There are various observational results which suggest that certain solar bursts have spectral components extending into the submm-w and infrared range. This is essentially unexplored for burst emissions in the continuum. The short time scales of burst structures (tens of milliseconds) correlated to hard X-rays bring serious constraints for interpretation. One possibility is to assume the impulsive phase made of explosions of compact synchrotron sources and self inverse-Compton reducing the electrons energy, producing the correlated spiky hard X-ray component. A new project for a solar submm-w telescope is now being developed in a collaboration between groups in Brazil, Switzerland and Argentina. It is expected to bring important observational clues for the understanding of the initial phase of flares.