[sdiy] Moving to Surface Mount - lots of questions

[Mattias Rickardsson]

On 8 December 2011 10:42, ChristianH <chris at chrismusic.de> wrote:
> It's true that you can stack them nicely, I did it for precision
> resistance ratios (5k vs. 10k using two paralleled 10k's for 5k).
>
> But you wouldn't expect the lower resistor to experience some
> significant air flow to get the 1/10W away, don't you? Ok, it's not
> looking like fat wire-wound stuff, but in the end it's all about heat,
> just on a smaller scale.

The thermal mass and cooling area of the PCB is HUGE compared to a
surface mount resistor. I guess surface mount components relies much
more on heat dissipation by conduction rather than by airflow &
convection & radiation, compared to hole mount components - which are
both bigger and more physically & thermally isolated from the PCB.
Maybe surface mount components don't need any air contact at all,
considering their low ratings.

/mr