Semiconductor package and circuit substrate thereof

A semiconductor package comprising:

• a chip including a plurality of first bumps and a plurality of second bumps;
• and
• a circuit substrate including a carrier, a plurality of first leads, and a plurality of second leads, the first and second leads are formed on a surface of the carrier and aligned alternately along a transverse direction, each of the first leads has a first upper wide portion, a first narrow portion, a first lower wide portion, an internal extending portion, and a first lead section which are connected sequentially, wherein the first upper wide portion, the first narrow portion, the first lower wide portion, and the internal extending portion are located in a first bonding area and bonded with the first bump, each of the second leads has an external extending portion, a second upper wide portion, a second narrow portion, a second lower wide portion, and a second lead section which are connected sequentially, wherein the external extending portion, the second upper wide portion, the second narrow portion, and the second lower wide portion are located in a second bonding area and bonded with the second bump;
• wherein the first upper wide portion and the first lower wide portion are wider than the first narrow portion and the internal extending portion along the transverse direction such that a first upper notch facing toward the second upper wide portion and a first lower notch facing toward the second lower wide portion are formed in the first bonding area of each of the first leads;
• wherein the second upper wide portion and the second lower wide portion are wider than the external extending portion and the second narrow portion along the transverse direction such that a second upper notch facing toward the first upper wide portion and a second lower notch facing toward the first lower wide portion are formed in the second bonding area of each of the second leads;
• wherein the first and second bonding areas are aligned alternately along the transverse direction and flush with each other;
• wherein the first upper wide portion is located on an end of the first bonding area;
• wherein the external extending portion is located on an end of the second bonding area;
• and wherein the first upper wide portion and the external extending portion are flush with each other, wherein a first pitch is defined between the first narrow portion and the second upper wide portion, and a second pitch is defined between the second narrow portion and the first lower wide portion, wherein the first pitch is substantially equal to the second pitch, and wherein the first upper wide portion and the first lower wide portion have substantially identical width, and the first narrow portion and the internal extending portion have substantially identical width.