Dear EU, stop messing with my PCB grids!

I was grown on metric units, but at some point I just learned how to work with imerial units, not only related to pcb, but also motors (torque in pft etc). Technically its not difficult to learn basics of imperial system. Idont personally care about this matter, what is weird is that EU is trying to impose senseless regulations, industry will be using units which it prefers. It like this silly thing with CO2 emissions, nobody in the world cares about that except Europe. Some things shouldnt be regulated from our tax money.

Hehe. Imperial units... I hope they die out as soon as possible! I grew up with SI units, and loved it for its easiness to use it in physical calculations. They fit in there without any conversion..

I could never get used to 1/2 and 1/4" units etc. But in Electronics the 1/10" was the measure of pins distance... so I also learned that this is 2.54mm. So what? no Problem.

All normal CAD programs were able to eat this unit as grid unit.

Guess what. For me  1Pa is the unit of pressure measurement. Once i ended up with a half flat tire in the US. Went to the gas station to fill the tire. And then shock!

What the Hell in the World is PSI??? I started calculating in head with the assumption PSI stands for "pounds per square inch", but I could not come to an end and had no calculator nor paper to write on, and was really "tired" of this stupid unit. I asked the gas station guy, who told me, 33 PSI should be OK. :D 

If I had one wish, I would wish that everyone on planet earth used the SI system!

I use both a metric grid and drill/pad sizes and the IPC-7x51 standard landpatterns, and have for some time now.

Metric is by far the better system to use particulary as all the mechanical engineers that I liase with use metric, and with the modern CAD systems and transfer of DXF/IDF/STEP data between both ECAD and MCAD is appropriete to standardise on the metric system.

I disagree with your assumption that PCB manufacturers are sticking to imperial measurements.  Many of the both the high-end and medium manufacturers that I use state their manufacturing capabilities in metric though some have helpfully provided imperial equivilents within brackets, meaning that these are not the controlling dimension.

At School in 80's and at University in the early 90's I was brought up with metric and used it exclusively.  My first job after leaving University was as a CAM Engineer for a PCB fabricator where most UK-based customers at that time provided imperial data for gerber layers but a mechanical drawing and drill sizes in metric.  UK companies whose parent company was Japanese, or continental Europe though used metric for everything.  Our CAM software had no issues with either kinds of data, and our CNC machines used metric sized drill bits.

My second job 1997-2004 was a PCB designer for a Japanese company in the UK and we used metric throughout the design process. When I joined my current company I found my predessor had used a mixture of both systems in designs which caused some discrepencies in board profiles as measured in the PCB CAD data and as specified on the Mechanical CAD data and drawings, so I quickly changed everything over to metric.

Doing a straw poll of the other engineers here all are happy to use metric and only one, the oldest, has ever used the imperial system for a PCB design!

Where you have to liase with others such as a mechanical engineers it's important you standardise, and most probably that's going to have to be with metric; and with the older engineers retiring and all the newer ones having been taught, and brought up with metric it's only going to be a matter of time before the imperial system is forgotton in the sands of time.

Metric for component/library and Imperial for the layout. Its easier working with whole numbers like 10thou than getting tuned to using 0.254mm.

Metric for component/library and Imperial for the layout. Its easier working with whole numbers like 10thou than getting tuned to using 0.254mm.

"So, how are you coping with the switch to metric?  Do you stick doggedly to imperial, use a mixture of the two or are you a Euro-friendly metric system devotee?"

Metric. Definitely.

"So, how are you coping with the switch to metric?  Do you stick doggedly to imperial, use a mixture of the two or are you a Euro-friendly metric system devotee?"

Metric. Definitely.

This switching grids used to be a big problem. But as stated in the original article, now all the tools that I use - I can switch grids with a key combination on the fly. It's really a non issue now - I make many SMT footprints in mm (since that's the way the new ones are specified), then layout in mils (since that's the way I'm calibrated). Then at the end - set the gird the way the customer wants it.

Metric units have been the preffered standard in the UK for years and years and whilst I too enjoy a pint, I can accept that 568ml of the same beer tastes just the same. The pint actually highlights the problem nicely - if you ask for a pint in the US you'll get less beer than the UK.

If you prefer to work in mil then carry on, no-one from the EU is going to stop you (despite what the Daily Mail tells you). But if you would like to avoid errors working with other enigeers, and during PCB production, population, testing and implementation, I suggest a common format makes sense.

I'm old enough to be used to mil too (I too still talk of 100thou pitch connectors and the like) but when it's common practice to get your PCBs made in one country, the components sourced from another, and the boards populated in yet another, I can see the sense in a common set of measurements.

Speaking as an Englishman, if it's us in the EU driving this standardisation, then good for us.

I normally use metric for surface mount and mixed technology boards, but still use imperial for through hole if that's the dominant component pin pitch.

I prefer to use mm for drawings.

I would note however that fractional inches makes more sense to me than decimal which always seems to need three digits of precision.

Best wishes,
Susan.

P.S. I still measure my waist in inches :)

To change makes a lot of sense but "bad word" the human being is a habitual animal and

habits are hard to change so i suppose it is just hang in there

The most recent PCB I designed was a nightmare. Mostly-imperial components (but a few metric) constrained to line up with external metric locations. And some .157" connectors to further destroy any chance of a PCB-wide consistent grid. I look forward to the day when everything is metric, with all components on sensible metric spacings. But I don't think that EU legislation would be useful. The transition is happening, at the commercially-rational speed. Our industry is good at responding to customer needs, in a sane way. And customer need is mostly to be as cost-effective as possible! Any b-euro-cratic intervention is almost certain to add cost without benefit.

Personally I think it's time to move on.

I hate having to jump between mil for tracks and mm for dimensions.

Lets bite the bullet and sort it out once and for all. Bring on mm for me!

I always recall this classic blunder by Nasa over use of the wrong units back in 1999

"A team of Lockheed Martin engineers sent NASA key maneuvering data for the $125 million Mars Climate Orbiter in non-standard units, probably since the craft was launched in 1998, according to a NASA official trying to explain the loss of the craft.

Miscalculations due to the use of English units instead of metric units apparently sent the craft slowly off course -- 60 miles in all -- leading it on a suicide course through the Martian atmosphere.

But the space agency was quick to deflect blame from Lockheed Martin, which had been controlling the day-to-day operations of the craft, saying that NASA should have had safeguards to catch the error."   See URL for full report

Full Report, Click here