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Imperf3kt
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Re: Help identifying tiny chip

Sun May 16, 2021 8:12 pm

razzjazz192 wrote:
Fri May 14, 2021 1:17 pm
How would you ever solder any of this?
As mentioned previously, reflow soldering.however hand soldering is possible.
Using a very fine strand of flux core solder, first pass over where you will solder the tiny chip to with a wiping motion, the solder should flow onto only the pads with no bridging if you do it right.
Then, lay the chip in position, add a tiny amount of solder and tap it with hot soldering iron.
If you find the iron tip too hard to work with because it's too big, there should be a screw on the side that is used to hold interchangeable tips, you can unscrew this a small amount, wrap a length of copper wire around it and retighten it. Now you have a very small tip for precision soldering.
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jojopi
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Re: Help identifying tiny chip

Sun May 16, 2021 10:47 pm

Imperf3kt wrote:
Sun May 16, 2021 8:12 pm
Using a very fine strand of flux core solder, first pass over where you will solder the tiny chip to with a wiping motion, the solder should flow onto only the pads with no bridging if you do it right.
Then, lay the chip in position, add a tiny amount of solder and tap it with hot soldering iron.
I am no soldering expert, but I happen to have tried that (specifically with 6-pad 5050-size [5mm x 5mm] RGB LED chips).

When tinning the pads, I found it impossible to get the same amount of solder on each one, meaning that the parts would not lie flat. Then it took multiple attempts applying firm pressure, reheating the joints, adding solder, to get them all to make contact simultaneously.

Have you tried my method? Scrub the pads with a flux pen, place the part flat onto the PCB, and rely on the solder wicking underneath as it is fed in from the edge?

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Gavinmc42
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Re: Help identifying tiny chip

Mon May 17, 2021 12:04 am

I found it impossible to get the same amount of solder on each one, meaning that the parts would not lie flat
Pre-tin the pad and the LED leads, use solder wick to remove most of the solder.
They will then sit flat and with a flux pens and 0.33mm solder and tiny tip iron it can be reflowed.

For those that have the resources, a solder paste mask and hotplate is less hassle.
A laser cutter and plastic paste masks and a tiny squeegee?
Avoid lead free solder, everything needs to be so much hotter.
Production lines can be set up to use lead free but they are horrible to repair.

If 138C solder was easier to get I would be using that.
A hot plate for 150-160C won't cook chips too much.
Easy to make tiny hotplates from 3D printer heaters and alloy block or a ceramic heat sink wrapped with Ni-chrome wire.
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Imperf3kt
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Location: Australia
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Re: Help identifying tiny chip

Mon May 17, 2021 2:06 am

jojopi wrote:
Sun May 16, 2021 10:47 pm
Imperf3kt wrote:
Sun May 16, 2021 8:12 pm
Using a very fine strand of flux core solder, first pass over where you will solder the tiny chip to with a wiping motion, the solder should flow onto only the pads with no bridging if you do it right.
Then, lay the chip in position, add a tiny amount of solder and tap it with hot soldering iron.
I am no soldering expert, but I happen to have tried that (specifically with 6-pad 5050-size [5mm x 5mm] RGB LED chips).

When tinning the pads, I found it impossible to get the same amount of solder on each one, meaning that the parts would not lie flat. Then it took multiple attempts applying firm pressure, reheating the joints, adding solder, to get them all to make contact simultaneously.

Have you tried my method? Scrub the pads with a flux pen, place the part flat onto the PCB, and rely on the solder wicking underneath as it is fed in from the edge?
No need for the parts to lie flat, when you add the second lot of solder and heat it, it will melt the solder below the part and gravity will do the rest. Usually the solder will wick itself properly, but you may occasionally have to clean up a little bit.
More often than not, I find the parts tend to "tombstone"

I use this method for soldering 8-pad 2020 size RGB LEDs which are a third the size of my soldering iron tip.

Naturally, some form of helping hands will be required. I tend to use tweezers and alligator clips.
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52:4C:52:42:41

Rose tinted glasses are difficult to see through.

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