In a message dated 6/24/98 6:24:19 PM Pacific Daylight Time,
[log in to unmask] writes:
> We are currently dealing with a serious problem while running 32mm carrier
> tape on CP642. The components are 8x2 SDRAM TSOP44. For every 5000 DRAM,
> we used to have 30-50 of them missing due to miss-pick (or other problems
> which we have not figured out yet). These components either being cut by
> the cutter plate or trashed away to the trash-box and end up we lost them.
>
> Do any one have the same problem and know how to fix them? Because when we
> call Micron guys, they said that if only one customer complain things that
> they never heard, then it is not sufficient enough for them to change their
> vendor...
>
> Please advise!!!
>
> My Nguyen
> Viking Components Inc.
> Rancho Santa Margarita, CA 92688
> (714) 643 7255 @374
>
Hello My,
When you say you're missing 30-50 of them per reel, are you getting those
numbers from doing the math on how many SIMM's or Modules you should have
built based on the number of components that were given to you, or are those
the numbers coming from the MCS when you look at the management data? The
reason I ask that is because if your operators are loading the feeders and not
advancing the first part of the reel up to the pick-up point, you'll get over-
inflated mispicks being logged while the machine is indexing the feeder with
all those empty pockets until a part is presented that the machine can pick.
Another thing that you can check if you already haven't, is the sharpness
of the cutter blades at the waste tape cutter. If they're not making a clean
cut, the tape will sometimes "furl-up" and not guide into the cutter area very
well. This causes the tape from being advanced properly and many times causes
the feeder to become mis-indexed throwing everything a half-pitch off...that's
when you hear the _KA-CHUNK_ of the blades slicing and a dicing them DRAM's
in half...better than a Ginsu knife I would say!! (GRIN) I'd just about bet
that if you say you're seeing disected DRAM's in your waste tape box, then
it's been cutting DRAM's like that fer a while, and them blades won't stay
sharp for long doing that...
Another area to check is that sometimes I've found that some tape and
reel houses will use masking tape to secure the end of the tape on to the
center hub of the reel when winding it all up on the reel, instead of using
the little slot at the center hub to stuff the end of tape into. Sure, masking
tape works good to keep the end on the reel when you're winding it up, but
when you've got it on the machine and you're coming to the end of the reel,
the tape adhesive can sometimes be so strong that it won't release the tape at
the end, which again causes the feeder to mis-index and put the pick-up a half
a pitch off...KA-CHUNK!! Whenever I've found that, I watch the feeder pretty
close and when it gets down towards the end, I'll pause the machine and loosen
that masking tape up, or rip it off so when the feeder indexes, it doesn't
have the added force of pulling the parts AND the masking tape from the center
hub.
One last, area to check, is that I've had operators change the stop-
blocks that set the pitch in the feeders without telling anybody, and come to
find out that it was the wrong pitch for the component...but if that happens,
you'll be missing more than just 50 parts out of 5,000...normally, it'll pick
one part, and throw the next one away, pick one part, waste the next one, and
so on, and so forth...
-Steve Gregory-
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