Metal spring contacts may be used for electrically connecting integrated circuit chips or dies to circuit boards or other devices and may also be used as probe needles on a probe card. Spring contacts allow for reduced pitch, and thus, smaller devices. Spring contacts and methods of forming them are known in the art.
Spring contacts may be formed by depositing a release layer on a substrate or some other underlying layer. In this approach, layers of engineered spring metal are deposited onto the release layer and conductive bond pads and patterned. The release layer is then etched away to release a free end of the spring which curls up and away from the substrate. Another approach involves overplating or cladding the released spring contact.
The method described above requires the spring contact to be formed on the wafer as part of the wafer manufacturing process, which requires the sputtering of metals not normally used in the manufacturing process.
Anisotropic Conductive Film (ACF) tape separates the application of conductive contacts from the chip manufacturing process. ACF tape has limitation as to how small a pitch can be used by the chip. Smaller pitch sizes may lead to short circuiting within the tape between adjacent landings. Also, ACF tape is not compliant and is not easy to rework.
USPTO Backgrounds
USPTO Backgrounds