Groups > sci.electronics.design > #429878

Re: beads and zero ohm resistors

From	boB <boB@theresnoplacelikehome.com>
Newsgroups	sci.electronics.design
Subject	Re: beads and zero ohm resistors
Date	2016-09-30 00:45 -0700
Message-ID	<rm5subptrlcput4qt3ecp39spp91krq282@4ax.com> (permalink)
References	<hb3oubh66n45tr3lfnc7s5im1plq8r72vt@4ax.com> <1dcoublnsvh3kggeaqb149b12lt6baockd@4ax.com> <nsj6qk01hni@drn.newsguy.com> <7pvqubhhml1ap7tnom7kpegtkh1bs52bvl@4ax.com> <nsk0kd01en@drn.newsguy.com>

Show all headers | View raw

On 29 Sep 2016 14:21:17 -0700, Winfield Hill
<hill@rowland.harvard.edu> wrote:

>boB wrote...
>>
>> Another thing regarding small-ish parts like these is
>> that, for all resistors, say less than a hundred Ohms,
>> should be "pulse rated"... meaning, they shiould at least
>> publish the overload specs for the resistors unless there is
>> just very very low current through them.  It's a rule my
>> company has adopted though.
>
> Ditto for SMT resistors with more than say 10V across
> them, and that might experience moderate power surges.
>
> My technician's front-loading washing machine control
> board (with elegant Analog Devices DSP six-IGBT three-
> phase VFD motor-drive controller) failed when an 0805
> resistor blew in the offline switching-supply circuit.
>
> My beautiful expensive Casablanca remote-controlled
> multi-speed reversible ceiling fan failed when an
> SMT resistor failed, similar story.
>
> And etc.

And SMT capacitors can crack, too.  For instance, try not
to place them next to the edge of a board... Place them such
that if the PCB is going to flex, the cap can flex the least.

SMT capacitor size seems to matter also,  Smaller is usually better
we find. 1206 is getting too big at times. At least for stiff ceramic
types like X7R.  Film is better maybe.

Then again, if you don't mind paying a bit more, there are these
semi-flexible SMT caps we heard about but would rather not spend
the extra money if possible.

All these things that are found out over time. We try to learn from
past mistakes and experiences but sometimes we have to learn again.

boB

Thread

beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 11:38 -0700
  Re: beads and zero ohm resistors Cursitor Doom <curd@notformail.com> - 2016-09-28 18:59 +0000
    Re: beads and zero ohm resistors Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-09-28 12:57 -0700
      Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 16:17 -0700
        Re: beads and zero ohm resistors John S <Sophi.2@invalid.org> - 2016-09-29 07:16 -0500
  Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-28 14:11 -0700
    Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-28 14:21 -0700
    Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 07:00 -0700
      Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-29 13:59 -0700
        Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-09-29 14:21 -0700
          Re: beads and zero ohm resistors boB <boB@theresnoplacelikehome.com> - 2016-09-30 00:45 -0700
            Re: beads and zero ohm resistors "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-09-30 22:18 -0500
              Re: beads and zero ohm resistors krw <krw@nowhere.com> - 2016-10-01 23:00 -0400
            Re: beads and zero ohm resistors krw <krw@nowhere.com> - 2016-10-01 22:58 -0400
  Re: beads and zero ohm resistors "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-09-29 00:06 -0500
  Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 06:16 -0700
    Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 07:42 -0700
  Re: beads and zero ohm resistors George Herold <gherold@teachspin.com> - 2016-09-29 07:00 -0700
    Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 07:46 -0700
      Re: beads and zero ohm resistors John Devereux <john@devereux.me.uk> - 2016-09-29 16:03 +0100
        Re: beads and zero ohm resistors George Herold <gherold@teachspin.com> - 2016-09-29 08:16 -0700
          Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 09:02 -0700
        Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 08:52 -0700
          Re: beads and zero ohm resistors John Devereux <john@devereux.me.uk> - 2016-09-29 16:56 +0100
            Re: beads and zero ohm resistors dagmargoodboat@yahoo.com - 2016-09-29 09:10 -0700
  Re: beads and zero ohm resistors Simon S Aysdie <gwhite@ti.com> - 2016-09-29 15:20 -0700
  Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-29 20:14 -0700
  Re: beads and zero ohm resistors Robert Loos <1209@baer-gmbh.com> - 2016-09-30 11:40 +0200
    Re: beads and zero ohm resistors John Larkin <jjlarkin@highlandtechnology.com> - 2016-09-30 07:40 -0700
      Re: beads and zero ohm resistors Winfield Hill <hill@rowland.harvard.edu> - 2016-10-02 08:57 -0700

csiph-web