this post was submitted on 18 Feb 2025
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Soldering

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looking for advice (lemmy.ca)
submitted 1 week ago by skankhunt42 to c/soldering
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So, I'm pretty new at soldering and I'm looking for some advice on how to not ruin a via while removing solder...

I was trying to remove the solder from a original Xbox 1.0 motherboard and I burnt the shit out of a via and caused issues with several others.

https://lemmy.ca/pictrs/image/d2d4a90b-aab2-4521-9cbb-25e3cd305ae7.jpeg

I was able to fix it and everything is working but I want to do better.

https://lemmy.ca/pictrs/image/b2d04556-025e-404d-940d-886247cdb97c.jpeg

I used a pointed tip, flux, and added some of my own solder to the via. I then cleaned, added new flux, and used solder wick to remove the solder. Some points, would NOT melt at all. I kept increasing the temp to 430°c and it finally melted and took everything with it.

Now, I know I fucked up and used too much heat. I probably should have used my rework station and a solder sucker but I JUST got the rework station and didn't want to popcorn the OG Xbox board... The solder wouldn't stay melted long enough from my iron for the sucker to work so I used wick.

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[–] [email protected] 5 points 1 week ago* (last edited 1 week ago) (1 children)

First, preheating the work area is important to prevent thermal energy from being soaked away. Board preheaters are helpful for thick boards (GPUs, PS5, etc). You can use a hot air station if you have one, or even a heat gun if you’re very careful and keep your distance.

Electronics are assembled with lead-free solder, which has a higher melting point. Add in some leaded solder and you’ll have a much easier time.

Get yourself a chisel tip or knife point. The wider surface area you can put in contact with the piece will transfer heat more effectively.

[–] skankhunt42 2 points 1 week ago (1 children)

A chisel tip is good for small vias?

What about lowmelt? I've seen videos and it just gets all over everything.

I've ordered a couple practice board, I'm going to try to replicate my mistake (burn the pad off) then preheat the board and try a few different things to see what works best. I'll order some leaded solder too, thank you!

[–] [email protected] 4 points 1 week ago (1 children)

A tip with wide surface area is good for quick transfer of heat to the piece. It avoids the situation where you’re sitting there with the iron in prolonged contact while the temperature of surrounding areas / adhesives steadily increases while the solder doesn’t wet.

Low melt can be helpful, I recommend against using it for anything where a mechanical mount is needed (HDMI, DC Jacks, USB Receptacles, etc) or for high temperature applications (e.g automotive) Once the bismuth is bound to a pad it’s almost impossible to get off without sanding/grinding, it permanently reduces the melting point in that area and increases the chance of losing that mechanical bond.

In case it wasn’t clear, the advice I outlined is to prevent burning the pad off in the first place. Once you’ve damaged pads / traces / vias you’re in restoration / workaround territory.

[–] skankhunt42 2 points 1 week ago

I understand, thank you.

The reason I burned the via was because I couldn't get the old solder out and didn't know how to do it safely. Sounds like the solution is to pre-heat the board, use leaded solder, and try a larger/different tip.

What I shouldn't do is use low melt or just keep increasing the temperature.

[–] [email protected] 4 points 1 week ago (1 children)

My advice for any future projects..

When solder doesn't want to cooperate with you, that generally means the heat is getting absorbed too quickly through larger board traces, often ground or power traces.

You don't want to focus too much heat in one spot, it's much better to preheat the board around such stubborn areas. Even if you gotta go redneck style and use a hair dryer, it helps a lot to preheat the board.

[–] skankhunt42 2 points 1 week ago (1 children)

I got a rework station about a week ago. Is there a good temp to heat the board with? I know I don't focus the heat in one spot and always keep it moving but as for temperature or air flow I have no idea.

I haven't read or seen many people preheat the board. Is this true for all soldering projects or just for the stubborn points?

[–] [email protected] 3 points 1 week ago* (last edited 1 week ago) (1 children)

Nah, mostly a thing just for the stubborn points, but a lot of parts unfortunately have to connect one way or another to said stubborn areas, as that's where they get power.

And those traces are typically way larger, even if you don't immediately see those traces, they can be buried in one of the middle layers of the board.

Different materials have a different thermal expansion/contraction rate, so it always helps to try to even out the heat level on the board, hence the reason to preheat it.

It's never good to try to suddenly put 430⁰ Celsius on one spot of a board when your room temperature might be about 30⁰ Celsius, that's a huge temperature change for any one focused spot.

You want the board overall to be pretty warm (and dehumidified if you're really getting serious like reballing a chipset or something), but yeah, stubborn spots like to be preheated.

It also partly depends on the type of solder being used, older lead based solder melts at lower temperature, but lead based solder is practically obsolete these days. Most solder these days is tin based, which has a higher melting point.

In my experience with soldering, I've found the temperature range between 370⁰ to 420⁰ Celsius to be sufficient, but when I have to crank it up to 420⁰ I'm already worried.

[–] skankhunt42 3 points 1 week ago

This makes me feel a lot better, thank you!

My usual temperature was 370°c but since I've burned the via I've dropped it down to 340°c and only go up when I really need to. I'll probably go back to 370°c

As for the stubborn points, I'm going to preheat and try different/larger tips before I go above 400°c.

Thanks again!

[–] [email protected] 4 points 1 week ago

i use a heat plate to pre-heat the board and then remove the solder with flux solderwick and on top the solder tip,.