I read in !emc-pstc that Price, Ed ed.pr...@cubic.com wrote (in
b78135310217d511907c0090273f5190d0b...@curly.ds.cubic.com) about 'best
screw/washer choices for attaching PCB to Chassis?' on Mon, 10 Feb 2003:
Put a dab of Locktite into the female thread on the PEM before assembly.
- provided you
, with zinc or other platings.
Angus McGill
Regulatory Engineer
Cascade Engineering Services, Inc.
ang...@cascade-eng.com
From: Robert Johnson
To: 'Kim Flint'; emc-p...@majordomo.ieee.org
Sent: 2/11/03 8:28 PM
Subject: RE: best screw/washer choices for attaching PCB to Chassis?
The product I'm referring
[mailto:john...@itesafety.com]
Sent: Monday, February 10, 2003 8:09 PM
To: Kim Flint; emc-p...@majordomo.ieee.org
Subject: RE: best screw/washer choices for attaching PCB to Chassis?
You should not include the PWB as part of the sandwich in an electrical
connection. It gradually squashes and leaves a loose
...@itesafety.com]
Sent: Monday, February 10, 2003 8:09 PM
To: Kim Flint; emc-p...@majordomo.ieee.org
Subject: RE: best screw/washer choices for attaching PCB to Chassis?
You should not include the PWB as part of the sandwich in an electrical
connection. It gradually squashes and leaves a loose
Kim,
Screw/Washer choice:
- should a washer be used or not? ONE COMPANY I WORKED FOR USED SCREWS WITH
INTEGRAL STAR WASHERS. WE NEVER HAD ONE WORK LOOSE EVEN IN MOBILE
APPLICATIONS.
- Is an adhesive like Loctite a reasonable alternative to lock washers in
this case? I WOULD THINK LOCKTITE WOULD
Kim,
Here's how I would do it. Note that I'm assuming that we're dealing
with SELV circuits here and your concern is SI/EMC on circuit packs for
a shelf system. Safety grounding is another issue entirely.
First screws:
I'd use split washers with flat beneath (if lock washers at all) to
in the surface layer pad connecting to the
ground plane?
- What electrical or reliability concerns relate to this choice?
- how large should the surface pad be assuming a 4-40 screw?
anything else we should be considering?
Thanks for any input you have!
kim
Title: RE: best screw/washer choices
-Original Message-
From: Kim Flint [mailto:kfl...@inkra.com]
Sent: Monday, February 10, 2003 6:15 PM
To: emc-p...@majordomo.ieee.org
Subject: best screw/washer choices for attaching PCB to Chassis?
Hi-
We have a fairly straightforward requirement of mounting a PCB
into a steel
Kim, you ask some interesting and well thought out questions. I'm sure you
will get a lot of diverse opinions. You have entered into the domain of system
grounding. System grounding may be governed by a number of codes, such as NEC,
UL, and CSE for the North American continent. A lot more for
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