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How can I get Solder Paste from a syringe to stick?

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TimCambridge:
I can apply solder paste to a blank board with a stencil and it sticks just fine.

Working with a syringe is the problem. Videos on YouTube show paste being applied and every blob sticks just fine - that doesn't work for me. I have tried all manner of cleaning the board, and I have tried HASL and ENIG pads.

Maybe there's no solution - my interim fix is to effectively tin the pads but it would be easier to apply a few blobs of paste, drop the component onto the blobs, and get out the hot air gun.

AlanS:
These are the questions I would try to answer re you problem:
   Have you tried other brands of solder paste or just the one?
   Has the solder paste aged paste what the manufacturer recommended?
   What temperature has it been stored at since you bought it?
   What temperature are you using it at?

Regards.

KL27x:
Paste comes in chunky and creamy, like peanut butter.

Stencil can come out good using larger, coarser solder balls, than syringe.

If the stuff comes out of a little jar, it might be too coarse for a syringe. Then when you push on the syringe, the emulsion can separate, some excess liquid getting squeezed out, initially. And then blobs of solder without enough flux, intermittently fall out.

Temperature is critical, too.

The guys who do it like this this swear by specific brands. Blueskull and some others have mentioned GC10. So, basically, you can't try one solder paste and expect it to work worth a darn.

 

TimCambridge:

--- Quote from: AlanS on March 28, 2019, 07:45:30 pm ---These are the questions I would try to answer re you problem:
   Have you tried other brands of solder paste or just the one?
   Has the solder paste aged paste what the manufacturer recommended?
   What temperature has it been stored at since you bought it?
   What temperature are you using it at?

Regards.

--- End quote ---


--- Quote from: KL27x on March 28, 2019, 09:55:08 pm ---The guys who do it like this this swear by specific brands. Blueskull and some others have mentioned GC10. So, basically, you can't try one solder paste and expect it to work worth a darn.

--- End quote ---

Thanks for the comments.

Currently Warton Microprint SAC305. The previous syringe was different, but these things are darned expensive so I can't really try more than a few. GC10 has its fans but it doesn't seem to be available in syringe form. I'll take the advice and try a different brand when this syringe runs out.

It's new paste (manufactured 02/19, use by 02/20), stored at a cool room temperature, the manufacturer recommends room temperature storage. And I use it at room temperature.

TK:
In the past I had to deal with dry solder paste and I mixed with alcohol, I don't know if it is the right method (of safe) but it worked help me applying small amounts to the PCB

I don't recommend it for volume production runs...

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