Multiple Same Footprint Name

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Hi, 
I am trying to create a Vishay SC70 3 lead device. In the library I have there are 4 SOT210X110-3 Footprints. They each vary in some of the dimensions. I realize we have been down this path but I have a few questions.

1. Shouldn't they have a different name or at least a -1 -2 -3 -4 at the end to distinguish between footprints?

2. If I Build a library do I get multiple entires for these different footprints?

3. If multiple footprints are created does the footprint name change?

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lalexman Members Profile Send Private Message Find Members Posts Add to Buddy List Expert User Joined: 30 Jul 2012 Status: Offline Points: 679	Post Options Post Reply Quote lalexman Report Post Thanks(1) Quote Reply Topic: Multiple Same Footprint Name Posted: 11 Jan 2013 at 8:52am
	Hi, I am trying to create a Vishay SC70 3 lead device. In the library I have there are 4 SOT210X110-3 Footprints. They each vary in some of the dimensions. I realize we have been down this path but I have a few questions. 1. Shouldn't they have a different name or at least a -1 -2 -3 -4 at the end to distinguish between footprints? 2. If I Build a library do I get multiple entires for these different footprints? 3. If multiple footprints are created does the footprint name change?



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: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(1) Quote Reply Posted: 11 Jan 2013 at 9:06am
	The component Package Height normally discriminates footprint names for the same package. What I do is create a full FPX file with these attributes - 1. Standard Component Family ID 2. Mfr. Component Dimensions 3. IPC-7351 Footprint Name 4. IPC-7351 Physical Description 5. Mfr. Package Case Code 6. Mfr. Name 7. Mfr. Part Number 8. Mfr. Logical Description 9. Mfr. Datasheet Link Then if the footprint name is the same I do add A, B, C for the different tolerances. The biggest difference in the SOT parts is the Terminal Tolerance which produces different pad length and width results. IPC is going to recommend that you add a Terminal Suffix of "TL or TW" suffix at the very end of the footprint name. Examples: There has to be a master footprint before you start adding suffix SOT210X110-3_TL40X75 = Terminal Length is 0.40 mm min X 0.75 mm max SOT210X110-3_TW20X30 = Terminal Width is 0.20 mm min X 0.30 mm max

lalexman Members Profile Send Private Message Find Members Posts Add to Buddy List Expert User Joined: 30 Jul 2012 Status: Offline Points: 679	Post Options Post Reply Quote lalexman Report Post Thanks(0) Quote Reply Posted: 11 Jan 2013 at 9:21am
	Thanks Tom, For me personally I do not like the height in the decal because that causes you to create many decals that are basically the same decal(for example resistors) and using the height to determine the package is correct is not fullproof. Would it be possible in the future to have the capability to automatically add additional information to the footprint name like you did with the terminal size ? This would make it much easier to just look at the footprint name to determine if its the correct footprint ? Also can you please look at item two from my pevious post about building the library. Thanks

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: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 11 Jan 2013 at 9:29am
	If you build a library and many manufacturer's create the same package, I make duplicates in the FPX library because I like to track every part I use by every manufacturer. The Batch Build feature will only create 1 of each footprint name even if you have 1,000 identical footprint names. It's called Profesional Library Management. Plus you get the benefit of searching for specific mfr. case codes or part numbers to quickly locate parts that you already built. Build it once, build it right and never build it again.

lalexman Members Profile Send Private Message Find Members Posts Add to Buddy List Expert User Joined: 30 Jul 2012 Status: Offline Points: 679	Post Options Post Reply Quote lalexman Report Post Thanks(0) Quote Reply Posted: 12 Jan 2013 at 6:54am
	Hi Tom, In the above example I provided I used the FPE library you sent me to look for the SC70 part. There are four footprints with the same name but different parameters . Based on your last statement , when the the library is built there will only be one of the four footprints in the library ?

kwgilpin Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 22 Sep 2012 Status: Offline Points: 58	Post Options Post Reply Quote kwgilpin Report Post Thanks(0) Quote Reply Posted: 18 Jan 2013 at 8:44am
	Hi Tom, I'd like to resurrect this thread. You suggest adding a _TL* or _TW* identifier to the end of otherwise identical package names to differentiate them. When I do that, all is great until I select "Tools -> Regenerate Library -> Names". As a result of that operation, FPE removes any custom suffix that I have assigned to a part's footprint name. Any suggestions for a work-around? Will you consider changing the code so that all part name suffixes beginning with an underscore are left in place when regenerating names? Thanks, Kyle

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: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 18 Jan 2013 at 8:52am
	There are hundreds of footprints that have the same identical name with different tolerances and thermal pad sizes. The FPE FPX file is intended to be used as a library source for users to quickly locate the correct component package data row and copy/paste that row from FPE FPX into your personal library. When doing so, it’s up to you the user to rename the footprint to avoid duplicate footprint names with tolerance and thermal pad differences. There is no guidance from IPC at this time on how to handle variations in Thermal Tab sizes. One of the recommendations PCB Libraries, Inc. has for various thermal pad sizes is to append the end of the footprint name with underscore _ and “T” (for Thermal) and the component Tab Size. Examples: QFN50P600X600X100-41 rename to QFN50P600X600X100-41_T365 = Thermal Tab size is 3.65 mm square QFN50P600X600X100-41_T365X200 = Thermal Tab size is 3.65 mm X 2.00 mm rectangular Using this technique will eliminate duplicate footprint names with various Thermal Tab sizes. There are also variances in the Lead Tolerance that will produce a different footprint pattern pad size and spacing with the same footprint name. There is no guidance from IPC at this time on how to handle variations in Lead Tolerances sizes. One of the recommendations PCB Libraries, Inc. has for various Lead sizes is to append the end of the footprint name with underscore _ and “L” (for Lead) and the component Lead Size. Examples:SOP65P490X110-8 rename to SOP65P490X110-8_L38X68 = Lead size is 0.38 mm minimum and 0.68 mm maximum We have narrowed land pattern name duplication problems down to 2 areas. 1. Thermal Pad Sizes - _T350 = Thermal 3.50 mm Square or _T350X200 = Thermal 3.50 mm X 2.00 mm Rectangle 2. Lead tolerance - _L38X65 = Lead tolerance is 0.38 mm X 0.65 mm If we add a radio button into component families that support Thermal Pads to append the end of a footprint name to add #1 then that would be the differentiator and make every footprint name unique for those parts – QFN, PQFN, SON, PSON, SOP, QFP. If we add a radio button to all Gull Wing lead component families to append the footprint name with the Lead tolerance, that would differentiate all duplicates in the Gull Wing parts for SOP, SOIC, QFP, SOD, SOT, TO, etc. With a Radio Button, users can turn this feature on/off as needed. We are lobbying IPC to add this to the next release of the IPC-7351C standard.

lalexman Members Profile Send Private Message Find Members Posts Add to Buddy List Expert User Joined: 30 Jul 2012 Status: Offline Points: 679	Post Options Post Reply Quote lalexman Report Post Thanks(0) Quote Reply Posted: 18 Jan 2013 at 8:54am
	Hi Kyle and Tom, I like your idea Kyle or perhaps an option to all any of the additional parameters to be added to the footprint name. I understand your point Tom that at one point all the parts will already created but here is my problem. I have a new 4 pin smt oscillator. I look thru my library that the decal name has body size, pad size and pad pin to pin pitch in x and y. I can easily see if I have a decal that matches by looking at the name. I did not so I go to the Footprint expert . The footprint name does not have all the needed info so I have to load each footprint to see if one is the same.(Yes I know I can look at the manufacturer name and package but this OSC did not exist there either). The height in the name does not help since the part is a different height. Having more info in the footprint name will make it easier to find matching footprints IMHO.

kwgilpin Members Profile Send Private Message Find Members Posts Add to Buddy List Advanced User Joined: 22 Sep 2012 Status: Offline Points: 58	Post Options Post Reply Quote kwgilpin Report Post Thanks(0) Quote Reply Posted: 18 Jan 2013 at 9:02am
	Hi Tom, Thank you, as always, for your blazingly fast responses. I really like your proposal, and I'm excited to see it implemented as soon as possible. Along with what you propose, one other option, that I think would make many people (including myself) even happier would be to add a "custom suffix" column to the library templates. Whatever is in that column would be appended with an underscore to the very end of the footprint name. My impression is that there are many users who want a little more flexibility in naming than what the IPC provides. These options would certainly give it to them.

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: 5716	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 18 Jan 2013 at 9:17am
	Are you referring to a new Column in the FPX file? Normally I add a "Notes" column and I add everything special that I did to create the library part. I especially keep a separate FPX file for every part when I use the mfr. recommended footprint feature so that I know that those parts do not use the standard Preference DAT files.