Another alternative is to form the resistor leads in the "hairpin"
style, and place the resistor perpendicular to the PWB.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kerry McMullen
Sent: Friday, August 17, 2007 1:03 PM
To: [log in to unmask]
Subject: Re: [TN] Solder mask as an insulator - illustration posted
Phil,
Dumb question, but can you put the resistor on the bottom of the board,
and live with it?
Kerry McMullen
Principal New Product Mfg. Engineer
LTX Corporation
825 University Avenue
Norwood, MA 02062-2643
(T) 781-467-5468
(C) 508-631-1832
(F) 781-461-0993
Phil Nutting <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
08/17/2007 08:14 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Phil Nutting <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Solder mask as an insulator - illustration posted
Good Morning folks,
I created a graphic to illustrate our "punch through" problem as I don't
have any photographs of the failed board/part.
Steve Gregory has posted the illustration at
http://stevezeva.homestead.com/files/LPI_punch_thru.jpg. Thanks Steve.
Phil
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, August 15, 2007 11:12 AM
To: [log in to unmask]
Subject: Re: [TN] Solder mask as an insulator
Maybe. How many components, and what type? Can you post a picture on
Steve Gregory's wall? It is a lot easier to solve the puzzle if we can
see what the situation is.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Wednesday, August 15, 2007 9:59 AM
To: [log in to unmask]
Subject: [TN] Solder mask as an insulator
Let me start with, I know that we should not rely on the LPI solder mask
as an insulator. So I need recommendations for a simple and cost
effective solution.
Problem parameters; 0.062 thick FR-4 with 2 oz copper and LPI mask. PTH
components laying on traces that go under the parts. PTH parts are
shorting to the traces.
Our fab house is against adding a second layer of LPI mask. On face
value a second layer sounds good and easy, but I know there are issues
too long to list.
Short of raising the components above the board, applying an insulator
under the components or a new board layout is there a better way of
preventing this shorting problem?
Thanks in advance.
Phil Nutting
Design for Manufacturing Engineer
Kaiser Systems, Inc.
126 Sohier Road
Beverly, MA 01915
voice: 978-922-9300 x1310
fax: 978-922-8374
e-mail: [log in to unmask]
www.kaisersystems.com
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