Measuring and testing – Instrument casing
Reexamination Certificate
1999-11-29
2001-12-04
Kwok, Helen (Department: 2856)
Measuring and testing
Instrument casing
C381S189000, C310S334000
Reexamination Certificate
active
06324907
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flexible substrate transducer assembly that integrates a transducer or a transducer system, such as a gas sensor or electro-acoustic transducer, with or without built-in signal processing capability, and a flexible substrate. The flexible substrate is used to provide connectivity between the transducer system and electronic equipment which house the transducer assembly. This integration of the transducer system and a flexible carrier substrate provides an integrated solution that supports cost-effective manufacturing of the flexible substrate transducer assembly by using standard components and proven manufacturing technologies. The present invention is particularly well adapted for use in compact electronic equipment such as mobile phones and hearing instruments that will benefit from the small outer dimensions obtainable by the present flexible substrate transducer assembly.
BACKGROUND OF THE INVENTION
Electronic equipment that utilises one or several transducers such as hearing instruments, mobile phones, medical dispensing devices etc. require that a number of electrical connections is established between signal and power terminals of the transducers and a printed circuit board housed within the electronic equipment and providing corresponding electrical contact pads or terminals. These electrical connections may be adapted to provide DC voltages and currents, digital control or data signals, digital or analogue transducer signals etc. between the printed circuit board and the transducers.
In mobile phones and hearing instrument applications, flexible transducer assemblies will typically comprise microphone(s), loudspeaker(s) or receiver(s), telecoils and, often, associated amplification circuitry which typically are required for audio signal reception/transmission and amplification.
Depending on the type of transducer assembly, it may require that two, three or even more terminals are electrically connected to the printed circuit board. These connections have previously often been provided by means of flexible leads, such as well known litz wires. However, the use of such flexible leads makes the electronic equipment unsuited for automated machine assembly. Consequently, human operators are required to carry out the process of soldering and correctly connecting the leads between corresponding terminal pairs of the transducer assemblies and the printed circuit board.
A fully silicon based sensor assembly or sensor system, which may comprise a transducer or transducer system, has recently been disclosed in assignee's pending application U.S Ser. No. 09/391,628. This sensor assembly may comprise three separate silicon substrates, that function as a transducer, an electronic signal processing circuit and a connectivity layer, respectively, assembled into a single silicon based transducer system. Even though such a silicon based transducer or sensor assembly has a number of desirable properties such as small volume, high reliability etc. it would be desirable to provide a transducer assembly that is better suited for manufacture in existing standard production equipment and processes, such as pick and place machines and re-flow soldering.
The flexible substrate transducer assembly or transducer assembly according to the present invention provides the desired ease of manufacture and may, furthermore, convey the transducer signals through a number of EMI shielded flexprint conductors and terminals or pads, thus making it possible to completely dispense with the common flexible connection leads.
U.S. Pat. No. 5,740,261 discloses a silicon based microphone having its connection terminals abutted against corresponding terminals of a flexible circuit. The silicon microphone is shielded against physical damage by a jacket that has a cylindrical top and bottom cup forming a housing that surrounds the silicon microphone. A hole in a top portion of the jacket provides an acoustic port that allows external sound pressure to enter the internal of the jacket and contact one side of a membrane of the silicon microphone. The disclosed transducer assembly is, however, not particularly well-suited for automated manufacturing. In particular, the jacket comprises a large number of relatively complex miniature mechanical parts that may require a time-consuming and manual assembly procedure.
Consequently, none of these transducer/sensor assemblies are fully satisfactory for applications in miniature or compact electronic equipment that require fabrication of large numbers of low-cost devices.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a flexible substrate transducer assembly suitable of integration within compact electronic equipment, such as a hearing instruments, mobile phones, a medical dispensing devices etc.
It is also an object of the invention to provide a flexible substrate transducer assembly suitable for manufacture by application of existing standard production equipment and processes to provide a low cost device.
A first aspect of the invention relates to a flexible substrate transducer assembly, comprising:
a flexible elongate member having an upper and a lower surface and comprising at least two conductors that each has an exposed part at a first end of the member and a contact pad at a second end of the member,
a transducer system adapted to generate or receive a transducer signal on two or more signal terminals and to convey the transducer signal from the two or more signal terminals to the respective contact pads, the transducer system being attached to the upper surface at the second end of the flexible elongate member, a lid attached to the upper surface of the flexible elongate member and covering and shielding the transducer system and a supporting area of the flexible elongate member from an external environment,
wherein the supporting area of the flexible elongate member comprises one or several holes extending through the flexible elongate member so as to provide a first passage to the external environment between the lower surface of the member and the transducer system covered by the lid.
In the present specification, the term “lid” designates various forms of covers, casings and housings that are capable of providing the shielding from the external environment. In some embodiments of the invention, the lid provides a substantially airtight acoustical seal to the external environment, while in other embodiments of the invention, a predetermined passage through the lid to the transducer system may be provided. In the last situation, a screen covering the predetermined passage may be utilised to prevent contamination from the external environment to enter inside of the chamber covered by the lid.
A number of electrical signals may be provided on respective electrical conductors, which is comprised within or disposed on the flexible elongate member or flexible member that may be a flexible foil strip or a strip of flexible printed circuit board. If the conductors are disposed on the upper or the lower surface of the member, they are preferably covered by an insulating layer, which protects the conductors from corrosion and physical damage. In order to provide an electrical connection pad to each of the conductors, an exposed part may be provided by forming an aperture in the insulating layer or mask of each conductor at the first end of the member. By forming a number of apertures, a number of exposed parts acting as connection pads or terminals is provided on the member. These connection pads are typically formed only on one side of the member while conductors that may be arranged on the reverse surface may be rendered completely covered by the insulating layer.
The supporting area of the flexible elongate member is bounded by the lid attached to the member's upper surface. The lid is, preferably, a closed lid without openings to the external environment so that when the lid is mounted over the transducer system and attached to the upper surface of the flexible member, the support
Halteren Aart van
Kristensen Poul Rosenkilde
Kwok Helen
Microtronic A/S
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