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Sensor package

IP.com Disclosure Number: IPCOM000241052D
Publication Date: 2015-Mar-23

Publishing Venue

The IP.com Prior Art Database

Abstract

A sensor package comprises a carrier comprising a through hole, and a sensor chip with a front side and a back side and a recess in the back side. The sensor chip is at-tached to the carrier with its back side facing the carrier by means of an attachment layer thereby defining a first area of the carrier the sensor chip rests on and a second area of the carrier facing the recess. The through hole is arranged in the first area of the carrier.

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Sensor package

Abstract

          A sensor package comprises a carrier comprising a
through hole, and a sensor chip with a front side and a back
side and a recess in the back side. The sensor chip is at-
tached to the carrier with its back side facing the carrier by
means of an attachment layer thereby defining a first area of
the carrier the sensor chip rests on and a second area of the
carrier facing the recess. The through hole is arranged in the
first area of the carrier.

Field of the Invention

The present invention relates to a sensor package and to a
method for manufacturing a sensor package.

Technical Background

          An increasing number of sensors are integrated into
semiconductor chips. Such a sensor chip may be placed on a
carrier such as a die pad, and possibly be encapsulated.

          In some applications, the sensor chip is thinned
from a back side of the sensor chip for building a thin mem-
brane that is thermally isolated versus the rest of the sensor
chip. This may serve the operation of a sensitive element on
or in the membrane, for example, in particular when the sensi-
tive element is provided for sensing a temperature or other-
wise is sensitive to temperature, or, for example, when a
heating operation is required during measuring or manufactur-
ing which heat is not desired to migrate elsewhere to the chip
but is desired to remain locally confined, e.g. in the mem-
brane.

          When such a sensor chip is mounted to a die pad
with its back side facing the die pad, a cavity is generated
between the sensor chip and the die pad in view of the recess
in the sensor chip. In such arrangement, the membrane of the
sensor chip lowers the total mechanical resistance of the sen-


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sor package, and the underlying cavity may promote an accumu-
lation of moisture, for example, during manufacturing, ship-
ment or handling. In particular, moisture may be absorbed by
an encapsulation of the sensor chip containing organic materi-
al, e.g. plastics, if applicable, which moisture may be re-
leased into the cavity in response to elevated temperatures.
During assembly, for example, a solder reflow process may in-
duce elevated temperatures to the entire sensor package in-
cluding the encapsulation if any. However, elevated tempera-
tures may also be induced from external, or from internal,
wherein during operation, for example, a heater may induce el-
evated temperatures if applicable. Irrespective of the source
of heating, such elevated temperature may result in a vapor
pressure increase inside the cavity, and in a plastic encapsu-
lation of the sensor chip if applicable. Such moisture uptake
may finally lead to delamination of material interfaces and /
or to cracks in the sensor package which is also referred to
as "popcorn" phenomenon.

          For moisture/reflow sensitive components such as
plastic-encapsulated surface mounted devices and other pack-
ages made with moisture-permeable materials, a moisture sensi-
tivity level is determined by tests and a resulting classifi-
cation determines stor...