Electrical connectors – With coupling movement-actuating means or retaining means in... – For direct connection to a flexible tape or printed circuit...
Reexamination Certificate
2002-04-01
2004-05-11
Paumen, Gary (Department: 2833)
Electrical connectors
With coupling movement-actuating means or retaining means in...
For direct connection to a flexible tape or printed circuit...
C439S067000
Reexamination Certificate
active
06733319
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a connection assembly and a connection method providing solderfree electrical connections between a number of conductors disposed on a main printed circuit board (main PCB) and associated conductors arranged on e.g. a flexible foil strip or on a flexible PCB. The present invention is particularly well adapted for use in compact electronic equipment such as hearing instruments or mobile phones where one can benefit from the small dimensions obtainable by the present connection assembly.
BACKGROUND OF THE INVENTION
Electronic equipment, such as hearing instruments, mobile phones, medical dispensing devices etc., may require that a number of electrical connections is established between a main PCB and various parts of the equipment, such as electro-acoustic transducers, LCD displays, keyboards, user operated switches and contacts etc. These electrical connections may operate to provide DC voltages and currents, digital data signals, transducer signals etc., from the main PCB to the peripheral units or vice versa.
Each of these parts, from now on referred to as peripheral units, typically comprises a number of electrical terminals which is used to establish the electrical connections to the main PCB and/or a ceramic hybrid circuit provided with corresponding electrical contact pads or terminals.
For hearing instrument applications, peripheral units such as microphone(s), receivers, telecoils etc. are required for audio signal reception and amplification as well as magnetic field reception and amplification.
Furthermore, hearing instruments may also require switches, contacts and programming plugs which are used for a variety of purposes such as turning a battery supply on/off, adjusting the volume, programming of instruments, changing between several pre-programmed listening programs or changing between a microphone and a telecoil audio signal, etc.
The signals provided to or from these peripheral units may comprise signals in a digital or analogue form. A digital signal may represent a logic state or a change of a logic state of a switch, such as a program selector switch, or it may represent digitally encoded analogue transducer signals provided to/from the microphones, receivers etc.
The main PCB of a hearing instrument typically comprises one or several integrated circuits and associated passive components to perform processing and storing of audio or control signals generated by the peripheral units.
Depending on the type of peripheral unit, it may require that two, three or even more terminals are electrically connected to the main PCB. These connections are often provided by means of flexible leads, such as well known litz wires, each lead having a first end soldered at the terminal of the peripheral unit, and having a second end soldered to the corresponding pad or terminal on the main PCB. To ensure that each of these connections is properly made during manufacture or repair of the hearing instrument, several litz wires of differing colour are often provided so that a particular transducer terminal and its corresponding contact pad on the main PCB are associated with a particular wire colour.
Several drawbacks exist in this well-known method of establishing the electrical connections by use of flexible leads between the terminals of the peripheral unit and the pads located on the main PCB.
A first drawback relates to the soldering itself. Since the peripheral units must, generally, be miniature for use in today's in-the-canal (ITC) and compact behind the ear (BTE) types of hearing instruments, the heat capacity of each of the terminals is, inherently, very small. The small heat capacity requires very strict monitoring of soldering temperature and soldering time to avoid overheating the terminals, which in worst case could destroy the operation of the peripheral unit, or at least severely damage the reliability. Furthermore, transducers are often provided with integrated circuits within their housings or casings and these integrated circuits are electrically and thermally connected to the transducer terminals. Consequently, overheating these transducer terminals may conduct sufficient heat to the integrated circuits to melt bonding wires and/or overheat the integrated circuits themselves. Obviously, similar soldering related problems also exist during soldering on the contact or connection pads arranged on the main PCB of a hearing instrument or of another compact electronic device.
Accordingly, overheating transducer or switch terminals is a serious problem, particularly during service in repair shops but also during factory assembly of the hearing instruments.
A second drawback related to the use of the flexible leads to provide the required electrical connections between the peripheral units and a PCB of e.g. a hearing instrument is that an operator may need to find and consult a wiring diagram in e.g. a repair manual to determine the correct connection pad for a given wire.
In some situations, the widespread use of litz wires as electrical leads may generate problems in the hearing instrument assembly or repair process, since this type of wire is prone to mechanical damage that often results in detachment of noninsulated strands of wires from the wire core. These strands may establish unintended connections to circuitry and/or terminals within the hearing instrument, and thus leave the hearing instrument in a non-operational state.
Another drawback of using flexible leads is that the leads are unsuited for automated machine assembly. Consequently, human operators are required to carry out the process of soldering and correctly connecting the leads between corresponding terminals or pads on the peripheral unit and on the main PCB.
Accordingly, it would be desirable to provide a method which is capable of establishing solderfree electrical connections between the terminals of a peripheral unit and connection pads of a PCB of an electronic device or apparatus, such as a hearing instrument, a mobile phone, a medical dispensing apparatus etc. Likewise, it would also be desirable to provide a, preferably compact, connection assembly adapted for utilisation in such a connection method.
U.S. Pat. No. 4,116,517 discloses a connection assembly providing solderfree electrical connections between a number of hollow contact pads arranged on a flexible circuit board or strip, and a corresponding number of exposed metallic pads or traces on a PCB. The hollow contact points on the flexible circuit strip are filled with an elastomeric material, thereby forcing these contact points against the pads on the PCB. Screws and nuts are used to keep the two boards properly aligned and the pads in electrical contact.
DE 41 36 204 A1 discloses a method of providing solderfree electrical connection between a number of conductors in flexible ribbon cable and a corresponding number of exposed metallic pads on a PCB. The contact points of the PCB and ribbon cable are kept in electrical contact by a clamping element secured by screws and nuts to the PCB.
However, these prior-art methods of providing solderfree electrical connections share a common drawback due to their requirement of allocating a significant area of the PCB to the screws and nuts. Furthermore, the assembling and fastening procedure required for the screws and nuts may require manual operation steps which are time consuming and therefore adds to the cost of an apparatus utilising such methods. Within housings of miniature electronic equipment such as hearing instruments, the space required to handle or operate tools for assembling the screws and nuts may not be available. Consequently, none of these connectors and connection methods are fully suitable for application in miniature or compact electronic equipment.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above-mentioned problems by providing a compact connection assembly establishing a solderfree electrical connections between a peripheral unit and a PCB of an electronic apparatus, such a
Harness Dickey
León Edwin A.
Microtronic A/S
Paumen Gary
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