Wiring substrate

A wiring substrate comprising:

• a substrate;
• and
• a wiring portion formed on the substrate,
• wherein the wiring portion includes:
• a first wiring portion made of Ag,
• a second wiring portion made of Au, the first wiring portion and the second wiring portion overlapping each other such that the first wiring portion is partially formed over the second wiring portion, and
• a high melting point metal portion interposed between the first wiring portion and the substrate and between the first wiring portion and the second wiring portion where the first wiring portion and the second wiring portion are overlapped, the high melting point metal portion having a melting point higher than those of the first wiring portion and the second wiring portion.

A wiring substrate comprising:

• a substrate;
• and
• a wiring portion formed on the substrate,
• wherein the wiring portion includes:
• a first wiring portion made of Ag,
• a second wiring portion made Au, and
• a composition changing portion which is interposed between the first wiring portion and the second wiring portion,
• wherein a composition ratio of Ag contained in the composition changing portion gradually decreases from a side of the first wiring portion to a side of the second wiring portion, and
• wherein the composition changing portion contains Ag and Pd and a composition ratio of Pd increases from the side of the first wiring portion to the side of the second wiring portion.

A wiring substrate comprising:

• a substrate;
• and
• a wiring portion formed on the substrate,
• wherein the wiring portion includes:
• a first wiring portion made of Ag,
• a second wiring portion made of Au, and
• a composition changing portion which is interposed between the first wiring portion and the second wiring portion,
• wherein a composition ratio of Ag contained in the composition changing portion gradually decreases from a side of the first wiring portion to a side of the second wiring portion, and
• wherein a high melting point metal portion having a melting point higher than those of the first wiring portion and the second wiring portion is formed between the substrate and at least the first wiring portion.

A wiring substrate comprising:

• a substrate;
• and
• a wiring portion formed on the substrate,
• wherein the wiring portion includes:
• a first wiring portion made of Ag,
• a second wiring portion made of a material different from that of the first wiring portion, and
• a composition changing portion which is interposed between the first wiring portion and the second wiring portion,
• wherein a composition ratio of Ag contained in the composition changing portion gradually decreases from a side of the first wiring portion to a side of the second wiring portion, and
• wherein the second wiring portion is made of Au.

A wiring substrate comprising:

• a substrate;
• and
• a wiring portion formed on the substrate,
• wherein the wiring portion includes:
• a first wiring portion made of Ag,
• a second wiring portion made of a material different from that of the first wiring portion, and
• a high melting point metal portion interposed between the first wiring portion and the second wiring portion and having a melting point higher than those of the first wiring portion and the second wiring portion,
• wherein the second wiring portion is made of Au and the high melting point metal portion is made of a metal material containing at least one element of W, Mo, or Ta.