Gary, I think pad centre to centre (in addition to edge to edge if wanted) would be good.
I agree that a readily accessible pin list that can be easily imported into CAD programs would be a huge help. This list should include name, number and type as a minimum. The names should list all the alternative functions in some suitable form. An example might be: GPIO4/SCL0/TXD0 Some programs already can import pin lists, eg P2004 and AD6, can import pins from a csv file using a script - see http://www.altium.com/forms/kb/kb_item.asp?ID=4441 Copying and pasting from a PDF to make a CSV is mostly easy enough (depending on the PDF table format used) but an industry standard form would be even better. An XML format would make sense - if one doesn't exist it should not be too hard to create a lightweight format - harder and take a decade to produce the all-inclusive future-proof formats so liked by some parts of the IT world. With QFNs, I have seen some that have a small metal flash on the corners (a bit of the lead frame I guess), it would be good if details like these could be documented - not so much for manufacture but during rework and probing it would be safe to know whether a short to these will be a catastrophe. Accuracy though is the most important things for me - we recently had a problem where an LT datasheet had 3x3(mm) QFN mechanical details for a 4x4 part (LT5546 for those possibly using this part - updated datasheet is on the web now I notice). Some QFN datasheets don't dimension the centre exposed pad - full accurate dimension is important. I have seen one part where the centre pad was shown as different sizes in different places on the datasheet - we had to get clarification from the manufacturer (and requested and measured physical samples - always a good idea). I would also like accurate revision info on the datasheets - some manufacturers are excellent at this and some make no effort at all. Ian On 05:31 AM 24/01/2006, [EMAIL PROTECTED] said: >Hi all, > >I happen to work at a component manufacturer, and at the moment I have >the opportunity to influence the next generation of component data >sheets for Micron Technology. I have often sat and fumed at data sheets >that were laid out poorly from the component librarian POV, so I'd like >to get as much input as possible on what would be an 'ideal' data sheet. > >One of the things I'm strongly recommending is a simple tabular pin >list, one line per pin, pin number/signal name, that can be selected off >the data sheet and dropped into a component pin list - no more error >prone hand entering names & numbers. > >I also wish that component footprint drawings would measure from body >center to pad centers, rather than the pad edge-to-pad edge measures >that are the usual. > >Clear enumeration and connection information for any 'exposed pad', like >the center pads on QFN parts. I have seen them called odd names ("down >paddle" on one sheet), and, lacking info in the data sheet, have had to >call several manufacturers to confirm that the pad could be connected to >ground (sometimes it isn't, and assuming so is a *bad idea*). > >Any other suggestions/requests/gripes? > >Gary Crowell, CID+ >Micron Technology ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
