Electronics
packaging is a method of providing power and electrical distribution,
mechanical protection and heat dissipation for integrated circuits. An
integrated circuit (IC) package is a package that gives environmental
protection to the IC chip whilst providing for different test methods and
high quality assemblies at the next level of interconnection. Packaging
is often considered the biggest bottleneck as it controls the system’s
electrical performance, cost, size and reliability.
Electronics Packaging
The major trend in the electronics industry today is to make products
smarter, lighter, smaller, thinner, and faster, while at the same time
making them more user and environmentally friendly, functional, powerful,
reliable, robust, innovative, creative, and less expensive. Factors such
as the feasibility of suitable substrates have to be considered when
selecting a packaging alternative for the future. From this point of
view, interconnection methods like flip chip become increasingly
interesting.
Most research has addressed the challenge of making the “smallest
structures” possible. Activities were mostly basic research oriented and
resulted in a multitude of processes and small structures. Now, increased
emphasis has been put on the device aspects and on the industrial
application of these devices. The emphasis has been changed towards
microsystems. This was done in order to concentrate on functionality and
performance, rather than on small dimensions as well as highlighting the
additional requirement to cover packaging, interconnection and
interfaces. Even today, much research is based on using silicon
technology.
Sensor System Packaging
Packaging and production options must be considered at an early stage of
microsensor development. New silicon technology cannot be commercially
successful until used in products and integrated with associated chips,
packages, circuit boards, base plates, housings, connectors, displays,
and switches.
Many MEMS researchers are experienced in silicon processing and tend to
concentrate on device fabrication. There is therefore an obvious risk
that packaging is regarded as a necessity that is not considered until
the device is already designed and processed. It appears that packaging
issues are often not taken into account until the industrialization stage
of the product. This approach makes packaging very complex and expensive.
Packaging must be considered from the device’s initial design phase. The
MEMS device must be designed for packaging and assembly. In other words,
it must be producible in an industrial sense.
Since MEMS often includes moving structures, the packaging requirements
of such components must take this into account. Some functions also
include interaction with the surrounding environment, such as pressure
sensors. This imposes new requirements on packaging, since in normal
microelectronics the chip must be protected completely from any impact
from the environment. Packaging also provides mechanical support to the
sensitive chip, facilitating handling and simplifying assembly. The most
important difference between packaging MEMS and microelectronics is the
fact that MEMS is more often required to be in contact with the
functional environment.
Most integrated sensors as well as integrated circuits require
encapsulation in order to have mechanical support, be protected against
the environment, be easily mounted on circuit boards and facilitate
easier handling of individual chips. In the case of MEMS, the device also
needs to be protected at wafer level in order to protect the structure
from water and particle impingement during the dicing process. A higher
level of integration will be required in future sensor systems. This is
so, as different sensor elements, electronics, complex optical elements
and optical filters (in the case of optical sensors) and fluidic elements
(in the case of biological and chemical sensors) will be combined.