Separators are prevented from being moved from a correct position before
completion of soldering. After calking portions 31a, 32a,
43 are plastically deformed and the separator 31, 32 are mechanically
fixed on a header tank 40 by calking, the separators 31, 32 are coupled
to the header tank 40 by soldering. Thereby, as the separators 31, 32
are prevented from being moved from the correct position with respect to the
header tank 40 before completion of soldering, it is possible to prevent
defects in soldering where gaps are created in coupled portions.
