Let’s Talk Testing: Professor Plum in the Library with the Candlestick…Right?

Who knew that a phrase from a decades-old popular board game could have some relevance in today’s ever-changing world? In the game of Clue, simply put, evidence is collected and then used to solve a mystery. In my world, testing is performed to gather data/results (evidence) and then this information is used to determine the root cause of some issue that is under investigation (solving the mystery). The recommendations made as a result of a failure analysis investigation commonly lead back to some step along the manufacturing process that now needs to be scrutinized and evaluated and then possibly improved and/or changed. To effectively do this, having information from the steps in that process (evidence, again) is a key component of the potential solution. This latter idea is the main subject of this month’s column, or in a simpler way, how traceable is your process?

When a manufacturing process is humming along, widgets whiz through many pieces of equipment and through many sets of hands until they eventually find their purpose out in the real world. Initial loading, component population, reflow, hand soldering stations, installation into a housing, cabling, functional checks, and potentially many, many more operations…are just some of the steps that a widget might be exposed to during its manufacturing. The process, by its nature, requires a myriad of steps, one potentially very different from the next.

Some steps are likely to be very repetitive in nature and very repeatable in execution from lot to lot, while others, maybe not so much. Regardless of the operation being performed and whether it’s heavily automated or not, having traceability of each individual step through the process as a whole is vitally important. Knowing who did it, when they did it, what tools/materials/supplies they used to do it, and the conditions under which they did it are just a few bits of information that should be known and readily available to someone investigating a process that has produced some bad widgets.

For example, let’s say our widget is a sealed unit that has a printed circuit assembly inside that is sensitive to moisture. The unit itself has a cover on it that is attached via screws with a gasket for sealing purposes. The client is experiencing failure of the widget when it is installed in a humid/wet environment. As a result of testing that would have been performed to investigate the issue, let’s say that the root cause of the field failures was determined to be water/moisture ingress around the cover.

From here, the owner of the widget would likely go to the manufacturing line to investigate the cover attach process. So, at this point, the more information that the investigator can get about that step in the process the better. A simple bit of information would obviously be to know which operator installed the screws and which screwdriver they used, but that might only be the tip of the iceberg in respect to what information could be known. Other examples of bits of information that would likely be of interest in this situation would be…How much torque was applied to the screws? What is the material (lot) traceability of the cover plate? What is the material (lot) traceability of the gasket? What is the material (lot) traceability of the screw? What were the environmental conditions on the line when the unit was sealed?

Those are just a few of the questions that the investigator might ask to try to solve the issue at hand. Thus, having complete traceability of your process will allow for easy dissemination of the needed information. Who knows…maybe the solution is as simple as a bad lot of gaskets? Or, maybe, the torque setting on the screwdriver was incorrect from 9–11 am on a given Tuesday? These are all very plausible answers to our example, but finding these answers would be impossible if the traceability information wasn’t being recorded and/or stored.

Traceability is not designed to be a blame game, although that does unfortunately sometimes happen given the world we all live in. From an analytical vantage point, establishing a mentality in which everyone understands that traceability allows for quicker and more efficient problem solving and troubleshooting when/if things go awry is really the greater theme. If you knew it was Professor Plum in the library with the candlestick from the very beginning….wouldn’t the game be much easier to play?

Keith M. Sellers is operations manager with NTS in Baltimore, Maryland. To read past columns or to contact Sellers, click here.

This article originally appeared in the August 2017 issue of The PCB Magazine, click here.

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2017

Let’s Talk Testing: Professor Plum in the Library with the Candlestick…Right?

08-28-2017

Who knew that a phrase from a decades-old popular board game could have some relevance in today’s ever-changing world? In the game of Clue, simply put, evidence is collected and then used to solve a mystery. In my world, testing is performed to gather data/results (evidence) and then this information is used to determine the root cause of some issue that is under investigation (solving the mystery).

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Random Thoughts on Employment, from Both Sides of the Table…

05-29-2017

Many years ago, as I began my senior year of college, the reality of getting a job slapped me in the face! After three years of college studies, it dawned on me that without a job after graduation, all my hard work would have been for naught. Luckily, my university had a solid interview/job program that helped me and many of my fellow undergrads find gainful employment upon graduation the following spring.

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Let's Talk Testing: You’re in for a (Thermal) Shock!

04-26-2017

Printed circuit board history stretches back to the early 1900s, with real promise shown in the industry after World War II. Through the 1940s, 1950s, and 1960s, PCB construction really started to progress when fiberboard and wood were replaced with resins and laminates, and rivets replaced early plated through-holes.

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Let's Talk Testing: How Strong is Your Foundation?

02-28-2017

In my December 2016 column, we discussed the idea of supplier surveillance and that one should put into place some type of doublecheck to ensure that you are getting exactly what you’ve asked for, designed, ordered, etc. To take that idea a step further and to circle it back to the main industry we are discussing here, let’s look at some of the testing that one might do under a supplier surveillance program as it relates to a standard printed circuit board—the foundation of most electronics in today’s world.

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Got Whiskers?

01-10-2017

The tin whisker phenomenon is an issue that has plagued the electronics industry for many years now; however, with even more sectors of the industry now looking to shift or go lead-free—eliminating or limiting lead—in their processes and products, focus on this potentially devastating issue appears to be on the rise once again.

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Back

2016

Let's Talk Testing: Are You Getting What You’ve Asked for?

12-15-2016

A lot of things are taken for granted nowadays. Even in our everyday lives, we order things, but are we always getting exactly what we’ve ordered? What we’ve paid for? Maybe… hopefully…but maybe not. In the testing world, we call this double-checking “supplier surveillance,” and it can influence and affect anyone and everyone in the printed circuit board and printed circuit assembly supply chain.

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Vias for Dummies

11-15-2016

In simple terms, a circuit board is but a composition of things designed to be connected and not. The number of layers and number of connections make no real difference as the geometry shapes the landscape.

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Don’t Reinvent the Wheel—Find an Expert!

10-15-2016

Back in the day when I was an engineer fresh out of college, I quickly learned that experience is the solution to many problems. Now that being said, experience comes in many forms…it could be knowledge learned from a textbook, it could be an observatory comment jotted down in a notebook, it could be a conversation with a co-worker or colleague, or it could be an Internet search that finds a scholarly technical article, etc.

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Does your Product have a Military Application?

09-15-2016

Just like any other industry segment within the circuit board world, the military sector has its own share of documents…and likely many more than most! These documents have been developed over the years to guide, shape, and test anything and everything that might go into a jet fighter, a radar system, a warship, a weapons system, etc.

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Welcome Your Product to the Real World!

08-15-2016

The days, weeks, and (sometimes) years that go into a product’s development usually are incomprehensible to the lay person. Like laws and sausages, no one wants to really understand what has gone on behind the scenes to make your “thing” a reality. They just care that your widget makes their life easier and/or more enjoyable!

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Let's Talk Testing: Seeing is Believing in Fractographic Analysis

07-13-2016

One of the more common types of failure analysis is the investigation of something that has broken. For this column, we will be discussing a broken material, or, more commonly, a fractured or cracked material.

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