Qualification of the Assembly Process of Flip-Chip BGA Packages ...

1.5.2 Tape Automated Bonding [4]
Texas Tech University, Nivetha Shivan, May 2012
It is also called as TAB, is the process of attaching a die on a flexible tape. This tape is
usually made of a polymer material, like polyimide. The bonding sites of the die are
connected to the fine conductors on the tape through gold or solder bumps. These bumps
are called Inner lead bonds (ILB). The tape connects to the package substrate through
copper leads called the Outer lead bonds (OLB). TAB interconnections have better
electrical performance than wire bonding because of short lead lengths between the die
and the substrate. Though TAB has better electrical properties than wire-bonding, it still
is not used widely because of the following reasons:
1. Package size gets larger as the I/O pin count increases
2. The infrastructure for the making TAB packages is less
3. Capital cost for the packaging equipment is high
1.5.3 Flip Chip Bonding [1]
In Flip chip technology, the IC is connected to the package substrate by having the active
side of the die facing towards the substrate (the die is flipped). The basic parts of a FC
package consist of an integrated circuit, an interconnection system, and a package
substrate. The flip chip interconnection system consists of four main functional
components which are under bump metallization (UBM), solder bumps, under fill
encapsulation and substrate metallization.
Flip Chip bonding provides minimal impedance and signal delays as they have the
shortest die to substrate bonding. The reliability of the Flip Chip technology varies from
highly reliable to adequate depending on the materials with which the package is
constructed. Figure 1.2 shows the components of a typical Flip Chip package.
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