Used a lead solder in a kitkchen range hood repair

Thread Starter

hotiron

Joined Dec 4, 2021
3
Hello all,

Our kitchen range hood failed to turn on one day, and the manufacturer stopped producing parts for it. So, I decided to try to repair it myself. While looking around, I saw one bulging capacitor, which I then went on the replace. I have no experience with anything electronics related, especially zero soldering experience, and had to learn everything from YouTube and online articles in a week. I ordered parts from DigiKey and successfully replaced the bulging capacitor. The failed capacitor didn't even have 1 capacitance.

The problem is, I used a lead-based solder, and all the other soldered areas in the circuit board seems to be dull and not shiny like the repair I did, which I then figured was from them being old. The circuit board is at least 16 years old.

I would replace lead solder if it wasn’t such a hassle, literally. The circuit board cannot even be uninstalled from the exhaust fan, and it was very tricky even removing the old capacitor and replacing it from the circuit board with the board being in a vertical position. Now, removing all the solder will be even more difficult, and I am afraid I will mess it up and turn this circuit board nonfunctional, needing a very, very expensive replacement of a kitchen range hood.

My question is, is there a danger in using lead-based solder for such application when constant air is pumped through the exhaust fan, some of which might leak out into the kitchen? From my reading, the lead paint was banned because it would chip and turn into dust, etc. which one would then inhale/ingest. I don’t think that will happen in this scenario. What do you guys think?

Thank you.
 

dl324

Joined Mar 30, 2015
13,857
Welcome to AAC!
My question is, is there a danger in using lead-based solder for such application when constant air is pumped through the exhaust fan, some of which might leak out into the kitchen?
The European concerns about solder containing lead are overblown. The only time I use lead free solder is when I'm soldering something that will touch things that will be consumed.
 

crutschow

Joined Mar 14, 2008
28,580
The only concern about lead solder is it getting into the environment when the soldered device is trashed.
Solder does not evaporate, sublimate, flake, or get into the environment other wise.
It's perfectly passive when on a circuit board.
 

Ian0

Joined Aug 7, 2020
4,169
You're probably safer with the tin-lead solder. It's a better solder. It therefore needs a less aggressive flux. Lead-free solder needs a more reactive flux. If any residue is going to flake off etc. and get into the environment it's the flux. (And I still think it's rather a low risk)
 

Thread Starter

hotiron

Joined Dec 4, 2021
3
Welcome to AAC!
The European concerns about solder containing lead are overblown. The only time I use lead free solder is when I'm soldering something that will touch things that will be consumed.
Thank you!

Funny you should mention Europe. This range hood is from a Spanish manufacturer. So, I guess they were under European standards as to which solder they can use in order to deter a landfill issue that crutschow mentioned prior.
 

dl324

Joined Mar 30, 2015
13,857
Funny you should mention Europe.
It's thanks to Europe that we rediscovered tin whiskers and why lead was added to solder in the first place. Airlines and space agencies are exempted because using solder with no lead can cause catastrophic failures. It will still affect consumers, but at least the damage or fires started can be dealt with more conveniently. Unless it's the autopilot in your car that stops working due to short circuits, or maybe a drone crashing, or ...
 

Audioguru again

Joined Oct 21, 2019
4,129
Why do you think that trashed electronic items are recycled and not buried? To keep the lead in its solder from eventually ending up in our vegetables and drinking water.
 

Ian0

Joined Aug 7, 2020
4,169
And where did that lead come from in the first place? I think someone dug it up.
But seriously, the RoHS regulations which banned lead were based on two studies about leaching from landfill, which came to opposite conclusions. The EU chose to use the one which found it was dangerous. Lead in solder is not particularly reactive and doesn't dissolve, much like mercury in dental amalgam.
 

MrSalts

Joined Apr 2, 2020
852
And where did that lead come from in the first place? I think someone dug it up.
But seriously, the RoHS regulations which banned lead were based on two studies about leaching from landfill, which came to opposite conclusions. The EU chose to use the one which found it was dangerous. Lead in solder is not particularly reactive and doesn't dissolve, much like mercury in dental amalgam.
People like to quote those studies that lead solder is stable in soil but, no soil is just soil and no water is just water. Lead and lead-tin alloys will dissolve in water that contains dissolved carbonates or carbon dioxide, phosphates, or sulphate (sulphates are especially soluble in caustic environments. pH needs to be carefully controlled to prevent lead leaching. Look at the Flint Michigan disaster - public water pipes were made of lead, kids were poisoned because the "stable" lead pipes that "were there for a hundred years" we're proven to be unstable because the pH was not controlled.

As per the alloy making it stable like mercury in dental amalgam, not nearly so stable and still dependent on pH as an alloy (as is the dental amalgam).

Finally, claiming the lead came from the ground in the first place, so we should be able to put it back. Well, lead metal does not exist in the soil. Lead exists as a very stable lead sulfide (galena). Galena has solubility constants that are 10 to 20 orders of magnetude less than carbonates, sulphates and phosphates. So, by all means, throw your lead into a landfill, just convert it to lead sulfide first.
 

Ian0

Joined Aug 7, 2020
4,169
People like to quote those studies that lead solder is stable in soil but, no soil is just soil and no water is just water. Lead and lead-tin alloys will dissolve in water that contains dissolved carbonates or carbon dioxide, phosphates, or sulphate (sulphates are especially soluble in caustic environments. pH needs to be carefully controlled to prevent lead leaching. Look at the Flint Michigan disaster - public water pipes were made of lead, kids were poisoned because the "stable" lead pipes that "were there for a hundred years" we're proven to be unstable because the pH was not controlled.

As per the alloy making it stable like mercury in dental amalgam, not nearly so stable and still dependent on pH as an alloy (as is the dental amalgam).

Finally, claiming the lead came from the ground in the first place, so we should be able to put it back. Well, lead metal does not exist in the soil. Lead exists as a very stable lead sulfide (galena). Galena has solubility constants that are 10 to 20 orders of magnetude less than carbonates, sulphates and phosphates. So, by all means, throw your lead into a landfill, just convert it to lead sulfide first.
I stand corrected. I should have expected someone who calls himself "Mr. Salts" to know all about minerals, especially soluble ones.
 
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