Contact Resistance of the Chip-on-Glass Bonded 48Sn–52In Solder Joint

Abstract

An average contact resistance of a COG joint bonded with 48Sn-52In solder was characterized using daisy chain structure. The average contact resistances of the 48Sn-52In solder joint of 29 mm diameter and 14 mm height were 132 m/bump, 28.5 m/bump, and 8.6 m/bump on Ti(0.1 mm)/Cu(1.5 mm), Ti(0.1 mm)/Cu(1.5 mm)/Au(0.1 mm), and Ti(0.1 mm)/Cu(3 mm)/Au(0.1 mm) UBMs, respectively. Such difference in the average contact resistance of the 48Sn-52In solder joint on each UBM could be attributed to partial oxidation of the Cu UBM layer during solder evaporation and a difference of the thickness of the Cu UBM layer remaining underneath the intermetallic compounds after soldering.

Highly reliable, fine pitch chip on glass (COG) joints fabricated using Sn/Cu bumps and non-conductive adhesives

“…In COG bonding fabricated using NCA, interconnection is retained by the direct contact between the metal bump and the pad on glass substrate [2,11,13,15] and the adhesive provides mechanical adhesion by tightly holding the bump and substrates. Variation in bump height can induce open failure [4,11,18].…”

“…Chip on glass (COG) bonding is widely applied to driver integrated circuit space (IC) packaging technology for liquid crystal display (LCD) [1][2][3][4]. In this COG technology, the driver IC is directly mounted to a glass substrate with Indium Tin Oxide (ITO) trace by the flip chip method.…”