08-03-2010, 08:35 PM
Diamond and flip chips
Wide-band gap (WBG) transistors give a real
breakthrough for power devices compared to Silicon (Si)
and Gallium Arsenide (GaAs) components. But thermal management is vital. Some packaging solutions dedicated to those power transistors are presented in this
paper.
Introduction
There are some passive thermal
management ideas with very dissipative substrates such
as diamond.
With a flip chip assembly, via hole
implementation in diamond could help increase this
maximum operating frequency. In the first method discussed here
components are soldered on a diamond carrier.In the second case, dice are flip chip bonded on a diamond circuit. Diamond and pyrolitic graphite are highly interesting
for their very good thermal conductivity
Thermal dissipation:
A compromise must be found
between thermal conductivity and mechanical properties
such as the Coefficient of Thermal Expansion (CTE) in the case of passive thermal management Diamond has high thermal conductivity but their CTE is low, which will make assembly delicate.
Two possible topologies with diamond:
Diamond is of great interest as it can be used either as
a carrier or as a RF circuit. The TRT GaN/SiC
components we used have RF and thermal bumps.Then diamond is a simple thermal carrier.Else they can be flip chip mounted and then, diamond is an RF circuit.
Thermal Simulations:
Thermal simulations show that a face-up assembly on a
diamond carrier is more thermally effective than a flip
chip assembly.Therefore active face-up mounting seems more interesting
than flip chip assembly for thermal considerations.
Higher frequencies:
B. Diamond circuit fabrication:
Metallized holes associated to thin film technology is
not an easy task with substrates such as diamond. thin film has been
performed on diamond with success.Thus thin film technology with metallized holes was almost ready . The whole process has been recently
performed with excellent results on a 300 m thick
diamond substrate. sides are very regular, clean
and smooth and film metallization on diamond and in those holes coul dbe done easily.
more details is available in this IEEE paper:
http://ieeexplore.ieeesearch/srchabstrac...Search+All
Wide-band gap (WBG) transistors give a real
breakthrough for power devices compared to Silicon (Si)
and Gallium Arsenide (GaAs) components. But thermal management is vital. Some packaging solutions dedicated to those power transistors are presented in this
paper.
Introduction
There are some passive thermal
management ideas with very dissipative substrates such
as diamond.
With a flip chip assembly, via hole
implementation in diamond could help increase this
maximum operating frequency. In the first method discussed here
components are soldered on a diamond carrier.In the second case, dice are flip chip bonded on a diamond circuit. Diamond and pyrolitic graphite are highly interesting
for their very good thermal conductivity
Thermal dissipation:
A compromise must be found
between thermal conductivity and mechanical properties
such as the Coefficient of Thermal Expansion (CTE) in the case of passive thermal management Diamond has high thermal conductivity but their CTE is low, which will make assembly delicate.
Two possible topologies with diamond:
Diamond is of great interest as it can be used either as
a carrier or as a RF circuit. The TRT GaN/SiC
components we used have RF and thermal bumps.Then diamond is a simple thermal carrier.Else they can be flip chip mounted and then, diamond is an RF circuit.
Thermal Simulations:
Thermal simulations show that a face-up assembly on a
diamond carrier is more thermally effective than a flip
chip assembly.Therefore active face-up mounting seems more interesting
than flip chip assembly for thermal considerations.
Higher frequencies:
B. Diamond circuit fabrication:
Metallized holes associated to thin film technology is
not an easy task with substrates such as diamond. thin film has been
performed on diamond with success.Thus thin film technology with metallized holes was almost ready . The whole process has been recently
performed with excellent results on a 300 m thick
diamond substrate. sides are very regular, clean
and smooth and film metallization on diamond and in those holes coul dbe done easily.
more details is available in this IEEE paper:
http://ieeexplore.ieeesearch/srchabstrac...Search+All
