Synthesizer Working

It turns out that the synthesizer was in fact damaged.  I swapped it out and here’s the result:

870MHz Local Oscillator

870MHz Local Oscillator

A nice 870MHz signal.

Update 10:00 PM:

The synthesizer probably failed because it was heated to long during the soldering process.  Most likely it wasn’t the soldering of the synthesizer itself that did it but my need to solder another leadless package on the bottom of the board with my experimental dual sided hotplate method.  Needless to say, I’ve abandoned that method.

Replacing these leadless packages can be tricky but it’s not to bad if you have the right tools.

Lead Frame Chip Scale Package

Lead Frame Chip Scale Package

First I preheated the board with a mounted hot air gun to around 250° F and removed the old synthesizer with a hot air soldering iron.  Then I cleaned and pre-tinned the work area leaving me with this footprint.

Leadless Footprint

Leadless Footprint

Next, I placed the part down on the board to warm up and placed it onto its footprint after a minute or so.  Then I took my hot air soldering iron and swirled it around the part until I felt the solder underneath the part melt.

Placing the Leadless Package Down

Placing the Leadless Package Down

Using a dab of solder on a fine tipped iron, I went around the part touching each pad.  Sometimes the pads might bridge but that’s usually not a problem because the flux in the clean up step with fix that.

Solder the Pads with a Fine Tip Iron

Solder the Pads with a Fine Tip Iron

Finally with my low solids flux pen, I go around touching each pad with the iron.  This will cause the solder to draw up onto the package and usually break solder bridges.  A little clean up with alcohol and were done.

Cleanup with Low Residue Flux and Alcohol

Cleanup with Low Residue Flux and Alcohol

I went ahead and cleaned up a bit more after the last photo but you get the idea.  You’ll notice that the alcohol and brush tend to break up the silkscreening a bit but that can’t be helped.