Tom H wrote: Tom left IPC on Thursday July 17, 2014 with the frameworkand a to do list from Dieter Bergman. Less than one week later, Dieter Bergmanpassed away on Wednesday July 23, 2014. Using Dieter’s instructions, Tom wentto work on 7351C and spent over 1,000 hours to create the original 109-page7351C draft that was submitted to IPC in June 2015. The sub-committee then metvia 1-hour webcasts. The original comments were to change some images andcontent and Tom went back to the draft for another 6 months to make the updatesproposed by the sub-committee. Tom submitted draft 2 of 7351C in May 2016 toIPC. The sub-committee reconvened for 1-hour webcasts for the next 3 years. Arecent decision by IPC was made to scrap Tom and Dieter’s 7351Cdraft and start over from scratch using the IPC-7351B as the base startingpoint.

Tom,

Have there been any changes since this update on 2019-12-28? If not, is there somebody you would recommend writing to to get things moving on approving your draft?

Unfortunately I'm just a lowely professional PCB designer rather than somebody who has any real pull, but I'm sure I (or anyone) could at least show that there is demand for a new update to 7351. We have already been using thermal pads in the name, different silkscreen outlines, and rounded rectangle pads in our work for a year (as described in http://www.pce-oc.org/archive/What_is_New_in_IPC-7351C_03_11_2015.pdf) and would love for it to finally be official.

So, let me know who I or anyone can talk to, so we can hopefully help get things moving.

Side note - I am 100% in favor of completely removing any reference to mils from the spec. With 95% of SMT parts giving their dimensions in mm, I don't think there are many people who still do their footprints in mil (even though they might route with them, and it's worth removing them to reduce unnecessary clutter in the spec.

Thanks,

Trevor

Whyis IPC-7351C not released yet?

Duringthe creation of the first draft, the main committee met face to face for 3-daysseveral times a year and large sections of the draft were worked on byindividual members and sent to IPC for update. Itwasn’t until the main draft was completedthat the sub-committee was invited to webcasts to review the new standard.

WhenIPC-7351 was first drafted, there was a main committee of dedicated people:

DieterBergman (IPC Leader in StandardsTechnology) –Deceased

Vern Solberg (TechnicalConsultantSpecializinginSMT) –Left the Committee

Gary Ferrari (Ex Vice Chairman)  –Left the Committee

RainerTaube (FED Director ofStandardization) –Left the Committee

John Perry (IPC Liaison) – Left the Committee

KarenMcConnell (Current Chairman) – In the process of retiring

Tom Hausherr (President & CEO of PCBLibraries, Inc.) –Still on the 1-13 Land pattern Committee since 1999

Tom,Rainer and Dieter met at IPC headquarters the week of July 14, 2014 for 3 days.We decided to rewrite 7351C into a new updated format because priorupdates to IPC-7351 were simply added to the end and Dieter wanted a fresh newrewrite that organized all the component families into special groups accordingto pin quantity. We wanted to add color to all the graphic images because allprevious versions were printed in Black & White. Update the namingconvention to include Thermal Pad Sizes and Terminal Lead Sizes which impactedthe resulting land pattern. We wanted to add the Zero Orientation “Pin 1 LowerLeft” to match the original IPC-SM-782 land pattern standard and the new IEC 61188-7standard for Pin 1 location. Introduce Rounded Rectangle pad shape and addadditional component families. All of these issues were discussed andorganized into an outline that clearly described the work that was required forthe 7351C rewrite.

Tom left IPC on Thursday July 17, 2014 with the frameworkand a to do list from Dieter Bergman. Less than one week later, Dieter Bergmanpassed away on Wednesday July 23, 2014. Using Dieter’s instructions, Tom wentto work on 7351C and spent over 1,000 hours to create the original 109-page7351C draft that was submitted to IPC in June 2015. The sub-committee then metvia 1-hour webcasts. The original comments were to change some images andcontent and Tom went back to the draft for another 6 months to make the updatesproposed by the sub-committee. Tom submitted draft 2 of 7351C in May 2016 toIPC. The sub-committee reconvened for 1-hour webcasts for the next 3 years. Arecent decision by IPC was made to scrap Tom and Dieter’s 7351Cdraft and start over from scratch using the IPC-7351B as the base startingpoint.

A revision to anIPC standard must be drafted, reviewed and approved bya base group of the sub-committee who attends the webcast meetings. Then thefinal draft is sent out to the entire sub-committee to vote on the revisiondetails. All changes are highlighted so the sub-committee knows all the datathat was updated. Since the main sub-committee group does not participatein the regular webcasts, when the final draft goes out, it’s the first timethey have seen it. They are given 30 days to vote on the changes. During thevoting process, every member hasthe opportunity toquestion the changes and submit alternate changes. The draft then goes back tothe base sub-committee to address all the questions and additional changes.After the base subcommittee adds the additionalcommentsand recommendations to the standard, a new final draft is created and sent back out for another30-day committee vote. Normally, this final draft gets approved and then thedraft is sent to a typesetter to officially organize the draft into a documentthat is ready to publish. This process can take up to 3 months or longerdepending on the scope of the changes.

Basically,it takes almost a half year to go to publication after the first draft is sentto a sub-committee vote. The IPC-7351C draft is still in committee and sendingit out for vote is not on the calendar schedule yet.