Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Microphone capsule only
Reexamination Certificate
2000-05-12
2003-02-18
Kuntz, Curtis (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Microphone capsule only
C381S173000, C367S181000
Reexamination Certificate
active
06522762
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a sensor system comprising a carrier member, a transducer element and an electronic device. The present invention relates in particular to condenser microphone systems assembled using flip-chip technology. The present invention further relates to condenser microphone systems adapted for surface mounting on e.g. printed circuit boards (PCB's).
BACKGROUND OF THE INVENTION
In the hearing instrument and mobile communication system industry, one of the primary goals is to make components of small sizes while still maintaining good electroacoustic performance and operability giving good user friendliness and satisfaction. Technical performance data include sensitivity, noise, stability, compactness, robustness and insensitivity to electromagnetic interference (EMI) and other external and environmental conditions. In the past, several attempts have been made to make microphone systems smaller while maintaining or improving their technical performance data.
Another issue within these component industries concerns the ease of integration into the complete system.
EP 561 566 discloses a solid state condenser microphone having a field effect transistor (FET) circuitry and a cavity or sound inlet on the same chip. The techniques and processes for manufacturing a FET circuitry are quite different from the techniques and processes used in manufacturing transducer elements. Consequently, the transducer element and FET system disclosed in EP 561 566 requires two (or possibly more) separate stages of production which by nature makes th e manufacturing more complicated and thereby also more costly.
The article “The first silicon-based micro-microphone” published in the Danish journal Elektronik og Data, No. 3, p. 4-8, 1998 discloses how silicon-based microphone systems can be designed and manufactured. The article discloses a three-layer micro-phone system where a transducer element is flip-chip mounted on an intermediate layer connecting the transducer element to an electronic device, such as an ASIC. The transducer element comprises a movable diaphragm and a substantially stiff back plate. On the opposite side of the transducer element a silicon-based structure forming a back chamber is mounted. It is worth noting that in order for the microphone system to be electrically connected to the surroundings wire bonding or direct soldering is required.
The development of combined microelectromechanical systems (MEMS) has progressed significantly over the last years. This has primarily to do with the development of appropriate techniques for manufacturing such systems. One of the advantages of such combined systems relates to the size with which relative complicated systems involving mechanical micro-transducers and specially designed electronics may be manufactured.
It is an object of the present invention to provide a sensor system where the different elements forming the sensor system are flip-chip mounted, applying standard batch-oriented techniques.
It is a further object of the present invention to provide a sensor system suitable for mounting on e.g. PCB's using flip-chip or surface mount technologies and thereby avoid wire bonding or complicated single-chip handling.
It is a still further object of the present invention to provide a sensor system where the distance between the transducer element and the electronics is reduced so as to reduce parasitics and space consumption.
SUMMARY OF THE INVENTION
The above-mentioned objects are complied with by providing, in a first aspect, a senor system comprising
a carrier member having a first surface, said first surface holding a first and a second group of contact elements,
a transducer element comprising an active member and at least one contact element, said at least one contact element being aligned with one of the contact elements of the first group so as to obtain electrical contact between the transducer element and the carrier member, and
an electronic device comprising an integrated circuit and at least one contact element, said at least one contact element being aligned with one of the contact elements of the second group so as to obtain electrical contact between the electronic device and the carrier member,
wherein at least one of the contact elements of the first group is electrically connected to at least one of the contact elements of the second group so as to obtain electrical contact between the transducer element and the electronic device.
The transducer element may in principle be any kind of transducer, such as a pressure transducer, an accelerometer or a thermometer.
In order for the sensor system to communicate with the surroundings the carrier member may further comprise a second surface, said second surface holding a plurality of contact elements. At least one of the contact elements of the first or second group is electrically connected to one of the contact elements being held by the second surface. The first and second surfaces may be substantially parallel and opposite each other.
The carrier member and the transducer element may be based on a semiconductor material, such as Si. In order to decouple thermal stresses, the carrier member, the transducer element and the electronic device may be based on the same semiconductor material. Again, the material may be Si.
In order to form a back chamber for microphone applications the carrier member may further comprise an indentation aligned with the active member of the transducer element. Also for microphone applications the active member of the transducer element may comprise a capacitor being formed by a flexible diaphragm and a substantially stiff back plate.
Furthermore, the transducer element further comprises a cavity or sound inlet. The bottom of the cavity may be defined or formed by the active member of the transducer element. The flexible diaphragm and the substantially stiff back plate may be electrically connected to a first and a second contact element of the transducer element, respectively, in order to transfer the signal received by the transducer element to the carrier member. The integrated circuit may be adapted for signal processing. This integrated circuit may be an ASIC. The integrated circuit is operationally connected to the at least one contact element of the electronic device.
In order to obtain directional sensitivity the sensor may further comprise an opening or sound inlet between the second surface of the carrier member and the indentation.
In order to protect the transducer element against e.g. particles or humidity an outer surface of the sensor is at least partly protected by a lid. The lid and the active member of the transducer element may define an upper and lower boundary of the cavity, respectively. Furthermore, at least one outer surface of the sensor system may hold a conductive layer. The conductive layer may comprise a metal layer or a conductive polymer layer.
The contact elements may comprise solder materials, such as a Sn, SnAg, SnAu or SnPb. Furthermore, the sensor system may comprise sealing means for hermetically sealing the transducer element.
In a second aspect, the present invention relates to a sensor system comprising
a carrier member having a first surface, said first surface holding a first, a second and a third group of contact elements,
a first transducer element comprising an active member and at least one contact element, said at least one contact element being aligned with one of the contact elements of the first group so as to obtain electrical contact between the first transducer element and the carrier member,
a second transducer element comprising an active member and at least one contact element, said at least one contact element being aligned with one of the contact elements of the second group so as to obtain electrical contact between the second transducer element and the carrier member, and
an electronic device comprising an integrated circuit and at least one contact element, said at least one contact element being aligned with one of the contact e
Kuhmann Jochen F.
Mullenborn Matthias
Scheel Peter
Harness & Dickey & Pierce P.L.C.
Kuntz Curtis
Microtronic A/S
Ni Suhan
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