[NLRS] Power on 5760 MHz

[Dr. Gerald N. Johnson]

There are about 10,000 hits on google with the search:
www.google.com/search?as_q=toaster+oven+reflow+soldering with hits from 
sparkfun to hackaday to IEEE spectrum. There are commercially available 
oven controllers for the application. 
www.karlssonrobotics.com/shop/reflow-toaster-controller/?gclid=CIXlvLWZwbMCFaOaPAodPEoA6g

The oven doesn't solve the need for precise solder paste application, 
usually through a stencil with a squeege so the stencil openings define 
the area with solder paste and the stencil thickness sets the thickness 
of the solder paste. Buying commercial soldering paste gets expensive at 
$25 a syringe that keeps less than a year in the freezer. Russ and 
Glen's sources of soldering paste do have a more reasonable price. 
Soldering paste and stencils are OK for short or long production runs, 
but a considerable bother for one board of a kind.

Toaster ovens have quick cool down which is nice at the cost of heating 
their environment, no insulation at all, just a layer of steel. Which 
can be a bit of a fire hazard, though they don't burn down too many homes.

I'm concerned about parts moving while sliding into the oven and maybe 
while sliding out if the board is needed to be removed for faster 
cooling. More than one chip maker says not to use forced air or a water 
application to cool faster because differential cooling effects will 
break parts if not the freshly soldered connections.

In concept I like the hot plate/skillet techniques better because they 
can be watched and the PCB can be assembled in place and left there 
until the solder is safely solidified, nothing has to be moved. I've not 
yet tried any but will.

I've not found anyone doing it but seems to me that tinning the pads 
with an ordinary soldering iron, then removing most of that solder with 
solder wick while slower than applying soldering past will be at least 
as precise as stenciling solder paste and unless the solder wick removes 
too much solder will help prevent solder bridges, especially under the 
QFN parts that depend on all the connections being underneath the chip.

I have a nice lab hot plate that I have used occasionally for soldering 
that should be better than a skillet, with better temperature control 
(and it takes up less space while giving better board access). I have a 
Fluke 62 IR thermometer for temperature checking.

I despise etching boards so much that I'm going to try carving them with 
diamond dental burs in a small battery dremel, maybe even under the 
stereo microscope. To put the board layout, I just bought some sheets of 
transfer film so I can print on that film and iron the traces to the 
bare PC board and carve away the bare copper. For large areas I may use 
the milling machine after I construct a vacuum hold down from a plastic 
conduit fitting. That vacuum hold down may be handy for assembly too.

One rub with the wicked solder is it won't hold the parts in place like 
the sticky soldering paste does, but perhaps a smear or dab of 
electronic soldering flux will, since that's the component of the paste 
that holds the parts.

I have more to learn and there are probably more experiments already 
done if I dig deep enough. Fiber was connected up to the phone and 
internet today so my bandwidth is way up and doesn't have the download 
limits of Verizon wireless. I'll dig and I'll try.

73, Jerry, K0CQ

On 11/8/2012 11:09 PM, Bill Ockert - ND0B wrote:
>
>
> There have been a few articles and I believe even one in QST (or QEX?)
> on converting a toaster oven to do reflow soldering.    Not sure if that is
> of help in this discussion but thought I would throw it in.
>
> 73 de Bill ND0B
>