Effects of helium implantation rate and temperature on the evolution of the bubble microstructure in copper have been studied by transmission electron microscopy and positron annihilation techniques. Results on the temperature and implantation rate dependencies of bubble density in the grain interiors, helium flux to and bubble density at grain boundaries are described and discussed. The bubble nucleation in the grain interiors and the helium flux to grain boundaries can be understood within the framework of the di-atomic type homogeneous nucleation. The nucleation in the grain interiors appears to be diffusion controlled in the low temperature regime and gas dissociation controlled in the high temperature regime. Although the flux of helium reaching the boundaries remains very similar, the bubble density varies enormously from boundary to boundary. These differences are suggested to arise from the differences in the structure of the grain boundaries.