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A listing in reverse chronological order of articles by:
Should an FMEA result in design or manufacturing improvements? Should it ensure that tests discover the right problems? What are the objectives of FMEAs? Whether you are new to FMEA or an experienced practitioner, there is always something to learn. This is the first in a series of articles on FMEA that should expand the knowledge of every reader.
“Successful engineering is all about understanding how things break or fail.” ~ Henry Petroski
Do you consider yourself new to FMEA, or are you an FMEA expert?
Or somewhere in between?
I’m a great believer that knowledge of any tool such as FMEA, is a lifelong journey. In the new series of articles called Inside FMEA, my intention is to bring to life the subject of FMEA, and provide value to readers from all levels of experience.
Each week I will publish a new article on Accendo. The topics will span the full range of FMEA applications, and offer guidance to real-world challenges that FMEA teams face each and every day. [Read more…]
In the previous article you learned to apply the Stuck at Fault Model (S@) to a small combinational circuit.
You can take the learning on the Full 1-bit adder and apply it to larger combinational circuit.
In testing lingo, you often hear people refer to this as the testing of random logic. Technically, there’s nothing random about the logic.
I think “random” gets used to contrast with the highly structured design of memory circuits into array of 1-bit cells. Memory test lends itself to algorithmic testing, for example the Marching 1. In random logic testing you may use algorithms to propagate your faults, that is automatically develop a test pattern.
You need to keep in mind that the logic being tested has a functional purpose and this can be implemented in a multitude of ways. Let’s take a second look at the adder function. [Read more…]
To work our ways towards understanding Design For Test (DFT)applications I am taking you back to the Stuck at Fault model (S@).
In the article which introduced you to the S@ model you learned the S@ model at the logic gate level.
Let’s build on this by applying it to combinational logic circuits.
Combinational logic has no clocked circuitry; sequential logic has clocked circuitry. In a few articles you’ll learn about test and sequential logic circuitry. [Read more…]
After the sponsorship and training are in place and resourcing is defined, there is still no guarantee that any investigations will get done. (See the end of the article for links to the blogs about these needs) This is where the definition of insanity applies – “doing the same thing over and over – and expecting different results” – so something must change. If there is no reason to perform an investigation, then things will continue to happen as they always have. [Read more…]
Historically, it has been relatively easy to meet customer system requirements using basic testing techniques. Today, however, customers require faster changes in technology and requirements are getting more difficult to meet. Competitive cost pressures have made the achievement of goals an even tougher task. In some cases, customers have requested and in a few cases mandated tools for companies to “be more efficient and organized in testing”. These facts create the need for organized and effective testing methods to be incorporated in all phases of the development process. [Read more…]
In the beginning– just test the specs.
Analog circuits have been around a long time. Consider a simple LRC circuit– the inputs and outputs are continuous wave forms.
This remains a key differentiator from digital circuits which operate on 1’s and 0’s.
Continuous waveforms require different test equipment and test techniques. Analog circuits have properties of impedance, 3Db points in the frequency domain, transform functions. They can be treated like a lumped circuit or a distributed circuit in which signal integrity and transmission line theory apply.
So testing is easy- you just test the specs. [Read more…]
The analysis of residuals helps to guide the analyst when analyzing data. It provides a way to select the model, analyze the data, develop parameter estimates, and to develop confidence in the results. [Read more…]
Perry defines Design of Experiments with one simple statement.
“A tool to assist in the process of understanding a system.”
Just 2 minutes and 10 second long, lets break down and understand each phrase in this basic definition of design of experiments. [Read more…]
Memory circuits store 1’s and 0’s for you so that you can retrieve them later. The 1/0’s can represent data or instructions.
Today, no computing device operates without some memory. Memory devices store pictures, music, documents. How many USB (Unified Serial Bus) memory sticks do you have scattered on your desk?
Semiconductor memory comes in many flavors: Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Read Only Memory (ROM), Erasable Programmable Memory (EPROM), NAND/NOR Memory (a.k.a. Flash), Solid State Drive (SSD). Without power volatile memories like SRAM and DRAM lose their stored values. Non-Volatile memories retain their stored value when power is absence. [Read more…]
Semiconductor Integrated Circuits (ICs) can have millions of digital circuits which can translate to billions of transistors.
I know these numbers can be intimidating, but I assure you the challenges of testing ICs started in the mid-late 1970’s. Lots of effort has been put into Electronic Design Automation (EDA) systems and Design for Test (DFT) techniques to manage the development and application of digital circuit testing.
In the beginning these software programs and DFT techniques used the Stuck at Fault Model. [Read more…]
Here is an example of a common engineering development task. A design engineer needed a life test plan for a switch verification in a safety system. We jointly developed a plan by taking a system view of the component function, considered corporate and regulatory requirements, customized it to the supplier’s test capabilities, executed the plan, and made design changes to remove product defects. [Read more…]
Depending upon the type of engineer you ask the word test evokes a different notion of goals and expectations.
Engineers who work on the design of semiconductors test that their designs meet the specifications.
This can be done pre-silicon and naturally verified in-depth on silicon.
Engineers concerned with manufacturing of a product test to find defects and to verify performance.
Similar approaches can be taken by both engineers though there exist differences in the amount of time. To be cost effective, a manufacturing test must be completed in as short a time as possible. Let’s continue to compare and contrast design validation with manufacturing test. [Read more…]
Before embarking on a complicated task one needs to have the basics understood.
In the musical “The Sound of Music,” Maria teaches the Von Trapp children to sing by first teaching them the musical scale.
She quickly discovers that the basics really do need to be learned one note at a time.
By the end of the “Do Re Mi” song she has them singing harmony while she sings a new melody with the words “When you know the notes to sing, you can sing most anything.” [Read more…]
Sometimes we get so used to managing without things that it becomes the way things are done. An astronaut giving a presentation at a conference I attended referred to this as “normalization of deviance.” In other words, we get so used to the way things are, that either right or wrong, they become the norm! Unfortunately, the obvious is many times ignored – because it is obvious. If you intend to have a sustainable Root Cause Analysis program, then there are things that must be done. People must be trained, reports must be written, analyses must be performed, and progress must be tracked and reported. Until a program becomes self-sustainable, it must continue to be driven. [Read more…]