Improved Plating and Tooling Technique for the Contactless Electro-Plating of a Probe in a High Density Matrix
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
A "cobra" probe (so named because of its shape) is employed to contact individual solder balls used to electrically and mechanically attach a semiconductor device to a substrate. The tip of the probe is coated with chromium to reduce its adherence to the lead-tin solder balls, thereby increasing the service life of the probe. This article concerns improvements in the means used to obtain a uniform plating thickness on the cobra probe tip [*]. By use of the funnel-shaped tool shown in Fig. 1, auxiliary cathode thievingis employed to control the distribution of chromium deposition while achieving a desired uniform plating thickness. The thumbscrew mechanism 1 allows close control of the probe 2 downward travel in this tool.