Lifetime Prediction

Lifetime & Reliability Considerations during Product Development

One essential goal of the design process of an electronic product is to create a robust and reliable design that meets the demands from field operation. Typical measurement values, the number of failures per operation time and their distribution are evaluated. By the use of accelerated aging tests together with numerical simulations, it is possible to get access to these quantities and to predict the lifetime of a product for different load cases.

A typical lifetime prediction analysis involves the following steps:

We support our customers during each step in order to avoid over-engineering, increase power density and enhance the competitiveness of your products.

Application and Research

Development of lifetime estimation strategies (experimental and theoretical).
Statistical methods according to industrial standards and guidelines.
Numerical and analytical modeling of physical degradation mechanisms.
Objectives: Electronic systems, subsystems and components (e.g. converter, power modules, semiconductors, capacitors, inductors, etc.).

Example: Lifetime Analysis of Electronic Power Module

© Fraunhofer IISB
Berkovich nanoindent on a silver-sintered bond line obtained by nanomechanical microscopy

1 - Mission Profile

Use cases, e.g. drive cycles
Operating data, e.g. V and I vs. time

2 - Power Loss Profile

Electrical simulations
Empirical mathematical relations

3 - Temperature Profile

3D-transient thermal Finite-Element-Analysis (FEA)
1D-modeling by electro-thermal analogue circuits

4 - Load Analysis

Constant, variable, block and random loads
Extraction of closed hysteresis loops from load signal by use of counting algorithms as input for lifetime model

© Fraunhofer IISB
Micro scale thick silver-sintered dog bone immediately before hot tensile test

© Fraunhofer IISB
Mechanical behavior of silver-sintered dog bone in tensile test at different test temperatures and sintering pressures

5 - Lifetime Model

Determination of system response and damage variables
Accelerated ageing tests (e.g. power cycling, thermal cycling, shock and storage tests, etc.)
Non-linear transient finite-element-analysis
Modeling of damage evolution
Empirical, by observable variables, e.g. temperature swing, heating voltage, thermal resistance
Physical, by internal variables, e.g. inelastic strain, plastic strain energy density, damage variables (CDM)

6 - Material Characterization for improved FEM

Temperature dependent characterization of mechanical properties including creep-, fatigue-, fracture- and failure-investigations
Material property mapping by spatially resolved nanoindentation. Application examples: Properties of intermetallic phases, die-attaches, bond wires and phase boundaries
Thermal analysis of materials: Specific heat of semiconductors, die-attaches, solder pastes (evaporation of fluxes, melting temperature, solidification behavior), sintering pastes (drying / sintering time, temperature and atmosphere), substrates, TIMs
Assembly of test specimens
Tensile and compression testing, temperature and time dependant
Nanoindentation, temperature dependant, according to test standard ISO14577

7 - Prediction of Lifetime

Accumulation of damage per load increment
Calculation of predicted lifetime