piece is "saturated" with tin and has no more "capacity" for further suction.
In this process, the rosin in a molten state will partially remain on the pcb, which is no problem.
When you clean the pcb from tin, as I mentioned, later a regular brush and nitro thinner remove and wash the pcb until it shines.
This is about the correct assessment of the measure of the use of the braid. And its "capacity" for vacuuming tin. It gets saturated very quickly, but it's easy to see from the color.
This is a method that is mastered in just a few tries. But that's why the final results are without competition.
This is written by someone who has done difficult and easy reverse engineering many times on many devices.
To make an identical pcb clone; i have to clean it to "factory state" in order to scan it properly on both sides.
The smallest tin residue can often cover a connection, but more often a "via" (joint of layers) and can lead to an error in later work.
That's why over the years I have perfected the methods of cleaning pcbs.