ESD CORNER
ESD Systems.com ESD Technical Newsletter
Issue 1, January 2000: Volume 3
Reference: http://www.esdsystems.com/newsletters/v3issue1.htm
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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 Let us know what you think. Tell us what
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IN THIS ISSUE:
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·
HOT TIP of the MONTH (CDM)
·
ESDA NE
Chapter's General Meeting (March 8, 2000)
·
NEPCON
WEST (VISIT US)
·
ESD Q&A CORNER (Standards)
·
PRODUCT UPDATES (Mini Monitor)
·
Dr. ZAP (ANSI/ESD S20.20)
HOT TIP of the MONTH (CDM)
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When developing or reviewing your ESD Control
Plan, make sure you’ve included the Charge Device Model (CDM) into the
program. Most plans only consider the
Human Body Model (HBM) and neglect the CDM which can compromise your program. Considerations to anything the ESDS electronic
devices come into contact with should be reviewed, such as: packaging; bins;
tubes; trays; slides; foam; automated handlers; sorters; etc. Review of the standards may be helpful (ESD
STM5.1, ESD DS5.3.1, and ANSI/ESD S20.20)
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/
Visit ESD Systems.com at this
years NEPCON West at the Anaheim Convention Center in California this February
29th – March 2nd at Booth 5708 which is right at the
front door in Hall C.
NEPCON West, Opens the door to a
world of innovative solutions and makes it easy to find the products, services
and information you need. The world's most important electronic manufacturing
event has leading suppliers from around the globe, a world-class conference,
exciting special events and more. If you want to be a leader in today's highly
competitive global electronics market; you have to be there.
For
general questions or comments on about any NEPCON event, please contact
Customer Service via e-mail,
telephone (800-467-5656), or FAX (203-840-9656). For technical questions or
comments on the web site, please send e-mail to the NEPCON Webmaster at webmaster@nepcon.reedexpo.com.
ESD Q&A CORNER
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The following questions and answers were selected from our FAQ WEB Page: http://www.esdsystems.com/question.html
concerning Questions about Standards.
Q1: We want to test our
floor but do not know the test range it should be in to pass. Can you give me
some guide lines for testing our flooring? - Anonymous, Clear Lake, WI
A1: The
ESD Association’s standard ANSI/ESD S20.20, (Protection of Electrical and
Electronic Parts, Assemblies and Equipment), which references standard
ANSI/ESD-S7.1, (Resistive Characterization of Materials - Floor Materials),
Item # 36026, recommends that the floor resistance be less than 1x10^9 ohms
when tested with an approved megohmeter at 100 volts and with two 5 lb ESD test
probes placed 3 feet apart. Our megohmeter, Item # 41273, can test within this
range and includes the proper 5 lb probes for testing.
++++++++++++++++++++++++++++++++++++++++++
Q2:
What
are the guidelines for acceptable resistance range limits for ESD wrist
straps/footwear? Are these ranges dependent upon types of devices being worked on?
- Anonymous, Skaneateles Falls, NY
A2: The ranges of wrist strap testers (testing a wrist strap
systems continuity) according to the ESD S1.1-1998 is less 10 Megohms. For
additional operator safety, the industry uses 1 megohm resistors in series with
the wrists straps ground path closest to the operator (usually at the
snap/buckle interface). Therefore the complete range that we set our units 750
kilohms to 10 Megohms (ESD Systems.com combo tester unit, Item # for is 41201),
refer to tech brief #ps-2057 found at - http://www.esdsystems.com/pdf/ps-2057.pdf.
For footwear, this is company dependent, but we factory set our standard
footwear testers between 750 kilohms and 100 Megohms. There are variations on
the high, e.g., 10 Megohms to 1 gigohm, but is application or internal program
dependent.
Summary:
Ranges for testing wrist straps and footwear for ESD control in the
semiconductor/electronic assembly is:
750 kilohm <
Wrist Strap < 10 megohm
750 kilohm < Foot Wear < 100 megohm
There
is movement from the ANSI/ESD S20.20 standard to change this to less then 35
megohm for either wrist straps or a foot wear-flooring system.
++++++++++++++++++++++++++++++++++++++++++
Q3:
Which
directives for ESD secure products are recommended for the latest &
greatest (up to date) approval?
- Is EN100015 the "hottest" norm?
- Can this approval include today’s approvals, is this norm "better"?
- Anonymous, Oslo, Norway
A3: The
ESD Association, out of Rome, New York, USA, has taken on a leadership role in
defining standards, test methods, standard practices and advisories for ESD
control. Most of their standards are ANSI approved as well. They have just
revised the MIL-STD-1686 into the standard ANSI/ESD S20.20.
There is a white paper that may help you with more info on ESD Standards
located at: http://esdsystems.com/whitepapers/wp_standards.asp
++++++++++++++++++++++++++++++++++++++++++
PRODUCT UPDATES (NEW!)
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Workstation Continuous Mini
Monitor - ESD Systems.com Model 41122
real-time monitoring of an ESD workstation and wrist strap
·
is a compact unit
·
real-time monitoring of an
ESD workstation including wrist strap, mat, and cords.
·
Red and green LEDs indicate
grounding status
·
Can be used with any brand of
industry standard single-wire wrist straps
·
True 100% continuous
monitoring, no pulsed current
·
cannot be fooled
·
There are no false alarms
·
no pulsed current that can
cause skin irritation
For
additional information contact ESD Systems.com at (508) 485-7390, fax (800)
805-5665 or visit our website: http//www.esdsystems.com
Dr. ZAP
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Topic:
Differences between ANSI/ESD S20.20 and EIA-625
NOTE: Receive
your free copy of this standard from: http://esda.org/pdf_files/s2020std.pdf
Having reviewed the ANSI/ESD S20.20 standard v. the EAI-625. Here are some of the obvious differences:
(Note: If this table is not formatted, please check out our HTML version at: http://www.esdsystems.com/newsletters/v3issue1.htm for your convenience)
ANSI/ESD S20.20 standard v. the EAI-625 |
|||
Area |
EIA-625 |
S20.20 |
Notes |
Static Generating Sources (Insulators) |
£ ±200 volts to be within 12” |
³ 2K volts keep at a min. 12” |
ESDA performed updated field studies |
Auditing frequency |
Tables 2 and 3 list item check frequency |
6.1.3.1
Compliance Verification Plan Requirement recommends that the frequency of
verification checks should be based on the control item usage, its durability
and associated risk of failure |
|
Humidity |
RH at 40% |
30% < RH < 70% |
|
Auditing Body |
Requires ESD Coordinator/team for compliance verification |
Recommends use of external audits for verification compliance |
|
Work Surface (General) |
Recommends dissipative, not conductive |
No statement (see notes) |
20.20’s Forward, part C, recommends dissipative |
Work Surface (specific) |
³ 1.0x105 to < 1.0x109 ohms |
< 1.0x109 ohms (no lower limit) |
No
lower limit was set to allow stainless steel (cleanroom) worksurfaces to
comply even though the worksuface’s committee disagrees |
Floor (General) |
Table 1 states - needed only when workers are mobile or workstations utilize floor grounding methods. |
Section
6.2.2.2 states ESD protective flooring, used with approved footwear, may be
used as an alternative to the wrist strap system for standing operations. |
625 is a requirement, 20.20 is a recommendation |
Floor (specific) |
1.0x105 £ to < 1.0x109 |
< 1.0x109 |
Suggested lower limit in 625 is for safety |
Footwear (General) |
Wear two |
No statement |
|
Footwear (specific) |
2.5x105 £ to £ 1.0x109 ohms for 120 volts |
< 1.0x109 ohms |
UL approves footwear with a minimum resistance of 1x106 ohms |
Floor / Footwear System |
Not covered |
< 3.5x107 ohms or < 100 volts charge generation |
First time a standard ties the floor and footwear together |
Wrist Strap System |
> 2.5x105 to < 1.0x107 ohms for 120 volts |
< 3.5x107 ohms |
UL approves wrist strap systems with a minimum resistance of 1x106 ohms |
Smocks |
£ ±200 volts |
105 £ to £ 1011 ohms |
|
Ionizers |
< ±35 volts balance |
< ±50 volts offset voltage |
Both reference ANSI EOS/ESD S3.1 |
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 V3I1