The question you want to ask yourself is what do you want to measure?
If you want to measure the placement accuracy of your placement machine then you will need to
mount the inspection system pre reflow as there is no point mounting the system post reflow as
the migration of the components will effect the results. You will need an AOI system that can
offer a gauging capability. If you just want to inspect for component defects then again pre
reflow would be better, as solder joint inspection causes the higher percentage of false calls
on the AOI systems I have used.
If you want the AOI system to complete a total inspection of components and solder joints then
post reflow is the position for you. BUT you will need to buy a system which doesn't give you
excessive false calls for solder quality and a system which can offer a short enough
inspection cycle time so as not to become a bottleneck in your process, or a system that can
complete a sample inspection on your product.

It's a difficult decision to make, and this is coming from an engineer who used to work for an
AOI manufacturer.

Steve Brown

praveen kumar manjeshwar wrote:

> Hi everyone,
> I just wanted to know where would it be preferable to postion an AOI
> equipment on a production line. I have known of people who prefer to use it
> before reflow and some who have suggested after reflow.
> What would the implications be if this equipment is placed prior to and
> after reflow?
> Also, if one had to evaluate an AOI equipment (not solder paste measuring
> equipments), then what factors would one have to consider to gage the
> capability of this equipment?
> Thanks
> Praveen
>
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