Every single country in the world used metric paper sizes A0, A1..., B0,
B1... etc. except two, the USA and North Yemen. Since North Yemen merged
with South Yemen, it, too, adopted metric paper sizes.
However, it gives me great pleasure to say that the IPC bucks the
transatlantic trend of Luddite ultra-conservatism and publishes its
ANSI/IPC Standards in a more-or-less A4 format. Moreover, these follow
ISO Standard 31-0 on values and units. This gives priority to metric
units but, above all, (here comes my hobby-horse) bravo!, the IPC puts a
space between the value and the unit, which avoids all ambiguity. I wish
whole-heartedly that all Anglo-Saxon publishers would do the same. Only
two days ago I fell into the trap of a stupid magazine that printed 35l
and I read it initially as 351 and I had to do a double take because it
made no sense: grrrrrrrrrrrrrrrr!!! :-(
Brian
Kenneth Wood wrote:
> The USA played golf on the Moon 40 years ago using that old arcane and
> archaic system...Metric system countries that have played golf on the Moon?
> Oh yeah...none
> :)
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad
> Sent: Friday, October 16, 2009 4:41 PM
> To: [log in to unmask]
> Subject: Re: [TN] No Soldermask between Fine pitch QFN and QFP
>
> Hello Amol
>
> Since all electronic components are now designed, registered and fabricated
> using the metric system, would not it be easier to ask for a 0.5mm pitch
> device with lands of 0.25mm by 0.7mm?
>
> This is one of the windmills I continue to joust and I am constantly
> curious why we in the US continue to be so wedded to such an arcane and
> archaic
> measurement system as that which we inherited/adopted from our English
> forefathers.
>
> Consider the following from the web:
>
> The metric system originated in France in the 1790's, a few years after
> Jefferson's proposals. (note: Jefferson proposed to metric English system
> for
> the US in the 1780 time frame where there were to 10 inches to the foot,
> 10 feet to a decade, 100 feet to a rood, 1000 feet to the furlong and
> 10,000
> feet to the mile) During the mid-nineteenth century, as expanding trade
> demanded a consistent set of measurements, use of the metric system spread
> through continental Europe. As they imported goods from Europe or exported
> goods to Europe, Americans became increasingly aware of the metric system.
> In
> 1866, Congress legalized its use in an act reading:
> It shall be lawful throughout the United States of America to employ the
> weights and measures of the metric system; and no contract or dealing, or
> pleading in any court, shall be deemed invalid or liable to objection
> because
> the weights or measures expressed or referred to therein are weights or
> measures of the metric system.
> As a result, the U. S. has been "metric" since 1866, but only in the sense
> that Americans have been free since that time to use the metric system as
> much as they like. Although there has always been popular resistance to
> changing the traditional measures, the metric system has actually enjoyed
> strong support from American business leaders and scientists since the late
>
> nineteenth century. In 1875, the U.S. was one of the original signers of
> the
> Treaty of the Meter."
> and I might add that we continue to move towards complete metrication of
> our national measurement systems "inch by inch"... ;-)
> Joe
>
>
> In a message dated 10/16/2009 10:55:25 A.M. Pacific Daylight Time,
> [log in to unmask] writes:
>
> I am looking at a 19.7 mil pitch QFN device with a center pad and
> peripheral pads at 9.8x27.5 mils, and a 176 pin fine pitch QFP with 11.8x63
> mil
> pads with HASL finish and without any soldermask in between the peripheral
> pads!...has anybody seen this type of a board design before? Any stencil
> design suggestions?
>
> I have a couple of pictures I have requested Steve to post for me
> regarding the parts ( I am awaiting Steve's reply)
>
>
> Thanks,
> Amol
>
>
>
>
>
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