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patchwork stencil

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patchwork stencil | 21 June, 2011

>> Has anybody have eperience with stepped ( down and up )laser cutted stencils? >> What is manufacturing method of "patchwork" stepped stencils ?? Thanks Jacek Tomaszewski SEMICON Sp.zo.o -Poland

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patchwork stencil | 22 June, 2011

I have purchased step up and down stencils for specific situations. What do you mean by "Patchwork"? Is this a rework process?

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patchwork stencil | 22 June, 2011

tTo explain what I mean...sorry for my bad Engilsh... please find short " patchwork stencil" description from EPP Europe. /art_co_INSTANCE_0000/maximized/

" A patchwork stencil family

The PatchWork version was originally designed in order to solve the issue with quite different solder paste volumes on PCB pads for very different components. "While other suppliers offer stencils with different thicknesses, we introduced a novel approach due to our patented stencil design". As Kleemann further explains, "We cut large apertures from the stencil metal sheet in the form of the components, produce a small piece of the appropriate thickness and weld this small item on the normal basis stencil." With this technology, every special component can therefore be provided with the solder amount needed. In principle, all pad volumes to be put on the stencil surface but differing from the base material thickness capability, say 150 µm, can be lowered (reduced thickness added) or amplified (with an inserted stencil piece of more thickness). This looks like a patchwork then, whereby the resulting stencil sheet thickness is guaranteed within ± 3 µm. Since the weald seam smoothly adjusts the level of the patches, the squeegee can closely accommodate to the outline.

...anybody have idea about welding so thin SS304 foils ? Up to now I've heard about electroformed nickel and chemically etched stepped stencils only...

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patchwork stencil | 23 June, 2011

That is a very interesting concept. It sounds very time sensitive and would require some specialized equipment to achieve consistant results. Unfortunately I don't have any experience welding anything that thin. If you ever figure it out I would be interested in seeing some photos of the results.

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patchwork stencil | 23 June, 2011

Leave it to the Eurolanders to come-up with a goofy, confusing name for something simple.

Stepped stencils are chemical etched or laser cut.

IPC-7525 provides guidelines on designing stepped stencils. Look here

Further, we've discussed stepped stencils here on SMT previously. Search the fine SMTnet Archives. Here's an example

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