A matched expansion probe card for high temperature LSI testing
This paper describes the fabrication process and mechanical properties of a novel probe card were described. To match the thermal expansion between the probe card and a silicon wafer in wafer-level burn-in test, a Pyrex glass substrate with feedthrough connections was used to support the probes. To make the slantwise probe contactors, spray coating was used to form a uniform photoresist film on a deeply-wet-etched silicon wafer. The fabricated probe card has 13185 p/sup +/ silicon probe contactors at a pitch of 150 /spl mu/m on an area of 44.0 mm /spl times/ 45.7 mm. The rigidity of the probes is approximately 91.45 N/m. The planarity of the probe tips is within /spl plusmn/ 1 /spl mu/m from the base level.
Laterally stacked glass substrates with high density electrical feedthroughs
This paper reports a novel method to produce high density feedthrough glass wafers with sufficient thickness for the packaging and interconnection of high density array micro electromechanical systems (MEMS). Pyrex glass wafers with thin film metal lines on the surface are stacked and bonded with each other using phenyl methyl siloxane-based adhesive. The stacked glass wafer block is then sliced using a wire saw as the slicing surfaces cross the adhesive bonding interfaces vertically. Prototyped feedthrough glass wafers were subjected to anodic bonding to a silicon wafer with diaphragms. The anodic bonding was successful, but hermetic sealing was not achieved. The bending of the bonded sample can be reduced by annealing the sample at 400 °C in a vacuum before anodic bonding.
Flip chip bonding reliability of advanced glass ceramic chip size package
In order to realize high-density wiring and to increase the reliability of chip interconnection to printed wiring boards (PWBs), we have developed glass ceramic chip size packages (CSPs). A 64M-DRAM chip was connected to the glass ceramic substrate via Au bumps by a flip chip bonding technique with high interconnection reliability, and the substrate was mounted on a PWB via solder ball bumps. To evaluate the reliability of the glass ceramic CSP, a thermal stress simulation was performed and the analysis indicated that thin glass ceramic CSPs were highly reliable. This finding was supported by thermal cycle testing using actual glass ceramic CSPs and identically structured alumina CSPs. The thin glass ceramic CSPs passed 1000 cycles, although failures were detected on the alumina CSPs between 500 and 1000 cycles. These failures were analyzed and it was confirmed that fatigue fractures occurred in the solder ball bumps due to coefficient of thermal expansion (CTE) mismatch and substrate rigidity.