IPC-7352 vs. PCB Libraries footprint naming option

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   I'm building out a new footprint library and I have the option to choose between IPC-7352 vs. PCB Libraries footprint naming convention option in FPE.
From the bits and pieces I’ve read on this forum, it sounds like PCB Libraries was based on the IPC-7351C standard that was never released.

Does anybody know the history of why IPC chose to abandon the IPC-7351C naming convention and come up with a different one in IPC-7352?

As I dig into IPC-7352 spec, I’m seeing a bunch of stuff that doesn’t really make sense to me, and I’m trying to figure out if there are good reasons for these changes, or if they just rushed out the standard without thinking too hard about it.

For example, in IPC-7352 BGA, CGA, LGA, etc has the pin qty in front (BGA + Pin Qty + …), but other component families like QFN have the pin qty at the end of the footprint name (QFN + … - Pin Qty). These kinds of inconsistencies make no sense to me, but maybe there is a good reason? It does not seem to be explained anywhere in the standard. Does anybody know if the land pattern committee published the rationale for WHY they chose the naming convention in IPC-7352?

In comparison, PCB Libraries consistently puts the Pin Qty at the front of the name, which seems to make a lot more sense, at least to me (e.g. "QFN64").

Essentially, I'm trying to figure out whether adopting the IPC-7352 naming convention is a bad idea. Usually I try to follow the IPC standard, but I'm finding all sorts of small issues, typos, etc in IPC-7352 which is making me question if the standard was rushed out with a bunch of unresolved issues.

One example: 3.4.3.2 recommends using the suffix "L" for lead tolerance (e.g. "L20" for 0.2mm lead tolerance), while the following 3.4.3.3 section recommends using the same suffix "L" for lead geometry (e.g. "L60X24" for 0.60 mm X 0.24 mm lead geometry). FPE simply chooses to ignore lead tolerance and will not include this in the footprint name to avoid any confusion, but this seems like an issue with the IPC-7352 spec.

For anybody who has adopted the IPC-7352 naming convention, what has been your experience? Have you run into any issues with naming conflicts between parts? Is it better just to stick with the PCB Libraries naming convention that seems to have been working well for years now?

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cgnd Members Profile Send Private Message Find Members Posts Add to Buddy List Active User Joined: 24 Mar 2021 Status: Offline Points: 28	Post Options Post Reply Quote cgnd Report Post Thanks(0) Quote Reply Topic: IPC-7352 vs. PCB Libraries footprint naming option Posted: 16 hours 21 minutes ago at 10:53pm
	I'm building out a new footprint library and I have the option to choose between IPC-7352 vs. PCB Libraries footprint naming convention option in FPE. From the bits and pieces I’ve read on this forum, it sounds like PCB Libraries was based on the IPC-7351C standard that was never released. Does anybody know the history of why IPC chose to abandon the IPC-7351C naming convention and come up with a different one in IPC-7352? As I dig into IPC-7352 spec, I’m seeing a bunch of stuff that doesn’t really make sense to me, and I’m trying to figure out if there are good reasons for these changes, or if they just rushed out the standard without thinking too hard about it. For example, in IPC-7352 BGA, CGA, LGA, etc has the pin qty in front (BGA + Pin Qty + …), but other component families like QFN have the pin qty at the end of the footprint name (QFN + … - Pin Qty). These kinds of inconsistencies make no sense to me, but maybe there is a good reason? It does not seem to be explained anywhere in the standard. Does anybody know if the land pattern committee published the rationale for WHY they chose the naming convention in IPC-7352? In comparison, PCB Libraries consistently puts the Pin Qty at the front of the name, which seems to make a lot more sense, at least to me (e.g. "QFN64"). Essentially, I'm trying to figure out whether adopting the IPC-7352 naming convention is a bad idea. Usually I try to follow the IPC standard, but I'm finding all sorts of small issues, typos, etc in IPC-7352 which is making me question if the standard was rushed out with a bunch of unresolved issues. One example: 3.4.3.2 recommends using the suffix "L" for lead tolerance (e.g. "L20" for 0.2mm lead tolerance), while the following 3.4.3.3 section recommends using the same suffix "L" for lead geometry (e.g. "L60X24" for 0.60 mm X 0.24 mm lead geometry). FPE simply chooses to ignore lead tolerance and will not include this in the footprint name to avoid any confusion, but this seems like an issue with the IPC-7352 spec. For anybody who has adopted the IPC-7352 naming convention, what has been your experience? Have you run into any issues with naming conflicts between parts? Is it better just to stick with the PCB Libraries naming convention that seems to have been working well for years now?



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: 5781	Post Options Post Reply Quote Tom H Report Post Thanks(0) Quote Reply Posted: 3 hours 38 minutes ago at 11:36am
	I've been on the IPC 1-13 Land Pattern Committee since 1999. All the IPC-7351, 7351A and 7351B standard series were developed by Dieter Bergman and me with a little help from Gary Ferrari and Karen McConnell. John Perry at IPC also helped to create the master Word document. John has been promoted to IPC Director Karen McConnell retired as chairman Gary Ferrari retired as vice chairman Dieter Bergman passed away on July 23, 2014 The week before Dieter passed (July 14 - 18), we meet IPC headquarters to start the development on IPC-7351C. Rainer Taube in Germany was web conferenced into our sessions. We defined everything that Dieter envisioned for the new standard. It was a complete rewrite to eliminate most of the old technology that had been carried forward since the 1980's and introduce new technology and component families. New updated solder joint goals that more closely aligned with IPC J-STD-001 standard. I took everything we accomplished back to my office to create the new framework for IPC-7351C. Dieter passed away the following Wednesday, but I knew what he wanted to accomplish so I worked on the development for the next 8 months. In 2015 I gave the preliminary draft to Karen McConnell and the 1-13 Land Pattern subcommittee and we started to have 1-hour webcasts every other week to review the development of IPC-7351C. The chairman Karen McConnell did not attend the original meeting at IPC headquarters in 2003 when John Perry and I created the Footprint Naming Convention for the original release. We didn't show Karen or the subcommittee our progress until 2004, after most of the standard was fully developed. Karen was not happy with the naming convention we developed as it had the pin qty. at the end of the footprint name. Karen said if she was involved, the pin quantity would be located at the beginning of the footprint name, following the component family prefix. So, in 2018 we redesigned the footprint naming convention to appease Karen McConnell and the subcommittee voted and approved the new naming convention. PCB Libraries, Inc. added the IPC-7351C naming convention to Library Expert in 2018 after it was approved by the 1-13 Land Pattern Committee. From 2001 - 2004 Dieter and I met several times a year for a week at a time developing the IPC-7351. This is very important as we accomplished milestones every time we met. And in-between the meetings, we worked tirelessly on the standard emailing each other the updates. We could have never accomplished everything we did without these week long meetings. After Dieter passed there were no more meetings, no more development and the progress was slowed to a one hour shouting match webcast meeting twice a month in which most of the volunteers on the subcommittee did not have the imperial knowledge that Dieter had. Then after years of development in 2021 we found out that Dieter never filled out the proper paperwork to the IPC TEAC leadership committee for permission to work on IPC-7351C. Once the TEAC committee found out we were working on IPC-7351C without authorization, they approved and instructed Karen McConnell to add through-hole technology to the standard. So Karen shelved IPC-7351C and opened a new project for the development of IPC-7352. Karen made the decision to revert back to IPC-7351B and just add through-hole. But Karen also added some of the advancements we made for IPC-7351C but not the footprint naming convention that she pushed so hard for us to create. IPC-7352 was released May 2023.
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