Instead of solder paste, use...?

Equipment
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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!

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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.

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Steven Hawes who @ChrisGammell interviewed recently, used almond butter for this purpose in one of his videos :grinning: https://www.youtube.com/watch?v=BFOmYFK7eTA

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

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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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