Taming the Silent Fire: A Die-Cutter’s Guide to Flexible Thermal Management Materials

If you’ve been following the battery industry over the past decade, you probably remember the chaos that hit South Korea’s energy storage sector between 2017 and 2019. Over 20 separate fires broke out in ESS facilities, bringing the entire industry to a standstill. Investigators eventually traced the culprit back to one recurring issue: thermal management failure.

What happened? In simple terms, the systems couldn’t handle temperature fluctuations during charge and discharge cycles. Combined with less-than-perfect Battery Management System (BMS) protection, internal short circuits led to thermal runaway—a chain reaction that turned stored energy into destructive heat.

The aftermath was immediate: South Korea tightened safety standards, making stricter thermal management designs and fire suppression systems mandatory. And that’s where we, as die-cutting experts, come in.

If you’re designing or manufacturing components for electric vehicle batteries or high-density electronics, you’ve likely been asked to source materials that can manage heat effectively. But with so many options on the market, how do you choose the right one—without over-engineering or blowing your budget?

Let’s break it down.

Why Thermal Management Matters More Than You Think

Thermal management materials do exactly what the name implies: they transfer or control heat between two surfaces. In a battery pack, for instance, they help keep cells operating within safe temperature ranges. When heat isn’t managed properly, you risk everything from reduced battery life to catastrophic failure.

But the real challenge lies in choosing a material that works in your specific application—and that’s where precision manufacturing meets material science.

The Great Divide: Liquid vs. Flexible Materials

If you’ve worked with thermal interface materials before, you’re likely familiar with liquid adhesives. They’re effective, sure, but they come with baggage: curing time, mixing requirements, dispensing equipment, and mess.

Flexible thermal management materials—think adhesive films, thermally conductive tapes, and silicone gap pads—offer a cleaner, more consistent alternative. They can be precision die-cut into custom shapes, applied quickly, and provide predictable performance without the need for complex dispensing systems.

Since most of us in the converting industry are dealing with flexible materials, that’s where our focus belongs.

4 Steps to Choosing the Right Flexible Thermal Material

When a client asks me which material they should use for their battery module or electronic assembly, I walk them through this four-step process.

1. Define Your Temperature Range

Start by identifying the operating temperature range of the device. Keep in mind that a material’s thermal stability is only as strong as its weakest component—whether that’s the adhesive, the carrier film, or the filler system.

For EV batteries, you might be looking at materials rated for -40°C to 150°C. For consumer electronics, the range is often narrower, but the risk of peak temperatures can still be significant.

2. Decide on Thickness

This is where die-cutting expertise becomes critical. Thinner materials (under 0.2 mm) offer excellent thermal conductivity and flexibility but provide little to no gap-filling capability. Thicker materials like foam-based thermal pads or gap fillers are ideal when you need to bridge uneven surfaces, provide vibration damping, or seal against contaminants.

Remember: thickness affects both thermal performance and assembly process. Too thick, and you risk crushing the material during compression. Too thin, and you may not achieve adequate contact.

3. Clarify Tolerance Requirements

Not all materials are created equal when it comes to cutting precision. Some thermally conductive films can be held to tolerances of ±0.1 mm or better. Others—especially soft foam or silicone-based pads—may shift during conversion.

If your design requires extremely tight tolerances, be prepared to pay for more precise tooling and possibly slower production speeds. Conversely, looser tolerances can help keep costs down without compromising safety.

4. Prioritize by Application Requirements

Finally, list out the secondary requirements. Does the material need to be electrically insulating or electrically conductive? Flame retardant? Compressible for high-cycle applications?

In EV batteries, flame retardancy is often non-negotiable. In consumer electronics, thinness and conformability may take priority. Matching the material to the application’s true needs—not just the data sheet specs—is what separates a functional design from an optimized one.

Beyond the Data Sheet: Test, Validate, Prototype

I can’t stress this enough: material selection doesn’t end at the data sheet. Real-world conditions—like compression force, surface roughness, and long-term thermal cycling—can reveal performance gaps that lab tests don’t capture.

That’s why I always recommend prototyping. Order samples, run them through your assembly process, and test them under actual operating conditions. A simple prototype run can save months of rework down the line.

And if you’re not sure where to start? Reach out to your die-cutter or material supplier. A good converting partner won’t just cut your parts—Deson will help you choose the right substrate, optimize the design for manufacturability, and sometimes even supply sample kits to get you started.