40% Better Cooling for 800V EV Power Modules with Embedded Copper & Heavy Copper

1. This Was Not About Performance — It Was About Survival

The customer didn’t come to us asking for better specs.

They came because their design couldn’t survive real operating conditions.

This was an 800V power module used in an EV platform.

Under load, the system behaved as expected — for a short time.

Then problems started to show:

• Local overheating around power paths
• Temperature imbalance across the board
• Long-term reliability concerns under continuous high current

Nothing failed immediately.

But it was clear — this design would not last in the field.

2. What They Were Really Dealing With

In 800V systems, the problem is rarely just “heat.”

It’s how heat is generated, conducted, and trapped.

In this case, the core issue was:

• High current density concentrated in limited copper area
• Standard PCB copper thickness unable to carry thermal load efficiently
• Heat spreading too slow to keep junction temperature under control

This is where many designs hit the limit of traditional PCB structures.

3. What We Changed — Not More Layers, But Better Current Paths

We didn’t start by increasing complexity.

We focused on one question:

How does current actually flow, and where does the heat go?

4. Embedded Copper — Turning the PCB into a Power Structure

Instead of relying only on surface copper, we introduced embedded copper busbars inside the PCB.

This changed the behavior completely:

• Current no longer concentrated in thin copper layers
• Heat distributed through a larger conductive volume
• Electrical resistance reduced significantly

At this point, the PCB was no longer just a board. It became part of the power path.

5. Heavy Copper — Used Where It Matters

We applied heavy copper not everywhere, but where it actually carried load.

• Thick copper layers aligned with power routing
• Optimized copper thickness based on current distribution
• Avoided unnecessary stress in non-critical areas

This avoided one common problem: adding copper blindly often creates new reliability risks.

6. Thermal Path Optimization — Not Just Dissipation, But Flow

Heat dissipation is not only about removing heat.

It’s about how efficiently heat moves through the structure.

We improved:

• Vertical heat conduction paths
• Contact efficiency between copper and surrounding materials
• Internal heat spreading across layers

The result was a more uniform temperature distribution.

7. Process Control — Making It Manufacturable

Embedded copper structures are not just a design challenge. They are a manufacturing challenge.

We controlled:

• Copper embedding accuracy
• Lamination stability with mixed thickness materials
• Void-free bonding between copper and dielectric

Without process stability, performance cannot be repeated.

8. What Changed in Real Terms

After optimization and validation:

• Heat dissipation efficiency improved by approximately 40%
• Peak temperature significantly reduced under full load
• Temperature distribution became more uniform
• No thermal-induced deformation or structural instability observed

More importantly:

👉 The system could now operate continuously without thermal risk.

9. Why This Matters for 800V Platforms

In high-voltage, high-current systems, thermal issues don’t always show up immediately.

But once they do, they affect:

• System reliability
• Component lifespan
• Safety margins

And at that point, redesign becomes expensive.

10. What This Project Really Shows

This was not about adding more copper.

It was about understanding:

• Where current flows
• Where heat accumulates
• How structure affects both

And then building the PCB accordingly.

11. Final Thought

At 800V, the PCB is no longer just a support layer.

It is part of the power system.

If it cannot carry current and manage heat properly, the system will eventually fail — even if it passes initial tests.

ULTRONIU Electronics 
We don’t just increase copper. We make sure the current and heat have a path that actually works.