Cold Plate Cooling of
IGBT Modules
Using CFD simulation to diagnose the thermal deficiencies of a cold plate system cooling three IGBT modules dissipating 368 W each — identifying critical thermal risks before physical prototyping.
01 · Problem Statement
The Engineering Challenge
Insulated Gate Bipolar Transistor (IGBT) modules are power semiconductor devices widely used in motor drives, renewable energy inverters, and traction systems. Excessive junction temperatures are the primary cause of IGBT failure, making thermal management a critical design concern.
In this study, three IGBT modules — each dissipating 368 W — are mounted on a single liquid-cooled cold plate. The baseline design produced temperatures far exceeding the safe limit, triggering this CFD-based thermal risk assessment to diagnose root causes before any physical prototype was built.
02 · Model Description
Geometry & Simulation Setup
The conjugate heat transfer (CHT) analysis was performed in SimScale. The geometry consists of three IGBT modules bonded to a cold plate via a thermal paste layer, with coolant flowing through internal serpentine channels.
03 · Baseline Results
Baseline Design: Failure Diagnosis
Simulation of the original design revealed two compounding failure mechanisms. All four IGBT junction temperatures reached approximately 160 °C — far above the 90 °C maximum acceptable value and nearly double the 70 °C ideal operating target.
Pressure Losses in Flow Channel
- Narrow cross-sections create high flow resistance
- Sharp bends generate local low-pressure zones
- Elevated pressure drop opposes coolant movement
- Uneven velocity across hot-spots
- Varying heat transfer coefficient → uneven cooling
Thermal Paste Resistance
- Large temperature gradient across 20 mm paste layer
- Thick paste acts as an insulating barrier
- Slows rate of heat removal from IGBTs
- Compounds with flow issues to push temps over limit
04 · Design Improvement
Geometry & Material Optimisation
Two targeted modifications were proposed and re-simulated before any physical prototype was manufactured — eliminating costly trial-and-error fabrication cycles.
Reduce Hydraulic Resistance
- Increase minimum cross-section area of the channel
- Add fillets to eliminate sharp 90° transitions
- Smoother flow path → lower pressure drop
- More uniform velocity → consistent heat transfer coefficient
Reduce Thermal Paste Thickness
- Reduce paste layer thickness by 60%
- Lower conduction resistance between IGBT and cold plate
- Higher cold plate surface temp confirms better heat extraction
05 · Outcome
Validated Improvement
After applying both modifications, re-simulation confirmed that all junction temperatures now fall below the 70 °C ideal target — a dramatic improvement from the 160 °C baseline — with no physical prototype required.
06 · Engineering Insight
Why CFD Before Prototyping Matters
The combined effect of high hydraulic resistance and a thick thermal interface layer created a scenario that simple hand calculations would not have caught. CFD simulation captured the interaction between fluid dynamics and conjugate heat transfer simultaneously, revealing that both flow geometry and material changes were required together to reach safe operating temperatures.
The results also illustrate a key principle in electronics cooling: optimising for temperature alone is insufficient. Pressure drop, flow uniformity, and thermal interface resistance must all be evaluated together in a CHT framework — and resolved before a single part is machined.
Need a Thermal Analysis for Your System?
BURAQ CFD provides conjugate heat transfer and electronics cooling simulations — before you build.
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