TABLE OF CONTENTS An assembly technique, called MiniMod, was introduced by the General Electric Co. in the early 1970s. Like flip chip, it was initially developed to address low cost assembly of the transistor and subsequently the integrated circuit. Common to flip chip, MiniMod featured Au bumped pads and gang or mass bonding of all connections to the die and to the package in a single operation. There were, however, differences. MiniMod incorporated use of a patterned metal on an organic film or tape (a flex circuit) to accomplish the interconnection between die and package.
The tape or film (polyimide, Kapton ) with the patterned metal interconnect is fabricated in a strip format similar to movie film. With pre-punched sprocket holes to facilitate machine handling of the tape through various manufacturing operations, an automated system presented itself. This combination of automation and gang bonding offered the potential for significant cost savings to be realized. MiniMod eventually became Tape Automated Bonding, or simply TAB.
Figure 9-1 is a schematic representation of a single frame TAB assembly with key features of the tape identified. It shows the IC bonded in place to cantilevered leads patterned and supported on the film. The patterned tape is in essence a flex circuit and represents the earliest application of flex in microelectronic packaging. In today s jargon the flex circuit is often referred to as an interposer and is the same basic technology used in the manufacture of the BGA CSP.
