Hello folks,

I recently watched a YouTube video where someone repaired a faulty Super Mouse Brick Game PCB, and I’m trying to understand some of the tools and techniques used in the process. I’ve broken my questions into a few parts so it’s easier for anyone who can help to respond

1. Tool for Scrubbing the Broken PCB Surface (Timestamp: 5:10)
In the video, after gluing the two halves of the broken PCB together, the person used a tool that looked like a rotating scrubber or grinder to scrape the surface of the glued area. After that, he applied solder:
1.a. What is this tool called?
1.b. Is there a specific name for it, and is it commonly used in electronics repair?
1.c . Why is this technique of scrubbing the glued area and then applying solder used? Is it some standard way of repairing a broken PCB to ensure continuity across the break?

2. Solder Mask Application and Drying (Timestamp: 6:25 & 6:46 )
After soldering, the person applied something called "solder mask" over the repaired area.
2.a. What exactly is a solder mask, and why would you use it after soldering?
Then, He used a device with a blue LED light to dry the solder mask.
2.b. What is this drying device, and why is it necessary for the repair?

I would be incredibly grateful if someone could answer my answers and explain to me as I'm still unfamiliar with this.

Thanks

 

So he fixed the track to one of the switches, and now the display works? Really?

All he did was scraped the solder-resist off and soldered the broken tracks back together. I would have removed the solder resist by scraping it with a scalpel, then soldered some tinned copper wire across the break, which is easier (and probably more reliable) than trying to bridge the gap with solder.

 

That looks like a rotary tool, a Dremel or similar, that he used to scrape off the solder mask. This exposed the copper trace beneath and allowed him to add a solder bridge to reconnect the signal.

The only thing I'd do differently is to scrape off more and add a short length of wire across. A solder bridge is not a really reliable connection.

 

You could quite easily go completely through the copper with a Dremel.

 

Hello folks,

I recently watched a YouTube video where someone repaired a faulty Super Mouse Brick Game PCB, and I’m trying to understand some of the tools and techniques used in the process. I’ve broken my questions into a few parts so it’s easier for anyone who can help to respond

1. Tool for Scrubbing the Broken PCB Surface (Timestamp: 5:10)
In the video, after gluing the two halves of the broken PCB together, the person used a tool that looked like a rotating scrubber or grinder to scrape the surface of the glued area. After that, he applied solder:
1.a. What is this tool called?
1.b. Is there a specific name for it, and is it commonly used in electronics repair?
1.c . Why is this technique of scrubbing the glued area and then applying solder used? Is it some standard way of repairing a broken PCB to ensure continuity across the break?

2. Solder Mask Application and Drying (Timestamp: 6:25 & 6:46 )
After soldering, the person applied something called "solder mask" over the repaired area.
2.a. What exactly is a solder mask, and why would you use it after soldering?
Then, He used a device with a blue LED light to dry the solder mask.
2.b. What is this drying device, and why is it necessary for the repair?

I would be incredibly grateful if someone could answer my answers and explain to me as I'm still unfamiliar with this.

Thanks

1.a.b. Hobby rotary tool, common brand name is Dremel, with an abrasive grinding bit.
1.c. You cannot solder to traces covered with solder mask. I use a sharp curved blade (i.e X-Acto blade) to scrape away the solder mask and to expose the copper trace. I would bridge the copper trace with a short piece of wire.

2. Once the board is glued together and the broken tracks are bridged the repair is done. You don't have to apply solder mask.
Solder mask is not necessary in DIY PCB. Solder mask is applied on commercial boards for various reasons:
(a) for flow solder operations
(b) to prevent solder bridges in closely spaced pads and tracks
(c) to prevent through-hole components any other stray material from causing shorts
(d) to provide a protection from moisture and other forms of corrosion
(e) it looks prettier than plain solder flow or bare copper tracks

If he used a blue LED to dry something, he might have used a UV-curable glue (e.g. Bondic). The LED is a UV source which is used to harden the glue instantly.

 

1.a.b. Hobby rotary tool, common brand name is Dremel, with an abrasive grinding bit.
1.c. You cannot solder to traces covered with solder mask. I use a sharp curved blade (i.e X-Acto blade) to scrape away the solder mask and to expose the copper trace. I would bridge the copper trace with a short piece of wire.

2. Once the board is glued together and the broken tracks are bridged the repair is done. You don't have to apply solder mask.
Solder mask is not necessary in DIY PCB. Solder mask is applied on commercial boards for various reasons:
(a) for flow solder operations
(b) to prevent solder bridges in closely spaced pads and tracks
(c) to prevent through-hole components any other stray material from causing shorts
(d) to provide a protection from moisture and other forms of corrosion
(e) it looks prettier than plain solder flow or bare copper tracks

If he used a blue LED to dry something, he might have used a UV-curable glue (e.g. Bondic). The LED is a UV source which is used to harden the glue instantly.

Thank you very much, I understand it much better now,

So, just to clarify, he scraped the PCB to remove the old solder mask and expose the copper trace underneath, then soldered the connection and applied a new layer of solder mask on top. You said, it might be better to bridge the gap with a small piece of copper wire before applying the solder mask instead of only applying Solder, Is that correct?

 

So he fixed the track to one of the switches, and now the display works? Really?

All he did was scraped the solder-resist off and soldered the broken tracks back together. I would have removed the solder resist by scraping it with a scalpel, then soldered some tinned copper wire across the break, which is easier (and probably more reliable) than trying to bridge the gap with solder.

By solder resist, you refer to the solder Mask , right?

 

By solder resist, you refer to the solder Mask , right?

Yes. Same thing.

 

...bridge the gap with a small piece of copper wire before applying the solder mask...

You won't be re-applying the solder mask. You will simply be soldering a short piece of wire across the gap.

 

you do not have to but...if you like... you can also apply something like this:
https://www.mouser.ca/datasheet/2/265/appguide0404-336676.pdf
https://www.mouser.ca/datasheet/2/401/TS-2211_ENG_TDS-1386670.pdf

solder mask is useful before soldering... so that solder does not stick to parts of board where it should not... after soldering is done, one may apply conformal coating to make the board more immune. for boards that are exposed to high humidity (dishwasher, car, things at very high elevation etc.) this is important. for TV it is not.

note, in video in first post, PCB is mechanically fractured. so this is not just about repairing electrical connections, board also need to be made mechanically sound. i did not watch the whole video so i am not sure if and what was done about this. probably he did not use solder mask but some sort of glue... solder mask is easy to scrape of off using any just about anything (screwdriver) and it would not hold the broken pieces of PCB ...but... some glues can. so the glue was expected to seep into the cracks before being cured by UV light. dentists use such tough glue.

 

1.a. What is this tool called?
1.b. Is there a specific name for it, and is it commonly used in electronics repair?
1.c . Why is this technique of scrubbing the glued area and then applying solder used?

2.a. What exactly is a solder mask, and why would you use it after soldering?
2.b. What is this drying device, and why is it necessary for the repair?

1.a. Its typically called a grinding pen. From my memory In the youtube creator world a guy named Northridge fix started trying to make it a "necessary" tool so he could sell it. Truthfully is a waste of effort (and money) if you ask me. Its easier to just scrape the solder mask away with a dull razor or the end of your tweezers.
1.b. Grinding pen is the term used these days but its just a baby rotary tool.
1.c. The solder masked is being removed to expose the copper trace so that solder can be applied. The way it was done in the video was not very good. That creator in the posted video tends to do a bit of shoddy work on purpose I think. It seems to be part of his shtick.

2.a/b. The solder mask protects the copper/soldered area's and is good for exposing only desired areas for soldering. The one used in the video is a liquid version used in rework and needs to be cured with a uv lamp which you see at the end. Personally I don't think it cures all that well unless you keep it super thin and do multiple layers. I prefer to just use silicone conformal coating after rework which provides better protection.

 

1.a. Its typically called a grinding pen.

Most commonly known here by its trade-name "Dremel".

 

Here (N.A.) also !

 

Most commonly known here by its trade-name "Dremel".

Splitting hairs a bit but Ive never really referred to or heard people calling the smaller pen sized rotary tools as Dremel's. It was pretty common for larger ones many moons ago when they were first popping up to be called that despite the actual brand but to be honest I think my area has become pretty accustomed to calling them rotary tools these days. As for the one in the video specifically, if you want to find it to buy, you would search by calling it a Grinding pen.
Term: Grinding pen
Term: Dremel

 

Strange!
I have always heard them and seen them referred to as "Dremel" across the board?

 

I did have a smaller compressed-air powered device, which was officially a "die grinder" - a cylindrical device of about 15mm diameter.
It had much better bearings than any Dremel I have ever owned, It could drill holes with 0.5mm carbide bits, and no Dremel could do that without breaking the bit, due to the amount of eccentricity.

 

If it was specifically designed as a die grinder then has to have extreme accuracy.

 

grinder and ... accuracy?

 

Per Definition :
A die grinder is a precision tool used for tasks like metal shaping and wood carving. With high-speed rotation and attachments, it excels in fine finishes and intricate work. Ideal for professionals and DIY enthusiasts in metalworking, woodworking, and more.

If a die maker uses such a tool, it has to be capable of very fine work.
Whether die is for use in a casting or pressing machine.
The operative word being "Die Grinder"

 

Most commonly known here by its trade-name "Dremel".

Actually, no. The “grinding pen“ is a much smaller tool that runs on an internal battery. It takes advantage of new motor technology to be very small but sufficiently powerful to do quite a few jobs.

I have this one from AliExpress. It’s doesn’t replace a dremel but for my small toolkit (travel, &c) it really adds some different capabilities. I haven’t used it for PCB work—yet, anyway. I think it might have come out of the nail care industry where it is a very popular tool.

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