Hi Tom,
I am quickly becoming a metric gal! I have a tendency to design the library part in the units which it is dimensioned in on the data sheet. If it is done in both, you can almost always tell which is the "dominant" dimension by which one is the "most rounded number". That is almost always metric these days... especially if it's BGAs, QFNs, and QFPs.
I always encourage people to at least try to designing in metric when I give my presentations because I believe that is the direction we are all going... sooner or later. I often suggest they switch over using the .05mm grid equivalents that you and the IPC suggest, for example....
0.050 mm = 0.0019” = 2 mil
0.100 mm = 0.0039” = 4 mil
0.125 mm = 0.0049” = 5 mil
0.150 mm = 0.0059” = 6 mil
We deal with a variety of fabricators and have never had any issues at all in either measurement. One thing I DON'T do is have the database in one set of units and the fab drawing in another set. Now THAT is confusing and I have to fight that battle at work all the time with the mechanical people.
BTW... Have a blast in Sydney! It's a WONDERFUL place too visit and the conference is a good one! Last year I was there and all my slides were in english units even though I was saying to design in metric. One of the attendees raised his hand and asked why I didn't change that. (I said because of lack of time.) Well, they use metric... and I have since changed all my slides to show both sets of dimentions!
That's my $.02 worth!... a confirmed fence straddler... at least in presentations!
Best Regards,
Susy Webb
---- Tom Hausherr <[log in to unmask]> wrote:
> Gilbert,
>
> That is great news! Now I have to give my presentation to the Orange County,
> CA IPC Designer's Council in an upcoming meeting to see if you are an
> isolated case or if the trend is finally turning. I'll get together with
> Scott McCurdy to set up a date in the near future to come up and visit your
> DC chapter to present and gather information.
>
> For everyone in the San Diego, CA area, I will be giving my presentaiton for
> the IPC San Diego Designer's Council Chapter meeting at the Del Mar
> Electronics Show on May 2, 2012 in the afternoon. Hope to see you there.
>
> And for those in the Dallas, TX and Phoenix, AZ area IPC Designer's Council,
> I'm coming your way this fall to discuss this topic. See you then!
>
> I can't forget the PCB designers in Australia. I'll be in Sydney speaking at
> the ElectroneX (SMCBA) convention, September 12 - 13 giving the same
> presentation and gathering information.
>
> And all of you PCB designers in the Silicon Valley / Bay area, I'll see you
> at PCB West on September 25th to present and gather information.
>
> Tom
>
>
> -----Original Message-----
> From: Gilbert Mayandia [mailto:[log in to unmask]]
> Sent: Monday, March 19, 2012 10:14 AM
> To: '(Designers Council Forum)'; 'Tom Hausherr'
> Subject: RE: [DC] IPC APEX Designer's Day
>
> Thank you Tom,
>
> We are now using millimeter from footprint design all the way to the Fab
> Dwg. Thanks to you.
>
>
> Gilbert Mayandia
> PCB Designer
> STEC
> Santa Ana, CA U.S.A.
>
>
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Tom
> Hausherr
> Sent: Monday, March 19, 2012 9:52 AM
> To: [log in to unmask]
> Subject: [DC] IPC APEX Designer's Day
>
> Hi Everyone,
>
>
>
> I posted my IPC APEX "Designers Day" Power Point presentation on "PCB Design
> Optimization Starts in the CAD Library" here -
> http://www.pcblibraries.com/Forum/ipc-apex-expo-2012_topic6.html
>
>
>
> This presentation contains recommendations for adding PCB library drafting
> elements such as Silkscreen and Assembly Outlines, Polarity marking,
> Reference Designator sizes, Local Fiducials, round-off resolution update and
> the implementation of Mil Units for the upcoming IPC-7351C standard.
>
>
>
> One note on the Mil Unit subject. As PCB Designers, we have been taught DFM
> (Design For Manufacturing) rules during our entire career. For the past 10
> years I have been all over the world promoting PCB Designers to transition
> to the metric measurement system and revealing why the metric system is
> superior for PCB design layout. However, our PCB fabrication shops prefer
> Mil unit Gerber or ODB++ data, drill data, fabrication drawings and layer
> stack-ups, panel sizes, material thicknesses, etc. The global electronics
> industry including component manufacturer's, CAD vendors, fabrication,
> assembly, mechanical and PCB design is split down the middle on this
> subject. I believe it will remain this way until the PCB fabrication process
> completely transitions to metric.
>
>
>
> I've been on the open market contracting PCB layout for DOD companies and
> they're ALL doing mil unit PCB design. Most PCB design service bureaus are
> doing mil (inch) based PCB layout because that's what their customers are
> asking for. I've submitted employment resumes to firms all over the USA to
> seek employment and the vast majority of them are doing mil unit PCB layout.
> At this year's IPC APEX conference there was a large crowd at the Designer's
> Day event and when I asked the question "How many of you are doing metric
> PCB layout?" only a couple people raised their hand. When I asked "How many
> of you are doing PCB layout in mil units?" the vast majority of the
> attendees raised their hands. When I asked people why they still do PCB
> layout in mil units the majority say "because our fabrication shops prefer
> mil units and we are big on Design For Manufacturing (DFM)".
>
>
>
> Most people in our industry refer to chip capacitors and resistors after
> their inch based names 1206, 0805, 0603, 0402 and not the IPC metric names
> 3216, 2012, 1608, 1005. All CAD vendors create their default software
> installation in mil or inch units (not metric). Popular PCB fabrication
> shops default to mil unit presentations in their private seminars to their
> customers or at IPC symposiums. Are we being brainwashed or are we in a
> state of chaos?
>
>
>
> I applaud IPC, JEDEC, NIST and the component manufacturing industry for
> fully transitioning to the metric unit system, but I fear that things are
> more messed up than ever before in our industry. Being split into two
> measurement systems is not exactly optimizing the electronics industry. So I
> propose that IPC go back and add mil dimensions in all of their standards to
> eliminate the confusion in dealing with dual measurement systems. IPC needs
> to recognize that a vast majority of the PCB industry is not transitioning
> to the metric unit system and that we need standards that are applicable to
> our profession today. Download my Power Point presentation from "Designer's
> Day" and you'll get a good taste of the metric / mil state of the PCB
> library industry.
>
>
>
> That's my opinion, what's yours?
>
>
>
> Best Regards,
>
> Tom
>
>
>
> Tom Hausherr
>
> President
>
> PCB Libraries, Inc.
>
> 13730 Sorbonne Court
>
> San Diego, CA 92128
>
> 858.592.4826 Office
>
> 858.859.5371 Cell
>
> [log in to unmask]
>
>
>
>
>
>
>
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