ok . open any electronics component catalog. ( digikey , mouser , avnet
, farnell ,newark arrow )and look at parts
you fill find things like 50 mils 25 mils 100 mils for lead pitch and
widths. and then look at the equivalent in millimeters. Which numbers
would you rather key in to create a new footprint ? Sure there are
metric parts but we don't use them ( yet ) . Ribbon cable is still a 100
mil pitch , Smd components ares still 50 mil pitch ( some tqfp and bga's
are in millimeters true ) and i'd rather key in 25 mils when creating a
part then a crazy value like 0.62954 millimeter.
i think we will only be successful in switching to millimeter when there
are no more parts made using imperial pitches. and that is not going to
happen for a long time.
And believe me i know what a pain converting is , I am from belgium and
have grown up with the metric system , after 2 years in the usa using
inches , and feet and pound and gallon that heve no linear relationship
to them is still a nightmare. But for board layout i translates in nice
round numbers.
> In a global economy standardisation is essential, do you really think
> that inches have a future?
> The IPC recognises this, which being American based is very
> surprising, but encouraging.
> Even Britain the bastion of Imperial is slowly but inexorably moving
> towards metrication.
> I was brought up on imperial and pounds and shillings, so I'm fairly
> understanding.
> As far as I'm aware the USA is the only country that doesn't have a
> metrication programme in effect
>
> Chris Mogford.
> ************************************************************************
> * Tracking #: E7E9D6B0EAA28E45B0C48EF8E6F4E50D563153A1
> *
> ************************************************************************
>
--
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/____________/ Vincent Himpe
// _____ ___/ Lab Manager
/ \ \ / / / ST Microelectronics
/___\ \ / / / 5510 Six Forks Road . Suite 200
/______//_/__/ Raleigh NC 27612
Tel : (919) 850 6070
Fax : (919) 850 6689
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