Engineering for Reliability: How Electronics Are Designed to Last

When we discuss the longevity of electronic products, a common assumption is that they are inherently engineered to fail in order to be replaced. However, from my extensive experience working on high-end electronics, this isn't always the case. Electronics are designed to last, but the trade-offs in the product development process can sometimes lead to the perception that they are engineered to fail. This article aims to explore the realities of electronic product engineering and the factors that influence their longevity.

The Product Development Triangle

To understand why certain electronic products may last longer or shorter than expected, we need to delve into the product development triangle, also known as the product management triangle (Figure 1). This fundamental concept posits that any given product development project must balance three critical factors:

These elements are interconnected and often serve as trade-offs. For example, improving the quality of a product can increase the cost or extend the development timeline, and vice versa. As a professional in this field, I have found that these trade-off decisions are rarely made by engineers but instead are set by the project managers.

The typical scenario involves engineers being provided with a loosely defined product idea and cost and time constraints that have already been determined well before they begin their work. The goal is to design a product that meets these objectives while striving to maintain a balance between the three critical factors.

Cost, Quality, and Reliability

One of the most significant factors affecting the reliability and longevity of an electronic product is cost. Protecting circuitry from user misuse and enhancing reliability often require additional resources, which can be a costly affair. In practice, the design decisions made by engineers are heavily influenced by cost constraints.

For instance, in one of my projects, I was tasked with designing a power supply to deliver rated power for a minimum of five years, 24/7. However, in reality, customers might not use the product to its maximum capacity, leading to a longer lifespan than anticipated. This balance between design capabilities and cost is crucial for the overall success of the product.

Reliability Testing

The reliability of a product is often tested through various methods, including highly accelerated life testing (HALT, Figure 2), which helps predict the statistical lifespan of the product. HALT involves subjecting the product to extreme conditions to identify any potential weaknesses.

While these tests are invaluable for ensuring long-term reliability, they also represent a significant cost in upfront non-recurring expenses. Companies must carefully consider the balance between the cost of these tests and the overall reliability of the product. Both are essential for maintaining customer satisfaction and extending the product's longevity.

The Bathtub Curve

The bathtub curve is a common statistical model used to describe the failure rates of electronic devices over time. This curve typically consists of three phases: an initial infant mortality phase, a time of steady-state operation, and a wear-out phase (Figure 3).

Understanding this curve is crucial for engineers and manufacturers to design products that can survive the initial failure phase and maintain reliable performance for as long as possible. By carefully analyzing the bathtub curve, companies can identify areas for improvement and enhance the overall reliability and longevity of their electronic products.

Conclusion

While it is true that certain electronic products may not be engineered to last indefinitely, the reality is more nuanced. Engineers strive to design products that meet quality, cost, and schedule constraints, while also ensuring reliability and longevity. Through careful product development processes and extensive testing, electronics can be made to last significantly longer than the initial user expectations.

By focusing on the product development triangle and understanding the various factors that influence reliability, companies can create electronic products that not only meet customer needs but also stand the test of time.