Top Paste Layer = solder paste already on board?

Archive BatchPCB
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Sorry, this is probably a newbie question, but I couldn’t find anything definitive. I’m working on a board to be sent to BatchPCB. Eagle has a layer called Top Paste, which implies that it’s a solder paste layer. This further implies that a stencil and manually-applied solder paste might not be requried, and that I could simply place my parts and put the board on a hot plate to secure them.

In your experience, do BatchPCB boards already include paste on the various pads, or will I need to look at a stencil? I don’t want to waste time with a stencil unless absolutely necessary.

Thanks!

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The board will have a very thin layer of solder covering the pads, but this is really too thin to solder the parts. You still need extra solder - either use a stencil (I recommend [Ryan O’Hara), a syringe with solder paste or manually solder with a soldering iron.](http://www.ohararp.com/Stencils.html)

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Thanks for the quick reply! Also, that link looks like a great source for stencils, I’ll have to investigate them when I get to that point. I’ve seen a few examples using syringes to apply the soldering paste, which seems tedious but obviously cheaper. I’ve got some research to do…

Thanks again!

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No problem. Applying solder paste with a syringe or toothpick is OK, and if I was soldering less that 100 components or so I’d just do that. Very fine-pitch parts with pads that are partly or totally obscured (eg QFN & BGA) can be problematic without a stencil, as they aren’t as forgiving about the amount of paste (and it’s hard to fix up with solder wick).

I recommend you have a look at Sparkfun’s SMD tutorials, particularly the SMD stenciling and “reflow skillet”.

http://www.sparkfun.com/tutorials/category/2

If you’re really on a budget Dealextreme has the cheapest solder paste:

http://www.dealextreme.com/p/lodestar-s … e-50g-4711

They also have special plastic needles for applying the paste, although I can’t see them at the moment. I think Sparkfun has them too. Normal hypodermic needles are too small; I found the “needles” that come with inkjet refiller kits are about right, used with a small (eg 1cc) syringe.