| abstract |
A circuit board capable of suppressing the occurrence of warping is provided. A first insulating layer 21 through which a conductor penetrates, a first circuit layer 22 provided on one side of the first insulating layer 21 and connected to the conductor, and covering the first circuit layer 22 And a second insulating layer 23 in which an opening for exposing a part of the first circuit layer 22 is formed, and the first circuit layer 22 provided in the opening of the second insulating layer 23 and exposed from the opening. A metal layer 27 in contact with a part, the metal layer 27 from the first circuit layer 22 side, a metal layer (a) 271 containing copper having a thickness of 0 μm or more and 55 μm or less, a thickness of 2 μm or more, The circuit board 1 includes a metal layer (b) 272 containing nickel of 15 μm or less and a metal layer (c) 273 containing tin of 3 μm or more and 30 μm or less in this order. [Selection] Figure 5 |