A 10 Sigma Solder Paste Printing Process?

Reading time ( words)


November 21, 2014

This featured blog was crafted by Ronald C. Lasky, PhD, Senior Technologist at Indium Corporation as well as a Professor of Engineering and the Director, Cook Engineering Design Center, at Dartmouth College. Dr. Lasky's blog has received acknowledgement for the value he brings to the industry. 


Let's check in on Patty as she is about to wrestle with claims of a 10 Sigma Solder Paste Printing Process involving the world's smallest electronics components, known as 01005s.

Patty was sitting in her office contemplating beginner’s luck.  She was adding this topic to her statistics class that she was preparing to teach next term.  At first, she thought that beginner's luck was a fallacy. But, she had recently read several accounts that convinced her that randomness can explain it.  These and other types of statistical phenomena are discussed in N. N. Taleb’s landmark series of books, Fooled by Randomness,  The Black Swanand Antifragile.

The beginner’s luck argument goes something like this: say a group of about 20 people go to Las Vegas to gamble for 5 days.  Five of the group have never gambled before, so they are considered to be beginners.  On average, the members of the group will lose money, but some percentage of them may end up winners. Let’s say that the percentage is about equal to about one third.  So at the end of five days, about 7 of our total entourage will end up winning, and, on average, about 2 of those will be beginners.   People look for reasons to assign to statistically random events, so the group will ascribe the winning of the two beginners to beginner’s luck.  No one thinks about the 3 beginners who lost.

The next year, the same group goes again.  Last year’s beginners have not played since last year, so they would still be considered beginners.  One of the two winning beginners from last year, let’s call her Mary, wins again.  This event would not be statistically unusual, but Mary is the talk of the group; "She won twice because of beginner’s luck," they will say.  In addition, no one notices that, of the three beginners that lost last year, one of them won this year.

The third year Mary loses, as the odds have caught up to her. Everyone concludes that, since she is now no longer a beginner, beginner’s luck has left her.  Yet, all of this story can be explained by simple statistical randomness and the human need to find a cause for a given result.

As Patty was finishing her Powerpoint® slides on this topic, she was disturbed by a knock at her door. It was Janice Austin, from Ivy University’s Development Office.

“Professor Coleman, I just want to thank you for saving the year for us,” Janice began.

Patty looked at her dumbfounded. The Development Office was the organization that sought contributions from alumni, wealthy patrons, and industry.  Patty’s confusion showed.

“How did I save the year?” Patty asked.

“ACME Corporation just contributed $100,000 and the citation accompanying the check stated that it was in recognition of the outstanding work you have done for ACME, the electronics industry, and the community.  Without this check we would have missed our target this year.  I’m quite sure President Hotchkiss will be over to offer his thanks, too.” Janice said.

After a few more pleasantries Janice left.  Patty stared off into space.  Then it hit her, Mike Madigan wanted a "blank check" to have her, Pete, and the Professor work on projects for him.  How could they say no to the company that donated $100K?  She had to chuckle at the cleverness. Madigan would avoid having to pay any consulting fee, which could add up.  As she returned to her work, Pete showed up at the door.

“Hey, Professor! Pack your bags. A trip is in play,” Pete cheerfully began.

“Looks like some statistical process control issues in ACME’s Charlotte facility,” Pete finished.

Patty didn’t know whether to be angry or amused that even now that they were at Ivy University Pete still always seemed to know what was going on before she did. Patty and Pete chatted for awhile and then he left.

Patty was really happy for Pete. Working in the engineering department at Ivy U had really turned out well for him.  He had been a machinist earlier in his career and these skills, along with his 25 years of experience in industry, had prepared him to be a godsend to the engineering students at the university.  Ivy U Engineering prided itself in being a place where students learned not just the “knowing” of engineering (ie the classwork) but the “doing” of engineering (making prototypes and models in the machine shop).  So, Pete was in demand as a resource to the several hundred Ivy U engineering students to help them with this “doing” aspect of engineering.  It was clear that Pete had never been so happy.

As she was thinking these pleasant thoughts, Patty was startled by the ringing of her phone.  It was Mike Madigan.

“Professor Coleman, it’s Mike Madigan.  Could you and Pete go to Charlotte and straighten out an issue with Cpk?" Madigan implored, getting right to the point. He continued, "They are claiming Cpks of over 3 and yet yields are off slightly.  As you will remember Cpks for printing are usually around 1. I’m having a bit of a challenge with the site manager, Byron Hansen, in staff meetings as he is claiming that the other sites should be able to improve their printing performance to match his team.  I give it right back to him about the slightly lower yields. The entire issue is causing me problems with the senior staff as Hansen has been teasing them about their lower Cpks. Can you help us straighten it out?” .

Since it was between terms at Ivy U, Patty and Pete were able to travel to Charlotte within a few days.  They both hoped they might squeeze in a little golf as there was snow in central New Hampshire.  However, Patty pointed out that, even though it was warmer in North Carolina, it still got dark abound 5PM, making golf after work impossible.

Patty and Pete arrived at their destination at 3PM for a brief kickoff meeting.  The meeting began with introductions. Patty was shocked to see one of her former statistics students (from spring semester), Frank Stockton, approach her.

“Professor, it is good to see you,” Frank sang out cheerfully.

“Likewise, Frank,” said Patty with much less enthusiasm.



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