264
S. Lee
Microscope (SEM) microgprah of the 2.5D Xilinx FPGA (Fig. 10.4b) depicts the
details of the SSI technology. TCB is used to attach the micro-bumped FPGAs to a
TSV interposer. The interposer, now with the four FPGA mounted to it, is assembled
to the organic substrate using C4 soldering technology.
10.2.2 Fundamentals of Thermal Compression Bonding
(TCB) Technology
The purpose of this session is to provide insight into Thermal Compression Bonding
(TCB) required for interconnections between substrates using TSV die stacking.
The TCB bonding technology will be compared with traditional mass reflow in
terms of process limitations and technical challenges. The details will be explored of
the TCB process mechanism with emphasis on the functionality and configuration
of TCB bonder. The technical insight shows how the TCB assembly process can
be characterized and developed by controlling the key process parameters such as
displacement, force, and temperature.
10.2.2.1 Technical Challenges of a Mass Reflow Process Compared
with TCB
Figure 10.5a illustrates the traditional flip assembly process steps beginning with
dipping a die into the flux reservoir or dispensing flux on a substrate, depending on
products. Next, the die is placed on the substrate followed by reflowing the die and
substrate to form the interconnections. Then, the flux residues are removed from the
bonded package and underfill will be applied in the gap between die and substrate.
Underfill curing process completes the traditional flip chip assembly process. In
general, memory manufactures prefer to use flux dipping but logic manufactures
use dispensing because of mostly assembly cost associated with equipment price
and throughput. This book chapter will not focus on the technical details of the
traditional flux application process; in fact, at least six process steps are necessary
to produce a single package of flip chip. Rather, attention is given to the mass reflow
process that establishes the metallurgical interconnects through a reflow profile as
described in Fig. 10.5b.
The mass reflow process can take several minutes. Temperature ranges and time
durations at each zone can be optimized through a number of iterations, which is
compatible with solder alloy composition and process materials in order to achieve
high, stable product yield. More details can be found on the publications about
traditional flip chip packaging assembly process [2, 3, 6].
In contrast, TCB can complete a bonding in two or three steps of assembly process
as shown in Fig. 10.6. Figure 10.6 describes TCB process using epoxy flux that is also
called as filled Non-conductive Paste (NCP) or no-flow underfill. The TCB process
S. Lee
Microscope (SEM) microgprah of the 2.5D Xilinx FPGA (Fig. 10.4b) depicts the
details of the SSI technology. TCB is used to attach the micro-bumped FPGAs to a
TSV interposer. The interposer, now with the four FPGA mounted to it, is assembled
to the organic substrate using C4 soldering technology.
10.2.2 Fundamentals of Thermal Compression Bonding
(TCB) Technology
The purpose of this session is to provide insight into Thermal Compression Bonding
(TCB) required for interconnections between substrates using TSV die stacking.
The TCB bonding technology will be compared with traditional mass reflow in
terms of process limitations and technical challenges. The details will be explored of
the TCB process mechanism with emphasis on the functionality and configuration
of TCB bonder. The technical insight shows how the TCB assembly process can
be characterized and developed by controlling the key process parameters such as
displacement, force, and temperature.
10.2.2.1 Technical Challenges of a Mass Reflow Process Compared
with TCB
Figure 10.5a illustrates the traditional flip assembly process steps beginning with
dipping a die into the flux reservoir or dispensing flux on a substrate, depending on
products. Next, the die is placed on the substrate followed by reflowing the die and
substrate to form the interconnections. Then, the flux residues are removed from the
bonded package and underfill will be applied in the gap between die and substrate.
Underfill curing process completes the traditional flip chip assembly process. In
general, memory manufactures prefer to use flux dipping but logic manufactures
use dispensing because of mostly assembly cost associated with equipment price
and throughput. This book chapter will not focus on the technical details of the
traditional flux application process; in fact, at least six process steps are necessary
to produce a single package of flip chip. Rather, attention is given to the mass reflow
process that establishes the metallurgical interconnects through a reflow profile as
described in Fig. 10.5b.
The mass reflow process can take several minutes. Temperature ranges and time
durations at each zone can be optimized through a number of iterations, which is
compatible with solder alloy composition and process materials in order to achieve
high, stable product yield. More details can be found on the publications about
traditional flip chip packaging assembly process [2, 3, 6].
In contrast, TCB can complete a bonding in two or three steps of assembly process
as shown in Fig. 10.6. Figure 10.6 describes TCB process using epoxy flux that is also
called as filled Non-conductive Paste (NCP) or no-flow underfill. The TCB process