I will also second that.
We have turned away from using yellow zinc coating, as well. We found that the
yellow zinc coating was prone to early oxidation which had a purple color.
This
oxidation was evident on most surfaces, but was most prevalent at the joining
surfaces (Murphy's Law). In fact if we needed to, we could always find out who
handled these parts by the oxidized fingerprints. Clear/bright zinc was found
to be more preferable than yellow zinc in this regard.
And as far as conductivity goes, the clear/bright zinc coating has much lower
readings. If memory serves me right from tests from a past employer:
Yellow zinc measured about 0.5 - 4.5 ohms/square
Clear/Bright zinc measured about 0.2 - 0.5 ohms/square
As for joining parts together, mating parts with yellow zinc coating were
sometimes difficult get a good low-impedance connection. We have never had
such
a problem with the clear.bright zinc coating.
The large yellow results were attributed to points of oxidation as the test
probes did not pentrate the surface.
Just some past experiences to share.
Best regards,
Ron Pickard
ron_pick...@hypercom.com
______________________________ Reply Separator _________________________________
Subject: RE: Yellow Zinc
Author: "Allan James" <james_al...@racal.com> at INTERNET
List-Post: emc-pstc@listserv.ieee.org
Date: 10/15/98 8:20 AM
I will second what Chris says. The yellow zinc has a surface resistance
that must be penetrated in order to have conduction across joints.
Jim Allan Racal-Datacom
-----Original Message-----
From: James, Chris [SMTP:c...@dolby.co.uk]
Sent: Thursday, October 15, 1998 5:49 AM
To: 'Knighten, Jim'; 'emc-pstc list server'
Subject: RE: Yellow Zinc
Don't have the figures to hand but having checked it out a while
ago we
have moved from the gold/yellow zinc passivation on steel parts
to the
silver/clear finish:
UK spec: BRIGHT ZINC PLATE TO BS 1706 Fe/Zn 8 c 1A
US spec: BRIGHT ZINC, ASTM B633, TYPE III, Fe/Zn 8
This has a much lower resistance. We found the "gold"
unacceptable for
emc considerations.
Chris James
Engineering Services Manager
Dolby Labs Inc.
-----Original Message-----
From: Knighten, Jim
[mailto:knigh...@exchange.sandiegoca.ncr.com]
Sent: Thursday, October 15, 1998 1:20 AM
To: 'emc-pstc list server'
Subject: Yellow Zinc
Hi Guys,
Does anyone know what a typical conductivity or resistivity is
for
yellow zinc coating???
Jim
Dr. Jim Knighten e-mail:
jim.knigh...@sandiegoca.ncr.com
Senior Consulting Engineer
NCR
17095 Via del Campo
San Diego, CA 92127 http://www.ncr.com
Tel: 619-485-2537
Fax: 619-485-3788
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