Universität Stuttgart

Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1

Browse

Filters

2022 - 20242

Settings

Institute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungAuthor: search.filters.author.Eberhardt, Wolfgang

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Dielectric properties of PEEK/PEI blends as substrate material in high-frequency circuit board applications
    (2024) Scherzer, Tim; Wolf, Marius; Werum, Kai; Ruckdäschel, Holger; Eberhardt, Wolfgang; Zimmermann, André
    Substrate materials for printed circuit boards must meet ever-increasing requirements to keep up with electronics technology development. Especially in the field of high-frequency applications such as radar and cellular broadcasting, low permittivity and the dielectric loss factor are key material parameters. In this work, the dielectric properties of a high-temperature, thermoplastic PEEK/PEI blend system are investigated at frequencies of 5 and 10 GHz under dried and ambient conditions. This material blend, modified with a suitable filler system, is capable of being used in the laser direct structuring (LDS) process. It is revealed that the degree of crystallinity of neat PEEK has a notable influence on the dielectric properties, as well as the PEEK phase structure in the blend system developed through annealing. This phenomenon can in turn be exploited to minimize permittivity values at 30 to 40 wt.-% PEI in the blend, even taking into account the water uptake present in thermoplastics. The dielectric loss follows a linear mixing rule over the blend range, which proved to be true also for PEEK/PEI LDS compounds.
  • Thumbnail Image
    ItemOpen Access
    Flexural fatigue test : a proposed method to characterize the lifetime of conductor tracks on polymeric substrates
    (2022) Petillon, Simon; Knöller, Andrea; Bräuer, Philipp; Helm, David; Grözinger, Tobias; Weser, Sascha; Eberhardt, Wolfgang; Franke, Jörg; Zimmermann, André
    High quality and long product life are two fundamental requirements for all circuit carriers, including molded interconnect devices (MID), to find application in various fields, such as automotive, sensor technology, medical technology, and communication technology. When developing a MID for a certain application, not only the design, but also the choice of material as well as the process parameters need to be carefully considered. A well-established method to evaluate the lifetime of such MID, respective of their conductor tracks, is the thermal shock test, which induces thermomechanical stresses upon cycling. Even though this method has numerous advantages, one major disadvantage is its long testing time, which impedes rapid developments. Addressing this disadvantage, this study focuses on the laser direct structuring of thermoplastic LCP Vectra E840i LDS substrates and the subsequent electroless metallization of the commonly used layer system Cu/Ni/Au to force differences in the conductor tracks’ structure and composition. Performing standardized thermal shock tests alongside with flexural fatigue tests, using a customized setup, allows comparison of both methods. Moreover, corresponding thermomechanical simulations provide a direct correlation. The flexural fatigue tests induce equivalent or even higher mechanical stresses at a much higher cycling rate, thus drastically shorten the testing time.