[Elecraft] Some reassurance needed please.

[Tom Hammond]

And I need to add a bit more info and illustration with specific regard to 
soldering to plated-thru holes (PTH) as well.

When soldering to PTH, it's not necessary to make solder fillets ON the 
pad. As long as you can 'flow' the solder down into the PTH and be certain 
that the hole is filled (at least 90% full), then there's no need for 
additional solder.

This is most easily accomplished using fine diameter solder. I use 0.020" 
diameter solder (Kester 285, if I recall), but 0.025" diameter should work 
as well. Larger diameter solders, even those at 0.030" and 0.035", can give 
you more solder than you really need the very first time you touch the 
solder to the tip of the iron. I didn't believe it until I tried it, and 
sure enough it did. I'm dedicated to 0.020" dia. solder when soldering PTH 
nowadays.

For what little it might be worth, I use a 700 degree F iron with a tip 
that's about 90% the width of the pad I'm soldering to. The slightly narrow 
tip helps to ensure tht I don't slip and accidently slop solder over to an 
adjoining PCB pad.

I place the tip of the iron AT the junctino of the component lead and the 
PCB pad, allow about 1/2 second for heat to flow and then I just 'touch' 
the 0.020" dia. solder to the junction. I then leave the iron on the joint 
and watch until the solder is 'sucked' down into the PTH hole. I might then 
carefully add just a wee bit more solder, but only if I have a concern that 
the hole might not be adequately filled. The result is generally no fillet 
on either top or bottom of the PC board.

This is just how I do it... not a directive for YOU to do the same... to 
each his own.

73,

Tom  N0SS

At 07:02 AM 6/16/03, Wallace, Andy wrote:
>Note Tom's excellent soldering tutorial at the Elecraft
>webpage:
>
>http://www.elecraft.com/TechNotes/N0SS_SolderNotes/N0SS_SolderNotesV6.pdf
>
>There's an illustration on P.4 which shows a nice picture of good
>solder fillets.
>
>Andy