2-sided PCB component soldering?

[Fred (FL)]

When I built my K2 spring 06 - and soldered along, day
and night after night.  I always made sure to have
my soldering tip set a high enough temperature, and
tried as best I could to get very good solder flow
with my Kester solder - both onto the component lead,
and the PCB's pad and "hole".  

The "hole" and Elecraft's 2-sided PCB's always puzzled
me a bit - as I was never sure if there were pads,
plated-thru hole, and lower pads - every time.  In
other words when I soldered a component on the top
side of the RF Board - and got a great solder flow -
was I supposed to look to see if there was a pad
and "great flow" on the bottom side too?

OR DOES THE PLATED-THRU HOLE, TAKE CARE OF THAT?

Apparently I must have figured right - none of my
solder connections ever gave any trouble, and K2
checked out right, after every section build!
Probably lucky.

"Solder Flow" - with lead based solder, and its tin
content, etc. - reminds me of my first career in the
newspaper field.  I was one of those rare birds who
fixed linotype hot-metal typecasting machines for 10
years.  In those days there were magic crayon-like
sticks we threw into the metal pot, and daily skimming
of the dross that built up on the top layer of the
pot's liquid lead/tin/antimony metal mixture.
Temperature was critical then, to ensure razor sharp
newspaper type letters on the top of each ejected
"line of type" that came out of those black beauty
machines.  I think I could still fix one of them
in my sleep.  Our daily newspaper in Buffalo, had
49 machines - for 5 editions a day.  By the by,
linotype metal supposedly the best for casting
pistol bullets.  Extra hard.

Kept a guy out of trouble .....

Fred
FL



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[Bill VanAlstyne W5WVO]

Fred (FL) wrote:

> The "hole" and Elecraft's 2-sided PCB's always puzzled
> me a bit - as I was never sure if there were pads,
> plated-thru hole, and lower pads - every time.  In
> other words when I soldered a component on the top
> side of the RF Board - and got a great solder flow -
> was I supposed to look to see if there was a pad
> and "great flow" on the bottom side too?
>
> OR DOES THE PLATED-THRU HOLE, TAKE CARE OF THAT?

Very early in the PCB days, double-sided PCBs did not have plated-through
component holes, so it was necessary to solder both sides of each component
connection. PCBs have had plated-through holes for a LONG time, so this is
no longer an issue. Nevertheless, insufficient heat and/or application time
can cause the solder not to flow smoothly through the plated hole and create
a good fillet on the other side of the board. This should ALWAYS happen,
because otherwise you're depending on the integrity of the plated-through
hole to conduct current between sides (or layers, in multilayer boards).
Murphy sez this ain't a good idea!

I always inspect all solder joints on both sides of the board to make sure
they look right.

Bill W5WVO


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