Karen Rayment, Case Forensics

Anchorage

Denver

Honolulu

Portland

Salt Lake City

San Francisco

Seattle

Spokane

[email protected]@case4n6.com

800.711.0704

Categorization of Failures

SMALL UNMANNED SYSTEMS BUSINESS EXPOSITION 2015Karen Rayment, MSEE, MBA, P.E., CFEI, PMP510-775-3394 Mobile

[email protected]

April 18, 2023Categorization of Failures © Case Forensics 2014 – 2015, All Rights Reserved

Categorization of Failures: Overview and Basic Concepts

1. Definitions- Categorize the Failure First, if Possible: Legal Framework

2. FA Tips and Techniques: Put up Walls!3. Business Considerations

a. Product Lifecycle to Help Clarify Remediesb. Artifacts of Catastrophic Failures- Business

and Human Factors Losses

April 18, 2023 2Categorization of Failures © Case Forensics 2014 – 2015, All Rights Reserved







Why We Study Framework

◊ “The biggest problem in communication is the illusion that it has taken place.”

- George Bernard Shaw


1. Definitions- Categorize the Failure First, if Possible, within the Product Liability Legal Framework


Failures within the Product Liability Framework – Important Distinctions1. Design Defect: Is a product inherently

dangerous, due to the design specifications, for its intended purpose?

2. Manufacturing Defect: Were sub-standard materials or processes used in producing the unit in question, but design is according to specifications?

3. Foreseeable Product Abuse: What would a “reasonable person” do within the intended use environment?


Categorization of Failures:Overview and Basic Concepts






2. FA Tips and Techniques: Put up Walls!

April 18, 2023

Available Energy, Failure Mode, and then Effects

Categorization of Failures © Case Forensics 2014 – 2015, All Rights Reserved

3. FA Tips and Techniques: Put up the Walls!◊ Engineers MUST set aside emotional

language, such as customer reports◊ Engineers MUST make a distinction

between a failure and its effects◊ Engineers should always follow the

standard Scientific Method process flowNOTE: With a working hypothesis, additional questions will

fall out- do one iteration of Scientific Method per question!!!


Engineers MUST Set Aside Emotional Language, Such as in Customer Reports!

April 18, 2023 10

◊ When products fail, people get panicky◊ When people get panicky and don’t

understand something, they tend to exaggerate the effects of failure

◊ CASE STUDY EXAMPLE 1 - Customer comment was, “You almost burned my house down, and my family almost died!”



April 18, 2023 11Consumer Product Field Failures © Case Forensics 2014 – All Rights Reserved

◊ The wall power supply had experienced overheating, and had a short between power and ground traces, which caused a SELF-EXTINGUISHING, SHORT DURATION, LOCALIZED FAULT

◊ NOT ENOUGH AVAILABLE ENERGY TO START A FIRE!

◊ Energy Considerations Include: Available Mechanical & Electrical Energy, and Time



April 18, 2023 12

◊ CASE STUDY RESULTS: The wall power supply experienced a FAST, SELF-EXTINGUISHING, LOCALIZED FAILURE


Engineers MUST Make a Distinction between a Failure and its Effects!

April 18, 2023 13

◊ We can’t both replicate root cause, and study field failure effects during the same iteration of an experiment – lose patterns

◊ It is much easier to form a hypothesis about root cause based upon observations of effects, and then replicate effects and backtrack to prove a hypothesis

◊ It is rare when a lab-created fault will EXACTLY replicate a field failure – don’t waste your time and effort


Engineers should Always Follow the Standard Scientific Method Process


CASE STUDY EXAMPLE 2 - Separate Cause and Effects: Intermittent CPU Failures

From Legal Definitions - Categorize the Failure First, if Possible: Most Likely a Manufacturing Defect – Why?

◊ Product Lifecycle in the Market – Product has been in Field Use for 3.5 Years, and CPU Design is Older than the Product

◊ FA Tips and Techniques: Put up the Wall! Hypothesis: Intermittent Fault in CPU is Likely Due to Assembly Issue, not Bad CPU’s


Methodology – Traced Clock, Data, and Power Paths on the Circuit Assembly


Visible Artifacts and Associated Study

April 18, 2023 17

◊ Case Study Results: Glue on printed circuit board was contaminated by water


Visible Artifacts and Associated Tests

April 18, 2023 18

Step 1: Photograph area of interest, where there is potential ionic contamination


April 18, 2023 19

Step 2: Use a scanning electron microscope (SEM) to identify sample of interest



April 18, 2023 20

Step 3: Use energy dispersive x-ray spectroscopy (EDS) to plot the elements

Green arrows on the plot show the presence of salt - sodium chloride (NaCl) which indicates

fresh water was present in or near the glue



SUCESSFUL EXAMPLE of Putting up the Walls in Formal Failure Analysis Study

From Legal Definitions - Categorized the Failure Legally: Most Likely a Manufacturing Defect – THIS WAS PROVEN

◊ Product Lifecycle in the Market – Product has been in Field Use for 3.5 Years, and CPU was Found to be Working Properly

◊ Outcome: Contaminated glue caused bridging between power and data lines - CPU was operating normally, but assembly defect caused intermittent data clocking errors








3. Business Considerations


Product Lifecycle

24April 18, 2023Categorization of Failures © Case Forensics 2014 – 2015, All Rights Reserved

Product Lifecycle Considerations for FA

1. Introduction: Not well-known across a wide variety of field conditions

2. Growth: May have several revisions in the field, may have deviated from regulatory compliance bill of materials

3. Maturity: Most likely lifecycle stage for Manufacturing Defects

4. Decline: The least amount of Engineering is dedicated, but more component issues


Artifacts of Catastrophic Events

26April 18, 2023

◊ Case Study: Test engineer for semiconductor company sent email to another engineer that was part of Discovery, “I don’t know why we bother to test and grade these processors- we know we are going to just sell them all anyway.”



27April 18, 2023

◊ Moral declined when the failures were mentioned by brand name in the news.

◊ Then the team became emotional - attention to detail declined, causing more sub-standard products to slip through the QA final checks, then more returns from customers.

◊ Downward spiral, company’s revenue plunged for 2 years due to one bad batch of approximately 50,000 units that were sold without internal communication that they may be sub-standard. People quit.



28April 18, 2023

“The San Jose, California - based company's fourth-quarter loss was $22.7 million,

or $0.18 per share, compared to net profit of $27.2 million

or $0.16 per share last year.”


April 18, 2023

Thank you!


Karen Rayment, MSEE, MBA, P.E., CFEI, PMP

Mobile: 510-775-3394

[email protected]

The Small Unmanned Systems Business Exposition

2015

Technology

Karen Rayment, Case Forensics