The SMT Plus book has at least 10 different SOT-23 footprints. Measured from outer edges of the pads:
For reflow: Smallest: 2.54mm x 1.65mm Largest: 3.45mm x 3.05mm For wave solder: 3.48mm x 2.82mm John Williams ----- Original Message ----- From: "Ian Wilson" <[EMAIL PROTECTED]> To: "Protel EDA Forum" <[EMAIL PROTECTED]> Sent: Monday, August 12, 2002 5:14 PM 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 #: BF64D1C4ED83AB4DBD426AA3C7D5C38FCD50143A * ************************************************************************ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
