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Flippin' My LEDs

#2995

Flippin' My LEDs | 18 September, 2000

Periodically, our operators insert PTH LEDs on boards incorrectly, because of an apparent lack of standardization in the way various manufacturers package LEDs. For instance, for alternate parts some manufacturers make: * Cathode leads long, some make anodes short. [Wasn�t that a Randy Newman song? ... "Short Anodes"] * Cathode lead wide at the top, some make anodes wide at the top. * A flat edge on the plastic package at the cathode, others don't. * A flag inside the plastic package near the cathode, others don't.

What's your approach?

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#2996

Re: Flippin' My LEDs | 19 September, 2000

This is a tricky one. One lead longer doesn�t count after cutting prior to assembly, from the other choices the flat edge is the one I prefer. But real life hits, we found us trapped the same way. First: We made sure they were not mixed in the same batch. Second: The workers had to check the led first before starting the job with me or somebody else in response and than follow that procedure for the whole batch. In addition I made a small Led-tester for each assembly place. Further on we discussed the possibility of mounting an "edding" to that cutting device to attach a mark at the foot of the plasticbody with a crossreference in the placementdrawing. Didn�t come to that cause today we got rid of those PTH-Leds using only ESD-safe devices for frontpanel applications and SMDs for inside.

Allowing only one specific LED from one distributor seems not to work in your case ?

Good luck

Wolfgang

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David Harper

#2997

Re: Flippin' My LEDs | 20 September, 2000

We have the very same problem.. In our next job our assemblers will be placing 2 million PTH LEDs. Fortunately we get all out LED's from the same manufacturer and hope they come in bags. If not we gotta cut them off the tape.. and well... that just makes me grumpy. Usually... our red LED's always come in bags... no problems there same with the greens and sometimes the blues. If the LEDs are on tape.. we cut them off.. and the assemblers make sure the *flag* is pointed in the right direction. .. and from there, I take them and give them a quick lookover before soldering them, and finally catch any remaining backwards LEDs during test. Using this method.. if you could call it that.. we generally get one misplaced LED per 1500 placed LEDs.

SO... our method for the placement is : if not cut we use the lead length. If cut: we use the flags as the indicator. it works well for us.

One question... how well would a axial inserter work in placing LED's?

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David Harper

#2998

Re: Flippin' My LEDs | 20 September, 2000

We have the very same problem.. In our next job our assemblers will be placing 2 million PTH LEDs. Fortunately we get all out LED's from the same manufacturer and hope they come in bags. If not we gotta cut them off the tape.. and well... that just makes me grumpy. Usually... our red LED's always come in bags... no problems there same with the greens and sometimes the blues. If the LEDs are on tape.. we cut them off.. and the assemblers make sure the *flag* is pointed in the right direction. .. and from there, I take them and give them a quick lookover before soldering them, and finally catch any remaining backwards LEDs during test. Using this method.. if you could call it that.. we generally get one misplaced LED per 1500 placed LEDs.

SO... our method for the placement is : if not cut we use the lead length. If cut: we use the flags as the indicator. it works well for us.

One question... how well would a axial inserter work in placing LED's?

reply »

David Harper

#2999

Re: Flippin' My LEDs | 20 September, 2000

We have the very same problem.. In our next job our assemblers will be placing 2 million PTH LEDs. Fortunately we get all out LED's from the same manufacturer and hope they come in bags. If not we gotta cut them off the tape.. and well... that just makes me grumpy. Usually... our red LED's always come in bags... no problems there same with the greens and sometimes the blues. If the LEDs are on tape.. we cut them off.. and the assemblers make sure the *flag* is pointed in the right direction. .. and from there, I take them and give them a quick lookover before soldering them, and finally catch any remaining backwards LEDs during test. Using this method.. if you could call it that.. we generally get one misplaced LED per 1500 placed LEDs.

SO... our method for the placement is : if not cut we use the lead length. If cut: we use the flags as the indicator. it works well for us.

One question... how well would a radial inserter work in placing LED's?

reply »

David Harper

#3000

Sorry about that, didn't mean to port that msg 3 times | 20 September, 2000

dang nabit

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