Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Squeege Snap off (MEASURED?)



Squeege Snap off | 12 January, 2001

What is squegee snap off and how is it measured?

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Re: Squeege Snap off | 12 January, 2001

Snap off is the distance from the top of the board to the bottom of the stencil.

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Re: Squeege Snap off | 12 January, 2001

SQUEEGEE snap off is the gap between the top of the stencil and the the bottom of the squeegee blades. You can measure it with a set of feeler gauges.

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Squeege Snap off (MEASURED?) | 15 January, 2001

I thought the stencil was flush to the top of the board when Screen printing. When does this snap off occur in the screen printing process?

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Squeege Snap off (MEASURED?) | 15 January, 2001

It is the distance between board and stencil. When your stenciling solder paste you usually want to contact print (which is "0" snapoff). When you are stenciling adhesive you can affect your dot size and quality by using a gap between board and stencil (positive snapoff).

good luck, pr

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Squeege Snap off | 15 January, 2001

Adrian, I'll go again. The term "snap off" on it's own refers to the distance between the bottom of the stencil and the top of the pcb. Sometimes referred to as "print gap". As you prefaced your question with "squeegee snap off" I thought you were asking about that. Most people measure the "stencil snap off" for solder paste by putting a piece of standard copy paper ( 0.004" thick )on top of the pcb and getting the pcb into its print position. You then lower the stencil, or raise the pcb, ( depending on your printer ) until you can no longer move the paper about freely underneath the stencil. Personally I "push" the paper until it no longer moves in rather than "pull" the paper - as you can always pull the paper out. This will generally give you on contact printing or close to it. After removing the paper, I usually decrease this gap by about another 0.004" to allow for the tolerances of the stencil frame/work table etc, though this will depend on your printer. This is the stage when you should set your squeegee snap off/height. You can use the same method for this. If you want to have a print gap for adhesives you can use thicker cardboard or Mylar etc, but the principle is the same. Jargon's tricky, isn't it!

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Squeege Snap off | 28 January, 2001

Hi Adrian,

If you do a "squeegee snap off" during solder paste printing...the result would be a very thick solder paste deposition. I think the correct term is stencil snap off or people say it "snap off distance".


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