288
S. Lee
Fig. 10.30 Correlation
between CTE (< Tg) and E
(< Tg) [30]
R² = 0.6041
20
25
30
35
40
45
50
55
3
5
7
9
1 1
1 3
CTE(ppm/˚C)
affect other characteristics such as processability, reliability, and component coplanarity. The processability of a flip chip underfill is sensitive to viscosity and resin
type while reliability and co-planarity are impacted by all mechanical properties.
Aw, et al. demonstrated TCB assembly process using NCP for 30 μm pitch Cu
pillar micro bumped die on organic substrate with Cu bond pads [31]. They also
address the technical challenge, filler entrapment induced failure in their research.
Figure 10.31 shows a typical failure, induced by filler entrapment, on micro bump
interconnection.
Jin-Ye, et al. investigated process conditions and TV design impacts on similar
NCP entrapment in TCB assembly process (see Fig. 10.32) [32]. They investigated
the interaction between bond force and bump design in order to minimize this defect.
At first glance, the development of an epoxy flux process appears to be simple.
However, significant challenges develop when scaling a prototype process to mass
production. A solid understanding is necessary of polymer based material properties
and TCB process technology to introduce an epoxy flux into an actual assembly
process. Even when a high yield process is achieved, poor reliability performance
can prohibit its use for certain package configuration.
Fig. 10.31 A SEM
micrograph of typical open
failure due to filler
entrapment [31]
S. Lee
Fig. 10.30 Correlation
between CTE (< Tg) and E
(< Tg) [30]
R² = 0.6041
20
25
30
35
40
45
50
55
3
5
7
9
1 1
1 3
CTE(ppm/˚C)
affect other characteristics such as processability, reliability, and component coplanarity. The processability of a flip chip underfill is sensitive to viscosity and resin
type while reliability and co-planarity are impacted by all mechanical properties.
Aw, et al. demonstrated TCB assembly process using NCP for 30 μm pitch Cu
pillar micro bumped die on organic substrate with Cu bond pads [31]. They also
address the technical challenge, filler entrapment induced failure in their research.
Figure 10.31 shows a typical failure, induced by filler entrapment, on micro bump
interconnection.
Jin-Ye, et al. investigated process conditions and TV design impacts on similar
NCP entrapment in TCB assembly process (see Fig. 10.32) [32]. They investigated
the interaction between bond force and bump design in order to minimize this defect.
At first glance, the development of an epoxy flux process appears to be simple.
However, significant challenges develop when scaling a prototype process to mass
production. A solid understanding is necessary of polymer based material properties
and TCB process technology to introduce an epoxy flux into an actual assembly
process. Even when a high yield process is achieved, poor reliability performance
can prohibit its use for certain package configuration.
Fig. 10.31 A SEM
micrograph of typical open
failure due to filler
entrapment [31]