The IPC standards committees had long discussions on this topic. A group was
tasked to evaluate your concerns and others, like vertical versus horizontal
alignment of the plates in multilayer ceramic capacitors.
No manufacturer voiced concern over reliability or performance of either
resistors or capacitors. One member attempted the quantify the performance
of capacitors in RF applications and found no difference. The committee
voted to relax the workmanship requirements in response.
Since that time, I used a thin film precision resistor where the maker
recommend mounting with the resistive element down. I asked about this and
the response was "it provides and measure of protection for the thin
resistive element."
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Thursday, July 31, 2008 3:12 PM
To: [log in to unmask]
Subject: Re: [TN] Repair Need for Inverted Chip Resistors
Dewey and others,
I've been told the concern lies with the resistive element being on top of
the component. With it being mounted upside down, the hottest portion of
the part when under power is in direct contact with the board. Would this
lead to shortened life or cause any type of a premature failure?
Are we being over-cautious about this, or is there some truth to what I'm
being told?
Leland
-----Original Message-----
From: Whittaker, Dewey (EHCOE) [mailto:[log in to unmask]]
Sent: Thursday, July 31, 2008 2:00 PM
To: TechNet E-Mail Forum; Leland Woodall
Subject: RE: [TN] Repair Need for Inverted Chip Resistors
I'll try to be discreet. If there is no functional impact, then a "let the
chips fall where they may" approach is acceptable. If the part markings are
not visible or the vision recognition algorithm of an AOI machine is
impaired, then they may be a problem.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Thursday, July 31, 2008 10:12 AM
To: [log in to unmask]
Subject: [TN] Repair Need for Inverted Chip Resistors
TechPros,
Can anyone tell me if there's a reliability concern with allowing chip
resistors to be mounted upside down? Our current policy requires that we
repair these, and I feel that to be unnecessary.
IPC-A-610D shows this to be an acceptable condition on all classes of
product, and our customer has no specific contractual requirement.
I'd like to try to change this policy at our facility, and welcome any
commentary you might have on the subject.
Thanks in advance for your help,
Leland Woodall
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in the
BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per
day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information,
or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in the
BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet
NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send
e-mail to [log in to unmask]: SET Technet Digest Search the archives of
previous posts at: http://listserv.ipc.org/archives Please visit IPC web
site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
