Hi,

the board finally arrived. So I assembled it (very funny when it comes to QFNs) and now... well, nothing. I have to design the motherboard which will utilise this.

The first mistake I found while assembling it is that R110 shouldn't be there. It can be simply shorted together when hand-assembling. Somehow, I forgot there is internal 50Ohm termination inside the ADCMP582 since I have a design laying around which uses the ADCMP576 which has no fancy internal terminations and I got these two mixed up.

There is one trick I use always when assembling anything with QFN or QFP packages. First I solder all the solder pads on BOTH the PCB and the chip, then I apply solder paste (manual), then solder it using heat gun. Then, the failure rate gets under maybe 5%, most of which are shorts, unsoldered pads are gone. And removing the shorts is easy with soldering station and a bit of flux. However, since I didn't make anything in months, I forgot to use this trick and I was fighting with 1 unsoldered pad for 20 minutes...

Ready to solder once coffee is made.

The problematic solder pad after being already solved (the leftmost one at the bottom row).

Cleaning in IPA in ultrasound cleaner:

Clean board with soldered SMA connector (Rosenberger 32K243-40ML5, a middle-class connector). There is one trick to solder the central pin (believe me, it is to be soldered, the high-class SMAs which can be easily reused have a springy pin, not a stiff pin) - first position and center properly the SMA on the feed line (the centering is quite important), then slightly tighten the screws, position again, tighten and check whether it is correctly placed. Then, using a solder-paste applicator with narrow tip, apply a blob of paste on the pin and the feed line, then using the tip, try to make sure the paste is applied to both parts. Then, solder using heat gun.

That's all for today :)