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SMT SOT-23 Part Rotation

SMT SOT-23 Part Rotation

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I have a SMT-460 machine that works pretty good for the most... - Jan 30, 2022 by Chuckphd53

In my machines (Yamaha / Assembleon / Philips) there is an o... - Jan 31, 2022 by Michał

Thanks for the reply... I have two camera types Low Res an... - Jan 31, 2022 by Chuckphd53

I had such problems with SOT-23, how I confused N and S - in... - Jan 31, 2022 by Michał

Make sure your pick up and Placement theta are correct. SOT-... - Feb 02, 2022 by DWL

The rotation is a fixed parameter..... and of the 9 parts, ... - Feb 02, 2022 by Chuckphd53

Something we've run into in the past, not on those machines,... - Feb 02, 2022 by Chris

wow that is wild....definetly will takea look at that ... - Feb 03, 2022 by Chuckphd53

Do you see foot indentations in the paste? If the part is be... - Feb 03, 2022 by DWL

Yes, it is being pushed into the paste, did a slow place mot... - Feb 03, 2022 by Chuckphd53

Another long shot. Are there any irregularities in the shape... - Feb 03, 2022 by Stephen

If the part makes it in the right location by leads touching... - Feb 04, 2022 by Evtimov

much appreciate the guidance... will be building next week a... - Feb 04, 2022 by Chuckphd53

Chuckphd53

#87548

SMT SOT-23 Part Rotation | 30 January, 2022

I have a SMT-460 machine that works pretty good for the most part. When placing parts I have an issue with the SOT-23 rotation 90deg. Using both Juki 503 / 504 nozzle it will pick and place all of the 0805 and 1206 resistors/caps just fine. I have 9 SOT-23 parts that most every time one or two of the parts will mount off a bit. The SOT-23 part gets picked then rotated right 90degs before being place. I was using 3 of the placement heads but decided to try just a single head to see if the error would correct the issue or make it better, but nope. I did try another Nozzle with same results. Wierd part is of the 9 SOT-23 parts being placed, it can be any of them or two or three.... Here is my thought, when the SOT-23 is picked, it has to rotate right 90 degs then be placed! I did notice that each time the rotation is shy of reaching its full 90Deg turn, Never over 90Degs, Like the rotate servo is sticking. But I tried on placment head 2,3,4 all with same results. So could I have all the heads with sticky servos ? Maybe. I also thought my Air supply (85-90psi Recommended) was suspect, so I turned it up to 95-100psi.... again same results.

So: keeping in mind using the same heads for the 0805 parts and rotating them and othe parts 90Deg, and one part 180deg all work fine...

Lastly I do have the feeder part pick up aligned dead center of the SOT-23. So not pick up on the edge.

I have also slowed the ROTATE speed down considerably, with no improvement.

Been having this issue for a couple years, and it is always the SOT-23..

Any of you guru's got an idea I should try?

I do need to lub. the servos, (oil type recommendations please )

Thanks Chuck

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Michał

#87551

SMT SOT-23 Part Rotation | 31 January, 2022

In my machines (Yamaha / Assembleon / Philips) there is an option to FIRST rotate the element and then check it with a camera (I do not use it, because it requires an additional better camera) - maybe you will find something like that at home?

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Chuckphd53

#87552

SMT SOT-23 Part Rotation | 31 January, 2022

Thanks for the reply...

I have two camera types Low Res and Hi Res... I use the Low Res which is just for the 'absence' of part ie. empty feeder etc so it just makes sure the part got picked up... I could try the High Res camera, but it does increase the place times..... which I usually just inspect the parts and fix before they go in the oven...

It baffles me that the Resistors 0805/1206 all place perfect but they do have a better surface to be picked up...

Oh well... this is strange...... I actually turned up the speed on PICKUP and PLACE to board and it helped with the misalignment....ugh would have thought that would have been disastrous.... but nope....

Gremlins......ugh..

:) Chuck

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Michał

#87554

SMT SOT-23 Part Rotation | 31 January, 2022

I had such problems with SOT-23, how I confused N and S - inversely I entered the number of pins, etc. Check again and again :)

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DWL

#87566

SMT SOT-23 Part Rotation | 2 February, 2022

Make sure your pick up and Placement theta are correct. SOT-23 are notorious for having bad theta data in part libraries.

I had an old placement machine that would center the part with an upward camera, looking at the feet. If I had the wrong pick theta in the program, the machine still managed to rotate the part around, so it fit the parameters it was looking for. the part would place on the board but 45 degrees off.

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Chuckphd53

#87567

SMT SOT-23 Part Rotation | 2 February, 2022

The rotation is a fixed parameter.....

and of the 9 parts, randomly it will skew the part, could be one or more... I was thinking maybe the solder paste was too dry and during the LIFT after placement it would blow the part sideways..

Yes I am on a wing and a prayer....

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Chris

#87568

SMT SOT-23 Part Rotation | 2 February, 2022

Something we've run into in the past, not on those machines, a different brand completely, and I have no experience with yours. We were having what you described and what we found was during the part being scanned, there was a bolt that held the shroud on the camera and as it scanned across it would ever so lightly(obviously)touch that screw and knock it out of alignment. We found it by video in slow mo. We replaced the bolt with a low profile one and that was the end. Maybe you have something similar going on?

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Chuckphd53

#87569

SMT SOT-23 Part Rotation | 3 February, 2022

wow that is wild....definetly will takea look at that

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DWL

#87574

SMT SOT-23 Part Rotation | 3 February, 2022

Do you see foot indentations in the paste? If the part is being blown after placement, you'll see the indentations in the paste.

Another random thought; We had worn nozzles and the camera would sometimes see a spot where the paint wore off and read it as a lead.

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Chuckphd53

#87575

SMT SOT-23 Part Rotation | 3 February, 2022

Yes, it is being pushed into the paste, did a slow place motion and you can see the nozzle press (spring) as it reaches the board height...

the nozzle is black, and I tried a new nozzle also...

good thoughts tho.... much apreciate the help...

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Stephen

#87576

SMT SOT-23 Part Rotation | 3 February, 2022

Another long shot. Are there any irregularities in the shape of the body or leads of the parts that are skewed? Any flash from the molding process for example? Almost all SOT-23s that I have seen are basically perfect but I seem to remember seeing some that were not perfect.

I personally suspect a vision alignment problem more so than a part shifting on the nozzle problem.

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Evtimov

#87579

SMT SOT-23 Part Rotation | 4 February, 2022

If the part makes it in the right location by leads touching the paste in the right location, you have very few places to check. 1. Check parameters like air kiss, or some timings you can keep the part down in placement position for a while. Sometimes nozzle will pick the part while leaving placement location as the vacuum did not let go. 2. Check cover tape/parts top surface for being too sticky because of glue on corer tape.

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Chuckphd53

#87580

SMT SOT-23 Part Rotation | 4 February, 2022

much appreciate the guidance... will be building next week and take a look again at those suggestions....

great info guys :) chuck

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