Abstract: A conductive ball is formed by coating a generally spherical-shaped core made of a non-metallic material with a coating layer composed of a Cu layer and an Sn-5.5Ag alloy layer of non-eutectic composition. The conductive ball is disposed on a land of an electronic component via flux and reflown at heating temperatures whose peak temperatures reach 250 to 260° C. The Sn-5.5Ag alloy of non-eutectic composition is put in the state in which a solidus portion and a liquidus portion coexist to keep flowability relatively small. The conductive ball is fixed on the land without exposing an SnCu layer formed on the Cu layer. An electrode is formed without exposing the SnCu layer having relatively poor solder wettability. Between the electronic component and a circuit board, a joint section having a good electric conduction property and mechanical strength may be formed.

Abstract: A semiconductor module that can realize a substantially fixed transmission time of signals transmitted through electric wirings disposed on a board via each semiconductor device mounted on a board and can reduce reflection of high-frequency signals and a method for mounting the same is provided. A plurality of semiconductor devices are mounted on a flexible board, and a semiconductor module is formed by folding the board so that the plurality of semiconductor devices are stacked. In an input signal line electrically and mechanically connected to each of the semiconductor devices and an output signal line electrically and mechanically connected to each of the semiconductor devices which signal lines are formed on the board, the sum of a first line length of the input signal line and a second line length of the output signal line for each of the semiconductor devices is set to a substantially fixed length.

Abstract: A semiconductor module that can realize a substantially fixed transmission time of signals transmitted through electric wirings disposed on a board via each semiconductor device mounted on a board and can reduce reflection of high-frequency signals and a method for mounting the same is provided. A plurality of semiconductor devices are mounted on a flexible board, and a semiconductor module is formed by folding the board so that the plurality of semiconductor devices are stacked. In an input signal line electrically and mechanically connected to each of the semiconductor devices and an output signal line electrically and mechanically connected to each of the semiconductor devices which signal lines are formed on the board, the sum of a first line length of the input signal line and a second line length of the output signal line for each of the semiconductor devices is set to a substantially fixed length.