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AOI usage

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AOI usage | 10 March, 2010

Currently I'm working on a study of the quality of our SMD process. For this I am investigating the possibility of adding an of-line AOI There has been previous research done (late 2007), bij the company I work for.

Since there could have changed a lot over the last two years I’m looking for some aditional information I couldn’t find in the available documentation. I'm looking for the following information to build a buissines case for it - Is it nescesary to write a program for every PCB design - How much time does it take to write such a program - Is it possible for the AOI inspection (on the SMD components) to perform after conventional components have been placed. - Are the prices for an AOI the same as 2 years ago or did they change (and how)? - Is it possible for the AOI to see how (and where in the proces) the errors were made? I hope that you can answere some, or all questions.

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AOI usage | 23 March, 2010

Hello Sibbe, Thank you for posting your questions.

There are a few approaches to AOI with the majority being program driven. There are a couple of systems that are simply comparative in that you use the system to compare a golden board to others that you wish to “inspect”. This may be a good first step into Optical Inspection, but they are very unreliable and very operator intensive.

The next step up from there is the systems at the mid range of the market that provide adequate inspection by way of pattern matching as the primary form of Optical Inspection. These systems are very good at post placement, pre re-flow inspection, but fall short at solder joint or lifted lead inspection. The downside to the pattern match systems are the usually high false failure rates and limited post-reflow solder inspection. Programming time for these systems is usually under an hour, but the debug time could last for hours or days depending on your component mix.

The High End AOI systems are very heavy into Algorithm based inspection. These systems are typically very programming intensive with the exception of a couple. Programming time can take anywhere from 2.5 hours (Complete program and Debug) to 1 week depending on the complexity of the assembly being programmed. These systems provide superior defect coverage with measurement capabilities and are typically the most reliable.

Omron AOI systems are a great blend of the Mid-Range systems’ ease of use, ease of programming and price point, and the High End Inspection Capabilities of our Algorithm based inspection method. Our programming is very user friendly and typically takes 2 to 3 hours to complete, debug included, which sets up apart from most of the other High End AOI systems on the market. We innovated AOI 25 years ago and are world leaders today.

If you have any more specific questions or would like to discuss further, please contact me at

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AOI usage | 24 March, 2010

I recommanded AOI inspection as I am a AOI programmer too. 1.Yes u have to write programm for every PCB design,but u maintain the standard library. 2.If u have standard library and SMT machine CAD file ,then it doesnt take more than 30 mins. 3.No I dont recommend this that inspection in AOI after insertion of conv. comp. 4.U can easily trace out the root cause of the defect detected by AOI.

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AOI usage | 25 March, 2010


Since it has been some time since I've posted this, we are few steps ferder with the search to an AOI. I'm already having contact with Duncan from Omron. He gave me almost the same answers to my questions.Accept for the programming time, which he said was 'serveral minutes'. I quess he didn't take the debug time with it.

Thanks for the reply on my questions.


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AOI usage | 26 March, 2010

The programming time depends on the system you are using. I use YesTech. It has been a reliable system for catching the majority of production issues. The programming time on this system is around 20-30 min. with a full library, meaning you don't have a lot of new components to train. Otherwise, it will take around an hour if your starting from scratch, and this includes debugging. But after a few recipes, you should have the majority of your parts trained. So yes, you can create a recipe with debugging in about 1/2 hour. Since your are creating your recipe from the library, there shouldn't be much debugging involved. Heavy debugging will occur when you have many new parts that haven't been trained.

Regarding your question about inspection with conventional components installed: You can do this but you need to keep a couple of things in mind. 1) The placement of the PTH components in relation to your SMD components can cause shadowing on your AOI which will make it difficult for the camera to see. So tall components next to an SMD part is not a good thing. 2) The clearance under the camera head is another consideration. Most AOIs will have a clearance of 1-1.5". If you have PTH parts that exceed this height requirement you won't be able to run the board through, unless you place the tall parts post-AOI, which is a possibility. 3) Question: Will the inspection happen post-wave? If so, this will effect your decision of where to place the AOI. If the board will fit, you can do this. If it's pre-wave, you need to decide how you will handle rejects with all the loose PTH components on it. These boards will need to go to rework, and handling will be an issue.

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