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AOI vs. electrical test

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Gary Kemp

#38776

AOI vs. electrical test | 3 January, 2006

Can anyone provide for me their prospective regarding AOI vs. electrical test? Which is better for generating REAL benefit in providing customer with a marked increase in defect free product? Thanks for any input you can provide.

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Cmiller

#38779

AOI vs. electrical test | 3 January, 2006

In circuit testing is expensive up front because of the fixture cost but the tests are fast. AOI programs can be develpoed in less than a day but take longer to run. If you have good test coverage, in circuit would be a better choice in my opinion-if the volume is there to justify the fixture cost. We are a small to mid volume EMS provider. Our YesTech AOI machine runs 12 hours a day and our HP-3070 ICT runs a few hours a month. In the real world, most customers are not willing to pay for ICT fixtures.

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#38801

AOI vs. electrical test | 4 January, 2006

Your process makes a bigger difference. What I have seen is ICT done early is better than AOI done more than a half shift later, and AOI done early is better than ICT done more than a half shift later. For high mix/low volume, I would go with AOI while the boards are still warm from the oven.

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#38812

AOI vs. electrical test | 4 January, 2006

In-Circuit Test is the best method for ensuring solder joint connections. It is a much more reliable than AOI. An ICT machine can ensure solder connections are made for array package devices such as BGA, PGA, etc... AOI is best for component I.D.- is there a component there, is it the correct component and is it in the correct orientation. That is for those components with markings. Many small packages do not, so there ICT has the advantage.

There are flying probe ICT machines that have AOI options. The concept here is that you ICT all your passives and AOI your ICs or any other component that cannot be electrically measured accurately. Flying probe ICT w/ AOI option is the best method for MDA (Manufacturing Defect Analysis) in my view because it gives more coverage, you can electrically test components with no markings to ensure they are correct. Of course some capacitors cannot be measured reliably, like filter caps, so in that case you can use the AOI option to at least confirm there is a capacitor there.

One flying prober is the Pilot from Seica- Italy, http://www.seica.com

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#38819

AOI vs. electrical test | 4 January, 2006

I have used all of test and inspection techniques available out there: AOI, AXI, Flying Probe, ICT, and FCT. The reality is that they all have a place in manufacturing based on the type and complexity of product you bild, the industry it is intended for, volumes, return rates and a bunch of other factors. What you need is a consultant to come in and suggest a strategy. Sometimes that strategy involves different pieces of equipment that inspect or test at various stages. The bottom line is that the sooner you find or even better prevent the defect the higher your yields and margins are going to be. Your goal should be the bottom line not how much it costs to implement a solution. It is also beneficial to draw from the experience of others by simply looking at industry data.

I would be happy to talk to you or anyone interested directly about test and inspection strategies, just drop me a note and we'll take it offline.

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