Lin, D.-S.D.-S.LinWodnicki, R.R.WodnickiZhuang, X.X.ZhuangWoychik, C.C.WoychikThomenius, K.E.K.E.ThomeniusFisher, R.A.R.A.FisherMills, D.M.D.M.MillsByun, A.J.A.J.ByunBurdick, W.W.BurdickKhuri-Yakub, P.P.Khuri-YakubBonitz, B.B.BonitzDavies, T.T.DaviesThomas, G.G.ThomasOtto, B.B.OttoTöpper, M.M.TöpperFritzsch, T.T.FritzschEhrmann, O.O.Ehrmann2022-03-042022-03-042013https://publica.fraunhofer.de/handle/publica/23370410.1109/TUFFC.2013.27092-s2.0-84880523388A promising transducer architecture for largearea arrays employs 2-D capacitive micromachined ultrasound transducer (CMUT) devices with backside trench-frame pillar interconnects. Reconfigurable array (RA) application-specified integrated circuits (ASICs) can provide efficient interfacing between these high-element-count transducer arrays and standard ultrasound systems. Standard electronic assembly techniques such as flip-chip and ball grid array (BGA) attachment, along with organic laminate substrate carriers, can be leveraged to create large-area arrays composed of tiled modules of CMUT chips and interface ASICs. A large-scale, fully populated and integrated 2-D CMUT array with 32 by 192 elements was developed and demonstrates the feasibility of these techniques to yield future large-area arrays. This study demonstrates a flexible and reliable integration approach by successfully combining a simple under-bump metallization (UBM) process and a stacked CMUT/interposer/ ASIC module architecture. The results show high shear strength of the UBM (26.5 g for 70-¿m balls), high interconnect yield, and excellent CMUT resonance uniformity (s = 0.02 MHz). A multi-row linear array was constructed using the new CMUT/interposer/ASIC process using acoustically active trench-frame CMUT devices and mechanical/ nonfunctional Si backside ASICs. Imaging results with the completed probe assembly demonstrate a functioning device based on the modular assembly architecture.en534journal article