Electronics Forum | Wed Apr 11 00:17:03 EDT 2001 | Dreamsniper
Hi, We got a 0.5mm pitch QFP144 from Altera with the below lead width specs. min. lead width = 0.17mm nominal = 0.22mm maximum = 0.27 What's the best pad or land width for the above? This is what our designer used. Land Width = Component Lead Wi
Electronics Forum | Wed Jul 09 10:15:57 EDT 2008 | aj
I have carried out some further measurements on the device and the results are as follow: Component Lead width measures 183 microns. Actuals PAD width measures 158 microns. What I am thinking is that the lead is attracting the solder hence prevent
Electronics Forum | Wed Apr 11 06:06:53 EDT 2001 | wbu
Hi Dreamsniper, the IPC land design standard is IMO a good reference. If you use the online calculator you can influence the result by varying for example manufactoring parameters. For the same lead width and same tolerances (and of course pitch) we
Electronics Forum | Wed Mar 29 22:30:13 EST 2000 | cklau
Hi guys; There are a few points that should be taken in to considerations regarding IPC-SM-782 land pattern and design rules. As a general rule all SMT reflow pattern should be in comply with SM-782 but however for special cases like : * PLCC land
Electronics Forum | Wed Mar 30 16:07:24 EST 2005 | Dreamsniper
If there's no shear strength standard for solder joint, how will I define my pad width and length then. I have a 8.5 mils width and my component lead width is 8.66 mils based on manufacturer's minimum width specification. How will I identify that it
Electronics Forum | Tue Nov 09 12:00:41 EST 2004 | Dreamsniper
Problem: PQFP208 Pad Width specified as 11.8 thou, PCB came and they are 9.5 thou. Component Lead Width is 10 thou to 10.6 thou. Operators have difficulty aligning and inspecting. Issue: Fed back to PCB Fab House and they said IPC accepts +/- 20% fo
Electronics Forum | Tue Oct 30 19:42:44 EST 2001 | davef
Jim Blankenhorn [www.smtplus.com] has the best understanding of designing pads for real life. That�s because he designs them like he wants to design them and doesn�t negotiate with a committee of thousands for an IPC standard. Consider doing this
Electronics Forum | Wed Oct 31 11:01:02 EST 2001 | dougie
Hi Dave, Thanks for the suggestions. To clarify a couple of the points... - What do you qualify as "small" & "large" parts? - Do not make the pad narrower than the lead width. The nominal or the maximum? If I use the maximum width I'll be back to s
Electronics Forum | Wed Jan 28 10:25:20 EST 1998 | Chris Fontaine
I have not been able to find a standard which governs component lead sweep. We use an internal standard of 4 mils here at Sanders, and your 6 mil sweep would definitely be unacceptable. I believe the reason there is no standard governing sweep is b
Electronics Forum | Tue Oct 30 08:48:01 EST 2001 | dougie
Hi, Our PCB designers are beginning to send up designs to manufacturing that have increasingly difficult footprints to work with. The footprints have been generated by the IPC-SM-782 calculator but just look wrong to me. The pitch of the devices in
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