Analysis of the flow behavior of thermally conductive thermosets during injection molding

随着当今电子设备的功率越来越大，同时尺寸越来越小，电子元件的热平衡已经成为一个挑战，因为越来越多的热量产生并且必须从系统中消散。这方面的一个具体例子是电动机外壳对散热的高需求，电动机外壳具有高额定功率，并且必须在广泛的环境温度范围内连续运行期间保持功能。相应的外壳由基于环氧树脂的热固性成型化合物制成。除了必要的经典性能，如电绝缘能力外，热固性绝缘材料的导热性也因此日益成为用户关注的焦点。这些材料应用的一个主要障碍是，由于缺乏对注射成型过程中流动行为和由此产生的填料方向的基本理解，因此很难预测零件的局部导热性。该研究项目的目的是使用一种创新的测量模具来研究与材料成分、生产过程和结构部件设计相关的方向相关的导热系数。这里的重点是更好地理解填充方向，因为在模具填充过程中流动行为的结果。为此，将根据Mooney概念设计测量模具，利用Mooney概念首次可以在实际边界条件下表征熔体的流动行为。通过在模具中集成超声波和介电传感器，可以直接观察到固化过程，并且首次可以分析固化速度与过程中流动行为之间的关系。还计划使用磁性填料和tes-lameter直接在模具中确定填料方向。此外，还计划在模具中使用磁性填料和三角形仪直接确定填料的方向。使用这种创新的测量技术，材料和工艺对流动行为的影响将在项目范围内进行根本性的研究。材料相关因素的重点在于填料的几何形状、填料的含量和填料的导热性。工艺研究的重点是成型复合材料的工艺热平衡和剪切效应。为此，对影响流动特性的主要因素，如机组温度、模具温度和注射速度进行了根本性的研究。

With the increasing power of today's electrical devices and simultaneously reduced size, the heat balance of electronic components has become a challenge, as more and more heat is generated and must be dissipated from the system. A concrete example of this is the high demand for heat dissipation for electric motor enclosures, which have a high power rating and must remain functional during continuous operation at a wide range of ambient temperatures. Corresponding enclosures are made of thermoset molding compounds based on epoxy resin. In addition to the necessary classic proper-ties, such as electrical insulation capability, the thermal conductivity of the thermoset insulation material is thus increasingly becoming the focus of users.A major obstacle for the application of these materials is that a prediction of the local thermal conductivity in the part is hard to make because the basic understanding of the flow behavior and the resulting filler orientation during injection molding is missing. The aim of the research project is to use an innovative measuring mold to investigate the direction-dependent thermal conductivity in relation to the material composition, production process and design of a structural part. The focus here is on a better under-standing of the filler orientation as a result of the flow behavior during mold filling. For this purpose, the measuring mold will be designed according to the Mooney concept, with which the flow behavior of the melt can be characterized under realistic boundary conditions for the first time. By using ultrasonic and dielectric sensors integrated in the mold, the curing process is observed directly in the process and, for the first time, it is possible to analyze the relationship between the curing speed and the flow behavior in the process. It is also planned to use magnetic fillers and a tes-lameter to determine the filler orientation directly in the mold.. In addition, it is planned to determine the filler orientation directly in the mold with the use of magnetic fillers and a teslameter. Using this innovative measuring technique, the material- and process-dependent influences on the flow behavior will be fundamentally investigated within the scope of the project. The focus of material-related factors lies on the filler geometry, filler content and ther-mal conductivity of the fillers. The process investigation focuses on the process heat balance and the shear effect in the molding compound. To that end, the main factors influencing the flow behavior, such as unit temperature, mold temperature and injec-tion speed, are to be fundamentally investigated.