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AOI-problems lifted lead on qfp-100

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AOI-problems lifted lead on qfp-100 | 29 September, 2010


We have a problem here in the company with AOI system, most of the problem is lifted lead on qfp components.We are using SAKI BF-planet-x.

Most of the defects like mising components 603 or 402 are no problem but if it comes to lifted lead even on SO-16, it generate to many false defects or it miss the real ones.

Please have anyone any experience with saki and with sofware they use ?

Or it is possible to detect such a defects like lifted lead on qfp 100 or higher with AOI that have cameras on top ?

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AOI-problems lifted lead on qfp-100 | 29 September, 2010

In my experience, the best way to do a lifted lead inspection on a QFP is by laser height measurement.

It is very difficult to consistently catch a lifted lead with only a top down camera. As you say, too many false calls, and still some escapes.

Side viewing cameras can improve the inspection and false call rate, but is still not a substitute for a lead by lead inspection of height using a laser, if that is the key defect you are chasing.

Don't forget to use the opportunities to inspect problematic parts before the parts hit the (Floor, SMT machine, and PCB).

Look at Mirtec, or Yestech for this kind of inspection at reasonable pricing. I am not familiar with the SAKI models.

I have no affiliation with the above referenced companies.

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AOI-problems lifted lead on qfp-100 | 1 October, 2010

Your real problem is further upstream. The limitations of your AOI aside, first find out why your leads are being lifted. Is it through handling or are they from the reel that way? To address your AOI question, Hegemon is correct, coplanarity inspection is the most effective way to test for lifted leads. I don't know if YesTech has any systems with this option or not. A simple call or visit to their website can answer this question. I believe Mirtec does have a system with a laser option for testing lead coplanarity. One technique that I have had some success with is a technique called "test tip gray." Your system may call it something else, but you create separate solder inspection boxes at the end of the pad (My system does this automatically by enabling it. Yours may not have this option but you might try using a separate solder inspection box). The idea is the inspection will show a deficiency of solder at the tip, as it should for a properly soldered lead. Most of the solder will wick around the lead. If there is a lifted lead, than there will be more solder than normal at the tip. This may help.

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AOI-problems lifted lead on qfp-100 | 2 October, 2010

Thanks for your feedback, both of you. But my problem is that we have high mix and low volume its obout 50-200 pieces. And we also have manual paste priter so the solder on the pad look always diferent. I believe that there is the problem but I canot compare it with other tipes of AOI.So it is fairly hard to explain it to why is it not working.

For any advice I ll be grateful.

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AOI-problems lifted lead on qfp-100 | 2 October, 2010

Yes it is possible to detect lifted leads with top view camera's. The camera's must be coupled with software that utilizes algorithm programs. MVP - Machine Vision Products out of Carlsbad, California uses algorithms in their software. Most AOI companies do not.

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AOI-problems lifted lead on qfp-100 | 2 October, 2010

Possible, but difficult. What algorithm programs are you referring to? Mirtec and YesTech both utilize algorithms in their respective software. The algorithm is simply a series of instructions to perform the inspection. In this case, rules-based, because you as the programmer, tell the system what the parameters are for the inspection. Such as pass-score, histogram threshold, offsets and the like. So then an algorithm, on the surface, is the inspection method used to inspect the device. This is what the programmer sees. The best thing for detecting lifted leads is laser inspection, hands down. Again, check out Mirtec and see what they have to offer.

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AOI-problems lifted lead on qfp-100 | 5 October, 2010

Reese is right. We use algorithm our AOI but the make it find liftead lead on qfp or such... it took me all day to set program and even then some defects pass so that is why Im asking..

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AOI-problems lifted lead on qfp-100 | 5 October, 2010

I checked with MVP after Reese's comment, they use special color lighting in addition and have many customers detecting lifted leads successfully. It doesn't really matter unless your looking for a better AOI system/supplier.

Hopefully your equipment supplier is giving you support on this, programming can be difficult making it critical to have good support.

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AOI-problems lifted lead on qfp-100 | 5 October, 2010

It is possible to infer that the lead is lifted based on the toe fillet appearance, but it's not as reliable as say a laser or xray inspection. This is usually done by varying the light source location and or color and looking at the images resulting from the different angle of incidences. A toe fillet is not required per IPC, and if the sheared end of the lead is not solderable then this method may reject a nonlifted lead.

Take a part with good leads and joints and a few lifted leads and see what looks different to the AOI vision, play with the lighting levels,inspection types/algorithims,...etc and see if you can find a good way for the SAKI to inspect for it.

Good luck, Mike

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AOI-problems lifted lead on qfp-100 | 13 October, 2010

Hello Patejl, Many AOI machines have issues with lifted leads. I recall SAKI failed to catch lifted leads on my test PCB when I evaluated them. If you are looking for replacement equipment, check out MIRTEC. We now have four of these systems configured with laser height inspection for lifted BGAs and lifted leads.

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AOI-problems lifted lead on qfp-100 | 14 October, 2010

Hello Pvasquez

Well that is not a good news but it is what I thought. Lets see what will say our headquarters.Could you send me some more information or materials obout mirtec machines so I can present it to our company.


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AOI-problems lifted lead on qfp-100 | 2 November, 2010

Hello Patejl,

Sorry, haven't been to the forum recently. Check out mirtec's website. There is some really detailed information there:

Chat with you soon.

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AOI-problems lifted lead on qfp-100 | 4 November, 2010

The best method i have for the few lifted/bent lead issues we have is i use a ic/bridge inspector with all its default options to check for bridges and solder at the tip. then i add a solder inspector but this time accrost all pins at the downslope of the pin. i set up the solder inspector so dark=black and light=white and set the binerise at about 50%. i set the pass threshold for a low number say 1% and then i invert the result.

if any leads are lifted they will show a lighter color than normal on the downslope and will cause the solder inspector to pass(thats why it has invert result enabled).

This is on a mirtec machine but id expect you can rig something up on yours.

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