Plasma cleaning of chip scale packages for improvement of wire bond strength

As the integrated circuit becomes ever smaller, the associated decrease in size of the wire bond pad, on both the chip and leadframe or BGA, brings many new and substantial challenges to the chip-scale packaging engineer. This decrease in size is generally linked to not only poor wire bond pull strength but also poor wire bond strength uniformity. In spite of this, there are techniques that will enhance wire bond strength and improve uniformity. One technique is the use of radio-frequency-driven, low-pressure plasmas to clean the bond pad surfaces and prepare them for wire bonding. Here, we report findings on the use of RF plasmas to clean wire bond pads and sites prior to wire bonding.