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Subject:
From:
Joe Fjelstad <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Sat, 17 Oct 2009 15:36:22 -0400
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Trust me when I say that the technology would have worked just as well in  
the metric system ;-) and the calculations and conversions would have  been 
much easier. (It was, in fact, a Soviet rocket designed using the  metric 
system that put the first man made device on the moon.)  

Who knows NASA might have even got there sooner if everything was  designed 
in metric and Shepard might have been able to complete an 18 crater  round 
instead of just hitting a couple of golf balls.  ;-)  

Joe
 
 
 
 
In a message dated 10/17/2009 6:24:21 A.M. Pacific Daylight Time,  
[log in to unmask] writes:

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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