I recently created out a prototype PCB for the PROC EZ-BLE module and I notice that the CY8CKIT-043 has an unpopulated footprint for this module. But I've not been able to summon the courage to actually attempt to solder one. Has anyone attempted this and if so could you offer any tips?
I have access to a hot-air rework station and some solder paste in a syringe. However whenever I've soldered packages with pitches this fine I've always ended up with a few solder bridges which I've had to rework with a solder wick. With two PCBs soldered face to face this will not be possible and it seems virtually certain I'd end up with some shorts or dry joints. Maybe it would help to put a small (heat resistant) spacer between the boards to give the solder a chance to collect on the pads under surface tension?
0.76 mm pitch is not too small. (I have hand-soldered an SHT21 with 1mm pitch on a hand-drawn PCB in the past). make the pads a little bit wider than suggested so you can reach with your soldering iron. Make sure you have solder mask / solder resist between the pads to avoid solder bridges under the chip. Then you solder from the outside with a soldering iron.
If you are careful with the solder paste this should work too. But don't apply too much paste to avoid bridges. If there is not enough paste on a pad you re-solder it from the outside later on.
Hm thanks, maybe I just need the courage to give it a go. Certainly I have soldered QFP packages this fine, but then you have access to the individual pins. I see maybe if you make the PCB pads bigger you can sort of push the solder under the package, but there would need to be a slight gap for the solder to wick into - a shim under the package? I wonder if Cypress have made the pads big enough on the CYCKIT-043 to do it this way - I did not on my prototype board, but fortunately I also put pin-headers to take the CY8CKIT-042-BLE modules.
I'm puzzled too how these modules should be soldered in a production environment. Surely the reflow oven would melt the solder on the components inside the module?
With a QFN-like package as this, where the pads are at least visible at the side you don't need solder under the package. If the pads are large enough you can solder from the side, which is much easier.
That is really what bothers me - the pads are not really visible from the side, they are not plated on the module edge so when you lay it on a PCB only the thickness of the copper laminate (negligible) is exposed. It is more like a BGA package which would need solder between the package pads and the PCB pads. Also there is no place to get a probe onto the package, so no way to test continuity between the board and the package after soldering (or for absence of bridges between pads).
PS: Sorry for the long delay, but the email notification of your post only arrived just now!
I just had a look a the EZ-BLE PCB that I got for my BLE Pioneer kit. Yes, the pads are not exactly visible on the side. But on this PCB the module is soldered partly from the side. So for a prototype I think it works, but for a production PCB you would need to do proper reflow soldering.