Chip Scale Review November • December • 2018[ChipScaleReview.com]
performance. eWLB can achieve the
minimum interconnection length and
excellent electrical performance up to
mmWave frequencies. The conversion
gain and the noise figure of the mixer
affect the performance of the overall
system. Therefore, a high-transmission
performance of the mmWave signal is
very important in the design of a package.
With the push toward autonomous
driving and automated vehicles, the
research and development programs for
sensors enabling the above mentioned
t e ch nolog ie s h ave gone i nt o h ig h
gear over the last several years. SRR,
MRR and LRR sensors are essential
components for the overall sensors
needed for the complete implementation
of automated vehicles. Many packages in
these segments use advanced packaging
options such as fan-out eWLB, with
lower parasitics at 77GHz .
For radio frequency (RF) and high-
f r equency dev ice s , eWLB showed
less parasitic electrical interference,
t he refore, sign if icantly improv i ng
overall device electrical performance.
In one example, a 77GHz SiGe mixer
p a c k a g e d w i t h eWL B a c h i e v e d
excellent high-f requency elect r ical
performance due to the small contact
dimensions and short signal pathways
o r i n t e r c on ne c t i on l e ng t h , wh i ch
decreased parasitic effects [15,16].
The sections below demonstrate the
advantages of the eWLB packaging
s o l u t i o n f o r t h e mmWave d e v i c e
or h igh -f r equency appl icat ion s a s
compared to subst rate or laminate-
based packaging, such as f lip chip or
I nt erconne c t i on l eng t h .
enables integration where the distance
has to be as shor t as possible (loss
increases with distance) to minimize
loss (assuming both technologies have
the same material loss).
Plated Cu used
i n organ ic subst r at e mat e r ials ha s
large surface roughness because of the
process used to improve adhesion and
plating process control. eWLB uses
a thin-f ilm fab process for the seed
layer and a well-controlled Cu plating
to achieve a smooth Cu RDL surface,
which is more effective for skin effect
i n h ig h -f r e que ncy r a nge s (i.e., a t
100GHz, Cu skin depth is ~0.2mm).
ma t e r i a l s h ave h ig h lo s s e s i n t he
m mWa v e r a n g e . F u r t h e r m o r e ,
het e rogeneou s mat e r ia l set s br i ng
complex it y i n t e r ms of ele c t r ic a l
b e h a v i o r s . eWLB u s e s mo l d i n g
compou nd a nd low-los s d iele c t r ic
materials that enable the achievement
of less dielectric loss.
Design f lexibility.
more design flexibility for less routing
interference with fine line width (LW)
and line spacing (LS) capability (less
than 10/10µm LW/LS).
One key element for the change from
a rather complex and expensive solution
t o a n e a s y- t o - u s e a nd , t he r e fo r e ,
inexpensive and affordable product
is the use of standard surface mount
device (SMD) packaging technology.
The eWLB package is SMD attached,
t he r eby simpl i f y i ng t he up s t r e am
assembly process and has already been
proven in a few mmWave applications.
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manufacturers in semiconductor, electronics assembly, medical
device and electro-mechanical assembly the world over.www.dltechnology.com .
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