Merge Common Footprints Into a Single Footprint

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   hi,I have a proposal.
Take for example a generic component to the event: SOIC127P600X175-8LXX. There are, suffixed LXX = L28, L43, L46, L60, L85, L87, with 6 different footprint
minor variations.

It would be possible to enable users to obtain a single footprint that
accept solder footprint for all selected, then the one with the broadest padstacks ??

Or, would it be possible if I am building a L70, the program tell me that is compatible with one or more of the existing ones ??

This would ensure a better chance of mounting number of alternative parts to assemble on the same footprint. !!

Thank You

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lorymg Members Profile Send Private Message Find Members Posts Add to Buddy List Active User Joined: 03 Oct 2013 Status: Offline Points: 13	Post Options Post Reply Quote lorymg Report Post Thanks(0) Quote Reply Topic: Merge Common Footprints Into a Single Footprint Posted: 16 Mar 2015 at 8:06am
	hi, I have a proposal. Take for example a generic component to the event: SOIC127P600X175-8LXX. There are, suffixed LXX = L28, L43, L46, L60, L85, L87, with 6 different footprint minor variations. It would be possible to enable users to obtain a single footprint that accept solder footprint for all selected, then the one with the broadest padstacks ?? Or, would it be possible if I am building a L70, the program tell me that is compatible with one or more of the existing ones ?? This would ensure a better chance of mounting number of alternative parts to assemble on the same footprint. !! Thank You



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 16 Mar 2015 at 8:34am
	You can do anything, but unfortunately when you try to combine Lead tolerances that range from L28 - L87 you are compromising solder joint goals. Why do you want to have one part in your library that handles multiple packages? Why not have a footprint for each different package? With Library Expert Pro it's way too easy to have thousands of line items in your FPX file all mapped to the Logical Part Number and Physical and Logical description. You can download any mfr. Part Number you need from Parts on Demand (POD) for $1 or $2 each. You can provide a Bill of Material and POD with provide all the FPX line items for your design in within 24 hours. Our goal is to provide a solution so that no one ever has to build another footprint library part and fully automate the entire electronics industry.
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lorymg Members Profile Send Private Message Find Members Posts Add to Buddy List Active User Joined: 03 Oct 2013 Status: Offline Points: 13	Post Options Post Reply Quote lorymg Report Post Thanks(0) Quote Reply Posted: 16 Mar 2015 at 8:45am
	In fact I it is often required to have the possibility of alternative parts of different manufacturers that can be used for a specific component. The program could easily do a check, and within certain tolerances set by the user, take a detour by the IPC but having this important flexibility. Thank You

jameshead Members Profile Send Private Message Find Members Posts Add to Buddy List Expert User Joined: 20 Mar 2012 Location: Oxfordshire, UK Status: Offline Points: 576	Post Options Post Reply Quote jameshead Report Post Thanks(0) Quote Reply Posted: 16 Mar 2015 at 9:00am
	This sort of task comes up here quite a bit so I can see where you're coming from. I am often asked to comment on a "concern note" that's been raised for an obsolete component fitted on a PCB asking it an alternative device will fit, and (less often) the electronic designers will ask me if the component they are fitting plus some alternatives they've considered are compatible with each other's land pattern. If it's a fairly standard component using a SOIC127P600X(whatever) or SOT95P280X(whatever) I usually don't even bother to use PCB Libraries and just tell them that although it may not 100% match the solder joint goal it's not going to be an problem. We're not going to be changing a PCB layout - with the added headache of re-certification - just because an Anolog Devices SOIC127P600 is a smigin different than a TI SOIC127P600. I doubt many people would. There are a few occasions where a bit more study is needed and I create both in PCB Libaries, export to the CAD system, and use that to overlay both components over each other before giving an answer. I guess having something where you could select two differnet footprints in a PCB Libraries fpx file, and view them overlayed over each other would be a nice time-saver but it's not something I'd be clammering for on a priority list. You could have something where different footprints had a different colour but that same colour for all layers (copper/Courtyard) and the colours "mixed" where they match (GC Prevue gerber viewer does this very well). You're should only be interested in copper land pattern and courtyard.

lorymg Members Profile Send Private Message Find Members Posts Add to Buddy List Active User Joined: 03 Oct 2013 Status: Offline Points: 13	Post Options Post Reply Quote lorymg Report Post Thanks(0) Quote Reply Posted: 16 Mar 2015 at 9:44am
	I simply say that I do not need much to have a library where there are about 25 different footprints for a component CAPC3225 where discriminating should only be the height but in fact there are several padstacks footprint with different .. The program could tell me for sure what could be the single footprint for all. The risk is that if I use the smaller one (see AVX) the padstacks are small for others ...... but not vice versa. In my experience, many components (eg passive and integrated standard) manufacturers often are different and it is imperative to give the maximum flexibility for mounting, both for reasons of availability and cost. Anyway, it is a better solder joint or minimum abundant ??

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 16 Mar 2015 at 10:15am
	In the near future, there is a proposal to develop new solder joint goal rules using the pin pitch and terminal height for pad calculations. You think the IPC-7351C 3-Tier system is complex? Wait for the new J-STD-001 / IPC-610 land pattern standard for SMD proportional pad stacks. I can't mention much of this new standard, but it will be in the Library Expert Pro as an alternative calculator in our V2016 release. I personally believe the new SMD proportional standard will eventually replace the 3-Teir system with one golden pattern for all density levels and fabrication classes. It's different strokes for different folks. Examples: I worked at Applied Medical Resources (AMR) and they used an AMR part number for every mfr. part number. They had 3,000 ARM part numbers for just resistors and capacitors. The AMR part number was the footprint name and went into the schematic symbol that way. Honeywell has 100,000 mfr. part numbers in their library and they assign a Honeywell part number to every mfr. part number just like AMR however, they use the IPC-7351 land pattern naming convention for most of their footprint names. Flextronics has over 2 million mfr. part numbers in their library, each with a unique footprint. I'm trying to give you the BIG picture where mfr. part numbers each have a unique set of package dimensions and tolerances and the footprint is unique for each package. It seems like a lot of work, but PCB Libraries, Inc. will soon be providing a global solution that will dramatically simplify this task of organizing and maintaining large libraries. It was mentioned that "What if my component goes obsolete and I need to find a replacement that fits the footprint". Well, I hope there's not to many PCB's in stock because the obsolete part needs to be designed out of the project and replaced with new Gerber's for new boards. In the meantime I hope you find a suitable replacement. If you used "Silicon Expert" to source your parts, they would alert you to upcoming obsolescence a year in advance and recommend alternate sources. If your company requires 2 or 3 sources for a single footprint, find 3 packages that have very similar package dimensions and tolerances and disqualify all manufacturer's that produce unique packages. Component manufacturer's are doing their best to create unique packages to corner the market into single sourcing their package. Get used to it, this is a trend that is growing at a rapid pace. For those who want to take short cuts and use 1 pattern for every 1206 chip capacitor, resistor and inductor in the industry, I wish you the best of luck with that option. It might work most of the time. But if you do 3D STEP modeling, you're going to need several options due to height.
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