Soldering Surface Mount Exposed Die Pads with an Iron

RE: Soldering Surface Mount Exposed Die Pads with an Iron

mcb1 — Tue, 31 Oct 2017 05:49:21 GMT

Nice trick.

Must add some tape to my next purchase.

I have been informed that if anyone has a hot air smd rework station, using a preheater underneath really does make it much easier for this sort of work.

Mark

RE: Soldering Surface Mount Exposed Die Pads with an Iron

rachaelp — Sat, 28 Oct 2017 22:24:26 GMT

Hi Shabaz,

Thanks for the look into how you go about soldering down parts like this. I use a similar method but I also sometimes use a makeshift PCB pre-heater so it's easier to get the joint to flow which can be tricky in there are a lot of thermal structures built into the board to conduct away and dissipate heat when the board is in operation.

I converted a spare heated bed PCB from an 3D printer design I did for somebody into a makeshift PCB pre-heater. I used a spare metal tray for my Rayburn oven and covered it in Kapton and then attached the heated bed PCB below it. I then put the PCB on top of this and I have another Kapton covered thermal insulated sheet which I place over the top to contain the heat so it warms up to temperature quickly. This can then heat up to 100+ DegC relatively quickly (not too quickly) and the board gets some heat soaked into it prior to trying to solder so it then takes less added heat from the iron to get the paste on the thermal pad to flow and give a good joint.

Best Regards,

Rachael

RE: Soldering Surface Mount Exposed Die Pads with an Iron

DAB — Sat, 28 Oct 2017 17:08:26 GMT

Nice result.

DAB

RE: Soldering Surface Mount Exposed Die Pads with an Iron

johnbeetem — Sat, 28 Oct 2017 17:03:06 GMT

I learned about resoldering a heat dissipation pad when we got the first prototypes of a new board. It had a dual switching voltage regulator with a ground pad, which was the only ground. When the voltages didn't regulate, I quickly found they forgot to solder the ground pad. Grumble grumble. The pad didn't have vias, so Shabaz' trick wouldn't work. However, the ground pad did connect to copper next to the chip, just like Shabaz' board. I cleared the solder mask from that copper with an X-acto knife, tinned it, and heated it up with a good iron. The heat conducted to the pad under the chip and reflowed the solder nicely. This lets you work from one side of the board.

Since then, I always made sure to leave some copper exposed next to the ground pad, if possible.