Re: Lead spacing for through hole resistor

On Sun, 04 Jun 2006 21:58:52 GMT, the renowned Roy L. Fuchs
<roylfuchs@xxxxxxxxxxxxxxxxxxxx> wrote:

On Sun, 04 Jun 2006 21:47:44 +0100, Pooh Bear
<rabbitsfriendsandrelations@xxxxxxxxxxx> Gave us:



Spehro Pefhany wrote:

On Sun, 04 Jun 2006 19:53:07 GMT, the renowned Roy L. Fuchs
<roylfuchs@xxxxxxxxxxxxxxxxxxxx> wrote:

On Sun, 04 Jun 2006 09:58:25 -0500, John Fields
<jfields@xxxxxxxxxxxxxxxxxxxxx> Gave us:

If the dissipation is miniscule, I agree.

But, if the resistor is dissipating a sizable fraction of its rating
I'd be leery of mounting it vertically without getting some
temperature data.

In either vertical OR horizontal mounting (without a reasonable space
between it and the PCB), I would say that one should be leery of
either choice.

Hundreds of millions of portable transistor radios were made with most
of the axial-lead components mounted vertically on the cheapest
paper-based phenolic boards. They were pretty reliable.

That kind of stuff used resistors that had 'enamelled' leads to prevent
inadvertent shorts and a kinked lead to help relieve the mechanical joint at the
pcb.


The kinked lead is for maintaining enough bare resistor lead in the
hole to form a proper solder joint. It has nothing to do with any
form of stress relief.

Any good QC will tag any resistor that sits in a hole where the body
of the resistor is actually butted up against the hole.

One of the problems with it (less serious on single sided boards with
typical generous-size punched holes) is that the lacquer doesn't quite
stop at the body, and usually goes down the lead a bit. So it will
affect the solder joint and maybe contaminate it. On a dipped or wave
soldered single-sided board you've got an effective standoff of 1.5mm
or so.

Kinked leads are used on horizontally mounted resistors as well, if
the application calls for the body of the resistor being elevated off
the surface of the PCB. The kinked leads are for maintaining a space
between a part and the hole the part's lead slips into.

Keeps the circuit board from getting all ugly and discolored, but can
be a problem in high vibration environments.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

Relevant Pages

  • Re: Lead spacing for through hole resistor
    ... Spehro Pefhany wrote: ... if the resistor is dissipating a sizable fraction of its rating ... That kind of stuff used resistors that had 'enamelled' leads to prevent ... has many of the components mounted in stress relieving cradles. ...
    (sci.electronics.design)
  • Re: 5V to 3.3V UART conversion
    ... Spehro Pefhany wrote: ... limited (there is a protection network between the input and Vdd). ... I've fallen over by simply using a resistor between a 5V system and a 3.3V system... ...
    (comp.arch.embedded)
  • Re: Lead spacing for through hole resistor
    ... hole to form a proper solder joint. ... Any good QC will tag any resistor that sits in a hole where the body ... The kinked leads are for maintaining a space ...
    (sci.electronics.design)
  • Re: Lead spacing for through hole resistor
    ... if the resistor is dissipating a sizable fraction of its rating ... between it and the PCB), I would say that one should be leery of ... The kinked lead is for maintaining enough bare resistor lead in the ... Any good QC will tag any resistor that sits in a hole where the body ...
    (sci.electronics.design)
  • Re: System 80: Volcano *sigh*
    ... Re: the pull up resistor. ... You are also correct about the hole ... are you sure you mean the "hole kicker" or should you be ... Lastly, some Gottlieb driver boards, in some games, cause what is ...
    (rec.games.pinball)