High-voltage CMOS detectors are being developed for application in High-Energy Physics. ATLASPIX3 is a full-reticle size monolithic pixel detector, consisting of 49000 pixels of dimension 50$\times$150 $\mu$m$^2$. It has been realized in in TSI 180 nm HVCMOS technology. In view of applications at future electron-positron colliders, multi-chip-modules are built. The module design and its characterization by electrical test and radiation sources will be illustrated, including characterization of shunt regulators for serial chain powering. Lightweight long structure to support and to cool multiple-module chain are also being realized. The multi-chip-modules performance shows no degradation with respect to single-chip devices and the level of integration achieved is suitable for tracking at future e+e- accelerators.