Töpper, M.M.TöpperSchmückle, F.J.F.J.SchmückleLenk, F.F.LenkHutter, M.M.HutterKlein, M.M.KleinOppermann, H.H.OppermannEngelmann, G.G.EngelmannRiepe, K.K.RiepeHeinrich, W.W.Heinrich2022-03-102022-03-102005https://publica.fraunhofer.de/handle/publica/34965010.1109/MWSYM.2005.15168372-s2.0-33749260546A flip-chip packaging approach for W-band GaAs chips is presented using thin-film structures on silicon as carrier substrate. Reliability investigations indicate that, depending on bump size, the CTE mismatch is not critical and an underfiller does not provide distinctive benefits. A 77 GHz VCO GaAs-HBT MMIC is flip-chip-mounted to demonstrate validity of the packaging scheme. Index Terms - Thin film circuit packaging, Flip-chip devices, MMIC oscillators.en621conference paper