Jetting fluids in non-traditional packaging and assembly applications
Figure 5: 3D roadmap slide courtesy Yole Development
generator; the user’s mobility is increased
because a battery charging outlet is not
required. The commercialization of an
mDMFC is dependent upon a successful
fuel cell technology implementation, and
a valid commercial partnership between
a semiconductor supplier, market leading
handheld device supplier and a properly
packaged fuel cartridge. Recently, BIC
(lighters), Nokia and ST Microelectronics
have begun to work toward developing and
bringing the mDMFC to market sometime
in 2009.
A DMFC works by reducing methanol
and water at the anode side of a catalyst
film allowing the proton exchange to occur
through a membrane in contact with the
!"#$%&'(
oxidation side at the cathode catalyst film.
)*#%+*,-(
The electrons necessary for the complete
reaction flow through the completed
Figure 5. 3D Roadmap slide courtesy Yole Development.
circuit like a battery. Figure 8 shows a
Figure 6: 8 wire bonded stacked die
Figure 7: Jetted lines for vertical interconnect
Figure 7: Jetted lines for vertical interconnect
schematic diagram of a fuel cell and the
chemical reaction.
Semiconductor
and micro electro
mechanical systems
(MEMS) manufac-
turing processes
are particularly
suited to making
mDMFCs. Figure 9
Figure 7. Jetted lines for vertical interconnect.
shows a diagram of
a semiconductor-
based fuel cell.
Figure 6. 8 wire bonded stacked die. cess. The interconnection uses jetting 200
On the anode side, the silicon wafer is
micron wide lines of silver epoxy instead of
etched with holes to allow a path for water
stacked die, the wire bond process em-
using gold wire bonds.
and methanol to diffuse into the catalyst
ployed 22 process steps versus eight for the
Figure 10: Wafer process for DMFC
vertical interconnect (Tables 1 and 2).
emerging applicaton: fuel cells
The wire bond process also required
A new application for semiconductor wafer
101 m
2
of floor space with 16 operators on
processing is the development of micro
46 machines resulting in 39 hours of cycle
direct methanol fuel cells (mDMFC). The
time versus 24 m
2
of floor space with eight
driving market force for DMFC is for the
operators on 16 machines with an 8-hour
replacement or recharging of batteries in
cycle time for the vertical interconnect pro-
portable and handheld devices. The tech-
nology driving DMFC is that its volumetric
Figure 8: Chemical reactions and DMFC schematic
energy density (800 Wh/kg) is greater than
Lithium batteries (200 Wh/kg) and by
Figure 9: Schematic of Silicon based FC
using a readily available fuel as the electron
Figure 8. Chemical reactions and DMFC schematic. Figure 9. Schematic of Silicon based FC.
layer. The semiconductor anode has con-
16 – Global SMT & Packaging – May 2009 www.globalsmt.net
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