Electronics Forum | Tue Sep 21 13:12:56 EDT 1999 | Dave F
| My stencil thickness is 6 mil and we got qfp's with fine pitch. | how many percent should i reduce my stencil aperture using a 6 mil stencil for 0.5 mm pitch and 0.4 mm pitch ? | | thanks | Greg: I was going to link you to the IPC land pattern c
Electronics Forum | Fri Sep 21 10:56:38 EDT 2001 | davef
Not as such. Look at IPC-7525 �Stencil Design Guidelines� The issues are: area and aspect ratios. They relate the size of the aperture opening to the thickness of the stencil. Check the fine SMTnet Archives for guidelines.
Electronics Forum | Thu May 09 00:08:01 EDT 2002 | techment
Could someone provide help regarding IPC's recommendation on Plated Through hole's --- lead to hole ratio. I can't find it in IPC-2221 and IPC-SM-782. Thank you very much
Electronics Forum | Sat Sep 28 05:30:44 EDT 2002 | ivanchu
Stencil cleaning process is taking by machine every 15 boards. We are using wet, vaccune, Dry, Dry cleaning process. The aperture of the stencil is fullfil the aspect ratio.
Electronics Forum | Tue Dec 17 20:25:13 EST 2002 | iman
Check : 1) design aspect ratio / are ratio required to fabricate the stencil you r using. 2) check if the stencil maker is using your checked aspect ratio / area ratio? if not the same, what are they using? any QA report confirming actual dimension
Electronics Forum | Wed Feb 26 14:37:57 EST 2003 | russ
Never used U shapes for 0603 but have used them for MELF pkg. Never had a problem printing as long as area ratio is acceptable. So just out of curiosity, why U shape for 0603? Russ
Electronics Forum | Tue Apr 01 18:21:48 EST 2003 | slthomas
I've never printed adhesive but I assume that aspect ratio still plays a part with release. Maybe that .006" is just to thick to get good release. Can you step your stencil down from .006" to .004" or .005" for the 0402's?
Electronics Forum | Tue Jun 17 08:27:13 EDT 2003 | davef
Consider searching the fine SMTnet Archives for discussion, for instance: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=7065
Electronics Forum | Tue Jun 24 10:38:47 EDT 2003 | ehess
Bruce, I have a spread sheet, in Excel, that helps in determining stencil thickness, based on smallest aperture size. If you are interested, I can email you this.
Electronics Forum | Thu Aug 07 01:23:43 EDT 2003 | craigj
Does anyone out there have any info on track balance ratios. i.e. heavy track entering 1 end of component (0402) and thinner track leaving other end and how this effects/causes problems like tombstoning. Am trying to put together design rules for cus
