I had a tuner fail about 5weeks ago.
I got online and discovered the max2104 failure mode and deivce recall.
I ordered 2 parts from Dallas/Maxim ($5 each/$10 shipping = $20 total)
The parts arrived in about 2 weeks from thier Phillipine factory( in sealed hermetic/humidity pak)
I had hoped to get access to a real hot air station at work, but no deal, just a
regular soldering station with really good magnification...
here is my experience:
successfully did the rework this weekend in the local lab, not for the faint of heart...
(sorry pics are so bad, thier off my cell phone w/ fixed focus)
however, I wasn't successful with solder paste... I'd like to know how to do it better next time so please review my process and point out errors... it was pretty crude so don't laugh... (I did no preheating... me bad)
I left the board in the chassis as adjacent connectors were well mounted on back panel.([IMG]image_008.jpg[/IMG])
The 7mm TQFP (image 023, thats a AA battery in pic next to the spare part) was in an RF Can that took up about 2 sq inches, the lid of the can was a press fit and poped right off.
1) draped board in tin foil as crude heat protection and poked a hole over the part, hole was size of a $0.25 coin.
2) fasioned a funnel from tin foil on my hardware store heat gun, down to about 3/8" outlet.
3) applied heat and flipped bad part with tip of xacto knife (almost dislodged a small passive as part landed back on the board...(did this part at home in the kitchen)
4) I wicked all solder off and cleaned w/ flux and flux remover.... nice shinny site
here's where it got hard...
5) applied a line of solder paste across pads (which looked way too fat, used smallest dispensing tip I could find)
6) applied smallest drop of flux
7) applied heat expecting solder to puddle onto pads
Solder paste just dispersed/mixed into the flux and resulted in grey goo I had to clean/wipe off.
should I have not applied flux?
applied too much heat? (heat gun, flux boiled... hmmm)
(I think I sould have not have removed the old solder and should have just reflowed it with flux and heat gun)
8) recleaned
9) placed part (hard, even under magnification, every nudge was a big displacement.) and applied a drop of flux
10) tacked down one corner with a pencil (used smallest metcal pointed tip I could find)
11) tacked down opposite corner
12) used pencil to solder legs (very ugly, applied flux as needed, appeared as many globby bridges)
13) cleaned, and wicked excess solder (under low mag view, some pads looked pretty empty of solder)
14) cleaned, fluxed and reflowed with heat gun. (results were better under high mag view)
15) scraped off the single goober remaining on one leg w/ xacto knife
checked mechancial connection and continuity on every leg to pad., "A OK", took home and it worked.
(image 007 is after rework)
working under magnification was hard, depth of field was poor and tools looked huge(xacto was like a butter knife!).
RF Can and the bench mounted magnifier interfered with getting the solder pencil onto the part (small range of angle)
took an hour start to finish. used 2~3" of wick, ~1" of thin solder wire, a dozen drops of flux, 4 swabs, maybe 6~10 seconds of spray can flux cleaner...
one side ended up mis-registered (legs were maybe 25%~30% off pads) in the end but I didn't want to try and correct it
as that would be pushing my luck.
btw, even a small drop of flux spread all over under heat (area of 6 or 7 sq inches) and I'm sure lots of surrounding passives reflowed a few times.
Some few joints didn't have the uniform shine as most and some adjacent passives lost the shine.
I'm assuming these could be cold joints or just have some residual crusty flux.
(I didn't "scrub" with flux cleaner just sprayed and let it run off)
the receiver is on 24/7/365 except for unscheduled down time so there is no on/off temperature cycles.
If the rework lasts 6mo I think that will be OK until receiver gets replaced...
hope this is helpfull to others...
darrell


