I have a couple of questions, plus I'd invite any comments/feedback/suggestions to improve my results.
I used solder paste Chipquik SMD291AX10 (Sn 63 / Pb 37) on the pads and also flux (Chipquik SMD291NL) on the pins/pads of the components. I wonder if this is the recommended practice, or whether the solder paste already has the necessary flux in the mix?
Notice that there is this "amber" touch around the components, and I believe it is the "cooked/possibly-burned" flux. Here is the link to a couple of pictures I took, plus the temperature profile:
My other question is: could it be that the temperature profile (in particular, how slowly it went) is negatively affecting the results? The image above shows the plot of the profile, as captured by a thermocouple some 5 cm away from the actual board inside the toaster-oven.
What I did is: set the oven to max. When the thermocouple temperature reaches 90 °C, I unplug and leave it unplugged for one minute. Then, when the temperature reaches 185 °C, I unplug it for good. Then, when the temperature passes through 200 on its way down, then I open the oven door to speed up the cooling down.
Does the above make sense to those of you with more experience on this?