3TDK-EPC CORPORATION
Development background and TDK-EPC's efforts
1608
1005
1005
0603S 0603Q
0603
0402S
MLG
MLK
MLK0603
Downsized/low-loss RF circuits essential for multi-
functioning
The low-loss and drastic downsizing of diverse RF mod-
ules such as PA, PLL synthesizers, VCO, and TV tuners
have been the utmost urgency for further thinner, light-
er, and increased functionality of mobile phones as,
while maintain the current size and thickness, the trend
of multi-functioning of mobile phones increases with
features such as QVGA wide LCDs where you can ex-
plore websites designed for PCs, mega-pixel digital
camera, high-capacity HDD that can save a large
amount of music source and movies, GPS systems, FM/
terrestrial digital TV tuners, wireless communication de-
vices, USB2.0 interface, bar-code generation feature,
and support for the FeliCa services. More control ICs
which comprises the module core are already shifting
to implement bear chips. Module components imple-
mented around ICs such as multilayer ceramic chip
capacitors which already have established mass pro-
duction system are also shifting from 0603 to 0402 type.
Chip inductors currently used for impedance matching
of mobile phones' RF circuits and modules, or used for
high-frequency chokes, are mainly the 0603 type. But
with the accelerated shift to downsized mobile phone
modules, developing a 0402 type with a superb Q value
in the range of 800MHz-2GHz and a well-balanced Rdc
value, as well as an expanded characteristic lineup, is
an urgent need.
These minimum chip inductors supporting usage in
high-frequency ranges are mass- produced through
the LTCC (low temperature sintered ceramics) process-
ing technology where internal conductor patterns with
optimized high-frequency characteristics are printed
and layered accurately on low temperature ceramic
sheets.
On the other hand, for impedance matching of high-
frequency circuits, chip inductors with thin-film technol-
ogy which realize high self-resonance frequency and
Q value relatively easily are also adopted. However,
these types of chip inductors where a thin-film conduc-
tor is formed in a spiral on the element surface have a
difficulty in controlling the aspect ratio of the thin-film
conductor (ratio of conductor width vs. thickness) and
show a limitation in the technology when it controls an
increased Rdc value as chip size is further downsized
(ie., narrowed conductor width).
The conditions of the chip inductors which can accel-
erate the downsizing, multifunctioning, and power sav-
ing of mobile phone RF modules
-
While seeking the
lowest limit of Rdc for the 0402 size by controlling the
characteristic parameters such as internal conductor
cross sectional shape, pattern shape, and inter-layer
connection structure, the inductance and Q support-
ing the latest design needs of the RF modules and a
superb frequency characteristic of the impedance
must be maintained.
In developing the super- small 0402 type chip, TDK-
EPC, following the guideline, utilized the knowhow of
“GIGASPIRA multilayer structure”, the super-small inter-
nal conductor forming technology supporting high-
frequencies, which had been established through the
mass-production processes of the MLK0603, based on
MLG0603S, which combines the world's lowest level Rdc
value and a superb Q characteristic. Through a tech-
nological approach advancing the inter-
nal conductor cross-section and the
pattern shape control accuracy,
the mass-production system
of the MLG0402S type ex-
ceeds the characteristic
advantages of MLG0603S.
GIGASPIRA multilayer structure
This is a high-Q multilayer chip in-
ductor supporting GHz bands with
minimized stray capacitance between internal conductor
and terminal electrode using the original GIGASPIRA multi-
layer structure where internal conductors and terminal elec-
trodes layered in a longitudinal direction are connected via
hole conductor formed on the center axis in the element's
longitudinal direction. The lateral sides(terminal surface) of
the MLK0603 series are 0.3 x 0.3mm. The advanced knowhow
of forming super-small internal conductor patterns in this nar-
row space of micron order is utilized in the mass-production
processes of the MLG0402 series.
FeliCa is a registered trademark of Sony Corporation.
Exceeding the conventional limits, new low loss/high
Q structure, which supports the innovative effort of
designing RF circuits, was sought.
Full-scale power-saving circuit designs, which allow
even longer continuous operation periods, are required
for mobile phones with built-in TV and MP3 players. In
terms of minimizing chip inductors for the RF modules,
this is very important to consider on development of
the product.
To respond to the most-advanced needs of mobile
phones, TDK-EPC has been developing each series of
MLK0603 (1- 33nH), MLG0603S (0.3 -100nH), and MLG
0603Q(Reinforced Q type:0.2-100nH) which combine
the industry's lowest Rdc value and superb Q frequen-
cy characteristic as the multilayer chip inductor 0603
type for high-frequency modules. These super-small
multilayer chip inductors have been adopted for many
uses in impedance matching of diverse RF circuits and
as power line chokes.