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Recommended solder paste for reflow

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DerStrom8

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Hi all,

I am preparing to do my first batch of SMD boards by reflow (in the past I have always hand-soldered my SMD boards, which was a real pain) and was wondering if anyone can recommend a type of solder paste and a supplier? Trying to keep things as cheap as possible at the moment, while still being effective. The individual boards are small (only about 0.6" x 1.4") and use 0805 capacitors/resistors. It also has a QFN and a SOT-89 package.

Thinking of going the toaster oven route at this point (probably following the temperature profile manually for now, and eventually will automate the process). Any comments, suggestions, and recommendations would be greatly appreciated.

Regards,
Matt
 
Did you try a search for 'solder paste'?
I would have to research the difference.

In other words, "I don't know".
 
Matt:

Sn42Bi58 is a low temperature paste that I have used, but not necessarily with re-flow.

This Bi57Sn42Ag1 looks a lot better property wise but I have not been able to find it (patented).

http://en.wikipedia.org/wiki/Solder

I HATE Sn96. 63/37, the lead based one was the easiest to use.

For fun and giggles, I've had my eye on this re-flow controller.
http://www.zallus.com/msp430-reflow-oven-kit/

A reminder is that there are adhesives that can be used when re-flowing both sides of the board.
I have something that I am currently breadboarding that will require soldering both sides with large components.
 
SAC 305 (no clean flux) lead free paste was recommended to me by our process engineer for the toaster oven. Amazon has it here https://www.amazon.com/MG-Chemicals-4900P-25G-Solder-Silver/dp/B00M1RC0IU

This is the routine our process engineer recommended:
Set the toaster oven to between 475-500F (246-260C) and when I you see the paste melt and turn shiny open the oven door and turn it off. About 15-30 seconds later remove the board and place it in front of a desk fan to cool.
 
Last edited:
Just curious: Is there any particular reason for going with lead-free solder paste. By all accounts, lead solder still works better than anything else, and it's still available. Unless you're building a product for sale in the EU, why not stick with lead?
https://www.digikey.com/product-search/en?x=0&y=0&lang=en&site=us&keywords=4860P-35G-ND

Many people are shying away from lead solder because it is not RoHS compliant and soon manufacturing/distributing it will be banned by the USA (just looking into the future here). I have always preferred lead-tin solder, but now that I am doing some professional work on PCBs I am required to use lead-free. Lead solder may work better, but that doesn't mean it is better.

Thanks everyone for the input!
Matt
 
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