Thermally Conductive Plastics (TCPs) Containing Boron Nitride

To enable thermal performance and create a pathway to lower cost !

Until recently, one of the main barriers to expansion into new markets for formulators using boron nitride (BN) was price. BN is a high-value additive and pricing can sometimes be a limiting factor to entering new applications requiring efficient thermal management solutions.

Good news: This is no longer true!

New hybrid fillers can provide thermal conductivity performance and improved physical properties.

These new hybrid fillers offer:

• High thermal conductivity at lower BN loadings
• Improved physical properties vs. high BN-loaded compounds

A tailor-made approach with a predictive tool to support TCP formulations

Momentive also has developed a predictive tool to enable compounders to determine a highly accurate starting point for a formulation based on the resin and the desired level of thermal conductivity. CoolFX* hybrid fillers are developed for a range of performance criteria, and Momentive can help compounders determine an optimized filler strategy to meet requirements with few tradeoffs.

Reliability of Supply & Easy-to-Compound Solutions

CoolFX hybrid fillers are supplied as a single powder and typically offer more consistent feeding. As a result, these hybrid fillers typically show faster in-mold cooling, can be molded in shorter cycles and can lead to higher yield and productivity.

Easy-to-compound solutions show good dispersion of the filler and more uniform behavior, plus Momentive experts can suggest optimized screw configurations to maximize performance.

When you need to ramp up quickly, Momentive - the world's largest manufacturer of boron nitride - is there to support you.

Combine Thermal Conductivity with Electrical Insulation using Boron Nitride

Various additives exist to formulate thermally conductive plastics but few deliver the range of possibilities offered by boron nitride (BN) in terms of design, performance and cost.

Limitations of other additives include:

• Design and cost issues: When a combination of thermal conductivity and electrical insulation is needed, metal particles, fibers, graphite or carbon can present significant challenges because they are usually offered as conductive or semi-conductive materials. Oftentimes, expensive additional electrical insulating layers are required.
• Limited color freedom: Graphite, expanded graphite or carbon fibers usually result in black compounds.
• Lower performance: Other ceramic materials typically require higher loadings, often compromising mechanical properties.(see table 1 below)
• Higher extrusion costs: Abrasive alternatives can reduce the life of screws, dies, runners and molds.

BN is a white synthetic ceramic that is both an excellent conductor of heat and a dielectric material.

As a result, BN can provide one of the best performance / cost ratios when compared to other electrically-insulating fillers, enabling it to:

• Deliver a unique compound / system offering excellent thermal conductivity and electrical insulation
• Help meet the needs of the miniaturization trend and help users explore new applications by enabling a more compact design and part integration (thanks to electrical insulation)
• Offer color freedom to meet market needs
• Help improve the lifetime of compounding components. BN is soft and lubricious and does not abrade screws or other components.

Strong technical and compounding know-how work together to help lower costs in thermal management applications

Momentive has introduced a range of new CoolFX* hybrid fillers that can provide thermal conductivity performance at potentially lower cost.

Applying advanced ceramic technology and b compounding know-how, Momentive has developed one of the potentially best cost / performance ratio options to address thermal management challenges. These new hybrid fillers can offer:

• High thermal conductivity at lower BN loadings
• Improved physical properties vs. high BN-loaded compounds

Users and formulators enjoy the design freedom of plastics, however the thermal insulating properties inherent in neat resins reduce opportunities for plastic-based solutions in electronics, LEDs and other thermally sensitive applications.

Plastics manufacturers trying to obtain better thermal management properties using traditional fillers face limitations in color flexibility and higher system costs due to additional components required to ensure electrical insulation.

In many electronics applications, fine features and design complexity increase the probability of system failure if a suitable thermal management solution is not used. Systems can suffer from sub-optimal performance and reduced component lifetime.

Therefore, in many cases, plastic compounds were abandoned and more costly metal-based systems were chosen.

Innovative compounds containing BN offer high thermal conductivity for new applications

Boron nitride (BN) is a white synthetic ceramic that provides excellent thermal conductivity while remaining electrically insulating. Compared to other insulating fillers, it can deliver superior thermal conductivity, be easier to process and kinder to extrusion and mixing equipment. See comparative Thermal Conductivity performance vs. other conductive fillers here.

Supported by Momentive's technical and compounding know-how, plastics formulators can now explore new applications and enter new markets by proposing innovative and efficient thermal management options to material specifiers.

Designers using thermally conductive plastics containing BN can now combine design freedom with appropriate thermal management solutions to:

• create significant market differentiation vs. competition (in cases where thermal management and electrical insulation are required)
• participate in expanding markets requiring thermal management, weight savings, or miniaturization

Momentive BN can enable market innovations in plastics combining:

• Differentiation through better thermal management with safe, electrically-isolating designs
• Design freedom with more compact design possibilities and feature integration (miniaturization) leading to system cost reduction vs. metal based systems
• Weight savings vs. metal
• Enhanced color freedom at similar thermal performance compared to electrically-conductive additives such as graphite or carbon

For applications in high heat environments, metal-based systems have historically been the solution of choice. Aluminum, copper or other metals often have been selected for thermal management solutions.

Metal-based thermal management options are still used today; however, these systems are increasingly being replaced by alternative solutions due to price increases in metal and ber requirements for weight savings.

Costly metal-based systems may perform well in terms of thermal management but can show limitations in weight savings and complexity (additional assembly steps or extra parts are needed). Weight and complexity are especially important in electronics, automotive and medical device applications where miniaturization and efficiency needs drive new requirements for thermal management solutions.

An appropriate thermal management system using TCP containing boron nitride (BN) can create a significant market differentiation for designers by optimizing overall system design, functionality and cost.

Design freedom offered by TCPs can yield weight savings and system cost reduction vs. metal

Users are discovering that, in spite of large differences in thermal conductivity between metal and plastics, plastics can offer suitable performance for many thermal management applications.

TCPs containing BN may enable specifiers to reduce overall system cost and meet demands for weight savings. TCPs with BN can offer the opportunity to differentiate through:

• Good thermal management performance (see LED bulb example below)
• Design freedom to meet requirements for compact and complex designs (part rationalization and feature integration)
• Color freedom (easy to color white compound) and good aesthetics (soft touch)
• Higher durability vs. metal (no corrosion)
• Weight savings opportunities

Good thermal management performance with electrical insulation

BN is a unique ceramic material that can improve thermal conductivity while remaining electrically insulating. It is, therefore, an attractive alternative to metal, which often requires additional parts or treatment to obtain electrical insulation properties.

The housing of an LED bulb is an example of an application where BN-filled TCPs have successfully replaced metals. In a number of applications, LED bulbs operate in convection-limited environments, which means the bottleneck in the heat dissipation pathway is the heat transfer from the heat sink to the ambient air. Theoretical modeling of heat transfer from a heat sink in convection-limited environments indicates that thermally conductive plastics can replace aluminum as the heat sink material. And with minor design changes, plastics can sometimes offer even more effective heat transfer.

Lower Cost & Similar Thermal Management Performance to Metal: TCP containing BN

The plot below shows the results from theoretical modeling of a simple heat sink made of either aluminum (6 fins x 5 mm thick x 25 mm long) or a 5 W/mK plastic (7 fins x 4 mm thick x 25 mm long). The temperature of the heat source was set so that both heat sinks dissipated 3 W. A total heat dissipation of ~3 W is typical of what might be expected for a 60 W-equivalent LED bulb. As shown below, the model indicates that the operating temperature of the plastic heat sink could be about 2°C lower than the aluminum heat sink at the heat source with a very minor design modification. Had the same design been used, the plastic could have been only 3°C higher than the aluminum.



The use of BN-loaded thermally conductive plastics for effective thermal management of an LED bulb was validated by success in a commercial application. The IR image on the right shows the steady state operation of a 10.4 W LED bulb (equivalent to a 60 W incandescent bulb) that used a BN-loaded plastic heat sink. The temperature of the hottest spot on the heat sink sink was 68°C, very much in line with what would be expected from an aluminum heat sink. Note: Test data. Actual results may vary.