help how to measure placement cpk

Here is a useful website that defines Cpk:

http://www.itl.nist.gov/div898/handbook/pmc/section1/pmc16.htm

For placement equipment, the manufacturers typically give you a glass plate, where the intent is to measure how far off the centroid you are placing - typically measured in microns or mils.

You can plug in Cpk formulas into a spreadsheet (get the formulas from that website above). The most significant effect on your Cpk numbers is your how you define your Upper and Lower Spec. limits, and how big (or small) your standard deviation (sigma) is.

...so, if you wanna give your boss a warm fuzzy...or satisfy your company's QE's...

reply »

We have talked about Cpk many times here on SMTnet, discussed source of glass slugs for placement assessment, and talked about placement Cpk a few times. Search the fine SMTnet Archives to find those threads to provide you with additional background.

reply »

I may suggest talking with the fellas at SMT Research. They have an awesome tool (POD) that can measure it for you if you're interested in having them do it. From my experience, they are always willing to talk with you over the phone too, so I'd imagine they would help in explaining it to you.

reply »