That 8x8 placement courtyard is in 0.5mm units, thus resulting in a 4x4mm area for the entire component courtyard The SOT23 device has maximum dimensions of 3x 2.6mm. Doesn't look too bad when you consider toe fillet and silkscreen requirements.
Dave Sanders -----Original Message----- From: Ian Wilson [mailto:[EMAIL PROTECTED]] Sent: Tuesday, August 13, 2002 9:44 AM To: Protel EDA Forum Subject: Re: [PEDA] Philips Wave and Reflow Footprints(Ex:IPC Footprint Standards) As an example: The SOT23 reflow footprint takes up 3.3x3 mm while the wave takes up 4.5x4.6mm. The IPC standard has a 8x8!! placement courtyard. Like, yeah right. Someone tell me this is a typo - at that size I may as well us a TO-92. Taking the distance of the outer edge of a pad on one side of the SOT-23 to the outer edge of the other pad (the IPC Z dimension): Philips Reflow: 2.7mm My footprint: 2.95 mm IPC: 3.6mm Philips Wave: 4mm In high density layouts what are you going to use? (Actually, I am a bit timid going as low as the Philips reflow footprint as it feels mighty small when you see it -it is not easy to hand solder. But the point about reflow footprints being able to be made very small is clear. My footprint has been in use for many years, on many boards, assembled by many manufacturers without any issues.) Also, if you have a look at the Philips wave footprint http://www.semiconductors.philips.com/acrobat/packages/footprint/FOOTPRINT-S OT23.pdf You can see that the single pad is very wide. This is different from the old data I have from the early to mid 90's so they have updated it. Also, I think they have changed the preferred wave direction - I think it used to be in the other direction. I am not sure I like the new wave footprint but maybe it heats the device more evenly or something. Ian ************************************************************************ * Tracking #: 8A5D2408FFCFC34097996673C214DBDF18CF4C6B * ************************************************************************ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
