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IPC7351-C Draft or Release date?

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MSM_KOPF View Drop Down
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    Posted: 20 Jan 2016 at 5:22am
Are there any new informations when IPC7351-C will be puplished or can be expected to be an available standard?
We can not use IPC7351-B as it is not an offical standard.

Any hint appreciated as we are planing our tool chain roadmap as well as the libraries when we might jump on the IPC7351-C for new projects.
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Tom H View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan 2016 at 11:57am
The IPC-7351C executive and sub-committee is meeting every 2 weeks until IPC APEX on March 15. Last meeting we reviewed and discussed Silkscreen Legend Polarity Markings - Download Here

The next meeting is Tuesday and we'll start reviewing the new SMD Proportional Pad Stacks which will replace the existing 3-Tier Density system. However, Library Expert will continue to support IPC-7351B through 2016 until everyone migrates to the new, much more accurate mathematical model to land pattern automation.

At IPC APEX on March 15 we will meet in Las Vegas to vote on the final draft and then it will go into the final Ballot for 30-day review by everyone on the committee. If everyone agrees then it will go directly to print. If there are disagreements, they will have to be resolved and a new 30-day voting Ballot will go out. This process will continue until everyone agrees and then it will go into print (PDF only due to all the color images).

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Post Options Post Options   Thanks (1) Thanks(1)   Quote ngist Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jul 2016 at 7:08am
I came across this thread but it doesn't appear 7351C is available for purchase yet.

Has something stalled the release process, or is it still cycling through 30 day reviews?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jul 2016 at 7:18am
Yes, IPC-7351C is stalled due to the solder joint goal tables and a solution for micro-miniature components.

You can download V2016.08 Library Expert Pro pre-release and test it out. It has our recommendations for incremental pitch solder joint goals - www.pcblibraries.com/downloads

IPC-7351C has not been submitted for 30-day committee vote yet, but it's expected to happen this year.

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Post Options Post Options   Thanks (1) Thanks(1)   Quote ddevries Quote  Post ReplyReply Direct Link To This Post Posted: 31 Oct 2016 at 9:48pm
Has there been any new updates on this since July? When will this be released by IPC?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2016 at 2:36am
I'm on the 1-13 Land pattern Committee and we do have meetings every 2 weeks.

IPC has made a decision on focusing on Through-hole technology and breaking it out of the IPC-7351B and creating an Addendum for IPC-7351B. So all progress has stopped on the Surface Mount since the beginning of September.

If you downloaded every piece of documentation on our website, you would have much of the IPC-7351C standard as far as component families, solder goal tables and naming convention. It's not going to change very much. www.pcblibraries.com/downloads

IPC will not release the official IPC-7351C until next fall. Now that Dieter Bergman is gone and Gary Ferrari is near retirement, there's a lot of bureaucracy and progress is slower than an ant walking through peanut butter.

However, we introduced IPC-7351C technology a year ago and many companies are using it and having great results.

If you really want to know the status of IPC-7351C, contact IPC.

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Post Options Post Options   Thanks (1) Thanks(1)   Quote ddevries Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2016 at 6:46am
Thanks for the update Tom. Too bad things are moving so slowly at IPC. I'll probably just purchase your latest tools and use those hoping that -C will eventually get released without many changes.

At work we have been discussing the "courtyard excess" and the "manufacturing excess" areas and trying to decide how best to make use of these when placing 0402" and smaller chip components on boards that will be produced on our in-house lines. We have new / modern P&P equipment with good placement accuracy. However, we have precious little real world data with which to determine manufacturing excess areas. From what I can understand reading the standard, IPC 7351 gives no guidance on the manufacturing excess and leaves that totally up to the designer. Am I understanding that correctly?

So we are faced with a decision. Do we simply make a guess as to an appropriate manufacturing excess - perhaps based on our limited experience with our equipment, tidbits that we can glean from the Internet, and prior experience getting PCBAs built at outside CMs? Maybe should we start with zero manufacturing excess and place the chip parts line-to-line based on the courtyard excesses, see what happens and build from there.

Do you have any recommendation / suggestion in this regard?

Thanks again all your work on PCB Libraries and with IPC working on 7351-C.
-Doug
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2016 at 7:47am
Due to manufacturing machine accuracy and advanced technology the Courtyard Excess for IPC-7351C is now -
  • Least = 0.10
  • Nominal = 0.20
  • Most = 0.40
IPC-7351B is -
  • Least = 0.10
  • Nominal = 0.25
  • Most = 0.50
We will release V2017.01 today or tomorrow and it will be fully loaded with IPC-7351C. I do not believe there will be any changes as it already went through committee approval.

The Manufacturing Zone is the additional space between Courtyards that your assembly shop needs. You cannot determine the Manufacturing Zone without the Assembly manager's assistance.

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Post Options Post Options   Thanks (1) Thanks(1)   Quote ddevries Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2016 at 9:08am
Hi Tom,

Thanks for that info.  That matches my understanding after reading through the B revision and the info on the C revision from your site.

The good news is that I can - within reason - do what is necessary to determine the appropriate manufacturing zone(s) for our equipment.  The bad news is that I don't know how best to do it.  Of course I know the stated placement positional capability for our P&P equipment but that is something like 30 microns, which is nearly an order of magnitude better than the 0.2mm between-component-spacing which would result from using the IPC 0.1 mm least courtyard dimensions and zero manufacturing zones.

I was thinking of setting the manufacturing zones all to zero, which will result in components being spaced based on their courtyard dimensions only - e.g. 0.2 mm for small chip parts.  We build mainly small hand-held PCBs that we design so we already use the IPC-7351B "Least" footprints and courtyards.  Presently each layout person uses their "best judgment" to further space components apart from one another for manufacturing - typically resulting in between 0.3 mm and 0.5 mm between small chip parts.  We haven't had any problems that I'm aware of at 0.3 mm spacing, but I'm having a tough time convincing others that we might go even closer.   I'd like to enforce using the manufacturing zones so that we can be more uniform when deciding on components placement, but I'm not sure where to start to determine the manufacturing zones. 

Based on your experience do you foresee problems placing small chip parts with 0.2 mm separation using the IPC-7351C Least footprints?  Is that just crazy?

What would you do if you were in my shoes to determine the manufacturing zones for our equipment?  Are there test boards available that help in determining the minimum manufacturing zones?

Thanks again for your help and advice.
Doug
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Tom H Quote  Post ReplyReply Direct Link To This Post Posted: 01 Nov 2016 at 9:14am
Placing 01005, 0201 or 0402 with a 0.20 pad to pad space is absolutely possible using today's updated assembly equipment. It's done every day.

Normally, in my PCB layouts, I have the body to body space gap for the DRC checker set to 0.05.

Today's assembly equipment has a tolerance of +/- 0.01, which is very accurate.

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