# Thermal & functional fillers Source: https://powdchem.com/applications/thermal-functional-fillers/ Page type: Application guide Applications Filler powder sourcing for polymers, coatings and electronic packaging, centered on the matrix and the final formulation. [Narrow your material choices]() [Ask about your requirement]() [Image: Heat sink, thermal interface pad and electronic package shown as an exploded assembly]() ## Must the finished part stay electrically insulating? This is the first useful split for a thermal-filler request. Then consider heat-flow direction and the way the resin is mixed. Narrow your material shortlist | Your requirement | Start by comparing | What can change the choice | Explore materials | | --- | --- | --- | --- | | Electrical insulation is essential | Alumina, h-BN or an appropriate AlN filler | Carbon and metal fillers can create an electrical-conduction path. Start with insulating candidates and verify the finished compound. | [Spherical alumina powder (Al2O3)]()[Platelet boron nitride powder (BN)]()[Surface-treated aluminum nitride powder (AlN core + surface treatment)]() | | Heat must cross a thin bond line | Compare platelet BN with an agglomerated BN grade | Platelets can orient during processing. Agglomerates offer a different architecture, but their structure may change during mixing. | [Platelet boron nitride powder (BN)]()[Agglomerated boron nitride powder (BN)]() | | Viscosity or packing limits the filler content | Compare particle-size blends and rounded alumina with the current filler | Use the same resin, treatment and solids basis. A powder thermal-conductivity figure does not predict finished-part performance. | [Spherical alumina powder (Al2O3)]()[Agglomerated boron nitride powder (BN)]() | | Electrical conduction is also a goal | GNPs, copper or another specified conductive filler | This opens a different material path. Evaluate resistivity as well as thermal behavior after curing. | [Graphene nanoplatelets powder (C)]()[Copper powder (Cu)]() | **Platelets** Orientation matters **Rounded particles** Size blend and packing **Agglomerates** Structure after mixing Particle-shape schematics, not microscopy or a size scale. Chemistry and powder architecture are separate selection criteria. Start with the task closest to yours. The examples identify material requests; a proposed grade still needs to fit your process and evaluation. ## Thermal-filler formulation Use the filler identity and shape already required by your resin or host-material formulation. Compare treated, platelet, spherical and agglomerated forms separately. ### Materials to explore [Spherical alumina powder (Al2O3)]() [Agglomerated boron nitride powder (BN)]() [Platelet boron nitride powder (BN)]() [Surface-treated aluminum nitride powder (AlN core + surface treatment)]() [Thermal & Composite Fillers]() [Nitride Powders]() ### What changes the comparison Keep powder content, particle-size blend, surface treatment and mixing/curing conditions with the final-part test. [Discuss this task]() ## Electrical or conductive formulation Begin with the intended electrical function and the material system permitted by your formulation. Elemental metals and doped oxides have different identities and analytical briefs. ### Materials to explore [Copper powder (Cu)]() [Nickel powder (Ni)]() [Indium tin oxide powder (Sn-doped In2O3 / ITO)]() [Non-Ferrous Metals]() [Electronic & Functional Ceramics]() ### What changes the comparison Assess the proposed powder in the actual host material; record resistivity method, powder content and processing conditions. [Discuss this task]() ## Optical or appearance effects Choose the effect mechanism first: pearlescent, temperature-responsive, light-responsive or fluorescent. ### Materials to explore [Mica-based pearlescent pigment powder (Mica + oxide coating)]() [Thermochromic pigment powder (Thermochromic system; composition varies)]() [Photochromic pigment powder (Photochromic system; composition varies)]() [Functional Pigments]() ### What changes the comparison Compare samples in the intended binder and curing process, with consistent viewing or activation conditions. [Discuss this task]() ## Prepare a useful comparison Here, the matrix is the resin or other host material; loading is the amount of powder added. State whether that amount is by weight or volume. A reference datasheet or your existing material code is useful. If you are still exploring, describe what you are making and which result needs to change. - Host matrix, loading and processing conditions - Filler chemistry and surface treatment - Particle-size blend and morphology - Final-part test method and target conditions [Prepare an application inquiry]()