Solder won't flow nicely on some PCBs

I recently bought lead free solder and I noticed a significant difference. Leaded is much easier to use. I use a Pace set at 700F and I never had issues. The unleaded stuff sometimes looks like it’s not flowing but then the resulting joint looks fine so I don’t know what to make of that!
 
Solder flow issues are almost always due to a lack of heat. If you're using lead free solder start with your iron at around 350C and go up from there maybe to around 450 if the solder doesn't melt within one second of touching to the iron and components.

Also a thicker tip transfers heat better, maybe try a 2mm
 
Robert said:
It's odd though, because it looks like some of the other ground pads didn't have that same issue.
Click to expand...

I've had the same issue when I soldere 3 or more of the same board (can't remember which ones right now) - the exact same through hole on every board was nearly impossible to solder, so it's not because of issues with the iron, solder or temperature like others suggest.
 
bechbox said:
I've had the same issue when I soldere 3 or more of the same board (can't remember which ones right now) - the exact same through hole on every board was nearly impossible to solder, so it's not because of issues with the iron, solder or temperature like others suggest.
Click to expand...
Thanks,
How did you manage in the end, or what did you do?
Mine look a bit dodgy, but before I cut a leg/pin (not on solder or pad) I use connectivity buzzer to see if the leg reaches next points in the schematic.
Not sure if this is proof of a working/good even, solder point, but I hope it counts for something. (Bridges are of course not found this way...)
 
bechbox said:
I've had the same issue when I soldere 3 or more of the same board (can't remember which ones right now) - the exact same through hole on every board was nearly impossible to solder, so it's not because of issues with the iron, solder or temperature like others suggest.
Click to expand...
This sounds like ground plane heat absorbtion
 
bechbox said:
I've had the same issue when I soldere 3 or more of the same board (can't remember which ones right now) - the exact same through hole on every board was nearly impossible to solder, so it's not because of issues with the iron, solder or temperature like others suggest.
Click to expand...
Digging into memory, I would say that there are about 1-3 pads with the problem. But I thought all ground ones go to the plane and have the thermal narrow connection to the plane. So I would have expected either all or none of the pads goint to ground exhibit the same effect/issue. This subset is a bit puzzling.
 
Matopotato said:
Digging into memory, I would say that there are about 1-3 pads with the problem. But I thought all ground ones go to the plane and have the thermal narrow connection to the plane. So I would have expected either all or none of the pads goint to ground exhibit the same effect/issue. This subset is a bit puzzling.
Click to expand...
Two factors that could still be different would be the components connected to each of those ground pads, and how much heat they suck up, and also the varying temperature of the board as it heats up and cools off.

If you solder one stubborn pad that takes a lot of time and heat, then move a short distance to the next one, that second one will have the advantage of a significant pre-heat.
 
Only time I ever run into something that doesn't want to wick solder almost immediately it's either the back of a guitar pot or a tremolo claw. :ROFLMAO: .. and that only takes a few seconds of heat and then that solder starts moving beautifully... I'm running a standard conical tip on Hakko 951 with Kester 63/37 leaded rosin core at 380C.... get in hot and come out fast.. wicks like a dream every time... Most of the time I'm actually applying a little too much solder to be honest... Not once have I ever had a pedalpcb pad not want to take solder through both sides of the board in mere seconds...
 
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