Actually Micron is a word, from the greek micros meaning "small" (Merriam
Webster) - not very precise.
I know Wikipedia is sometimes suspect, but the google search...
Micrometre
From Wikipedia, the free encyclopedia
"Micron" redirects here. For other uses, see Micron (disambiguation).
"Microscale" redirects here. For other uses, see Microscale
(disambiguation).
For the measuring instrument, see Micrometer.
1 micrometre =
SI units
1.000×10−6 m 1.0000 μm
US customary / Imperial units
3.281×10−6 ft 39.37×10−6 in
A micrometre (or micrometer) is by definition 1×10−6 of a metre (SI Standard
prefix "micro" = 10−6). In plain English, it means one-millionth of a metre
(or one-thousandth of a millimetre, 0.001 mm, or about 0.000039 inches). Its
unit symbol in the International System of Units (SI) is μm. The latter may
be rendered as um if Greek fonts are not available or not admissible.
"Micron" comes from Ancient Greek: μικρόν mikrón, which means "small".
The term micron and the symbol μ, representing the micrometre, were
officially accepted between 1879 and 1967, but officially revoked by the ISI
in 1967.[1] In practice, "micron" is a widely used term in preference to
"micrometre" in many English-speaking countries, and in American English the
use of the term helps differentiate the unit from the micrometer, a
measuring device, which would otherwise be spelled as a homonym with
micrometre. The term "micron" has particular currency in science, and is
extensively used in most English-speaking countries in the fields of
geology, biology, physics, astronomy, machining, and the semiconductor
industry.
The micrometre is a common unit of measurement for wavelengths of infrared
radiation.[2]
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Tom
Hausherr
Sent: Tuesday, March 20, 2012 12:33 PM
To: [log in to unmask]
Subject: Re: [DC] Updated "Designer's Day" Presentation
Scott,
Here we go again. Micron is not a word. You're going to hear from Jack Olson
on this. In one of my magazine articles I used the term "Micron" and the
editor and myself got blasted from the Metric Society.
The word "meter" must appear in every metric measurement unit.
The official term is Micrometer (Micron is American slang and not an
official word or term). I know, some CAD Vendors use Micron Units, but they
invented that term, not the International Standards committees.
Micrometer
Millimeter
Centimeter
Decimeter
Meter
Kilometer
Note: In all my presentations, the #1 reason why PCB designers use Mil units
is because there are no decimal points and it's vastly superior when
entering numeric data in a CAD tool.
Fact: Inserting metric component dimensions into a Footprint Calculator
takes twice as long than using Mil units.
Example: 0.025 mm = 1 mil what is faster to type (0.025 or 1)?
So it's the decimal points in the metric system that are slowing designers
down. The PCB design industry needs a Mil equivalent in Metric, but
Micrometers is to granular for PCB layout. The PCB designer never needs to
go past 0.01 mm for any PCB feature size. It would be great to have 0.01 = 1
or 0.05 mm = 5 or 1.50 mm = 150 (anything to get away from having to use
decimal points), but what would you call that unit?
Tom
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Scott
Riley
Sent: Tuesday, March 20, 2012 8:42 AM
To: [log in to unmask]
Subject: Re: [DC] Updated "Designer's Day" Presentation
Like most of you, I have to smile when following this thread. I have been in
this business for a long time (I'm 50+), and deal with several OEM's and
suppliers for both PCB's and flex circuits. Everyone I deal with has their
own set of standards and terminology and I stopped trying to straighten it
out many years ago. Too many arguments and it seems to go in circles.
The latest designs we're doing are in "microns", the engineers speak in
"mils" during the design review and the FAB drawing must be in "MM" for
their corporate standards. Once you get used to it, it's not that bad.
Regarding footprint vs. land pattern, same thing applies. We try to adapt to
what the customer wants. We have an extensive "footprint library", unless
you want me to send you a land pattern, then we have one of those as well.
Pad vs. land is interesting. I had always been told that a pad had a PTH in
it while a land does not.
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Tom
Hausherr
Sent: Tuesday, March 20, 2012 11:23 AM
To: [log in to unmask]
Subject: [DC] Updated "Designer's Day" Presentation
All,
Our web-server crashed so you'll have to wait until it comes back on-line.
Nick Ban and our web team are hot on it.
Thanks for the fantastic feedback and excellent dialog. In the IPC world,
Jack Olson & Mike Buetow are correct that the term Footprint is the
component package dimensional data and Land Pattern is what the Footprint
solders to. The term "Land" is what the component lead attaches to. However,
no one uses the term "Land" because all the CAD vendors call it a "Pad".
It's what we deal with every day.
At IPC APEX "Designer's Day" I made an announcement -
"This is my last presentation... that I will ever give using Metric Only
dimensional data in my Power Point files. From now on I will always include
both Metric and Imperial dimensions side by side with Imperial being the
dominant number and (metric) secondary until there is clear evidence that
the industry has successfully transitioned. And I will always use the term
Footprint when referring to PCB library parts because that is the term most
widely used. And I will refer to Chip components using the EIA Imperial
names of 1206, 0805, 0603, 0402 until the component manufacturer's refer to
them using the IPC metric names 3216, 2012, 1608, 1005."
Some of you reported typos in the Power Point Presentation. I updated the
website last night -
http://www.pcblibraries.com/Forum/ipc-apex-expo-2012_topic6.html
The updates also affected the "Proportional Through-hole Padstacks" chart -
Proportional_Through-hole_Padstacks.pdf
<http://www.pcblibraries.com/Forum/uploads/1/Proportional_Through-hole_Padst
acks.pdf> (you can still access this file on our server)
People have been asking me off-line to explain the Proportional Through-hole
Padstacks and I will post the explanation of the mathematical formulas here
(once the server is back on-line) -
http://www.PCBLibraries.com/forum/forum_posts.asp?TID=15
<http://www.PCBLibraries.com/forum/forum_posts.asp?TID=15&PID=60#60>
&PID=60#60
One more thing, PCB Libraries, Inc. is 6 weeks away from launching the 5th
generation IPC Calculator and after hearing your feedback we officially
named it "PCB Footprint Calculator". This is brand new "coded from scratch"
over the past 8 months and the Designer's Day Power Point Presentation is
the blueprint for the new tool. Example: The user can insert the component
dimensions in metric and then switch to mils and all the Footprint
dimensions are converted to 1 mil increments, the Footprint & Padstack names
are generated in Mil units. However, if you stay in metric units, the
Footprint (Land Pattern) dimensions and library name will be in Metric
Units. Example: you enter the component dimensions for a 3216 using metric
dimensions and when you switch to Mils the Footprint name automatically
changes to 1206 and all the Footprint dimensions are in 1 mil increments.
The new tool boosts many new features including rotation to create the IPC,
IEC or EIA Zero Component Orientation. Coming May 1, 2012 when the official
PCB Libraries.com website opens. This is a Free download without any
registration required, it will have regular updates that will have an
auto-update notification and it will come with the Texas Instruments
"Standard Parts" product line which includes over 35,000 TI part numbers.
It's our gift to the electronics industry. No strings attached.
Tom
Tom Hausherr
President
PCB Libraries, Inc.
13730 Sorbonne Court
San Diego, CA 92128
858.592.4826 Office
858.859.5371 Cell
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