Amol,
 One of the biggest issues we encountered over the years doing SPI Evaluations is the positioning accuracy of the printer up line. Not sure which equipment you are evaluating but with the equipment we have the measurements were referenced off the surface area of the PWB. When we ran the tests we seen significant impact of the repeatability of the printer which affected the gasketing on the test vehicle which affected our volume and area measurements. So you might want to take this into count when you chose your test vehicle. If your using a stencil that is cut one to one and the printer exhibits drift then your gasketing will be affected causing variation in your readings of area and volume. This would reflect more on the printer than the SPI but a good SPI you will see this and make conclusions as to the effect on your process.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Wednesday, March 21, 2012 8:13 AM
To: [log in to unmask]
Subject: Re: [TN] Evaluating solderpaste inspection machines

Amol,

 One possible small paste target deposit is the small round solder deposits
used to define "Solder Bump" test point. I think they were 10 mil rounds.
Not sure.

 Just an idea.

Bob K.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane
(Asteelflash,US)
Sent: Wednesday, March 21, 2012 8:08 AM
To: [log in to unmask]
Subject: [TN] Evaluating solderpaste inspection machines

Dear All,

I am in the process of coming up with a testing plan for evaluating
solderpaste inspection (SPI) equipment and have some questions. One of the
first things I want to perform is a GR&R study on a NIST certified target of
the smallest possible size. I can understand the repeatability part, but is
reproducibility a valid measurement criterion as the only operator
involvement in this case will be assembly loading/unloading and all other
external conditions will remain the same?

 

I also plan to evaluate the effect of board rotation (0 vs 90 degrees) on
volume measurements by a simple DOE using ANOVA, investigate process control
using control charts and calculate Cpk for the calibration target and actual
volume measurements on the most technologically complex assembly we build
(0201s, QFNs, fine pitch BGAs etc.,). Don't have anything with a 01005 as of
yet.  Is there anything else that I have not included (but is a critical
data driven factor for evaluation)?
Also, If anybody else has performed SPI evaluation in the past and is
willing to share their evaluation plan, I can combine it what I have and
publish it on technet for future use with due credits.

 

Thanks,

Amol

 


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