10 Fundamentals of Bonding Technology and Process Materials …
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processes was fixed. While the TCB process employed a pressure of 3.43 N and
heat applied onto the die surface, reflow process was only controlled by the reflow
oven operated as a heat source. Each temperature profile of TCB process and reflow
process was used from the thermal profiles illustrated in Fig. 10.52. As stated in
the introduction, temperature variations of the solder joints were estimated during
the cooling phase (i.e. beginning and the end of the cool down stage), particularly
at 3.5 and 5.6 s in TCB process and at 170 and 220 s in reflow process. As shown
in Fig. 10.51a, b, TCB process led to a temperature difference of 1.39 °C at 3.5 s
and 0.26 °C at 5.6 s; however, reflow process maintained an uniform temperature
variation depicted in Fig. 10.51c, d. Such difference could be a factor that affects
the solder microstructure, thus a poor EM-reliability for TCB-processed package.
Therefore, based on these simulation results, it is concluded that the effect of TCB
process on the temperature variation of the solders should be thoroughly examined”
[83].
10.6 Summary and Discussion
This chapter reviewed the TCB technology designed for 3D TSV stacking by examining the associated process steps, equipment, and materials. An understanding of the
fundamental properties and engineering sciences of TCB interconnections remains
insufficient, despite two leading DRAM manufactures such as Samsung and SK
Hynix have released TSV products into the consumer electronics market. Therefore,
the discussion conpared the TCB process and the conventional reflow processes in
terms of unique process signatures, which can be found on units only were assembled
using the TCB process in order to emphasize process characteristics and technical
challenges of 3D stacking process.
Technical details, which are needed to build the engineering sciences knowledge
base, are also limited because a few manufactures have the infrastructure to execute
TSV process that needs TCB and such, research and development efforts are still
too few. To minimize the technical gap between the leading manufactures and the
others, this chapter explores four major building blocks, water-soluble flux, no-clean
flux, epoxy flux, and NCF. Advantages and disadvantages were highlighted for each
process materials category. The understanding on major assembly building blocks
will improve assembly process quality in terms of throughput and cost, bringing
the TCB process closer to the success of the traditional flip chip reflow process.
Furthermore, an understanding of the proposed methodologies to develop a TCB
assembly process is based upon a design having the building block that is most
compatible with package configuration. Indeed, use of NCF is the building block
that two leading DRAM manufactures selected for TSV 3D stacking technology.
A primary drawback from TCB with NCF is poor throughput because of a long
bonding cycle time induced by NCF material properties. Also, so that several multimillion dollar capital investment on the order of several millions of dollars is required
to produce the desired production quantities at acceptable yields, thus increasing
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processes was fixed. While the TCB process employed a pressure of 3.43 N and
heat applied onto the die surface, reflow process was only controlled by the reflow
oven operated as a heat source. Each temperature profile of TCB process and reflow
process was used from the thermal profiles illustrated in Fig. 10.52. As stated in
the introduction, temperature variations of the solder joints were estimated during
the cooling phase (i.e. beginning and the end of the cool down stage), particularly
at 3.5 and 5.6 s in TCB process and at 170 and 220 s in reflow process. As shown
in Fig. 10.51a, b, TCB process led to a temperature difference of 1.39 °C at 3.5 s
and 0.26 °C at 5.6 s; however, reflow process maintained an uniform temperature
variation depicted in Fig. 10.51c, d. Such difference could be a factor that affects
the solder microstructure, thus a poor EM-reliability for TCB-processed package.
Therefore, based on these simulation results, it is concluded that the effect of TCB
process on the temperature variation of the solders should be thoroughly examined”
[83].
10.6 Summary and Discussion
This chapter reviewed the TCB technology designed for 3D TSV stacking by examining the associated process steps, equipment, and materials. An understanding of the
fundamental properties and engineering sciences of TCB interconnections remains
insufficient, despite two leading DRAM manufactures such as Samsung and SK
Hynix have released TSV products into the consumer electronics market. Therefore,
the discussion conpared the TCB process and the conventional reflow processes in
terms of unique process signatures, which can be found on units only were assembled
using the TCB process in order to emphasize process characteristics and technical
challenges of 3D stacking process.
Technical details, which are needed to build the engineering sciences knowledge
base, are also limited because a few manufactures have the infrastructure to execute
TSV process that needs TCB and such, research and development efforts are still
too few. To minimize the technical gap between the leading manufactures and the
others, this chapter explores four major building blocks, water-soluble flux, no-clean
flux, epoxy flux, and NCF. Advantages and disadvantages were highlighted for each
process materials category. The understanding on major assembly building blocks
will improve assembly process quality in terms of throughput and cost, bringing
the TCB process closer to the success of the traditional flip chip reflow process.
Furthermore, an understanding of the proposed methodologies to develop a TCB
assembly process is based upon a design having the building block that is most
compatible with package configuration. Indeed, use of NCF is the building block
that two leading DRAM manufactures selected for TSV 3D stacking technology.
A primary drawback from TCB with NCF is poor throughput because of a long
bonding cycle time induced by NCF material properties. Also, so that several multimillion dollar capital investment on the order of several millions of dollars is required
to produce the desired production quantities at acceptable yields, thus increasing