“Change is a part of life,” and “Change is good,” are two often-repeated clichés, but for engineers ranging from product designers to quality-assurance specialists, change can cause major problems, and these are often unexpected and challenging ones.
Once a component is designed-in and the overall product is fully vetted, the last thing a vendor wants is to get reports of field failures. Finding the root of the problem is annoying, time consuming, and costly with respect to both the hours and money spent – that’s obvious. But what if the root cause is not a design or a manufacturing flaw such as improper mounting or adhesive curing, but a small, likely unnoticeable change in a supplied component?
Let’s face it, cars have a long life these days; the average age of a car on the road in the United States is 11 years. Even though a car of that vintage is not expected to be free of failures, a component problem can show up early, such as in the early-on three-to-five-year window, while a vehicle is still under warranty. Even worse, some failures can lead to mandated recalls even if the vehicle is out of warranty.
How to Deal with Inevitable Changes in Passive Automotive Components
Given that change is inevitable, along with the risks involved, the auto industry and its component suppliers have developed standards and procedures for assessing the impact of even the smallest changes to a component, by building on the initial design-in qualification standards. The AEC-Q200 qualification matrix for inductive products (magnetics), (TABLE), shows the level of detail and scrupulousness in evaluation that any change requires.
Even a seemingly trivial change in the base materials, processing, fabrication, or test of a component can affect dependability, often in unforeseen ways. These changes could be down to logistics issues, production changes, the drive to reduce costs, or even a customer’s request for improvement in one or more performance specifications.
Furthermore, the industry-wide move to lead-free components in recent years, driven by the RoHS and REACH directive, meant that many components with long histories and solid track records had to be requalified to AEC-Q200.
The AEC-Q200 standard outlines where a stress test should be considered due to a change in materials, process, or design. Note the critical caution at the top: “For a given change listed below, the supplier should justify why a suggested test does not apply for the given part(s) under consideration. Collaboration with their customer base is highly recommended.”
Some automotive customers follow an alternative to the AEC approach, instead selecting the similar German-based ZVEI (Zentralverb and Elektrotechnik- und Elektronik industrie e.V.) standard. Their “Product/Process Change Notification Method in Automotive Electronics” offers anofficial set of notification documents and forms as part of the Product and Process Changes Notifications (PCN) procedure.
Irrespective of the motive for the modification in a passive component, there are well-established, formal procedures for ensuring the impact is clearly understood, and is hopefully zero or minimal. As electronics increasingly permeate the design and function of automobiles and vehicles, the need for passive components is also growing at a dramatic rate.
Despite the wide use of custom and application-specific ICs (integrated circuits) and discrete active devices at the center of many of these vehicle functions, there is no substitute for what these passive components: resistors, capacitors, and magnetics, perform as part of a circuit’s functions.
That’s why any changes in their design or fabrication is carefully assessed with respect to both elementary performance specifications and long-term reliability. As a result, the industry has established demanding procedures to document and enumerate the effects of even small changes to these less-glamorous yet vital components.
This information has been sourced, reviewed and adapted from materials provided by TT Electronics plc.
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