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chip placed upside down

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Hello all Good morning. I just want to ask with you guy... - Jun 07, 2014 by Aberon  

#72218

chip placed upside down | 7 June, 2014

Hello all Good morning.

I just want to ask with you guys about the problem that we always experienced in our production. We could not get our target ppm due. to inverted placement of chip resistor. We are using 2000 series juki mounter and cf03hp juki feeder. At the end of the month we always encounter this problem with 0603 and 1005 chip size. Our analysis is that the packaging is too big for the chip causing the chip to move around which therw is a possibility that the nozzle will pick the chip at the causing it flip. Please give some other items to look for that will eliminate this problem

Thankyou

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#72228

chip placed upside down | 10 June, 2014

Your target ppm in on the Juki machine a take it. So it's rejecting these parts due to the inversion? Any way to disable this. A right-side down resistor is not ideal, but it will certainly work electrically.

Reese

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#72232

chip placed upside down | 10 June, 2014

Yes it will electrically but on the appearance side it is no good. Does it have something to do with the feeder or the nozzle?

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#72233

chip placed upside down | 10 June, 2014

Perhaps neither. I assume the part is T&R. It's flipping inside the tape before placement. I don't know how the nozzle could be doing it. There could be excess vibration on the feeder which is causing the part to flip. Just a thought.

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#72234

chip placed upside down | 10 June, 2014

Possibly the components have been re-taped in that particular reel, with only electrical function in mind?

Hard to see a nozzle causing a flip, and I am thinking if your feeders are vibrating bad enough to flip the components in the tape, that you might have other things to worry about!

Are the components sitting in the correct size pocket in the Tape? Is there actually room for a flip?

A mystery wrapped in an enigma. Nice. 'hege

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#72235

chip placed upside down | 10 June, 2014

I have seen this on a MyDATA machine and we had to slow our feed rate of the feeder down. That seemed to do the trick. We concluded the carrier tape was too large for the part, but our vendor didn't really seem to care.

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#72237

chip placed upside down | 10 June, 2014

Our observation also is that the tape size is too big for the chip which allows the tape to move around. With this i would like to know if there is is a setting in the machine that would slow the feeding rate. We are using juki mounter 2000 series. And also can you give me some idea on what are the possible causes to make the feeder vibrate so bad.

Thank you

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#72238

chip placed upside down | 10 June, 2014

In our assumption also, nozzle is magnetized because the chip termination is made up of alloy so possibilty that when there is excessive contact between two metals there magnetic field produce, so during z up chip is magnetize on the nozzle causing it to flip. Please gve me ur thoughts on this

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#72239

chip placed upside down | 11 June, 2014

That would be easy to check. Degaus the whole nozzle not just the tip. It should take more than a week to become magnetized again. If it becomes magnetic sooner maybe degauss the head? I would also make sure your vacuum does not come on till the nozzle contacts the chip. In running experiments on nozzles we have seen some parts leap up to the nozzle as the nozzle approaches.

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#72240

chip placed upside down | 11 June, 2014

I do not know the Juki machines, but on my Essemtec I need to turn on the vac after the nozzle is down for 0402 parts. I also cannot touch/hit the current part/tape because it tends to flip the next part from the tape bounce. Then there is also the tape covers from certain mfg that appear to have a static charge when pealed back.

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#72241

chip placed upside down | 11 June, 2014

Do you mean that the vacuum will lift up the chip before it touches it? We are planning to evaluate a ceramic nozzle to get rid of magnetization. What is your thoughts on this?

Thank you

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#72242

chip placed upside down | 11 June, 2014

Do you mean that pick up z height is taught too deep thats why it can possibly flip the next chip. I will check our machine if have the same setting as yours. Thank you for this thought.

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#72243

chip placed upside down | 11 June, 2014

I do not have machine experience, but I think vacuum too early would be a more likely cause of chips leaping to a nozzle. Juki nozzles are made of hardened stainless and could be slightly magnetic, but the end is relatively small and would not have the ability to lift like the vacuum. If vacuum is applied to early I would thing the cause would be an inappropriate setting on whatever triggers the valve to open or a mainenance issue such as a torn oring in the valve. One other thing top look at, is your feeder (tape pocket) accurately centered under your nozzle during picking? Off center with excessive room in the pocket could cause the chip to be 90 degrees of the intended surface, but probably not picking from the bottom of the chip.

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#72244

chip placed upside down | 11 June, 2014

As has been mentioned, it's likely that the component is moving in the tape, and flipping over. It is not likely that the pick/place operation is causing this.

What I haven't seen mentioned is that there is an acceptability criteria in IPC for inverted chip components. It isn't ideal, and could be a process indicator; but, if it's the only thing affecting your PPM goals, I'd suggest that the PPM goals need to be reviewed.

When quality is rejecting product for things that are acceptable within IPC, money is being wasted throughout the process; whether it's at the analysis phase, or, certainly at the rework phase.

Chase down the potential issue, for sure, to make sure that your process is remaining robust; but, don't get beaten up for quality failures that aren't actual failures.

cheers, ..rob

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#72246

chip placed upside down | 11 June, 2014

With Essemtec software you can specify to turn on vacuum once the nozzle is down at the part. The default method is to turn on the vacuum while the nozzle is up, but starting to move down. For light/tiny parts this can have the effect of making them jump up to the nozzle as it approaches the part.

The minimum size for my machine is 0402. I haven't had a problem with my nozzles getting magnetized, but a different mfg might use different materials to make their nozzles.

My machine is equipped with an auto part height detection (for the feeders), but different tapes and parts will measure slightly different, so I end up checking manually on smaller parts. I adjust for the nozzle to not quite touch the part during pickup. I can see the part jump up to the nozzle when I turn on the vacuum while setting the nozzle height.

If the nozzle comes down too far (and too fast) the next part can get flipped as the tape bounces.

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#72247

chip placed upside down | 11 June, 2014

yes, you should look to see on that particular feeders Z axis setting. When the tip goes down to the part it may be traveling down little too much. Just make sure you check which way is your - and + increments going and do not exceed more than 30 or 40 ten thousandths of it to begin with. Little bit of trail and error you can down tune it. Good luck and best regards, hope it might work for you. Aybars

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#72248

chip placed upside down | 11 June, 2014

Thank you for all the suggestions.I will conduct evaluation bbase on our discussions

God bless

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