[NLRS] LFCSP (was re:power measurement)

[Ford Peterson]

Chris moaned...

...snip...

> And these are indeed very cool...  but how on earth do you work with
> them at home given the packaging?  The AD8317 (1 MHz to 10 GHz) Log
> Detector is in a 2mm x 3mm 8-Lead LFCSP package.  Geez!  First you
> gotta make a board and then you have to figure out how to solder
> it down.
> 
> I just ordered samples of a cool ADI synthesizer (ADF4360-6) that will
> let me generate 1152 MHz from a 10 KHz GPS reference directly--  and
> I failed to pay close enough attention to the packaging... and that
> one too is in a 4mm x 4mm LFCSP package.  I know I am getting old
> (43) but I never had trouble working with stuff at home until I
> encountered these beasts.  I had to order the eval board to play.
> What looked like a $6 project is now $120.  Geesh.
> 
> So, how do people make use of these things in a hobby context?
> 
> Chris NØJCF

I feel your pain Chris.

I found one of the kewelest (turned into a cruelest ...snicker...) RF Gain Block I've ever run into.  The AD8354 is nothing short of awesome.  1 MHz to 2.7GHz fixed 20dB gain block.  Linear output power up to +4dBm.  In/out matched to 50 ohms.  NF 4.2dB.  Vcc 3v or 5v.  Total supply current 23mA.  Compare that power to a MAR!  Input power maximum 10dBm.  This thing looks to be awesome.  Digi-key p/n for either the 8354 (20dB) or the 8353 (25dB) is $1.45.  LFCSP package is new to me.  But the eval board on the data sheet looks like a 1/2 pitch SOIC8 part.  How tough can this be?  So I order up a few just to play...

What a disappointment!  These are 2mm by 3mm.  8 leads!  4 on each side!  Traces need to be like 0.005"!  The center of each pad is 0.0127" apart!  The eval board graphic in the data sheet must have been blown up by about 4X!  No way does the graphic characterize just how small this stuff really is.  You don't have a good feel for it until you pick one up with the tweezers and see that the needle tweezers shorts out about 3 pins on each side!

I tried super gluing them upside down to get at the pads on the bottom.  (there are no leads)  Completely hopeless!  My smallest iron touches 3 pads at once!  Short of having a gold wire bonding apparatus, I think this stuff is establishing the limits of homebrewed capability.  I too would be interested to know how these must be placed in production.  

I feel your pain OM.

Ford-N0FP
ford at cmgate.com