1. Field of the Invention
The disclosure relates in general to a metal circuit structure, a method for forming a metal circuit and a liquid trigger material for forming a metal circuit, and more particularly, to a method for forming a metal circuit on a substrate by electroless plating, a liquid trigger material applied for electroless plating and a metal circuit structure formed using the same.
2. Background of the Related Art.
To integrate more functions into a single portable electronic device or to miniaturize the size of a portable electronic device, developers and manufacturers strive to reduce the volume of components inside the device. For example, transceiving antennas previously dominated by printed circuit boards are gradually being replaced by a laser direct structuring (LDS) technology that directly electroplates a conductive material on a device casing.
However, the LDS technology is applicable to only certain plastic substrates, with a limited range of dielectric constants, and thereby is not suitable for high-frequency antennas. Besides, due to injection molding adopted, the LDS technology yields an overall structure that exceeds 2 mm. Further, the thickness of a laser-etched conductive circuit needs at least 10-15 μm, and only a single-layer conductive circuit can be formed.