Make PCB Tinning Solution ("Liquid Tin") by Redox Flipping
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- Опубликовано: 20 окт 2017
- In this video we make a tinning solution for printed circuit boards.
Tinning solutions coat copper metal with a thin layer of tin. This is used to protect them from oxidation as well as make them somewhat easier to solder.
To make the solution we first get 1g of lead-free tin solder containing 95% or more of tin metal. Check the MSDS to be sure. Now to the solder we add 10mL of 30% hydrochloric acid. What we're making is tin chloride. The solution will bubble hydrogen as the tin dissolves. Leave it overnight and pour off the clear supernatant into 100mL of commercial metal polish that contains thiourea. I used "Tarn-X" brand for my experiments. You can also buy thiourea directly and use 5g per 100mL of water directly along with 1g of sulfuric acid. Anyway, however you obtain your thiourea solution, the added tin chloride will make it into a tinning solution.
Now just add in copper metal like that of a PCB and a thin layer of tin will coat it.
What's happening is that normally Tin chloride does not displace copper metal so you can't make tinning solution from just tin chloride. One perspective is that Tin has a lower redox potential than copper so it would actually consume energy to displace copper.
But thiourea forms very strong complexes with copper. This drives down the redox potential of copper to below that of tin. Now tin can displace copper.
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You don't need Tarn-X specifically, any thiourea based cleaner will work. Usually check under the categories of "Metal polish" "metal cleaner" or "Tarnish remover" when checking the hardware store. If you can buy thiourea directly then use 5g per 100mL of water and follow the rest of the video for making the tin chloride.
Excellent... sometimes NurdRage is one of the best ELECTRONICS channels on RUclips.
Hey Nurdrage you told us in a previous video where you replaced the heating elements of your hot plates to remind you in 1 year on doing a follow up regarding the quality of the new heating elements and if the hot plates are still fine. Now it has been almost 1 year and here i am! Sorry if you already made a video regarding this, i might have missed it
This is very good to know that the ingredients for this solution are available. I don't normally tin my PCBs because I don't need that extra protection against oxidization but maybe one day I'll need this.
This will SAVE A US A LOT OF MONEY!!! Thanks NR, for this great explanation! Companies have been harvesting ridiculous amounts of money on their proprietary tinning-solutions for too long now! Thank you so much!
Absolutely fantastic, I am a long time user of your peroxide/muriatic acid etchant recipe and this video has been on my wish list for years. Thanks so much.
I've had everything I need all along, but have been buying fairly expensive liquid tin for some time. Awesome, I can't wait to try it out. Thanks
So many people will find this handy! Thanks!
You know...I haven't actually taken chemistry. Watching you and a couple of other channels, I can follow along but sometimes I get REALLY lost! Now I have a few new terms to look up and expand my knowledge base. Just wanted to say thank you for being such an awesome springboard :)
Thank you Nurdrage! I love your videos and I do not have a strong background in chemistry so I really appreciate the explanations. (I still have to look things up, but you give me a place to start!)
This is great, cause I just started making PCBs yesterday. Thanks!
Great stuff! I could have used this back when I worked in the electronics industry. I may yet use it for one of my infrequent projects.
Thanks so much. Iv been wondering about this stuff for years.
Heeey, this is actually really useful knowledge for me. I knew subbing to this chemistry channel would pay off for an electrical engineer.
Thanks for this! I just made a batch and it works as good as the Liquid Tin that I've used in the past. I got a gallon jug of 31% muriatic acid at the hardware store for about $8 and a bottle of TarnX for $6. I didn't have a way to heat the final solution, but after straining it through a coffee filter, the solution was pretty clear. I think I'll purchase thiourea crystals and use the 5g/ 100ml distilled H2O to replace the metal polish. Looks like I'll be investing in a hot plate/ stirrer as well.
That was awesome to see. Just some back grounds from a PCB-Designer:
This was very interesting, thanks!
This made my day, my nomad grandpa (& best friend-RIP🌹) taught me how to build circuit boards, read (reed) circuitry components (eg. transistors are color coded) & how to solder when I was a young child😌. We use to make everything from fm listening devices that would fit inside pens to metal detectors, etc...what a gift he gave me.
A long time ago I regularly used commercial tinning solution - the made-up solution didn't last very long - maybe a week or two
Excellent. That was good to know.