Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


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Please dewscribe the advantages and disadvantages of digital video inspection syatem vs optical microscope system for visual inspection of elctronic assemblies . Also please advise the suitable system (whether optical or video microscope )for visula inspection of SMT PCBs including QFPs & fine pit ICs .

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By "digital video inspection system", I'll assume you mean AOI. I have only dealt with one AOI system, YesTech, and in my opinion I'd say that AOI is much more consistent and advantageous than manual microscope inspections. Specifically, with the YesTech systems, there is a level of SPC data-logging that will show you exactly where, how many, and sometimes why the defects are occuring. The EMS that I work at now is a HIGH mix, low-mid volume supplier and if we didn't have an AOI system, I'm pretty sure we would not be in buiness anymore. There are many AOI systems to choose from, but from what I've heard, Mirtec and YesTech are the more popular choices. Mirtech can be a little more expensive, but I have been told it is much more consistent with defect inspections and has a lower false call rate. As with any AOI system, the amount of effort and attention to detail will DIRECTLY affect the quality that comes out of it. Good luck and happy hunting.

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Many thanks for your reply. We would like to clarify two things;

1. We have recently purchased a vision system with oblique viewing facility to rotate the camera with 40x magnification, which we find useful to inspect fine pitch components .

2. What about the cost of AOI . Even if we buy an AOI , we will not be 100% sure about the soldering joint result especially for fine pitch QFPs and J leaded packages and other fine pitch SMDs . I believe when we inspect these components with max. maginification (with oblique viewing facility) by using optical high end vision system , we can manually see the image and review the results if required.

Please have your views.

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My company is also looking at AOI. There is one group that is promoting flying probe ICT as well. We can only afford to purchase one or the other this year. Does anyone have data that compares advantages/disadvantages of each? I see them as complimentary, not competing but there is some degree of overlap in benefits. We're a high mix low volume shop working to IPC Class 3. For AOI, so far we like Orbotech (excellent OCR/OCV combination that they call OCX), Yestech (for price vs features), Marantz & Mirtec. I am interested in any comparison data for these or other machines.

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Hello First let me state that I work for an AOI vendor. I will not reference any particular brand of AOI.

When considering AOI you need to ask your self several questions. These are in no particular order.

What is you product mix (IE High mix low volume or low mix high volume)? this can be the determining factor for your purchase. Some machines take longer to program but with that can give better features and defect capture capability.

Do you need a multi camera machine, And what does it buy you? And is it cost/time effective. (how much extra programming and debug does it add)

Are you looking for price being your driving factor or is it performance?

How easy it is to program and how long does it take to program. Also do the quoted programming times include how long it takes to actually get the program usable for production inspection (Debugging). IE with a low false call rate and how easy is it to deal with part variation and alternate vender updates to the program.

Also be careful of advice. AOI developments are fast paced and the machine you or the advisor saw 2 years ago may have improved dramatically or sat stagnant.

Look at what each vendor has to offer in after sales service, Training, support warrantee and reliability.

And make sure you compare apples to apples. Make a comparison table for both features and price. And lastly get a demo on each machine in you facility and get them to run a set of boards with your hot points for inspection on it. That you supply the boards when they arrive.

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And I might suggest AOI at post print and post place to hone your process before even considering post reflow AOI.

Post reflow AOI alone is iffy and an absolute chore to keep up with. But monitoring paste and placement are very easy. Establish a stable processes and you will be very able to predict post reflow results.

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