Battery wiring module
A battery wiring module includes a plurality of connecting members to be connected to electrode terminals and a flexible printed circuit board having a plurality of voltage detection lines for detecting the voltages of a plurality of power storage elements via the plurality of connecting members, at least one of the plurality of voltage detection lines being constituted to include a front surface wiring and a back surface wiring respectively formed on a front surface and a back surface of the flexible printed circuit board, and a front-back conduction part passing through the flexible printed circuit board in the plate thickness direction and connecting the front surface wiring and the back surface wiring, and the resistance value per unit length of the front-back conduction part being less than or equal to the maximum resistance value per unit length of the front surface wiring and the back surface wiring.
1. A battery wiring module to be arranged on a plurality of power storage elements each having an electrode terminal, comprising:
a plurality of connecting members to be connected to the electrode terminals; and
a flexible printed circuit board having a plurality of voltage detection lines for detecting voltages of the plurality of power storage elements via the plurality of connecting members,
wherein at least one of the plurality of voltage detection lines includes a front surface wiring and a back surface wiring respectively formed on a front surface and a back surface of the flexible printed circuit board, and a front-back conduction part passing through the flexible printed circuit board in a plate thickness direction and connecting the front surface wiring and the back surface wiring,
wherein the front-back conduction part includes:
at least one via consisting of a through hole passing through a multilayer wiring region where the front surface wiring and the back surface wiring overlap each other in projection in the plate thickness direction of the flexible printed circuit board, and
a metal plating layer adhered to a peripheral wall of the through hole to form a continuous electrical tubular shape and respectively connected, on an upper end side and a lower end side, to the front surface wiring and the back surface wiring,
wherein the through hole has the continuous electrical tubular shape whose long axis is in a lengthwise direction of the front surface wiring and the back surface wiring, and
wherein the metal plating layer is thicker at both ends of the through hole in the lengthwise direction, such that a resistance value per unit length of the front-back conduction part is less than or equal to a maximum resistance value per unit length of the front surface wiring and the back surface wiring.
2. The battery wiring module according to claim 1 , wherein the front-back conduction part is constituted by a plurality of the via adjacently disposed.
3. The battery wiring module as according to claim 1 , wherein a hole diameter of the through hole constituting the via is larger than a minimum wiring width dimension of the front surface wiring and the back surface wiring.
4. The battery wiring module according to claim 1 , wherein the front surface wiring and the back surface wiring include a metal base layer provided on the flexible printed circuit board and a surface layer provided on the base layer, the surface layer being formed by plating at a same time as the metal plating layer provided by being adhered to the peripheral wall of the through hole constituting the via, and a thickness dimension of the surface layer being larger than a thickness dimension of the base layer.
5. The battery wiring module according to claim 1 , wherein the front surface wiring, the back surface wiring and the front-back conduction part are covered by an insulating film overlaid thereon.