Hi Mark!!

Yeah there's studies out there, and they're done by the companies who make
the equipment to overcome the inadequacies and frailties of the human
inspector. Not to say that these studies are not valid, but one just has to
keep in mind that these studies MAY have a possible slant to justify their
equipment. With that in mind, there's a good spreadsheet that Teradyne has
put out that shows defect rates and missed oportunities using visual
inspection/ICT vs. AOI. It's at:

http://www.teradyne.com/prods/cbt/products/aoi/optima_anim/downloads/3_2sectio

n.xls

(Type all the letters in with no spaces)

For the ergonomic side of things, go to:

http://www.visioneng.com/casestudies/health_and_safety.htm

It's at Vision Engineering's web site and the link has a *.PDF file of a
study that was done at medical screening laboratories and the problems that
people have where medical slides are inspected under magnification on a daily
basis. It's a pretty good article...

-Steve Gregory-

Does anyone out there have a lead to any specific research or studies on
the effectiveness of manual inspection of PCBA's? A crude rule-of-thumb
that we've often used is 80% (80% of actual defects are found by a single
inspection). I know there's a ton of variables (PCBA complexity, component
technology, magnification, fatigue, etc...) but I would think someone would
have documented a thorough study sometime. We've got a customer that's
demanding justification for our rule-of-thumb.

Also, can someone recommend a good ergonomics reference regarding manual
inspection? Thanks in advance.