Re: [CAD_CAM_EDM_DRO] Re: 2 Fried G210's in a single day :-(

mariss92705 wrote:

>
> That means in 12 months over 1 million parts were assembled using
> 3.25 million solder joints.

Yes, it's amazing that anything works when you figure out how many
solder joints are in there.

> Most problems are caught during microscope inspection of the drive
> panels (12 drives per panel) as they come out of the conveyor oven.
> The failure rate per drive is about 10%, consisting of solder
> bridges, tombstoning of parts and parts that have flipped upside down
> during SMT placement. These errors are corrected using SMT rework
> equipment under a microscope.

Yikes! I was envying you with your pick-and-place machine and soldering
ovens, but now I'm not so envious. Do you use glue dots to hold the
parts until reflow? Some of my boards have 800+ parts, so it would be a
nightmare!

> After the thru-hole parts are mounted and the drives are de-
> panelized, they undergo initial electrical power-up. The failure rate
> here is about 3%, consisting of primarily of individual component
> failure. Again, these drives are reworked and retested. If they still
> don't work, (<<1%) they are trashed.

Hmmm, well power electronics is different, of course, but I have approximately
0% component failure in the stuff I build. A VERY occasional component
failure in the field, other than obvious abuse, but almost 100% (I'd say,
maybe 99.75% if I had to assign a number) of all failures are soldering
problems or connectors that are not making proper contact.

> These tests catch well over 99% of all problem drives. Some of the
> ones that get away (the 22) would have been caught by a 24 hour burn-
> in cycle. This however is not economical (cost vs. benefit) for the
> price range drive we manufacture. It would require at least 50 drives
> running continuously while consuming 250W each (load and drive
> dissipation). That's 12,500W 24 hours a day with no certainty that
> every bad drive would be caught.

If you wanted to be really inventive, you could build a test stand that recycles
the power output from the drive back to the test stand. This might not
actually be that hard.

Jon