Abstract:The hygrothermal aging of short glass fiber-reinforced polyamide 6 materials (PA6 GF) represents a major problem, especially in thin-walled components, such as in the automotive sector. In this study, therefore, the thickness and the glass fiber content of PA6 GF materials were varied and the materials were exposed to hygrothermal aging. The temperature and relative humidity were selected in the range from´40˝C up to 85˝C, and from 10% up to 85% relative humidity (RH). In the dry-as-molded state, the determined Poisson's ratio of the PA6 GF materials was correlated with the fiber orientation based on computer tomography (MicroCT) data and shows a linear dependence with respect to the fiber orientation along and transverse to the flow direction of the injection molding process. With hygrothermal aging, the value of Poisson's ratio increases in the flow direction in the same way as it decreases perpendicular to the flow direction due to water absorption.

This paper provides an experimental performance analysis of advanced layers for electronic circuit boards. The base material of the advanced layers used in the experiments is Al-5052, with the dimensions of 100mm x 20mm x 1mm. As insulating material between the base and conductor, two aluminium coatings were investigated and the surface structure and thermal conductivity of the coatings were examined. Furthermore, three electroconductive adhesives were applied onto the coatings. Initially, electrical performance is investigated and electrical components were applied onto the new surface structure. Finally, the environmental tests were performed to determine the robustness of the evaluated system.

This paper proposes the replacement of a conventional Insulating-Metal-Substrate (IMS) dielectric layer with an electroconductive adhesive which is applied onto a treated aluminium heat sink. The adhesive based structure results in a lower thermal resistance of the system compared to IMS based on Aluminium. The model covers the investigation of two IMS structure with a Copper conductor layer with a thickness of 200µm, a dielectric layer of 50µm with different thermal conductivities and an Aluminium base layer with a thickness of 920µm. However, the IMS is placed onto a 100 x 100 x 33 mm Aluminium heat sink. The investigated adhesive based structure consists of the same Aluminium heat sink treated with an oxidation layer with a thickness of 50µm and an adhesive conductor layer with 30µm thickness. Furthermore, the use of forced convection to reduce the junction temperature of all three models is also considered.

This paper provides a steady-state thermal characterisation of advanced insulating layers for isotropic electroconductive adhesive based Metal Core Printed Circuit Boards. Thermal measurements were conducted using the Thermal Transient Tester to analyse the properties of layers applied onto two different base materials -aluminium and copper. For each base material, four types of insulating layers were characterised. Size of the specimen plate for both base materials was selected as 100mm x 20mm x 1mm. The isotropic electroconductive adhesive was applied onto insulating layers to ensure electrical connection between seven SMD heat-generating components. These components are mounted in the identical distance to each other. The thermal characterisation of power SMD components and the assembling process based on isotropic electroconductive adhesive were evaluated. Application of advanced insulating layer was analysed to assess the thermal performance of complete MCPCB structure. It has been shown that the lowest thermal resistance of the aluminium based insulating layers is 21.1K/W, whereas the lowest thermal resistance of the copper based insulating layer is 15.5K/W.