From: "Leo Potjewijd" <[EMAIL PROTECTED]> To: "Protel EDA Forum" <[EMAIL PROTECTED]> Sent: Saturday, February 07, 2004 4:47 AM Subject: Re: [PEDA] Semiconducto rmfg Footprint creation
> Calculating SMT footprints can be quite laborious as the datasheet-supplied > measurements often need serious work: calculating that > needed-but-not-supplied dimension, (re-)calculating tolerances and offsets etc. > The online SMT footprint calculator from IPC asks for numbers that are > often not in the datasheets but are required to complete the calculation of > the footprint.... > Calculating the footprint yourself also requires knowledge of the PCB > stuffing and soldering techniques that will be used later on.... And even > then, some footprints cannot be calculated (but that might be my > misunderstanding of the mathematics involved ;). This is why I created my QFP & TSOP footprint generator, It does all that math for you automatically. get it here: http://www.proteluser.com/download/Pcb_99SE_add-on/BriansStuff/ The "brians_public.txt" describes the contents of the "brians_public.zip" file. Take a look at the library footprint generator & it's documentation. No more mathematics to understand or do, all you need are the footprint's general drawing dimensions. _____________ Brian Guralnick ----- Original Message ----- From: "Leo Potjewijd" <[EMAIL PROTECTED]> To: "Protel EDA Forum" <[EMAIL PROTECTED]> Sent: Saturday, February 07, 2004 4:47 AM Subject: Re: [PEDA] Semiconducto rmfg Footprint creation > Well, I've got 2 (euro)cents to spare: > > I'd settle for footprint definitions in DXF, preferably also showing the > paste mask and component outline. > > That would already make a huge difference in work when defining a library > component, with virtually no extra effort on the manufacturer side. I mean, > they probably designed the mechanics of the component too, so they must > have that information in some sort of CAD system (and what CAD system > doesn't export DXF? virtually none..) > > After spending considerable time de- and refining a DIN41612C96 footprint > by manually entering the data from the manufacturers' datasheet (and ending > up with a less-than-perfect footprint) I stumbled upon their DXF drawings. > I imported them in a scratch PCB file, stripped all unnecessary > information, added the pads on the positions indicated and then copy-pasted > the whole thing to the PCB library (P99SE you know). The whole process took > no longer than the manual definition even though it was the first time I > tried this procedure; the result not only looks great but is stunningly > accurate... > > Calculating SMT footprints can be quite laborious as the datasheet-supplied > measurements often need serious work: calculating that > needed-but-not-supplied dimension, (re-)calculating tolerances and offsets etc. > The online SMT footprint calculator from IPC asks for numbers that are > often not in the datasheets but are required to complete the calculation of > the footprint.... > Calculating the footprint yourself also requires knowledge of the PCB > stuffing and soldering techniques that will be used later on.... And even > then, some footprints cannot be calculated (but that might be my > misunderstanding of the mathematics involved ;). > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
