| 摘要 |
Described is a device for performing weldings in microcircuits by pressure and ultrasonic vibration between a ball formed at the end portion of a wire and a terminal of the dice of a microcircuit, which includes a capillary inside the channel through which the wire to be welded is passed, near the conical-shaped end portion of the capillary are arranged the following elements: an electrode intended to form, by a spark, the ball located at the end portion of the wire, also including a tube that blows inner gas towards the ball for avoiding the corrosion thereof. The ball is pressed against the terminal to be welded, applying force and ultrasonic vibration controlled by the capillary, while the dice is heated from beneath by an electric heater. The disadvantage of this device is the formation of irreversible fractures in the dice as a result of the application of excessive force in case of welding wires made of rigid materials such as copper and silver. This disadvantage is avoided by p lacing a laser always focused on the ball formed at the end portion of the wire to be welded, arranged at the conical end portion of the capillary. The laser beam heats the ball at a temperature higher than 100°C, reducing therefore its hardness and respectively the force required for welding the ball, protecting the dice from breaking. |
