| CPC H05K 1/0298 (2013.01) [G02F 1/133603 (2013.01); G02F 1/133612 (2021.01); H05K 1/116 (2013.01); H05K 3/282 (2013.01); H05K 2201/10106 (2013.01); H05K 2201/2054 (2013.01)] | 20 Claims |

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1. A circuit board, comprising:
a substrate;
a first conductive layer disposed on a side of the substrate; the first conductive layer including a plurality of signal lines and a plurality of first conductive portions;
a first insulating layer disposed on a side of the first conductive layer away from the substrate; the first insulating layer being provided with first via holes extending through the first insulating layer; and
a second conductive layer disposed on a side of the first insulating layer away from the substrate; the second conductive layer including a plurality of second conductive portions; a second conductive portion passing through a first via hole to be in electrical contact with a first conductive portion; the second conductive portion including a plurality of pads, and a pad being a portion of the second conductive portion exposed by the first via hole in the first insulating layer; wherein
the first conductive layer and the second conductive layer each include at least one main conductive layer, and the main conductive layer is configured to be capable of creating a first intermetallic compound with solder; at least one of the first conductive layer and the second conductive layer further includes a stop layer, and the stop layer is disposed between two adjacent main conductive layers and is configured to be capable of creating a second intermetallic compound with the solder; and a rate of a reaction between the stop layer and the solder is lower than a rate of a reaction between the main conductive layer and the solder.
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