Method for manufacturing busbar assembly

A method for manufacturing a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between lateral surfaces facing one another, and an insulative resin layer including a gap filling portion filled into the gap and a bottom-surface-side laminated portion extending integrally from the gap filling portion so as to be arranged on bottom surfaces of the plurality of busbars, wherein a top surface of each of the busbars is at least partially exposed to form a top-surface-side connection portion, and wherein the bottom surface of the busbar includes a first bottom surface region which is located at the same position in a thickness direction as a lower end portion of the gap and on which the bottom-surface-side laminated portion is arranged, and a second bottom surface region which is located farther away from the top surface than the first bottom surface region and is exposed to the outside to form a bottom-surface-side connection portion, the manufacturing method comprising:

• a step of preparing a conductive metal busbar-directed flat plate having a busbar assembly forming area that has a planar shape corresponding to a busbar-connected body in which the plurality of busbars are connected to one another by a busbar-side insulating layer and that has the same thickness as a thickness between the top surface and the second bottom surface region;
• a thickness adjustment step of adjusting the thickness of the busbar assembly forming region such that a thickness of a first-bottom-surface-region forming area, out of a bottom surface of the busbar assembly forming region, that corresponds to the first bottom surface region is made to coincide with a thickness between the top surface and the first bottom surface region of the busbar;
• a slit forming step that is performed after or before the thickness adjustment step and that is configured so as to form one or a plurality of slits that penetrate the busbar assembly forming region in the thickness direction and have the same width as the gap so that the busbar assembly forming region is divided into a plurality of busbar forming parts corresponding to the plurality of busbars;
• a busbar-side insulating layer forming step of applying an insulating resin coating material at least into the inside of the slits and to the entire area of the bottom surface of the busbar assembly forming region and then curing the applied insulating resin coating material to form the busbar-side insulating layer;
• a laser light irradiation step of irradiating the laser light to, within a range that does not include the slit, at least an entire area of a second-bottom-surface-region forming area corresponding to the second bottom region and a boundary between the first-bottom-surface-region forming area and the second-bottom-surface-region forming area to expose the entire area of the second-bottom-surface-region forming area;
• and
• a cutting step of cutting the busbar assembly forming region from the busbar-directed flat plate.