Speaker
Description
A cost-effective single-die pixel-detector hybridisation technology based on Anisotropic Conductive Films (ACF) is under development, to replace fine-pitch bump bonding with thermo-compression of conductive micro-particles embedded in an epoxy film. It can also be used for the integration of hybrid or monolithic detectors in modules, replacing wire bonding or solder-bumping techniques. An in-house Electroless Nickel Immersion Gold (ENIG) plating process is being developed for single-die chips to achieve the required topology of the pixel pads. This contribution introduces the ENIG and ACF processes, and shows first test results from Timepix3 hybrid pixel assemblies.
Summary (500 words)
Hybrid pixel detectors require a reliable and cost-effective interconnect technology adapted to the pitch and die sizes of the respective applications. During the ASIC and sensor R&D phase, and in general for small-scale applications, such interconnect technologies need to be suitable for the assembly of single-dies, typically available from Multi-Project-Wafer submissions. Within the CERN EP R&D programme and the AIDAinnova collaboration, innovative hybridisation concepts targeting vertex-detector applications at future colliders are under development. We present recent results of a newly developed in-house single-die interconnection process based on Anisotropic Conductive Film (ACF). The ACF interconnect technology replaces the solder bumps with conductive micro-particles embedded in an epoxy film. The electro-mechanical connection between the sensor and ASIC is achieved via thermo-compression of the ACF using a flip-chip device bonder. A specific pad topology is required to enable the connection via microparticles and create cavities into which excess epoxy can flow. This pixel-pad topology is achieved with an in-house Electroless Nickel Gold (ENIG) plating process that is also under development within the project. The ENIG and ACF processes are qualified with Timepix3 ASICs and sensors with 55 μm pixel pitch and 12-20 µm pad diameter. The ACF technology can also be used for ASIC-PCB/FPC integration, replacing wire bonding or large-pitch solder bumping techniques. This contribution introduces the ENIG plating and ACF processes and presents first test results on Timepix3 hybrid assemblies.
