Advanced Accelerated Test of Power Modules
Author
Zhang, Kaichen
Term
4. term
Education
Publication year
2020
Abstract
This thesis investigates how advanced accelerated tests can be used to assess the lifetime and reliability of wire-bonded IGBT power modules. It begins by outlining common failure mechanisms (including bond wire fatigue, metallization reconstruction, solder fatigue, and burn-out) and how thermal loading from variable operation drives degradation. The work centers on the power cycling test, in which current and cooling are held constant while junction temperature (Tj) and case temperature (Tc) evolve over time. The test setup defines and controls parameters such as Tj, Tj,max, on/off times (ton, toff), duty cycle, and temperature swing (∆Tj), and includes measuring the temperature dependence of the on-state resistance. Thermal resistance is determined using transient thermal impedance and a Foster network derived from manufacturer data, enabling estimation of temperature rise from power loss. Several test control strategies (constant timing, constant Tc swing, constant power, and constant ∆Tj) are compared; prior studies indicate they can lead to notably different lifetimes, with constant timing being the harshest and constant junction-temperature control extending lifetime substantially, albeit with limitations at very short on-times. The thesis also frames qualification criteria for bond wire failures, discusses empirical and physics-based lifetime models, and employs finite element simulation of an IGBT module (including housing, silicone gel, bond wires, DBC, and copper baseplate) to analyze geometry, materials, boundary conditions, mesh refinement, sub-modeling, pulse duration, and thermo-mechanical stresses. The provided pages present the methodology, assumptions, and expected trends; detailed quantitative test outcomes are not included in this excerpt.
Dette speciale undersøger, hvordan avancerede accelererede tests kan bruges til at vurdere levetid og pålidelighed for wire-bondede IGBT-strømmoduler. Udgangspunktet er typiske svigtmekanismer i sådanne moduler (bl.a. bondtrådstræthed, metalliseringsrekonstruktion, loddefugetræthed og burnout) og hvordan termiske belastninger fra skiftende drift påvirker dem. Arbejdet fokuserer på power cycling-testen, hvor strøm og køling holdes konstante, mens junction-temperatur (Tj) og case-temperatur (Tc) udvikler sig over tid. Testopsætningen definerer og styrer parametre som Tj, Tj,max, on-/off-tid (ton, toff), duty cycle og temperaturudsving (∆Tj), og omfatter måling af on-state-modstandens temperaturafhængighed. Den termiske modstand bestemmes via transient termisk impedans og en Foster-model baseret på leverandørdata, så temperaturstigning kan estimeres fra effektab. Der sammenlignes styringsstrategier for testen (konstant timing, konstant Tc-sving, konstant effekt og konstant ∆Tj), som litteraturen viser kan give markant forskellige levetider; konstant timing vurderes som den hårdeste strategi, mens styring mod konstant junction-temperatur kan forlænge levetiden betydeligt, dog med begrænsninger ved meget korte on-tider. Specialet indrammer også kvalifikationskriterier for bondtrådssvigt, diskuterer empiriske og fysikbaserede levetidsmodeller og anvender finite element-simulering af et IGBT-modul (inkl. hus, silikonegel, bondtråde, DBC og kobberbundplade) til at analysere netop geometri, materialer, randbetingelser, maskeforfinelse, submodelteknik, pulsvarighed og termomekaniske spændinger. De første kapitler beskriver metode, antagelser og forventede tendenser; detaljerede, kvantitative forsøgsresultater ligger uden for det viste uddrag.
[This apstract has been generated with the help of AI directly from the project full text]