WO2014162174A1

WO2014162174A1 - Medium for providing electrical connectivity between end terminal connections

Info

Publication number: WO2014162174A1
Application number: PCT/IB2013/056835
Authority: WO
Inventors: Roshan Kumar Jha; Bala Subramanyam JAYANTHI
Original assignee: Satyam-Venture Engineering Services Pvt Ltd
Priority date: 2013-04-01
Filing date: 2013-08-23
Publication date: 2014-10-09

Abstract

Exemplary embodiment of the present disclosure is directed towards a medium for providing electrical connectivity between end terminal connections. The medium includes a flexible circuit comprising three or more layers for carrying a signal and carrying a power between at least two automotive components which are in relative motion. The medium for providing electrical connectivity between end terminal connections further includes a plurality of lead frames affixed to the ends of the flexible circuit.

Description

MEDIUM FOR PROVIDING ELECTRICAL CONNECTIVITY BETWEEN END

TERMINAL CONNECTIONS

TECHNICAL FIELD

[0001] The present invention relates to the field of flexible electronics. More particularly, the present invention relates to medium for providing electrical connectivity between end terminal connections.

BACKGROUND

[0002] In the past decades, many functions have been migrating from their traditional positions on the dashboard onto the steering wheel. For example airbag, heated steering relay switch, horn control, radio controls, phone answering, cruise control operation, and several others have been integrated into steering wheel. The clock-spring or steering rotary connector is a device that allows an electrical connection between two members that are in relative motion with respect to each other. For example, a motion of the steering wheel and the steering column with respect to steering column control module is always rotating or oscillating and the steering column control module is always stationary.

[0003] Typically, clockspring or a steering rotary connector is a device that allows an electrical connection between two members that are in relative motion. In existing systems, a flexible flat cable is wound inside housing which carries an actual electrical connection from horn, cruise control, airbag and the like mounted on steering wheel to the steering column control module or the dashboard. In general, shifting an interface from the dashboard to steering wheel improves driving safety by positioning the most commonly used controls on the steering wheel.

[0004] Furthermore, based on the present requirements of shifting the controls to the steering, the usage number of flexible flat cable in clockspring or steering rotator connector also increases proportionately. This need can be addressed by increasing the cassette size to accommodate more number of flexible flat cables. Increasing the number of flexible flat cables would also increase mechanical cost, frictional problem, SCCM (Steering Column Control Module) size, noise, flexible flat cables rotational problems and the like. Moreover to achieve this, a complex

l mechanism is required and the number of assembly steps of the clockspring or steering rotator connector also increases.

[0005] In the light of aforementioned discussion there exists a need for using multilayer flexible circuits for use in an existing clockspring or a steering rotary connector.

BRIEF SUMMARY

[0006] The following presents a simplified summary of the disclosure in order to provide a basic understanding to the reader. This summary is not an extensive overview of the disclosure and it does not identify key/critical elements of the invention or delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to the more detailed description that is presented later.

[0007] A more complete appreciation of the present invention and the scope thereof can be obtained from the accompanying drawings which are briefly summarized below and the following detailed description of the presently preferred embodiments.

[0008] Exemplary embodiments of the present disclosure are directed towards a medium for providing electrical connectivity between end terminals. According to an exemplary aspect, a flexible circuit comprising three or more layers for carrying a signal and carrying a power between at least two automotive components which are in relative motion. The each individual layer connection of the flexible cable connected to another individual layer's connection by a vertical interconnect access. The each individual layer of the flexible circuit is taken out to the outer layers for connecting to the plurality of lead frames using vertical interconnect access. The flexible circuit positioned in a clockspring of an automobile. The flexible circuit comprising a plurality of passive components embedded in substrate of the internal layers and connected to circuit by conductive track of the internal layer.

[0009] According to the exemplary aspect, a plurality of lead frames affixed to the at least one end of the flexible circuit. The plurality of lead frames comprising laser direct structuring based lead frames, laser direct structuring based lead frames comprising a plurality of passive or active components embedded, rigid printed circuit board based lead frame and the flexible circuit based lead frame. The plurality of lead frames affixed to the plurality of ends of the flexible circuit by ultrasonic welding and resistance welding.

BRIEF DESCRIPTION OF DRAWINGS

[0010] Other objects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments, in conjunction with the accompanying drawings, wherein like reference numerals have been used to designate like elements, and wherein:

[0011] FIG. 1 is a schematic diagram illustrating a three layered flexible circuit for providing an electrical connectivity between end terminals.

[0012] FIG. 2 is a schematic diagram illustrating a simple three layered flexible circuit.

[0013] FIG. 3 is a schematic diagram illustrating a cross-sectional view of a flexible circuit embedded with passive components.

[0014] FIG. 4 is a schematic diagram illustrating a top view of conductive layer of flexible circuit with plurality of exposed end terminal.

[0015] FIG. 5 is a schematic diagram illustrating a VIA connectivity between layers of a flexible circuit.

[0016] FIG. 6 is a schematic diagram illustrating the multiple conductive layers of the flexible circuit.

[0017] FIG. 7 is a schematic diagram illustrating VIA connectivity between four layers of a flexible circuit. DETAILED DESCRIPTION

[0018] It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practised or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0019] The use of "including", "comprising" or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. Further, the use of terms "first", "second", and "third", and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

[0020] Referring to FIG. 1 is a schematic diagram 100 illustrating a three layered flexible circuit for providing an electrical connectivity between end terminals. According to a non limiting exemplary embodiment of the present disclosure, the schematic diagram 100 includes a flexible circuit 102 including three or more layers for carrying signal and power between two automotive components which are in relative motion. The multiple lead frames 104a, 104b, 104c, 104d, 104e, 104f, 104g and 104h are affixed at the ends of a flexible circuit 102 through a multiple exposed conductive end terminals 106a, 106b, 106c, 106d, 106e, 106f, 106g and 106h. The multiple exposed conductive end terminals 106a, 106b, 106c, 106d, 106e, 106f, 106g and 106h may also be connected to electrical wires too.

[0021] In accordance with a non limiting exemplary embodiment of the present disclosure, the multiple lead frames 104a, 104b, 104c, 104d, 104e, 104f, 104g and 104h affixed at the ends of a flexible circuit 102 that may include but not limited to a laser direct structuring based lead frame, a rigid printed circuit board based lead frame and a flexible circuit based lead frame and the like. The flexible circuit 102 with three or more layers is positioned in a clockspring or a steering rotary connector to carry signal and power between two automotive components. The flexible circuit 102 positioned in clockspring/steering rotary connector is coupled with an input interface or other module to transmit user input/signal/switch input between dashboard/steering column control module and also transmit power from battery to steering wheel heating unit for heating steering wheel and the like. The automotive switches may include but not limited to horn switches, cruise control switches and radio controllers and the like.

[0022] According to a non limiting exemplary embodiment of the present disclosure, each individual layer of the flexible circuit 102 is connected with another individual layer of the flexible circuit 102 by a vertical interconnect access. The vertical inter connect access used for interconnecting conductive layers are of the three types which may include vertical interconnect (VIA) access through hole, blind vertical interconnect access and buried interconnect access. The flexible circuit 102 is connected with the multiple lead frames 104a, 104b, 104c, 104d, 104e, 104f, 104g and 104h through exposed conductive end terminals 106a, 106b, 106c, 106d, 106e, 106f, 106g and 106h respectively. The lead frames 104a, 104b, 104c, 104d, 104e, 104f, 104g and 104h are affixed to the exposed conductive end terminals 106a, 106b, 106c, 106d, 106e, 106f, 106g and 106h respectively by an ultrasonic welding or resistance welding and the like. The each individual layer of the three or more layers included in the flexible circuit 102 may be taken out to the outer layers using VIA. Further the multiple passive components which may include but not limited to capacitor, embedded passive resistors and the like are embedded in the substrate of internal layers of the flexible circuit 102.

[0023] Referring to FIG. 2 is a schematic diagram 200 illustrating a simple three layered flexible circuit. The flexible circuit may include but not limited to a printed circuit board or the like. According to a non limiting exemplary embodiment of the present disclosure, the simple flexible includes three layers 202, 204, and 206. Each individual layer includes an insulation layer 1, adhesive layer 2 and a conductive layer 3. The insulation layer positioned at the top is made with the polyimide, polyester, epoxy, teflon and other. The adhesive layer positioned below the insulation layer is made with acrylic, epoxy and the like and the conductive layer positioned below the adhesive layer is made with copper plated on top and bottom and the like. [0024] Referring to FIG. 3 is a schematic diagram 300 illustrating a cross-sectional view of a flexible circuit embedded with passive components. According to a non limiting exemplary embodiment of the present disclosure, the cross-sectional view of a flexible circuit depicts embedded resistor 310, and embedded capacitor 308. The passive components are embedded in the internal layers of the flexible circuit.

[0025] Referring to FIG. 4 is a schematic diagram 400 illustrating a top view of conductive layer of flexible circuit with plurality of exposed end terminal. According to a non limiting exemplary embodiment of the present disclosure, the exposed conductive end terminals 404a, 404b, 404c, 404d, 404e, 404f, 404g and 404h are respectively connected to the conductive layer of the flexible circuit. According to a non limiting exemplary embodiment of the present disclosure, the exposed conductive end terminals 404a, 404b, 404c, 404d, 404e, 404f, 404g and 404h of the flexible circuit connected to the ends of the conductive layers 402a, 402b, 402c and 402d of the flexible circuit.

[0026] Referring to FIG. 5 is a schematic diagram 500 illustrating a VIA connectivity between layers of a flexible circuit. According to a non limiting exemplary embodiment of the present disclosure, the flexible circuit with multiple conductive layers 502a, 502b, 502c and 502d are interconnected by vertical interconnect access (VIA) 504, 506 and 508.

[0027] In accordance with a non limiting exemplary embodiment of the present disclosure, the vertical interconnect access are categorized into three types which includes vertical interconnect access through hole 504, blind vertical interconnect access 506 and buried vertical interconnect access 508. The vertical interconnect access through hole VIA 504 connects the first layer 502a and the fourth layer 502d. The blind vertical interconnect access 506 is connects the first layer 502a and the third layer 502c and also the second layer 502b and the fourth layer 502. The buried verticals interconnect access 508 connects the second layer 502b and third layer 502c. Buried VIA 508 connects the internal layers and the blind VIA 504 connects the one internal and one external layer [0028] Referring to FIG. 6 is a schematic diagram 600 illustrating the multiple conductive layers of the flexible circuit. According to a non limiting exemplary embodiment of the present disclosure, the exposed conductive end terminals 604a, 604b, 604c, 604d, 604e, 604f, 604g and 604h of the flexible circuit connected to the ends of the conductive layers 602a, 602b, 602c and 602d of the flexible circuit. In the present schematic diagram the flexible circuit with multiple conductive layers are provided with a visibility of all conductive layers by hiding the insulating and adhesive layers of each individual layer of the flexible circuit.

[0029] Referring to FIG. 7 is a schematic diagram 700 illustrating VIA connectivity used between four layers of a flexible circuit. According to a non limiting exemplary embodiment of the present disclosure, the flexible circuit included with multiple layers 702a, 702b, 702c and 702d are interconnected with each other by vertical interconnect access 704, 706 and 708.

[0030] In accordance with a non limiting exemplary embodiment of the present disclosure, the vertical interconnect access are categorized into three types which may include vertical interconnect access through hole 704, blind vertical interconnect access 706 and buried vertical interconnect access 708. The vertical interconnect access through hole 704 connects the layers 702a and 702d. The blind vertical interconnect access 706 connects the layers 702a and 702c and also the layers 702b and 702d. The buried vertical interconnect access 708 connects the layers 702b and 702c.

[0031] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. A medium for providing electrical connectivity between end terminal connections comprising: a flexible circuit comprising three or more layers for carrying a signal; and carrying power between at least two automotive components which are in relative motion; and a plurality of lead frames affixed to a plurality of ends of the flexible circuit.

2. The medium of claim 1, wherein the plurality of lead frames comprising laser direct structuring based lead frames.

3. The medium of claim 2, wherein the plurality of lead frames comprising laser direct structuring based lead frames comprising a plurality of surface mount electronic devices.

4. The medium of claim 1, wherein the plurality of lead frames comprising rigid printed circuit board based lead frame.

5. The medium of claim 1, wherein the plurality of lead frames comprising flexible circuit based lead frame.

6. The medium of claim 1, wherein the plurality of ends of the flexible circuit connected to a plurality of electrical wires.

7. The medium of claim 1, wherein an each individual layer connection of the flexible cable connected to another individual layer's connection by a vertical interconnect access.

8. The medium of claim 1, wherein an each individual layer of the flexible circuit is taken out to the outer layers for connecting to the plurality of lead frames using vertical interconnect access.

9. The medium of claim 1, wherein the plurality of lead frames affixed to the at least one end of the flexible circuit by ultrasonic welding.

10. The medium of claim 1, wherein the plurality of lead frames affixed to the at least one end of the flexible circuit by resistance welding.

11. The medium of claim 1, wherein the flexible circuit positioned in a clockspring of an automobile.

12. The medium of claim 1, wherein the flexible circuit comprising a plurality of passive components embedded in the internal layers.