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ATLAS ITk

Development of flexible PCBs for ITk modules

Our group participated in designing the flexible PCB for the prototype hybrid modules equipped with FE-I4B chips. The hybrid module (Fig. 1) consists of a flexible PCB (flex), a sensor glued to the flex, and front end chips, which are bump bonded to the sensor and wire bonded to the flex, which routes the signals and provides the HV (high voltage) to the sensor. In our labs, we built and tested modules for the main structure demonstrator, consisting of the longeron (i.e. global carbon structure), pixel quad and dual modules, a cooling system, and a radioactive source for testing purposes.

Hybrid module
Fig. 1: Hybrid module consisting of a flexible PCB, a sensor, and front end chips

 

 

For the FE-I4B demonstrator program, we designed a quad and double module flex (Fig. 2), and built and tested the quad modules equipped with the next generation prototype front end chips produced with a 65 nm technology, called RD53A and developed by the RD53 Collaboration. These modules are part of a demonstrator located at CERN, for which RD53A and RD53B (also called ITkPixV1) chips are used.

Siegen flex
Fig. 2: The flexible PCB from Siegen designed for four RD53A front end chips

 

More information on the pixel module flex design, prototype module assembly, and testing can be found here.