A New COG Technique Using Low Temperature Solder Bumps for LCD Driver IC Packaging Applications

Sn58Bi Solder Interconnection for Low-Temperature Flex-on-Flex Bonding

“…Unlike an ACF, which enables electrical conduction through mechanical contact between electrodes, solder forms strong intermetallic joints with electrodes [5]. Moreover, the addition of an underfill protects the joints by relieving the thermomechanically induced stresses and promotes overall adhesion strength between flexible substrates.…”

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

“…[1][2][3][4] Chipon-glass (COG) technologies using an anisotropic conductive film (ACF) or solder bumps have been investigated to attach an IC chip directly on a glass substrate of a LCD panel. [5][6][7][8][9][10][11][12][13][14] COG technologies can accommodate high density and fine pitch interconnection between the LCD panel and the driver IC, reduce an interconnect distance, and make the LCD devices thinner and smaller. [5][6][7][8][9][10][11][12][13][14] Compared to the COG process with ACF where conducting particles are randomly distributed in an adhesive film, the COG process using solder bumps has several advantages such as low contact resistance of the solder joint and self-alignment during reflow of solder.…”

“…[5][6][7][8][9][10][11][12][13][14] COG technologies can accommodate high density and fine pitch interconnection between the LCD panel and the driver IC, reduce an interconnect distance, and make the LCD devices thinner and smaller. [5][6][7][8][9][10][11][12][13][14] Compared to the COG process with ACF where conducting particles are randomly distributed in an adhesive film, the COG process using solder bumps has several advantages such as low contact resistance of the solder joint and self-alignment during reflow of solder. 13,14) Such advantages of the COG process using solder bumps become valid for fine pitch interconnection of the driver IC on the LCD panel.…”

“…[5][6][7][8][9][10][11][12][13][14] Compared to the COG process with ACF where conducting particles are randomly distributed in an adhesive film, the COG process using solder bumps has several advantages such as low contact resistance of the solder joint and self-alignment during reflow of solder. 13,14) Such advantages of the COG process using solder bumps become valid for fine pitch interconnection of the driver IC on the LCD panel.…”

“…Thus, it is necessary to use low melting solders such as Sn-In, Sn-Bi, Ag-In in order to prevent damage of the LCD panel during solder reflow process. [12][13][14] In spite of the advantages of the COG process using solder bumps, a few works have been reported for the COG process using low melting solders and the contact resistance of the solder joint of the COG structure. [12][13][14] In this study, COG bonding was conducted using 48Sn-52In (mass%) solder bumps on three different under bump metallurgies (UBMs) of 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), and the average contact resistance of the COG joint bonded with 48Sn-52In solder was characterized on each UBM.…”