additives feature | Thermal conductivity
Tecacomp Tc thermally-conductive polyamide com- pound which is made using ESK Boronid fillers. This type of design makes best use of the
Fig 5: The LED heat sink made by Oechsler using Ensinger’s Tecacomp PA66 compound filled with hBN
Figures 2 and 3 show the result of Boronid Tcp15- 100 in a nylon pA66 matrix without the use of other fillers. Boron nitride is compatible with all the other common filler materials used to improve properties such as mechanical performance. Applications are certainly not limited to
polyamides. Excellent results have been achieved in other thermoplastic polymers like pBT, ppS, pEEK, TpE, pET and pp. in addition, applications in thermosets and sintered polymers have been successfully demonstrated. The type and set-up of the twin-screw extruder
plays a significant role in achieving these results. High-torque extruders with high do/di ratios, such as the leistritz ZSE mAXX, yielded the best results. ESK ceramics has performed extensive test series on leistritz extruders identifying optimum parameters and screw set-up in order to assist customer applications and optimize the Boronid filler products.
Application technology oechsler of Ansbach, germany, has produced an lEd heat sink demo application (Fig. 5) using Ensinger’s
References
[1] r.H.c. Janssen, ir.K. douven, H.K. van dijk, “Thermally-conductive plastics: balancing material properties with application needs”, compounding world 2/2010, 38-42
[2] S. Amesoeder, “wärmeleitende Kunststoffe für das Spritzgießen“, phd Thesis 2009, lKT, university Erlangen-nuernberg , 39f
[3] d. Schmiederer, c. Tuechert, c. weiss, “Ein heißes Eisen”, plastverarbeiter 9/2010, 126-128
[4] J.c. Halpin, J.l. Kardos, „The Halpin-Tsai equations: A review“, polym. Eng. Sci. 16(5) (1976, 344-352
[5] l.E. nielsen, “The thermal and electrical conductivity of two phase systems”, ind. Eng. chem. Fundam., 13(1) (1974), 17-20
[6] Ensinger compounds, Tecacomp Tc Thermally conductive polymers, product brochure
www.ensinger-online.com
[7] l. Sherman, “Hot topic: adding thermal conductivity to plastics”, compounding world2/2010, 28-35
anisotropic thermal conductivity of hBn compounds. Fig. 2 shows a pronounced difference between bulk and in-plane thermal conductivity (parallel to the surface). This orientation is a common effect of high aspect-ratio fillers. in order to make best use of the excellent thermal conductivity in-plane, the design of the moulded parts should take this characteristic into account. The high conductivity in the substrate plate dissi-
pates heat away from the lEd source and effectively transfers it to cooling pins at the backside using conductive paths parallel to the surface of the pins. This heat sink demo shows not only the possibility
of realizing complex shapes with an industrial net- shape process, but also the potential system cost advantages. The raw material cost for the dimen- sions 25.4 x 25.4 mm (1” x 1”) is around E0.08/part. processing costs are comparable to or even lower than those for standard thermoplastic compounds, because of the shorter cooling time in the mould, or for die-cast aluminium parts. However the biggest saving originates from
reduced overall system costs: improved thermal management allows the use of lower-cost electronic components or an increase of power density within one component. Advantages in the system design and assembly process are self-evident. Every one of these effects more than compensates for the higher raw material costs.
Summary The new generation of Boronid fillers allows easy processing by twin-screw extrusion and enables compounders to meet current oEm market specifica- tions for thermally conductive engineering polymers. The application of these compounds leads to significant reductions in system costs in lEd technology and automotive high power density electrical systems. This opens up new, lucrative business opportunities for compounders and injection moulders. optimization of the filler material, processing parameters and mould design plays a significant role in achieving the best possible results. This is assisted by close cooperation along the value chain of polymer filler supplier, compounder and design engineers.
About the author
Armin Kayser is senior manager, business development at ESK ceramics in Kempten, germany. ❙
www.esk.com
30 compounding world | February 2012
www.compoundingworld.com
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