Creating meaningful derating graphics

Derating is the practice of selecting components with sufficient ability to withstand stresses with the intent of increasing the reliability of an electronic system. Derating tables exist within many organizations. They often only include a list of component types and a recommended derating percentage for each applicable stress. For example, capacitors often have the recommendation of a 50% derating for voltage. Such tables do not provide sufficient information to consider tradeoffs among cost, size, weight, and durability. For some technologies, a small change in temperature may cause a significant change in reliability, whereas others have almost no response to the change. Being able to see the relative responses to the common stresses for a component allows for a deeper understanding. This leads to decisions that result in reliable products. This paper examines one way to create derating graphs that allow your team to understand the importance of component technology and sizing to achieve the desired reliability performance. Reliability happens at the point of decision all though the development process; therefore, it is important to provide your team with the best available information that is easy to understand and use.