Re: Solder Paste Temp for KD1JV Rigs


 

It sounds like we use the same techniques.
About the only thing I use solder paste on is QFN packages if the pads are too small
for hand soldering to allow some wicking.  And then I use a
cheap hot air gun I picked up at a garage sale.

The tray is a good idea surface mount of through hole.

I have used both a good microscope and a head magnifier to see better.
My back prefers the scope.  They're a little pricey, but once you have one
you'll get spoiled quickly.  I've seen some inexpensive video scopes that
I've been tempted to try.  It would be nice to be able to work even more
upright.


On 4/26/2018 7:37 AM, ajparent1/kb1gmx wrote:
If it gets hot enough to melt the low temp you have issues... 137C is 278F, that's hot! 
I used the nominal lead material Kester-44 63/37.  I have that in .015, .030, .040 diameters
as its just handy.

Seriously the only place where there is any heating of significance is the final transistor.

That said I really hate the non-led solders they do not make good looking joints.   I soldered my
si5351 down using Kester-44 63/37 in .015 diameter.  It was the flood (aka don't sweat bridges)
then clean(flux impregnated silver braid from RG316) up technique.  HINT:  RG316 teflon coax
has a very good silver plated braid and having lots of small pieces I strip it flatten the briad
and use a drop of rosin flux as a substitute for Solderwik.  Because of the silver plating
it wicks solder vigorously.

The crystal I pre-tinned the pads and added a tiny bit of flus then used my hot air tool.

The rest of the stuff was fine tip and the kester solder by hand, been doing SMT for years
and a good set of tweezers and what I call a spare finger (spring loaded hold down)
makes for easy assembly.  Periodically cleaning flux from the tweezers makes it easier
place parts as they can get flux on them and become sticky.  I also Degauss mine as
some of the small parts are magnetic, that removes that form of cling too.   I put the
board in a PANA-Vise, and position and solder everything on one side then flip it. 
The biggest thing is organizing all the parts and I use a plastic tray (about 6x12 inches)
with large shallow compartments for keeping them under control and sorted as to what
component group is being used at a given time.

Oh, and never ever sneeze!  ;-)

Allison


-- 
John Sutter
W1JDS CM87xi

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