Electric device, its circuit board and method of manufacturing the electric device

A circuit board, comprising:

• a plate body, one surface of the plate body having a chip-mounted area with a rectangular shape, and the chip-mounted area comprising a center zone and a plurality of corner zones;
• a plurality of first conductive pads spaced to be arranged in the center zone or all of the corner zones of the chip-mounted area;
• and
• a plurality of second conductive pads spaced to be arranged within a rest area in the chip-mounted area,
• wherein each of the second conductive pads is sized smaller than one of the first conductive pads.

A method of manufacturing an electric device, comprising:

• providing a semiconductor assembly having a substrate, a die fixedly mounted on one surface of the substrate, and a plurality of solder joints formed on the other surface of the substrate;
• designing a circuit layout pattern for a circuit board;
• making the circuit board according to the circuit layout pattern, wherein the circuit layout pattern comprises a chip-mounted area, a plurality of first conductive pads spaced to be arranged in a center zone or corner zones of the chip-mounted area, and a plurality of second conductive pads spaced to be arranged within a rest area in the chip-mounted area, wherein each of the second conductive pads is sized smaller than one of the first conductive pads;
• and
• respectively soldering the first conductive pads to one part of the solder joints through a plurality of first solder-ball portions, and respectively soldering the second conductive pads to another part of the solder joints through a plurality of second solder-ball portions,
• wherein a maximum width of each of the second solder-ball portions is greater than a maximum width of each of the first solder-ball portions.