  Characterizing the physical properties and compositions of circumplanetary
disks can provide important insights into the formation of giant planets and
satellites. We report ALMA 0.88 mm (Band 7) continuum observations of six
planetary-mass (10-20 $M_{\rm Jup}$) companions: CT Cha b, 1RXS 1609 b, ROXs 12
b, ROXs 42B b, DH Tau b, and FU Tau b. No continuum sources are detected at the
locations of the companions down to 3$\sigma$ limits of 120-210 $\mu$Jy. Given
these non-detections, it is not clear whether disks around planetary-mass
companions indeed follow the disk flux-host mass trend in the stellar regime.
The faint radio brightness of these companion disks may result from a
combination of fast radial drift and a lack of dust traps. Alternatively, as
disks in binary systems are known to have significantly lower millimeter fluxes
due to tidal interactions, these companion disks may instead follow the
relationship of moderate-separation binary stars. This scenario can be tested
with sensitive continuum imaging at rms levels of $\lesssim$10 $\mu$Jy.
