# Solder mask removal Vessel issue



## ahmadbayoumi (Aug 9, 2017)

Dears,

I was working with 11kilos of cell phone boards.

After depopulating all the boards using hot sand bath which was very effective in terms of time, I decided to run the whole batch into 1st HCL hot bath to remove the remaining solder/tin then hot 20% NaOH bath to remove the solder mask.

ALL went well but before completing the whole patch, I found some pinholes in the used vessel so i stopped.

The used vessel was as in the below pic.




Now the question is:

What kind of vessels that could be used without have these pinholes ?

I know that glass may do great job but here I need to use a very large vessel for mass production.

So PLS advsie


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## jason_recliner (Aug 9, 2017)

Your pail is not at all suitable for both acid and alkaline.
Even glass will slowly be etched by NaOH, which even maybe not a problem, but it presents a serious safety risk with that volume of hot NaOH if it breaks.

Polypropylene will be better, and be sure it will withstand the heat of the NaOH solution.


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## rickbb (Aug 9, 2017)

Think about what you did. 

You put HCL in a tin bucket to dissolve tin solder. 

Use a plastic bucket, (for the HCL), not one made of the very metal you are trying to dissolve.

Use a stainless steel rated for NaOH.

edit to clarify.


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## ahmadbayoumi (Aug 9, 2017)

How would i heat a plastic or Polypropylene vessel?

I think both can't withstand with heat .. aren't they ?!


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## Palladium (Aug 9, 2017)

ahmadbayoumi said:


> How would i heat a plastic or Polypropylene vessel?
> 
> I think both can't withstand with heat .. aren't they ?!



Use a 5 gallon bucket inside a turkey fryer like this.


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## 4metals (Aug 9, 2017)

Please note there is water in the stainless pot between the plastic pail and the stainless pot. That is why this works.


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## ahmadbayoumi (Aug 10, 2017)

Great Idea 

But I have 2 things need to understand her:

1- does this setup provide the needed heat/boil for both HCL and NaOH bathes. and what about the Plastic bucket .. it wouldn't get affected by this heat and boiled water inside the stainless pot ?

2- For cost reasons, can I use the same setup but with tin pot instead of stainless one as it's much less ?

Thanks a lot for helping


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## anachronism (Aug 10, 2017)

ahmadbayoumi said:


> 2- For cost reasons, can I use the same setup but with tin pot instead of stainless one as it's much less ?



The point was already very well made earlier by Rickbb. Why would you use a tin pot to dissolve tin from solder? What's the end result of that likely to be?


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## ahmadbayoumi (Aug 10, 2017)

What I mean here is to use a plastic pail inside a tin pot but I wont use the tin pot directly.


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## anachronism (Aug 10, 2017)

Ahh! Yes you did say that, apologies! 

If you're not splashing acids or alkalis then it should be alright but bear in mind that if you do you'll be degrading your bucket.


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## g_axelsson (Aug 10, 2017)

rickbb said:


> Think about what you did.
> 
> You put HCL in a tin bucket to dissolve tin solder.
> 
> ...


To point out the obvious...

Tin pots are not made from tin. The name comes from tinned iron/steel plate used in cans for preserving food.
https://en.wikipedia.org/wiki/Tin_can

Still, HCl dissolves iron so it will dissolve that metal bucket.

Göran


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## ahmadbayoumi (Aug 11, 2017)

ahmadbayoumi said:


> Great Idea
> 
> But I have 2 things need to understand her:
> 
> ...




Dears,

Any help regarding my query PLS ..


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## 4metals (Aug 11, 2017)

> What I mean here is to use a plastic pail inside a tin pot but I won't use the tin pot directly.



Any pot that can take the heat applied can serve as the outside container and the plastic pail goes inside with the water being between the 2 pails to transfer the heat. 

The problem with the thin metal pail you showed is it appears to be zinc (galvanized) coated which won't take the direct heat well, and the bottom of those pots are quite thin, so it won't last. 
The pot Palladium showed in his post has a heavy bottom which can take and transfer heat well.


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## Palladium (Aug 11, 2017)

It's a Polar Ware Stainless Brew Kettle!


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## ahmadbayoumi (Aug 14, 2017)

Many thanks for all of you dears 

Will try this setup and share the results with you.

Mean while, I'll try not use heat at all and leave the whole patch overnight how things will go on without heat


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## ahmadbayoumi (Aug 16, 2017)

Dears,

Seems it went well even without heating  

I tried the same 20% NaOH in a plastic bucket and left the whole patch for almost 24 hours.

Then, I found that almost 90% of the boards have expelled their green solder mask.

So the conclusion now would be:
if you have more free time then you might not use heat but if you are in rush then, heat should be your choice.


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