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J U L Y 2 0 0 9 i s s u e n ° 1 1
N e w s l e t t e r o n 3 D I C , T S V , W L P & E m b e d d e d T e c h n o l o g i e s
C O M P A N Y P R O F I L E
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YD: WLC manufacturing involves new
technologies to be mastered. How the
“traditional” camera module supply chain
will be impacted by the introduction of
WLC?
GH & BK: The camera module supply chain is
currently built around the premise of component-tocomponent
assembly. Lenses and other optical
components are obtained as discrete items, and
assembled in to a barrel. Meanwhile, the imager die
is attached and interconnected to a substrate using
chip-on-board processes. A housing that goes over
the die is attached to the substrate and the barrel
screwed into the housing. Once the camera focus is
correct the lens barrel is set in position.
However this is not the entire picture. Camera
modules manufactured from discrete parts are not
compatible with solder reflow assembly.
Consequently, the camera module has to be
mounted on a flexible circuit that has an expensive
connector at one end. Then, in yet another unique
and serial process the camera module has to be
aligned, attached and integrated into the cell phone
housing or digital still camera body and the connector
mated with its socket on the main PCB. The net
result is that it can costs the cell phone manufacturer
upto $4 to incorporate a $2 camera module (see
Figure 3). The value proposition of the wafer level
camera is that not only is the camera module
cheaper per se, but it is reflow compatible so can be
mounted on the main PCB at the same time as all
the other surface mount components. In other words,
at zero incremental cost to the cell phone
manufacturer.
One of the difficulties of any disruptive technology is
that it is difficult to adapt the existing supply chain to
start production, no matter how compelling the
economic case. This is true in the case of reflowable
wafer level cameras and thus far the majority of
companies servicing this product are new entrants to
the field of camera modules. New companies can
afford to enter this space as they have no legacy
contracts to fulfil, or equipment to write-off and the
first adopters always get the highest value, which is
sufficient to offset their investment costs. The
emergence of wafer level cameras will either force
the remainder of the supply chain to adopt to this
technology or the new entrants simply grow until the
volume demand is satisfied.
In evaluating the impact wafer level cameras will
have on the supply chain it is important to recognise
that this innovation merely addresses cost and form
factor. Wafer level cameras do not yet have any
significant impact on performance. Performance
improvements are likely to follow from the
incorporation of technologies like Smart Optics,
which give rise to features like continuous depth of
field, ultra fast lenses and optical zoom with no
moving parts. These developments can all be easily
integrated into wafer level camera modules, but are
either difficult or impossible to integrate with discrete
assembly techniques. This will eventually lead to
camera modules built using discrete assembly in the
unhappy position of being physically larger, costing
more and offering inferior performance. Based on
this understanding, it is perhaps not surprising that
market analysts predict that wafer level cameras will
take more than 30% market share by 2012 [TSR,
2008].
YD: What are the benefits for camera
module manufacturers to invest into new
equipment and facilities for WLC?
GH & BK: Although the raw cost benefits of wafer
level camera technology may appear compelling, to
enter this market still requires substantial investment
in new equipment and facilities. Once this investment
is made it provides the camera module manufacturer
with great flexibility in terms of the product range and
mix they can offer. This arises because the much of
the equipment is common, irrespective of whether
the manufacturing company wants to pursue a
strategy of wafer level packaging of imagers,
manufacturing wafer level optical assemblies or
building complete camera modules. A combined
product line maximises the return from the
investment as the capacity of most equipment
exceeds the requirements of relatively high volume
manufacture, enabling multiple product types to be
run simultaneously. Even better is that the same
equipment set is used for camera modules ranging
from QCIF to multi-mega pixel resolution so no
additional investment will be required until the
transition to 300mm diameter wafers occurs, towards
which there are not yet any obvious moves.
The current supply chain for camera modules
fabricated from discrete parts is long with many entities
involved, each adding margin. Wafer level camera
assembly is done as a one-stop endeavour making it
simultaneously a more profitable venture for the
camera module manufacturer and reduced cost
component for the system integrator. It is therefore
unsurprising that the production of reflowable camera
References:
modules has ballooned from less than 1,000 per year
in 2006 to 10,000 per month in 2008 [TSR 2008].
YD: Do WLC necessitate specific
packaging, in particular with through Si
vias?
GH & BK: As might be expected, there are several
competing wafer level optics technologies
commercially available. To manufacture a camera
module entails not just lens technology, but also the
ability to package the imager at the wafer level and
provide the package with a ball grid array interface.
Connection of the bond pads on the die to the
package lands requires a through silicon via (TSV)
technology. The problem with TSVs is that they are
bedevilled by high cost and questionable reliability.
Several companies now offer TSV technology for
image sensors, although only one meets the base
cost necessary to achieve the sub-$1 VGA camera
module and has published reliability data
demonstrating the package will not only surpass by
a wide margin the cell phone specification for
reliability but also the more arduous automotive
specification as well [IEEE 2008].
YD: To conclude, what is your future
vision for WLC?
GH & BK: Wafer level cameras are manufactured by
combining, parts that are fabricated and assembled
at the wafer level. Their value proposition is based
on substantial savings in cost, much smaller form
factor and a manufacturing line that is product
agnostic. Realising this value entailed solving many
technical issues. Wafer level camera technology is
still in its infancy but so compelling are the benefits
that fully reflow compatible, wafer-level cameras with
VGA resolution have been developed, designed in
product and manufacturing volume is ramping fast.
Multi megapixel variants are not far behind. It is
forecast that within 4 years reflowable wafer level
cameras will account for more than 30% of the 2bn
camera modules manufactured annually.
Contact :
Sales@tessera.com
• SSEC 2009 Semiconductor International, 6th February 2009, “Inside wafer-level Cameras”
• TSR 2008 Techo Systems Research Company Ltd, December 2008 Researching Report, “Market
breakdown of camera phone – 1st half 2008 & 2nd half 2008 forecast”
• IEEE 2008 G Humpston, “Novel and low cost through silicon via solution for wafer scale packaging of
image sensors”, Proceedings IEEE Electrical Design of Advanced Packaging and Systems
Symposium, Seoul, 10-12 December, 2008
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