We have a low volume PCB with only three SMT components, two LEDs and an IDC connector, which I've previously made up in small batches, applying the paste manually. I recently needed one for a repair job and rather than making another batch I thought I'd give the V1 a go. It made the job much simpler, looked great, and I sent it out into the plant with a test label on it.
I was disappointed when it came back less than a month later with the IDC connector popped off. Looking at the joints it appeared that the copper traces were fine and there was good wetting on both sides of the joint, but in the middle looked a bit grainy, as if it hadn't made temperature there. Understandable, as the PCB is 2mm thick and I had used the standard V1 reflow profile.
I then hot-air reworked the part, let it cool, and applied pressure with my thumb. Unfortunately it didn't take a lot of pressure to pop the part off again. (I figure this is what happened in the plant, an operator thought he'd just give it a test!)
I then manually applied Sn63Pb37 paste and hot-air reflowed, this time achieving a solid joint. (Normally the copper pads will come off the board before the joint gives way)
If weakness is an inherent property of the standard paste supplied, can I easily substitute another paste for use with factory made PCBs? The paste application with the V1 is such a huge improvement over the manual or stencil experience, and I would love to make future use of it. I assume if I change the paste I'll have to run it through the oven (not a problem) rather than using the V1 reflow cycle?