for all who attached a heat sink on the altera chip a big warning!
in my case the altera chip is not attached very thight. i recognized this by jumping my lime sdr from the desk on a carpet in an proper plastic casing. because of the heatsink (a Standard direct attached one, light alu) it got kicked right of the print.
i’m not very happy with this board cos first is started with the weak hf Performance and finally with a weak mechanical stability.
for me i’m done with limesdr cos i see no chance to get the chip reattached. Have had such never before in my many years experiance with such heavy chip boards.
i hope this warning will help someone else not running in the some issue and consider cooling the Altera without heat sink…
Mine survived heavy drop from desk without any problem.
Case is die cast Al, all 4 points screws and metal stand off.
USB attached inside therefore only cable goes out…
73
PS
In case you may like to sell your board as is
PM or email (find call on QRZ) pls.
I was going to suggest a toaster oven but that looks like pads were pull up.
I wonder a bit about the reflow recipe they used in production.
I have heavy copper sinks on my chips.
Agree, heavy damage… wondering about the magnitude of that drop.
I have coolers too, but my Lime for sure can not flex in any direction when
case is closed. That plastic case was closed or not?
73
Djani
the more strange is that the case was closed and shows no damage at all. i assumed that the plastic mounts would have blocked a swinging. posted some more pictures after the “jump” (1m wooden desk to carpet below…)
maybe as important note. the dark spots on the gpu picture is caused by some solder or sinter material. basically the pins are all usable but i dunno how to resolder such. placed an inquiry at the vendor for guidance/next steps
This one survived without any problem approx 1m drop on marble stone floor
with closed case one extra cooler on top of the case and one internal
plus one external fan…
The traces on the left side would need to be repaired. The ones in the middle you would need to make sure they are NC, or not connected. It could be why they pulled up easy. The chip would have to be removed from the heat-sink. If you used cement adhesive, it would be a no go. In all likely hood I would consider the board totaled.
I do reflow profiling at work. Doing BGA lead-free would make me shutter. The chip leaving so many clean pads has me to believe there were many cold joints. Or the ENIG finish had oxidized a bit before processing. I was going to re-ball and re-flow the lime chip with lead but I honestly dont know how they flowed it as there is zero clearance between the chip and board. Presumably to keep rf out.
If I were lime I would request to see the reflow profile with the probe tracking and placement to ensure it’s in spec.
@KBBF5 did a great job of describing this issue - - Any chance that reflow profile can be shared with him to ensure there isn’t a timebomb out there for many other Lime users?
I believe my USB connector detached too easily. The metal shell slipped out of the holes and only one trace pulled off the PCB. The others broke clean. I consider the LimeSDR as fragile now.
I have a couple of spare boards from the software development which I’m not using, I could send you a board which hasn’t been modified for the HF performance (but does work) if you send your mail address to simon@sdr-radio.com .
Out of the thousands shipped this is the first time we’ve heard of this and the number of returns has been very low.
Have discussed with a colleague who has many years experience with design for high volume manufacture — 10K+ units/week, lead-free — and he’s erring on the side of this being excessive force on the BGA.
Will flag this up with the hardware team for further investigation just to be sure.
