Any disadvantages in mounting PCB's upside-down?

Brett Duggan bduggan at netcom.com
Fri Jan 22 11:28:43 CET 1999


Hello fellow DIY'ers:

I have constructed two synth-DIY projects in small aluminum boxes so far. 
I am in pursuit of what I would consider to be the "perfect" construction
design for such a project.  My second attempt was a definite improvement
over the first but still not what I would like it to be.  I am hoping that
my third time will be the charm, so I ask the question in the Subject
line: 

Can any of you please tell me if there are any disadvantages in mounting 
PCB's upside-down?  My initial guess would be some kind of heat buildup.
However, the kind of modules I am dealing with here are not real high 
power consumption devices.  In the case of this one project sitting here 
with me, the tallest component on the PCB is a 470uF 25V electrolytic cap.
Would drilling some holes in the sides of the box for ventilation make 
such a mounting possible, or would this even be necessary?

I got the idea for this from my Sequential Circuits Six-Trak, of which the
PCB is mounted upside-down (though at a slight downward angle), including
the heatsink.  There are no dedicated ventilation holes anywhere on the
panel.  However, all of its analog circuitry is completely
microprocessor-controlled, so maybe that's how it is able to get away with
the upside-down mounting?  Anyway, it's really nice to have easy access to
trimpots while the unit is powered up, and for reseating IC's in their
sockets. 

Sorry to be so wordy with my question, but I'd really appreciate hearing 
from any of you that have knowledgable opinions.

Thank you very much!
Brett D




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