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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


SMT Stencil Aperatures

#34726

SMT Stencil Aperatures | 3 June, 2005

Hello, I was wondering about specs on SMT stencil ordering. I am looking to make some sort of template for aperature layout of some parts. I was wondering some issues that you have all came across or made to change to better suit your boards. For instance: 200ml or larger dpaks with window paned etched pad, 25ml with a 6mil stencil, etc, etc. I just would like to see what some standards are that you all go by. Or is it basically a hit and miss type thing when ordering a stencil for a new design? Any input would be helpful. Thanks

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#34729

SMT Stencil Aperatures | 3 June, 2005

Who is your stencil vendor? I'd ask them if they have any standard guidelines. That's what I did. I took their standard design guidelines, made them mine and have been making additions and changes since.

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#34734

SMT Stencil Aperatures | 3 June, 2005

Search the fine SMTnet Archives for "aspect ratio" and for "area ratio".

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#34739

SMT Stencil Aperatures | 4 June, 2005

IPC-7525 is a document that provides guidlines for the design and fabrication of stencils for solder paste and surface-mount adhesive. This is the first time this important information has been collected and published in an industry consensus document. Stencil design for surface-mount technology, as well as mixed technology with through-hole or flip chip components is discussed; this includes overprint, two-print and step stencil designs. A sample order form and a user inspection checklist are also included. 14 pages. Released May 2000. I think a new one is coming out this year or next.

Find it at the SMTnet book store:

http://www.smtnet.com/bookstore/index.cfm?fuseaction=view_item&item_id=848

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#34762

SMT Stencil Aperatures | 6 June, 2005

Thanks for all the information all.

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#34774

SMT Stencil Aperatures | 6 June, 2005

Don't forget follow up is very important with stencils. Check with SMT after the first run with each new stencil and see how it went. If you follow industry accepted standards you probably won't have any problems but you never know when you will run into something that doesn't fit right.

In theory there is no difference between theory and practise, in practise there is.

Stephen Olan

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#34779

SMT Stencil Aperatures | 6 June, 2005

I worked with our stencil vendor for a about a year tweaking our aperture guidlines for our printer. Of course we upgraded to a better printer and all of that went out the door. Work with your vendor and they should be able to make suggestion as to where to start.

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