stupid question:  What's the difference between mil and mm?

No stupid questions. But sometimes you might get an ignorant anwawer

"mil" is short for 1/1000 inch, or 0.001 inches. It is an English unit.

"mm" is mili-meter, or 0.001 meters. It is a metric unit. By convention,

most PCB measurements are done is "mils" and typical spacing is 100 mils,

or 0.1 inches. This is equal to 2.54 mm, 5.08 mm, or 10.16 mm spacing. This

is equivalent to 0.1, 0.2, and 0.4 inch spacing or 100, 200, and 400 mil

spacing

IC's typicall use a 100 mil spacing, or 0.1 inch, 2.54 mm.

David

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On Fri, 14 May 2010, David Ingebretsen wrote to us saying :

"mil" is short for 1/1000 inch, or 0.001 inches. It is an English unit.

Actually it's a unit that the English generally call "thou" (for

thousandths of an inch), but since Eagle is not an English program the

more European "milli-inch" is used. I don't know what American

convention is.

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AL wrote on Fri, 14 May 2010 22:12

I see a mix of mil and mm (millimeter) units?  Isn't mil also

millimeter?

No!  A mil is 1/1000 inch.

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dingebre wrote on Fri, 14 May 2010 22:59

No stupid questions.

That's rediculous.  Of course there are stupid questions.  A stupid

question is one where the OP should have known better or been easily able

to find the answer in a obvious place.

This one is a good example.  I went to Google and entered "mil measure" and

the very first hit was http://www.thefreedictionary.com/mil, which is a

dictionary entry for "mil".  The first definition is "A unit of length

equal to one thousandth (10^-3) of an inch (0.0254 millimeter)".  Duh.

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AL[1

wrote on Fri, 14 May 2010 22:12]Hi,

 

I see a mix of mil and mm (millimeter) units?  Isn't mil also

millimeter?

This is not a stupid question.  I highly recommend never using the term

"mil"--it is too ambiguous.  It may have an "official" definition but in

practise it is used for all sorts of things.  I've personally heard it

refer to

1/1000 of an inch

millimeter

milliamp

millivolt

In my company using the word "mil" is a no-no.  If you mean mm, then say

"millimeter".  If you 1/1000 of an inch then we use the term "thou".  If a

customer ever uses the term then I ask for a clarification.

Cheers,

James.

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email:  james@eaglecentral.ca

web: http://www.eaglecentral.ca

Specializing in CadSoft EAGLE

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• Electronic Design Services

• EAGLE Enterprise Toolkit

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Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

James Morrison schrieb:

I highly recommend never using the term "mil"--it is too ambiguous.

...

If you 1/1000 of an inch then we use the term "thou".

Sorry, but in my eyes "thou" is exactly as ambiguous as "mil". :-\

It could mean a thousandth of about /everything/.

Maybe it's from my european background, but additionally I have never

heard "thou" before, except for Olin's post and yours - but "mil" is

pretty common and (for me) unambiguous for tens of years... I never

would have imagined someone could misinterpret it - one more evidence of

small differences in language that can be dangerous...

Tilmann

Olin wrote on Sat, 15 May 2010 06:31

dingebre wrote on Fri, 14 May 2010 22:59

No stupid questions.

 

That's rediculous.  Of course there are stupid questions.  A stupid

question is one where the OP should have known better or been easily able

to find the answer in a obvious place.

 

This one is a good example.  I went to Google and entered "mil measure"

and the very first hit was http://www.thefreedictionary.com/mil, which is

a dictionary entry for "mil".  The first definition is "A unit of length

equal to one thousandth (10^-3) of an inch (0.0254 millimeter)".  Duh.

I see your point about using other resources. However, I will always defend

the cliche that, "the only stupid question is one that is not asked."

However, there are always abundant stupid and ignorant answers to any

question...

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AL skrev:

Hi,

 

I see a mix of mil and mm (millimeter) units?  Isn't mil also millimeter?

Page 26 in the Tutorial.

Mogens Dreier

Obviously the term "mil" is created from sloppy English engineers that found

it hard to write/say "a milli inch"

On 5/14/2010 7:12 PM, AL wrote:

Hi,

 

I see a mix of mil and mm (millimeter) units? Isn't mil also millimeter?

Thank you, David I. and Robert P. for answering...I always always deal

with mm or 0.1 in., the actual "in." that "mil" got me confused.