ESD CORNER
ESD Systems.com ESD Technical Newsletter
Issue 2, February 2000: Volume 3
Reference: http://www.esdsystems.com/newsletters/v3issue2.htm
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Sender : ESD Systems.com, 19 Brigham
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Phone
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Fax : 508-480-0257
E-mail : editor@esdsystems.com
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This is a free monthly newsletter, which specializes on issues in static
control in the semiconductor/electronics workplace.
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We will have a new look next issue with color, images in an HTML e-mail format.
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IN THIS ISSUE:
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·
HOT TIP of the MONTH (ANSI/ESD-S20.20)
·
ESDA NE
Chapter's General Meeting (March 8, 2000)
·
ESD Q&A CORNER (Static Electricity)
·
PRODUCT UPDATES (Paddles)
·
Dr. ZAP (Static Electricity)
HOT TIP of the MONTH (CDM)
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Receive
your FREE copy of the new ESD Association’s standard, ANSI/ESD
S20.20 from:
http://esda.org/pdf_files/s2020std.pdf,
also a Spanish version of this
standard is available at:
http://www.esdsystems.com/techinfo/2020SPANISH.htm
ESDA NE
Chapter's General Meeting
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Date: Wednesday,
March 8, 2000
Time: Registration
4:30 PM, Tour 5:00 – 6:30 PM
Location: Desco Industries, 90 Hudson Road,
Canton, MA 02021, Ph: (781)821-8370
Topic: Plant
Tour of Desco Industries Canton Facility
Speakers:
Darryl Allen and Mike Malkasian, Floor Care and Bag Product Managers,
Complimentary Admission and Refreshments, Your Colleagues are Welcome!
Plant tour includes introduction to ESD Control Floor Care
Products and ESD Bags as well as a tour of DII’s Aqueous production and ESD Bag
conversion processes.
For more information on this General Meeting, contact the Northeast
Chapter of the ESD Association, P.O. Box 394, Wilmington, MA 01887. Phone: 508-485-7390; Fax: 508-480-0257; e-mail: noreast@eosesd.org Web Site: http://www.esdsystems.com/ne_esd/
ESD Q&A CORNER
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The following questions and answers were selected from our FAQ WEB Page: http://www.esdsystems.com/default.asp?PageNo=QANDAINDEX
concerning Questions about Standards.
Q1:
"Static electricity is NOT a
build up of electrons".
As I see it protons & electrons are in balanced numbers in an atom. When
charge separation tales place it is usually the electron that is moved from one
surface (atom) to another. Using the example of a person walking across a
carpeted floor - as they collect electrons they leave behind and equal and
opposite charge on the atom that lost the electron but don't the electrons that
are collected build up in the recipient? Otherwise how can varying levels of
static charges be generated? - Bernard McTernan, Woolhope, UK
A1: Refer to: http://www.eskimo.com/~billb/redgreen.html
This article may clear a few things up. It is an imbalance of electrons….just
semantics
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Q2: "Electrons in metals move around and between the
mass of atoms.."
Does this mean that on the surfaces the electrons are whizzing round in orbit
but underneath the surface they are held in check by the protons? Or does it
mean that throughout the metal the electrons are whizzing about but that they
are not connected to any particular atom, so they move from end to end at
random but always maintaining the balance with protons within any one atom? - Bernard
McTernan, Woolhope, UK
A2: In general,
metal atoms have what’s called a fair amount of valence electrons (an electron
that belongs to the outermost shell of an atom) and they tend to be ‘free
electrons’ (an electron that is not constrained to remain in a particular atom,
and is therefore able to move in matter or in a vacuum when acted on by
external electric or magnetic fields) hence making them good conductors. All
molecules (grouping of atoms) want to be in a neutral state (electrically
balanced). Metal molecules usually share their free electrons to obtain a
balanced state.
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Q3:
(In describing antistatic
bags) "A conductive (in the dissipative range) ...."
What does this mean? Is it that dissipative is a conductor of such an area that
any charge will be conducted and spread across the whole width to the point
where it does not pose a threat AND THAT THE CONDUCTOR IS NOT GROUNDED? - Bernard
McTernan, Woolhope, UK
A3: There are two definitions for conductive, In ESD
control, conductive refers to the resistance of a material that is less than
1x10^4 ohms and dissipative being greater than 1x10^4 ohms. Conductive also has
another definition, the ability to conduct free charges. By this definition,
anything that is less than 1x10^11 ohms is considered conductive.
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Q4:
How does a static discharge
damage a device?
Is it because the voltage discharged can burn out a track in the same way as
trying to pass too much current through a fuse will burn it out. The fuse wire
is essentially a resistor capable of carrying a certain amount of current (amps
x volts) and if it's exceeded the wire heats up and very quickly burns out.
Tracks in Integrated Circuits are now as thin as one micron (remember 1 micron
is roughly one hundredth the thickness of a piece of copying paper) and so are
similarly vulnerable to burn out if the current is too high? - Bernard
McTernan, Woolhope, UK
A4: It is not really a static discharge but an ESD event
(an arc or large current pulse between two conductors). It is this large
current that does the ESD damage.
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PRODUCT UPDATES (almost NEW!)
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ESD Training Paddles easily generate high static
voltages
Ideal for Demonstrating Electrostatic Principles
·
ESD Systems.com’s training paddles are an excellent
tool for training employees and demonstrating electrostatic principles.
·
Demonstrations include electric fields, field
suppression, ionization, triboelectric generation, grounding, charge storage,
capacitance, field induction, and electrical properties for both conductive and
insulative materials.
·
This kit includes one acrylic and one aluminum paddle
for optimum charge generation, both with insulative handles.
·
The 6” paddles are to be used in conjunction with a
static field meter, ionization test kit, or charged plate analyzer.
Item #36080 is ideal for training, and we encourage you to
give them a try! For more information
and experiments to perform with the paddles, request Tech Brief PS-2079.
Dr. ZAP
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Topic:
Static Electricity
First
a few good links to reviewing the static electricity phenomena:
What is
static electricity? "Static
electricity" appears when two dissimilar materials are placed into
intimate contact and then separated. This is a charge separation or an
IMBALANCE between quantities of positive and negative particles. During contact
electrification, it is usually only the negative electrons, which are moved. As
negative particles are pulled away from the positive particles, equal and
opposite areas of imbalance are created. In one place, you'll have more protons
than electrons, and this spot will have an overall positive charge. Elsewhere
you'll have more electrons than protons, for an overall negative charge.
"Static electricity" exists whenever there are unequal amounts of
positive and negative charged particles present. It doesn't matter whether the
region of imbalance is still or is flowing; only the imbalance is important.
All solid objects contain vast quantities of positive and negative particles
whether the objects are electrified or not. When these quantities are not
exactly equal and there is a tiny bit more positive than negative (or vice
versa), we say that the object is "electrified" or
"charged," and that "static electricity" exists. When the
quantities are equal, we say the object is "neutral" or
"uncharged." "Charged" and "uncharged" depends on
the sum of opposite quantities. Since "static electricity" is
actually an imbalance in the quantities of positive and negative, it is wrong
to believe that the phenomena has anything to do with lack of motion, with
being "static." In fact, "static electricity" can easily be
made to move along conductive surfaces. When this happens, it continues
to display all it's normal characteristics as it flows, so it does not stop
being "static electricity" while it moves along very non-statically!
In a high voltage electrical system, the wires can attract lint, raise hair,
etc., even though there is a large current in the wires and all the charges are
flowing. Last, when any electric circuit is broken and the charges stop
flowing, they do not turn into "static electricity" and begin
attracting lint, etc. A disconnected wire contains charges, which are not
moving; yet, it contains no "static electricity!"
For more
information on Static Electricity visit our Web Site at http://www.esdsystems.com or William J.
Beaty’s page on electricity http://www.eskimo.com/~billb/ele-edu.html
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If you
have any comments, suggestions or feedback about the above table, please send
them directly to the editor@esdsystems.com,
thanks.
<<<=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=>>>
This is a
free monthly newsletter, which specializes on issues in static control in the semiconductor/electronics workplace.
Need your own copy? Want to subscribe to this Newsletter? All you or your
colleague(s) need to do is simply fill out the subscription form at http://www.esdsystems.com/forms/esdmail.asp
This
Newsletter is never sent unsolicited. To unsubscribe from this mailing, send an
e-mail to ESD_Corner@esdsystems.com
and put " UNSUBSCRIBE ESD_Newsletters"
in the subject.
Let us know what you think. Tell us what you would like to see in future
issues. Want to contribute articles or other related information to our
Newsletter? Send your comments to the editor@esdsystems.com
Copyright © Desco Industries, Inc. 2000
END V3I2