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Using an AOI for TH solder checks

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We have a YesTech YTV 2000. I'm being asked to set up a prog... - Aug 02, 2013 by SimplyComplex85  

#70177

Using an AOI for TH solder checks | 2 August, 2013

We have a YesTech YTV 2000. I'm being asked to set up a program to test the destination solder on through hole parts to make sure there is a lead in the hole and there is solder in the hole. If possible I need to test for bridging also. This is being done after they go through our wave. Has anyone accomplished this? Everything I've tried doesn't work.

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#70180

Using an AOI for TH solder checks | 2 August, 2013

Haven't done this but would start by contacting YesTech tech support and explaining what you are trying to do. They should be able to provide guidance including "..our equipment isn't intended for this application..." if that applies.

Good luck.

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#70181

Using an AOI for TH solder checks | 2 August, 2013

We use our Yestech and Mirtec to do that same thing. Verify the lead is in the hole and check the solder fillet. This is done as part of our normal solder inspection for mixed technology high runners.

You may not be able to put together a program that is 100%, but you should be able to come up with some criteria that would make you comfortable with the inspection. Yestech in particular has algorithms like "pattern matching" and "blob analysis" that should be helpful. Detecting bridging between through holes should be pretty simple too. You might try placing a solder inspection between the leads, and look for a "negative" result. (no solder = PASS)

A call to Yestech support would never be a bad thing.

I receive no benefit, and have no affiliation with any company mentioned above.

'hege

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#70222

Using an AOI for TH solder checks | 5 August, 2013

Our model of machine does not do "blob analysis" so I'm not sure what you mean by that. "Pattern matching" will only pass if I set the pass percentage down to about 45% and I don't feel comfortable with that. When using a solder inspection everything is at about a 0 when tested - solder, green board, everything. Solder only fails above a 60 or so. Granted I'm not real sure how the solder check works, I've just stuck with the defaults most of the time since they seem to work.

My boss said he was going to try to call the company to see what they had to say, I thought I might find out how other people have done it though. It is lead free solder if that matters.

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#70230

Using an AOI for TH solder checks | 5 August, 2013

I haven't done this either but have an idea of how I would address it. First, let me ask, are your leads crimped or straight? Most likely they are crimped which means you should get reflection from the lead. You could try a solder inspection (reverse image) on the lead itself (off-center from the pad). Or perhaps a solder inspection at the pad center, which should be black under red light. If there is no lead, your histogram should be mostly wight at pad center.

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#70273

Using an AOI for TH solder checks | 7 August, 2013

They're hand placed and hand trimmed so they may be straight, may not be. And the solder (I think because its lead free) is a dull grey color to there is no reflection from any of it. The solder, lead, and board all show as a dark grey color under red light.

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#70275

Using an AOI for TH solder checks | 7 August, 2013

By "dark grey color" do you mean with the histogram? Red or black maybe, but grey? Are you using a color camera? Can you use a reverse image? Does a bare unsoldered joint appear bright or reflective under red lighting? You could look for a low white total, like under normal conditions for a solder inspection if this is the case.

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#70279

Using an AOI for TH solder checks | 7 August, 2013

http://imgur.com/a/ujk7k

Maybe pictures will help.

The solder is dull (not dark) grey, so its not reflective.

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#70280

Using an AOI for TH solder checks | 7 August, 2013

You should be able to distinguish between solder and absence of solder. Have you tested it without solder?

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#70282

Using an AOI for TH solder checks | 7 August, 2013

Absence of solder is just black/super dark red which still falls under any percent I could put in there. So it passes. Maybe I'm a bit confused on how the machine checks solder in general anyway... 0%-60% is a pass by default. Thats anything dark - solder, board, black hole, etc. If its above 60% or so (an unsoldered lead for example that shines) it reflects too much light and fails. A lot of times I set it to 80% or so normally because shiny metal reflects a lot more light and is always above that 60% default and always failed. A solder test seems pointless to me no matter how I do it.

Then again, I have had basically no training on this machine. I've only read the manual here and there and just figured things out so far.

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#70283

Using an AOI for TH solder checks | 7 August, 2013

What type of filtering are you using? Your solder inspection should be using Histogram Inspection as the Decision and red filter for preprocess. Make sure your settings are correct and check your binarized image under Histogram setup. you should see reflection (large white areas) with a flat metal surface.

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#70284

Using an AOI for TH solder checks | 7 August, 2013

The pictures show you what I'm seeing and the settings. There aren't flat metal surfaces. There is a lead and a fillet there. So its shown as black, not white. We are using the red and the histogram.

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#70285

Using an AOI for TH solder checks | 7 August, 2013

I did not see the histogram image (didn't scroll down). My point about the flat metal surfaces is they should have a large white total under top-light with red filter. You should be able to distinguish between the two (fillets and no fillets). I know there is not one showing in the image, but you said you tested this and it still shows black, correct?

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ben

#70303

Using an AOI for TH solder checks | 8 August, 2013

Hi,

i use saki AOI and he have special algorithm for inspect TH that analyse presence of pin,angle of filet and short above the round of solder...

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#70306

Using an AOI for TH solder checks | 8 August, 2013

I found a manual for a slightly newer version of my machine and it explained some of the terms that I wasn't familiar with. That helped. Also it seems a slightly newer version of the YTV-2000 series has TH built right in. Mine just doesn't.

I played around with the machine this morning. Flat metal surfaces (soldered holes with no leads) passed with as low as 10% white. Holes with leads in them were 0%-6% white. So if I set the parameters down to 0-6% then I can test for a lead being present though I need to program in a bunch more to see how reliable that is. It still doesn't help me with bridging though since the board reflects randomly black/white.

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#70307

Using an AOI for TH solder checks | 8 August, 2013

I am not that familiar with the older systems. The software should be supported on both old and new alike unless you are limited by the operating system, but the camera will obviously have a lower resolution and perhaps the filtering is not quite as good. I have not used PTH Solder Analysis; although I do have it in my software. All of our products inspected are SMT. I know on our M1 systems that a flat TH pad reflects a lot of light because I have used them for fiducial marks in the past. They presented very good contrast compared to the empty hole.

If you have a license agreement with YesTech, the upgrade on the software is free (I believe they are at v2.8 currently). If not, you may want to consider purchasing it. If you are a current customer, the price is $2500.00, $15,000.00 if not. This is a bit steep, but may be cost justified if it gives you more tools for better analysis. But then again, your camera may limit you in this respect. I would call YesTech and talk to them about your system and what a software update could do for you.

Regarding your threshold on solder inspection, there is not much of a gap between a "good" and "bad" joint (4%). I suspect when you start running production you will experience a lot of false-calls. Regarding solder bridging, I assume you are using bank inspection correct? You should be using white light with blue filtering. You may need to tweak the lead bank parameters to fit your inspection needs.

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#70312

Using an AOI for TH solder checks | 8 August, 2013

I will mention purchasing the updated software with him but last time he looked into it he decided against it. So I was trying to see what we could with what we currently have.

As for blue filtering, we don't have that that I've seen. Red or white is it.

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#70314

Using an AOI for TH solder checks | 8 August, 2013

What version of sw do you have? What operating system? I don't think you are referring to filtering when you discuss "red and white." You're talking about the light source. You should have RGB filtering under "Preprocess" in your "Edit Solder Parameters" window. Lead bank inspection uses blob analysis with blue filtering. Do you have the ability to train a lead bank?

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#70450

Using an AOI for TH solder checks | 20 August, 2013

If the parts are hand placed and hand trimmed, why do you need to inspect whether the lead is in the hole. The operator should be inserting the part correctly. We have MIRTEC machines and they do a pixel comparison to "known good images". With a manual lead insertion and trimming, the good images could be infinite. Not sure how to help you there.

As for bridging, set up an inspection site that looks for the solder mask between the leads. Just a solid green area or whatever would be your known good. If a solder short is present, it would fail.

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#70455

Using an AOI for TH solder checks | 20 August, 2013

I read through this thread somewhat and checked out the pictures. I've programmed TH lead checks on a newer Yestech and an older Mirtec. I personally use the Yestech white-top/histogram check and the only solder inspection Mirtec has. In my experience capturing the lead tip causes too many false fails because they are trimmed in a random way or the lead is much smaller than the hole so they wander, you end up with a ton of alt pics and still manual overrides. Place your solder inspection on the actual fillet beside the lead. Nothing is perfect in AOI, but this is the best way I've found.

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#70456

Using an AOI for TH solder checks | 20 August, 2013

61443293@N03/9555358689" target="_blank">http://www.flickr.com/photos/61443293@N03/9555358689

Compiled some screen grabs. The only example I had offline is a top inspection of a TH leg. Same idea.

Picture 1: Add Solder Insp. Picture 2: Hist Perams. Adjust bottom slider until what you know is solder fillet, is black. Picture 3: Solder Perams.

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