On Mon, 9 Oct 2017 14:17:15 -0400, bitrex
wrote:

On 10/08/2017 05:54 PM, Neon John wrote:
On Sun, 8 Oct 2017 15:40:58 -0500, "Dave M"
wrote:

Anyone have any experience or have colleagues who have experience using the
Chinese-made reflow soldering ovens such as those being sold on the evil
auction place? The one I've looked at is item number:262955348183 (Model
T962).

My concern (mainly because I have no experience with infrared) is that
the black chips and components would get hot faster than the shiny
pins and solder paste.

I have an oven that I built using a tabletop convection oven and a
programmable timer. It works great but it's using hot air to do the
heating.

My eyes have become the major challenge to producing the one- or two-off
projects, since many of the parts that are available today are only made in
SMD packages. I realize that placing them onto the board still remains a
challenge, but at least with a proper oven, I won't have to hold a soldering
iron steady enough to build the boards.

The neat thing about reflow is that if you put the proper amount of
paste on each pad, the surface tension of the solder will pull the
part or chip in line with the pads.

I've developed an unconventional technique for pasting 0.5 mm pin
spaced ICs. I put the chip on its back and use my pressure/vacuum
paste dispenser to lay a solid stream across each side of the chip.

I then hold the chip with some pliers while I wipe the other side with
a Q-tip. This removes paste between the pins. Drop the chip in
place, populate the rest of the board and reflow. Both my vision and
my steadiness of hand have declined over the past few years and this
is how I compensated.

Technique I've used occasionally that so far has always seemed to work
pretty good for soldering say 14 or 16 pin SOIC "surfboards":

SOICs are a piece of cake. They're *huge*.

Use regular soldering iron and thin 60/40 solder to tin the pads. Put
the IC down using tweezers and "tack" the top left and bottom right to
the board. Apply pressure on the center of the IC using a jeweler's
screwdriver with one hand (wear a protective glove!) while blasting the
pins on one side of the IC with hot air from a lightweight heat gun for
about 10 seconds, back and forth until you visibly see the solder on the
pads go shiny. Remove heat and hold for another 15 seconds or so, then
remove pressure and let cool for about a minute. Then repeat for the
other side.

Remove all solder from all of the pins except one, then tack that pin
down and position the part. Go around and solder the rest. Yes, I
always use leaded solder (being careful to remove all of the socialist
solder from all pads).

Then continuity test from the junction of the pin and the package to the
hole on the board for the mounting hardware. Meter should beep just from
light contact without applying any pressure at all from the probe to the
pin. Sometimes there's one pin that didn't quite get a solid connection
and won't test for continuity without pushing down a bit, but a single
pin is easy to touch up by hand.

Your soldering technique needs work if you have to test continuity.