R0402 very high fail rate while placing

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Hi, I need help with placing 0402 resistors 90% of them are ... - Nov 08, 2022 by jojoLED

1. For laser machines, there should be setting for Z - at w... - Nov 09, 2022 by Evtimov

Take all of the nozzles out that are being used to place the... - Nov 09, 2022 by Sr. Tech

Those are pretty old machines at this point, are they rated ... - Nov 10, 2022 by dontfeedphils

Are you using the correct nozzle for 0402? Cant remember the... - Nov 10, 2022 by sarason

jojoLED

#88600

R0402 very high fail rate while placing | 8 November, 2022

Hi, I need help with placing 0402 resistors 90% of them are picked correctly, but are not placed(thrown away) giving me error : LASER retry over. Slightly higher varistors in same package have slightly better placing rate, about 50%, but still not sufficient. Machine is JUKI KE 750L, components are picked correctly, so there seems to be problem with Laser alignment I guess only. Lasers on both heads seems to work OK, checking on monitor shows laser recognized path OK I guess, laser optics are cleaned with IPA.... I have tried to change recognition algorithms from 1 to 0(and 2 and 3 too), changing to 0 helped a litle , now the rate of NOT placed R0402 is about 30%, but still super too much. Any more ideas how to make it work solidly?....all other larger components are picked and placed perfectly OK, with fail rate bellow 0.01%. PLEASE HELP, I am lost, need to start assembling one design and I am stuck with it....

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Evtimov

#88603

R0402 very high fail rate while placing | 9 November, 2022

1. For laser machines, there should be setting for Z - at what level you should cut measure the part in Z axis. 2. Check all calibrations are in place and passing 3. Check resistor package setup in the software - all dimensions

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Sr. Tech

#88604

R0402 very high fail rate while placing | 9 November, 2022

Take all of the nozzles out that are being used to place these parts and look at them under a microscope closely for blockages or dings in the surface that contacts the component.

Check that the nozzle travel moves up and down smoothly and freely with very little resistance.

Additionally, I have seen junk aftermarket nozzles cause this.

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dontfeedphils

#88606

R0402 very high fail rate while placing | 10 November, 2022

Those are pretty old machines at this point, are they rated for 0402 placement?

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sarason

#88611

R0402 very high fail rate while placing | 10 November, 2022

Are you using the correct nozzle for 0402? Cant remember the number OTTOMH but 501 rings a bell. somewhere I have the table, it is in the Juki service manual IIRC. This would explain placing all others okay but 0402 is not very good , Senoirtech is correct a little solder pasts on the barrel or in the tip can cause lots of problems. Also hieght of laser relative to component is critical. Shadows falling on the component affecting intensity cause very occasional problems.

sarason

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