Electronics Forum | Mon Dec 16 13:05:20 EST 2002 | k_h
Are you using "on-contact" printing? (is the stencil touching the PCB during squeegee travel)
Electronics Forum | Mon Dec 16 13:24:25 EST 2002 | Stephen
What paste are you using?
Electronics Forum | Thu Dec 19 13:20:55 EST 2002 | russ
Your area ratio for this aperture is fine (.78) usually any value greater than .66 will provide a reliable paste release. I would make sure however that the stencil is polished. I agree with other posts regarding your setup and/or paste type is prob
Electronics Forum | Thu Dec 19 13:10:49 EST 2002 | gramsey
Really? Where does it say that? I have had the opposite experience and 3.2.2 from the IPC-7525 states for square or rectangular apertures - "Having a radiused corner for all apertures can promote stencil cleaning". It actually recommends circular ape
Electronics Forum | Tue Feb 22 12:03:32 EST 2005 | russ
You may to reduce a little bit more with HASL. for .4mm pitch and such I would maybe go to a 5 mil with your standards.
Electronics Forum | Mon Dec 16 13:33:09 EST 2002 | pjc
square apertures provide better paste release than round in most applications. See IPC 7525 Stencil Design Guidelines
Electronics Forum | Mon Dec 16 21:35:46 EST 2002 | grantp
Hi, We tried AIM no clean, and one other paste which I cannot remember the name offhand. We have been using Koki lately, and that's been the best. It seems to leave less residue behind in the stencil. Regards, Grant Petty Blackmagic Design
Electronics Forum | Tue Dec 17 09:10:57 EST 2002 | Stephen
Are your stencils electropolished? I still haven't used an electroformed stencil, but I understand they can be worth the extra money, because of the better release characteristics.
Electronics Forum | Thu Dec 19 09:04:01 EST 2002 | bdoyle
You can also get that IPC standard in the SMTnet Bookstore (along with a couple hundred others) http://www.smtnet.com/bookstore/index.cfm?fuseaction=view_item&item_id=848
Electronics Forum | Thu Dec 19 13:17:20 EST 2002 | gramsey
Huh?! The area of a square that fits in a circle is clearly less than the circle. Paste release is better in a circle than a square because the circle has maximum area per perimiter lenght.
