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I purchased a Weller reflow set

Jan Cumps — Sat, 08 Oct 2022 21:17:58 GMT

The title says it all. I have a Weller solder station. They have IC reflow gizmos that work together with its hot air gun.

image source: sinuss.nl, the element14 retailer in Belgium and the Netherlands

These are little ovens, that you put on top of the IC you want to rework. Then you put the hot air pencil inside, to flow the solder.
There's a chip lifter (think: coal mine headframe) that can then lift the IC.
It can also be used to place ICs. Should help me with BGA designs.

It may be over-fancy. Paul Daniels and Louis Rossmann do all of this with just a heat gun. But I'm not that skilled - don't do it enough to be repeatedly successful.
My kit is also expensive. The one I bought, with support for 10x10 mm to 33x33 mm (with 6 steps in between), costs 500 €. An amount that I do not easily give away for tools.

Here's a video from Weller:

[View:https://youtu.be/-7GZz-C5peI:640:360]

I have now burned my budget for the next two years (three years actually, but last year I didn't buy anything). It 'd better work as promised.
Send me your old PCBs, so that I can practice.

RE: I purchased a Weller reflow set

Jan Cumps — Thu, 11 Dec 2025 13:53:48 GMT

shabaz , this could be a candidate for your MSPM0 temperature controller.

Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Sat, 18 May 2024 19:35:38 GMT

Removing castellated PCBs, once soldered, can be a tricky task. It's not easy to get the solder on all castellations heated up at the same time.

I had to replace the XIAO RP2400 board on my [mention:ea8acba6d62c44d4a813ef3fbde438dc:f7d226abd59f475c9d224a79e3f0ec07]. Doing this with a high capacity iron, or with hot air isn't easy. By the time you get to pin 14, pin 1 has gone solid again.
You may get away with prying under the board while attacking each castellation, but chances are that you 'll tear off the pads from the motherboard.

One possible solution is to ply a thick copper wire in such a way that it surrounds the PCB and touches all castellations. Then, with a decent iron and a lot of flux, heat up that wire.
I decided to try removing the IC with a Weller WRK SMD reflow kit.

This kit has little ovens that you can put on top of something. And it has a vacuum-actioned suction cup that you can stick on top of the device that needs to be removed.

When you then put a hot air pencil in the little oven's opening, the inside gets hot very fast. No risk of burning the neighbour components. And very efficient heat usage.

When I tried this at 380° C, the castellated board lifted off in 20-30 seconds. Without any damage.

This is the motherboard after the action:

And the castellated board survived too:

There is a little alchemy and experience involved. In my case, the XIAO used lead-free solder, and the castellated board was placed with leaded.
That meant that the castellations melted faster than the components on the XIAO. And when the lift-off happened, the whole board came off.
It's not that easy in every case.

But you can prepare for this. In case the castellated board is placed with lead-free, You can first wick off most of that, and replace it with leaded solder (or even lower melting point specialised products). Then use the oven to remove everything.

Anyways, after this exercise, I cleaned up the motherboard and put on a new XIAO RP2040.

Thanks for reading.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Sun, 10 Aug 2025 15:20:54 GMT

The USB still works. And the rp2040 cores too. I can still program it. I lost a gpio.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

shabaz — Sun, 10 Aug 2025 15:16:34 GMT

I was wondering if the Xiao might not have ESD protection on the USB connector, but according to the circuit diagram it does:

Maybe due to the tiny size of it, minute flexing on the socket could cause a capacitor to crack or something : (

There's a load of tiny resistors in a line, but there's also a capacitor (C2) which is across the 3.3V rail, so it's possible it could have shorted. It's 0201 sized which is insanely tiny of course : ( If it's possible to pull that part off (it's the second part in that row, see the yellow arrow), if it was indeed faulty then the XIAO might start working perhaps. Anyway this is all just speculation, it might be something completely different. I've never used an 0201 part, all I know is that those small parts (0402 too, which I've experienced this with) are so easy to crack, especially with hot air tools too.

(btw I looked at a slightly older revision in EAGLE, because I happened to have downloaded the XIAO files in the past, I didn't download the most reccent ones).

RE: Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Sun, 10 Aug 2025 14:18:20 GMT

In total, I have 3 victims:

2 XIAOs that I killed in virtually the same fashion, while serving as PicoProbes
a Pico 1 lost a GPIO pin while I was playing with stepper motor drivers.

I have to admit that I'm not careful. In particular with the XIAOs. I ordered a batch of 14, and that makes me a bit reckless.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

scottiebabe — Sun, 10 Aug 2025 14:00:42 GMT

great work! I don't want to jinx it, but so far I haven't had an rp2040 fail

RE: Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Sun, 10 Aug 2025 13:47:25 GMT

Back in business. The most difficult part was to transfer shabaz ' debugger sticker without damaging it 🙂.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Fri, 08 Aug 2025 14:50:30 GMT

yes. It's used as a PicoProbe. I made a mistake when connecting both Xiao and Pico to USB, and lost a GPIO

RE: Remove a castellated PCB with Weller WRK SMD reflow set

scottiebabe — Fri, 08 Aug 2025 14:02:26 GMT

Did your XIAO fail?

RE: Remove a castellated PCB with Weller WRK SMD reflow set

Jan Cumps — Fri, 08 Aug 2025 13:40:30 GMT

another year, another victim 🙂

That rework set proves to be helpful. 2nd time that I replace the XIAO debugger on this board, and all the copper pads survived. After the last repair, I used lead-free. So I had to up the temperature a little. I used 350°C.

This time, I think I'll place headers instead of soldering the new XIAO direct on the PCB.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

scottiebabe — Sun, 19 May 2024 01:07:42 GMT

Bismuth solder is a miracle worker when your desperate...

RE: Remove a castellated PCB with Weller WRK SMD reflow set

shabaz — Sat, 18 May 2024 22:25:38 GMT

Impressed that it all worked out! Great work.

RE: I purchased a Weller reflow set

Jan Cumps — Sat, 18 May 2024 20:03:57 GMT

A test with a castellated PCB: Remove a castellated PCB with Weller WRK SMD reflow set

RE: Remove a castellated PCB with Weller WRK SMD reflow set

DAB — Sat, 18 May 2024 19:57:00 GMT

Good post Jan.

RE: Remove a castellated PCB with Weller WRK SMD reflow set

javagoza — Sat, 18 May 2024 19:43:18 GMT

That tool is really useful. Good job desoldering. I usually do it quite badly, using the technique you indicate with the thick wire, but many times I end up ruining a track.

RE: I purchased a Weller reflow set

Jan Cumps — Fri, 14 Oct 2022 19:00:48 GMT

My experiment with caps was a disaster. They explode inside the little oven.

RE: I purchased a Weller reflow set

Andrew J — Fri, 14 Oct 2022 18:52:32 GMT

Good job with the inductors, I always find them and electrolytic caps the hardest to de-solder.

RE: I purchased a Weller reflow set

Jan Cumps — Fri, 14 Oct 2022 18:09:39 GMT

Some success stories

Some failures

The left one, I'm not 100% sure if it's a failure, May be that some of the solder splashed up when the part lifted, and this is the residue. May be fixable.
At least, nothing ripped.

The right one didn't go very well. Two pins were still clinging to the board when the chip lifted.
Damage: board OK, pins bent but can be fixed. Still: this could have gone wrong if the pad traces would not keep up with the pull tension...

Photos are fairly high resolution. Click for zoom.

RE: I purchased a Weller reflow set

Jan Cumps — Fri, 14 Oct 2022 15:05:03 GMT

I have Kapton tape. It doesn't have the same shielding, but I'll try it anyway ...

RE: I purchased a Weller reflow set

shabaz — Fri, 14 Oct 2022 14:12:41 GMT

For the connectors, one idea (I have not tried it) could be to obtain some ceramic paper, and cut a small piece into the shape of the inside of your metal cover, and pierce some holes or cut out notches all around the sides, so that all the heat hits the sides of the connector only. Basicallty the ceramic paper acting like the space shuttle tiles 😂 The ceramic paper is cheap (it's used for art/craft pottery etc). However the suction won't suck up the part, but I guess for a connector the suction won't work all that well anyway, so maybe that's no big issue.

(Just remembered I may have some of that paper, I'll take a look).

RE: I purchased a Weller reflow set

shabaz — Fri, 14 Oct 2022 14:07:31 GMT

That's very neat! That video makes it clear how it works. Nice design, using the suction to gently lift up the chip once the heat has reflowed all around the chip,

RE: I purchased a Weller reflow set

Jan Cumps — Fri, 14 Oct 2022 00:15:45 GMT

I tried to use the ovens on non-IC parts: connectors, transistors, electrolytic caps. Without the lifting mechanism, just put the nozzle on top to concentrate the heat.
After a few seconds, remove the nozzle, and complete the exercise with the air pencil and some tweezers only.

In most cases, it made desoldering faster. With a few SMD plastic connectors, I managed to lift them off fast, before the plastic started to give away - something that fails often when I use an iron or heat gun in isolation.

One thing failed miserably: an SMD electrolyte cap: that one exploded inside the little oven after a few seconds. Definitely not a good match with this desoldering kit.

Action photo:

RE: I purchased a Weller reflow set

Jan Cumps — Thu, 13 Oct 2022 18:51:20 GMT

I should have RTFM first:

Small oven: nozzle. Big oven: no nozzle

RE: I purchased a Weller reflow set

Jan Cumps — Thu, 13 Oct 2022 18:04:55 GMT

Test 2, with a bigger IC and one of the bigger ovens. This was more eventful. Not because of the kit, but because of me, learning while on video.

https://youtu.be/lWrsRHoDSZM

The editing is very limited. I only cut out those parts where I was walking away from the bench to get different tools. I never cut during the actual performance.
You hear some voice-over, to give some comfort to the people that sit out this video, but that's it. No editing, no sound is omitted.
Bless the ones that manage to finish viewing this 🙂.