Instead of solder paste, use...?

I ask a strange question. As part of a ramp up to produce small batches, we’re seriously looking at making a custom machine that dispenses paste and stencils it onto each board. There are pros/cons of course but this topic is about how you would test said machine. I do not envisage using real solder paste until the process was fairly well developed and so, in the meantime, what low hazard substance would you use as a solder paste proxy for testing a stencil machine? Toothpaste is not miles off the mark. Probably needs to be:

  • Paste but not runny, even when it warms up slightly - we should be able to test alignment and coverage
  • Water soluble and not irritating/smelly etc
  • Not too abrasive
  • Cheap!
  • only a few components with 0805-0603 scale pads are going to be stencilled and nothing fine pitch

Bonkers and conventional ideas are both welcome. Please don’t question the premise too hard!

Suggestion added only for the hilarious imagery: mayonnaise

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Like this, you mean? :laughing:

I didn’t have to go full “George’s Marvellous Medicine” but this lithium/teflon grease will do to start with. Not water soluble and not mayonnaise but a good candidate to start with, especially as it gives some nice definition.

Steven Hawes who @ChrisGammell interviewed recently, used almond butter for this purpose in one of his videos :grinning:

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Doh, I even listened to that - great idea. Will try the peanut butter first, although ours looks pretty runny.

I was thinking peanut butter, too. Get the “organic” kind that tends to separate and you can remix to the desired ratio.

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Yeah, almond butter would be pretty close, though I think the granule size might be a bit too large for a really good analog.

My first thought was to try toothpaste. Specifically look for the type without the gel stripe. And if memory serves, there was a brand that included baking soda, which ended up having a little more grit in it. However, the baking soda might make the paste basic, causing other grief.

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