10 Fundamentals of Bonding Technology and Process Materials …
289
Fig. 10.32 SEM micrographs of open failure due to filler entrapment in TCB [32]
10.3.5 Pre-applied Epoxy Based Materials (Non-conductive
Film and B-Stage Material)
Non-conductive Film (NCF) and B-stage material also allows for eliminating the
flux cleaning process because encapsulation happens on wafer. In addition, this preapplied material includes flux so that a separate flux application is unnecessary like
epoxy flux. Pre-applying materials at the wafer level reduces assembly costs.
Figure 10.33 shows different configurations of pre-applied epoxy that have been
introduced into the packaging industry. Figure 10.33a–c are methods that were
designed to avoid filler entrapment that can cause open failures during TCB process.
Both TSV HBM and RDIMM selected configuration (d), NCF, for the building block
of their TCB assembly architectures. The NCF will be bonded to the wafer through
vacuum lamination process. The vacuum lamination process can produce voided
NCF (see Fig. 10.34a) caused by improper process parameters or irrelevant material
formulation. The pre-existing voiding can grow and form macro size voids during
289
Fig. 10.32 SEM micrographs of open failure due to filler entrapment in TCB [32]
10.3.5 Pre-applied Epoxy Based Materials (Non-conductive
Film and B-Stage Material)
Non-conductive Film (NCF) and B-stage material also allows for eliminating the
flux cleaning process because encapsulation happens on wafer. In addition, this preapplied material includes flux so that a separate flux application is unnecessary like
epoxy flux. Pre-applying materials at the wafer level reduces assembly costs.
Figure 10.33 shows different configurations of pre-applied epoxy that have been
introduced into the packaging industry. Figure 10.33a–c are methods that were
designed to avoid filler entrapment that can cause open failures during TCB process.
Both TSV HBM and RDIMM selected configuration (d), NCF, for the building block
of their TCB assembly architectures. The NCF will be bonded to the wafer through
vacuum lamination process. The vacuum lamination process can produce voided
NCF (see Fig. 10.34a) caused by improper process parameters or irrelevant material
formulation. The pre-existing voiding can grow and form macro size voids during