You got it, Jerry. That is exactly what I plan to do. Given a single printed PWB, induce known defects, run it through the machines, and evaluate the results.
Paste can be printed and then lightly baked onto the test sample, so the bricks do not slump over time. This allows you to test the golden boards on several machines. Granted, you do have to handle the golden unit(s) carefully.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jerry Dengler
Sent: Wednesday, March 21, 2012 1:50 PM
To: [log in to unmask]
Subject: Re: [TN] Evaluating solderpaste inspection machines
Amol,
I think a head to head comparison of the 2 technologies is in order. After all only you can tell how they will work in your process.
Regards,
Jerry Dengler
Production Manager
Pergamon Corporation
380 Crooked Lane, Unit# 3
King of Prussia, PA 19406-2567
U.S.A.
(610) 239-0721 Phone
(610) 239-0720 Fax
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane (Asteelflash,US)
Sent: Wednesday, March 21, 2012 11:51 AM
To: [log in to unmask]
Subject: Re: [TN] Evaluating solderpaste inspection machines
Thank you for your comments Richard. The comment about laser vs white light was very enlightening as I was leaning towards white light due to disadvantages of laser (contrast issues due to different color PCBs, laser dispersion, laser beam width introducing errors in measurements etc.,) which were put forward by the light using machine manufacturers. I will hear from the laser SPI manufacturers this week.
Regards,
Amol Kane
Process Engineer
AsteelFlash US East Corp
Tel: (607) 687.7669 x349 (O)
www.asteelflash.com
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-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Wednesday, March 21, 2012 9:16 AM
To: TechNet E-Mail Forum; Carl Ray
Cc: Amol Kane (Asteelflash,US)
Subject: RE: [TN] Evaluating solderpaste inspection machines
Amol,
Carl brings up some good points. I am also evaluating SPI systems. I believe you are correct, only repeatability testing is required for conveyorized or hand-loaded systems. However, many of the new SPI machines do have the capability of communicating with the printer upstream and autocorrecting it, provided the printer has the same capability.
Even if your current printer does not have this capability, it may be important in the future. If you do intend for the two machines to communicate and autoadjust, then the reproducibility becomes a required factor in the gauge R&R DOE.
My DOE also includes testing at both x and y directions, and that is a good idea because it determines the best print position for the best repeatability.
I am currently leaning towards the laser SPIs like Parmi, rather than camera systems. It appears that the laser systems can screen the entire CCA to pick up paste smudges outside of the standard targets (printed pads), and the laser systems also have better smallest feature detection capabilities, which are extremely important for inspection of paste deposits with Type 4, 5, or smaller grain sizes for 0201, 00105, and flipchip deposits. To get the same feature discrimination with a camera system, you need at least a 6 megapixel camera, and then the cost gets really spendy. The laser systems also continually scan the z-axis of the surface location of the PWB for more accurate brick height readings.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl Ray
Sent: Wednesday, March 21, 2012 7:32 AM
To: [log in to unmask]
Subject: Re: [TN] Evaluating solderpaste inspection machines
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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