[Purpose] To provide is a method capable of producing a heat-dissipating unit easily and at low cost.
[Solution] The method of producing a heat-dissipating unit 12 includes: inserting pins 17 punched out of a second plate member 22 for pins into a plurality of through-holes 16 formed in a first plate member 20 for a substrate. In the first plate member 20, a plurality of substrate forming portions 25 is provided side by side in the longitudinal direction of the first plate member 20. In the second plate member 22, a plurality of pin punch-out portions 26 is provided side by side in the longitudinal direction of the second plate member 22. The method includes: a step A of forming the through-holes 16 in the substrate forming portion 25 of the first plate member 20; a step B of subjecting the pin punch-out portion 26 of the second plate member 22 to a half-punch out process to form half-punched-out pin forming portions 27 protruding from one surface side of the second plate member 22; a step C of forming the pins 17 by punching out the pin forming portions 27 from the second plate member 22 and simultaneously inserting the pins 17 into the through-holes 16 in the first plate member 20; and a step D of forming a substrate by cutting the substrate forming portion 25 with the pins 17 inserted in the through-holes 16 from the first plate member 20.