  A new design of a detector module of submillimeter thickness for an
electromagnetic calorimeter is presented. It is aimed to be used in the
luminometers LumiCal and BeamCal in future linear e$^{+}$e$^{-}$ collider
experiments. The module prototypes were produced utilizing novel connectivity
schemes technologies. They are installed in a compact prototype of the
calorimeter and tested at DESY with an electron beam of 1 GeV $-$ 6 GeV. The
performance of eight detector modules and the possibility of electron and
photon identification is studied.
