Derating Analysis for Electronic Components

What is component derating analysis?

The upper limits (rating) for applied component stress (current, voltage, power, temperature, etc.) are defined by the manufacturer.
In order to take extra precaution measures and increase the design robustness, stricter guidelines are defined.
Component derating analysis checks if the operating point of each component is below electrical and temperature guideline levels.

 

Derating analysis for electronic components: Why is it important?

Component material damage may occur with a higher probability when an electronic device is subjected to power, current, voltage, or temperature that is beyond its maximum stress rating.
EOS (Electrical Overstress) affects product performance until the component burns. It is the leading cause of returns in components, ICs, and system failures during operation (see figure below).

Component derating analysis can prevent EOS

Figure 1: Typical failure Pareto analysis (NTF = No Trouble Found)

 

Typically engineers select components that have a maximal rating which is twice the expected actual stress. However, as temperatures is increased, component performance deteriorates and this rule of thumb becomes insufficient. For this reason, derating guidelines should be applied.

Component derating Analysis helps you to select the appropriate components rating according to stress load and temperature. This is achieved by comparing the calculated worst-case scenario electrical stresses with the maximum component rating and  the predefined derating guideline.

Derating analysis for electronic components

Figure 2: Example component derating guideline

 

The analysis detects over-rating (red) and over-derating (yellow) components. Over-designed components are also detected when stress is much lower than the rating.
While the advantages of component derating are clear, the process includes several time consuming tasks:

  1. Calculating component stresses
  2. Defining the derating guidelines for each component type

BQR’s solutions for component derating analysis

BQR provides software and professional services for quick and accurate component stress and derating analysis.

Software Features:

  • Plug-Ins for major E-CADs (Altium, Mentor, OrCad) provide easy BOM import as well as presenting results on the schematic.
  • Stress can be inputted semi-automatically, or calculated using a unique circuit stress simulator.
  • The derating guidelines can be customized according to standards [1-6] or your company’s practice.
  • The software generates thermal placement guidelines in the form of a Pareto list, for optimal placement during layout.

Additional uses for stress results:

Once the component stresses are defined, additional analyses can be conducted:

  • BQR’s patented schematic review detects a wide variety of design errors before layout! Some of the errors depend on stress, for example: incorrect applied voltage.
  • BQR’s MTBF calculation software uses the defined stresses for MTBF prediction.

 

 

References:

[1] ECSS-Q-ST-30-11C Space product assurance – Derating – EEE components
[2] US Navy Derating Guideline, SD-18
[3] Air force space command SMC Standard SMC-S-010
[4] NASA EEE-INST-002 Instructions for EEE Parts Selection, Screening, Qualification, and Derating
[5] IPC-9592 Performance Parameters for Power Conversion Devices
[6] Mil-Hdbk-338 Military Handbook Electronic Reliability Design Handbook