There is learning on all brands requiring fine tuning the test parameters. The first point is not to allow defects to escape. Many brands can do a good job with preventing escapes. The struggle with all the brands becomes false calls. The companies rate their machines at defects per million opportunities. When the oportuninties are calculated for a PCA and a panel as many as every 3rd panel could be rejected for a false call. It all depends on wether the work is IPC 610 class 1,2 or 3 and the density and part count of the assembly. At this shop Orbotech was the better of the machines used. We are considering using them for paste inspection as well. There is a full time engineer reviewing the inspection criteria based on defect data, including false calls and escapes detected at other operations. This work has paid off with contiuing improvements in dection and reduction in false calls. AOI is a continous improvement activity. Plan to spend a great deal of time supporting it. If the line thinks that everything is a false call the next problem is they will pass real defects after reviewing them. Without knowing the type of work and volume it would be difficult to say if this is an apporpriate solution.
There is another difficulty in comparing AOI machines. The computational power available has been growing at such a great rate it has caused large differences in performance in generations of equipment. Some of the companies were badly stunned at the start of the century and are only know getting updated machines out. The increase in computaional power has allowed more and better alogrythems which are modified based on experiance. One engineer dislikes a brand because of the enoumous support they used to require 6 years ago. There have been changes since then. You need to determine what are the requiremnts for your site. Then go looking for what might work for you.
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