Re: How to protect circuit boards that must be exposed to weather?

On 02/08/2024 06:27, Jan Panteltje wrote:

On a sunny day (Thu, 1 Aug 2024 17:50:29 -0700) it happened John Robertson
<jrr@flippers.com> wrote in <v8hagn$2f8eq$1@dont-email.me>:
 

I have another problem - display panels on an outdoor hammer game - the
style that you swing a hammer at a pedestal and it lights up a column of
LED panels with 8x8 graphics.
>
The one I am repairing was made in 2001 and it is breaking down. The
surface mounted serial drivers are loosing connection to the PCBs from
being thermally stressed over a couple of decades of outdoor use and I
want to make replacement panels (the original company has abandoned the
product) that will be more durable.
>
Currently on the rear (somewhat protected) side of the board is the
electronics, covered (or course) with a conformal coating. The outer
side is an 8 X 8 matrix of LEDs in groups of 8 for each pixel of the 64
pixels on the panel.
>
There are 40 - 8 x 8.75 inch panels going up around 30 feet...
>
Is there a better way to solder on SMD devices to help avoid thermal
solder failure? After connection corrosion, the biggest problem is
solder failure of the SMD pads to the PCBs.

 I have this Motec satellite dish positioner, bought around year 2000,
sits outside in the very cold (freezing) and very hot (glowball worming) weather,
has GHz electronics and connectors, and motor drive electronics.
Never ever failed.
I once opened it up, it was covered (the electronics) in what looks like candle wax...
I wanted to see something about the motor drive (curiosity) and pressed my scope probe point through the wax.
Did I melt it gain? Dunno, but it still works 100% every day.

It might be worth using 3528 automotive LEDs.  These have a leadframe
which gives some mechanical compliance.  Also, make the SM pads larger
than usual to get more solder into the joint.
John