  The goal of the ECHo experiment is a direct determination of the absolute
scale of the neutrino mass by the analysis of the end-point region of the
Ho-163 electron capture (EC) spectrum. The results of the first phase of the
experiment, ECHo-1k, have paved the way for the current phase, ECHo-100k, which
aims at a sensitivity below 2 eV on the effective electron neutrino mass. In
order to reach this goal, a new generation of high-resolution magnetic
microcalorimeters with embedded Ho-163 have been developed and characterised.
The design has been optimised to meet all the challenging requirements of the
ECHo-100k experimental phase, such as excellent energy resolution, wafer scale
implantation and multi-chip operation with multiplexing read-out. We present
the optimisation studies, the final design of the detector array and the first
characterisation studies. The results demonstrate that the detectors fully
match and even surpass the requirements for the current experimental phase,
ECHo-100k.
