Characterization of Ni/SnPb-TiW/Pt flip chip interconnections in silicon pixel detector modules

A. Karadzhinova (Corresponding Author), A. Nolvi, Jaakko Härkönen, Panja Luukka, Teppo Mäenpää, E. Tuominen, E. Hæggström, Juha Kalliopuska, S. Vähänen, I. Kassamakov

Research output: Contribution to journalArticle in a proceedings journalScientificpeer-review

Abstract

In contemporary high energy physics experiments, silicon detectors are essential for recording the trajectory of new particles generated by multiple simultaneous collisions. Modern particle tracking systems may feature 100 million channels, or pixels, which need to be individually connected to read-out chains. Silicon pixel detectors are typically connected to readout chips by flip-chip bonding using solder bumps. High-quality electro-mechanical flip-chip interconnects minimizes the number of dead read-out channels in the particle tracking system. Furthermore, the detector modules must endure handling during installation and withstand heat generation and cooling during operation. Silicon pixel detector modules were constructed by flip-chip bonding 16 readout chips to a single sensor. Eutectic SnPb solder bumps were deposited on the readout chips and the sensor chips were coated with TiW/Pt thin film UBM (under bump metallization). The modules were assembled at Advacam Ltd, Finland. We studied the uniformity of the solder bumps using Scanning White Light Interferometry (SWLI). According to our results, the Ni/SnPb-TiW/Pt interconnections fulfill the requirements in [1] for flip-chip bonding pixel detector modules. This study proposes a way to decrease the number of dead channels of the silicon pixel detector modules by precisely measuring the soldered bump diameter to ensure that they fulfil the specifications.

Original languageEnglish
Article number092
Number of pages8
JournalProceedings of Science
VolumeTIPP2014
DOIs
Publication statusPublished - 2014
MoE publication typeA4 Article in a conference publication
Event3rd Technology and Instrumentation in Particle Physics Conference, TIPP 2014 - Amsterdam, Netherlands
Duration: 2 Jun 20146 Jun 2014

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