Electrical cables may have an end portion entirely stripped of insulation and shielding materials in order to bond with a circuit board.
In some aspects of the present description, an electrical cable including a plurality of substantially parallel insulated conductors extending along a length direction of the cable is provided. Each insulated conductor includes an electrically conductive inner conductor covered with an insulating layer, such that when the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for at least one insulated conductor in the plurality of insulated conductors, a longer first portion of the inner conductor of the at least one insulated conductor is exposed on the top side of the cable, and a shorter second portion of the inner conductor of the at least one insulated conductor is exposed on the bottom side of the cable. The longer first portion at least partially overlaps the shorter second portion. The inner conductor is adapted to mate with an electrically conductive mating conductor at the exposed longer first portion of the inner conductor.
In some aspects of the present description, an electrical cable including a plurality of substantially parallel insulated conductors extending along a length direction of the cable is provided. Each insulated conductor includes an electrically conductive inner conductor covered with an insulating layer. At least 70% of a periphery of each insulated conductor is encompassed by a substantially co-extensive electrically conductive shield. When the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for each insulated conductor, portions of the insulating layer and the conductive shield are removed from the top side of the cable to expose a portion of the inner conductor of the insulated conductor, such that from a top plan view, an average lateral width of the exposed portion of the inner conductor is less than an average lateral width of the inner conductor. The exposed portion of the inner conductor includes a first end of the inner conductor on a same first end of the cable. The insulated conductor is adapted to mate with an electrically conductive mating conductor at the exposed portion of the inner conductor.
In some aspects of the present description, an electrical cable including a plurality of substantially parallel insulated conductors extending along a length direction of the cable is provided. Each insulated conductor includes an electrically conductive inner conductor co-extensive and covered with an insulating layer, and an electrically conductive shield substantially co-extensive with and surrounding each insulated conductor. When the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for each insulated conductor, portions of the insulating layer and the conductive shield are removed from the top side of the cable to expose a portion of the inner conductor of the insulated conductor, such that from a top plan view, an average lateral width of the exposed portion of the inner conductor is less than an average lateral width of the inner conductor. The exposed portion of the inner conductor includes a first end of the inner conductor on a same first end of the cable. The insulated conductor is adapted to mate with an electrically conductive mating conductor at the exposed portion of the inner conductor.
In some aspects of the present description an electrical cable assembly including the electrical cable attached to a circuit board is provided.
In the following description, reference is made to the accompanying drawings that forms a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.
Circuit boards are often electrically connected to another electrical component using an electrical cable which includes a plurality of parallel insulated conductors. Conventionally, the electrical cable is stripped at an end of the cable and the conductors in the cable are attached to solder pads on the circuit board. When the cable is shielded, this stripping removes the shielding and insulation from the entire end portions of the conductors. According to the present description, it has been found that stripping the entire end portions of the conductors causes increased crosstalk near the termination area and an impedance mismatch which degrade signal transmission performance and can result in higher return loss and lower bandwidth or data rate, and that this crosstalk and impedance mismatch can be substantially reduced by leaving the insulation and shielding, if included in the cable, at least partially intact on one side of the cable. This can be achieved by using a razor blade, for example, to remove the shielding and insulation from one side of an end portion of the cable. The razor blade can used to cut into the cable at a shallow angle so that is cuts through shielding and insulation without cutting into conductors. Keeping the lower portion of the insulation intact can aid in making a connection to a circuit board since the insulation keeps the conductors aligned at the desired pitch for making the connection.
In the illustrated embodiment, the electrical cable 1000 further includes an electrically conductive shield 400. In some embodiments, the electrically conductive shield 400 is substantially co-extensive with and surrounds each insulated conductor 100. In some embodiments, at least 70% of a periphery of each insulated conductor 100 is encompassed by the electrically conductive shield 400.
The longer first portion 210 has a length L1 which may be, for example, at least 0.5 mm, or at least 1 mm long, or may be in a range of 0.5 mm to 30 mm. The shorter second portion 220 has a length L2 which may be, for example, less than 0.5 mm. In some embodiments, the longer first portion 210 fully overlaps the shorter second portion 220. In some embodiments, the shorter second portion 220 is absent and the length L2 is zero. The first and second portions 210 and 220 can be exposed using a razor blade to strip insulating layer 300, and other layers such as the electrically conductive shield 400, from the inner conductor 200.
The at least one insulated conductor 201 extends along the length direction (x-direction) of the cable between opposite ends (first and second ends 230 and 240) of the at least one insulated conductor 201. In the embodiment illustrated in
Electrical cable 1000 includes layer 114 between electrically conductive shield 400 and insulating layer 300 and includes electrically insulating jacket 112 adjacent the electrically conductive shield 400 opposite the insulated conductors 100. The layer 114, which may include one or more sublayers, may be or may include one or more of an insulating substrate and an adhesive layer. The insulating jacket 112 may also include one or more sublayers, and may be or may include one or more of an insulating substrate and an adhesive layer. In some embodiments, the insulating jacket 112 is wrapped longitudinally around the electrically conductive shield 400. In some embodiments, the insulating jacket 112 covers all or substantially all of the electrically conductive shield 400. In some embodiments the electrically conductive shield 400 comprises two shielding films, one disposed adjacent first side 1200 and the other disposed adjacent second side 1300. The two shielding films may be attached along edges of the shielding film. In some embodiment, the electrically conductive shield 400 includes separate portions which partially or completely surround one or more of the insulated conductors 100.
The exposed portion 610 has a length 630 on the top side 2100 of the electrical cable 2000. A shorter portion of the insulated conductor 600 having a length 633 may optionally be exposed on the bottom side 2200 of the electrical cable 2000. The length 633 may be less than 0.5 mm or may be zero, for example. The exposed portion 610 of the inner conductor 700 comprises a first end 620 of the inner conductor 700 on a same first end 2300 of the cable 2000. The insulated conductor 600 is adapted to mate with an electrically conductive mating conductor 500 at the exposed portion 610 of the inner conductor 700.
In the illustrated embodiment, electrical cable 2000 includes layer 940, which may be or include and adhesive layer and/or an insulating substrate, between electrically conductive shield 900 and insulating layer 800 and includes electrically insulating jacket 960 adjacent the electrically conductive shield 900 opposite the insulated conductors 600.
In some embodiments, the inner conductors (e.g., inner conductor 200, 202, 282 or 700) in the plurality of insulated conductors (e.g., insulated conductors 100, 181, 881, or 600) of the electrical cables of the present description may include one or more ground conductors and the electrically conductive shield may be bonded to one or more of the ground conductors. The shield can be bonded to the ground conductors with an ultrasonic weld (e.g., a 40 kHz ultrasonic weld), for example. Such bonding can be utilized near one or both ends of the cable near a mating conductor as described in U.S. 62/155,599, filed May 1, 2015 and entitled “CONNECTOR ASSEMBLY”, for example. This may be done in order for the electrically conductive shield to provide improved electromagnetic interference (EMI) shielding at low frequencies, and this can improve the performance of the electrical cable in single ended signaling applications.
The insulating layer (e.g., insulating layer 300, 301, 331, 800) covering the inner conductor of the plurality of insulated conductors can be formed around the inner conductors via extrusion, for example. In some cases, an insulating jacket may be extruded over the insulating layer. Suitable material for insulating layer and/or the insulating jacket include extrudable thermoplastics such as thermoplastic elastomer (TPE), polyolefin (PO) such as polyethylene (PE) and polypropylene (PP), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP), for example. The material chosen for the insulating layer may have a dielectric constant less than about 3.0, or less than about 2.5, and may have a minimum elongation of 50 percent.
The electrically conductive shield (e.g., electrically conductive shield 400, 490, 493, 900) of the electrical cables of the present description may be robustly bonded to the insulating layer so that the electrical cables can provide a desired electrical performance (e.g., a predetermined impedance (e.g., between 85 and 100 ohms for differential signaling or 50 ohms for single ended signaling) and a low attenuation (e.g., less than −3 db/m at 3 Ghz or less than −6 db/m at 3 Ghz)) that is robust in a broad range of typical use conditions which include bending, folding and varying temperature and humidity. The electrical cables may be used for one or more of differential signaling, single ended signaling, differential driven single ended signaling, and power.
The electrically conductive shield may be any type of film capable of providing electromagnetic shielding to the conductors of the cable. Suitable shielding films are known in the art (see, e.g., U.S. Pat. No. 9,064,612 (Gundel), which is hereby incorporated herein by reference to the extent that it does not contradict the present description). The shield may include metalized film, metal foil, braided copper (or other metal) or expanded copper (or other metal), for example. The shield may include metal foil (e.g., aluminum foil) laminated to a substrate or laminated between two substrates. Suitable substrates include polymeric substrates such as polyethylene terephthalate (PET). In some embodiments, the thickness and material choice (which determines a dielectric constant) of a substrate between a metal shielding layer and the insulating layer of the insulated conductors and/or the thickness and material choice of an adhesive between the metal shielding layer and the insulating layer may be selected to give a desired impedance. The electrical cable may have any useful impedance. For example, the impedance may be in the range of 40 to 110 ohms, or 50 to 105 ohms, or 80 to 105 ohms, or 85 to 100 ohms. In some embodiments, the impedance may be in a range of 40-60 ohms (e.g., about 50 ohms) for single ended applications. In some embodiments, the impedance may be in a range of 75-110 ohms, or 85 to 100 ohms for single differential applications.
The inner conductors (e.g., inner conductors 200, 202, 282, 700) may be wires adapted for maximum data transmission rates of at least 100 Mb/s, or at least 1 Gb/s, or at least 3 Gb/s, for example. An electrical cable assembly including the electrical cable terminated at a connector or a circuit board may be adapted for maximum data transmission rates of at least 100 Mb/s, or at least 1 Gb/s, or at least 3 Gb/s, for example. The wire gage may be in a range of 20 AWG to 34 AWG, or 26 to 31 AWG, for example. The conductors may be solid or stranded and may be made from copper, tin, silver, copper alloy with no plating, copper alloy with tin plating, copper alloy with gold plating, or copper alloy with silver plating, for example.
The following is a list of exemplary embodiments of the present description.
Embodiment 1 is an electrical cable comprising a plurality of substantially parallel insulated conductors extending along a length direction of the cable, each insulated conductor comprising an electrically conductive inner conductor covered with an insulating layer, such that when the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for at least one insulated conductor in the plurality of insulated conductors, a longer first portion of the inner conductor of the at least one insulated conductor is exposed on the top side of the cable, and a shorter second portion of the inner conductor of the at least one insulated conductor is exposed on the bottom side of the cable, the longer first portion at least partially overlapping the shorter second portion, the inner conductor adapted to mate with an electrically conductive mating conductor at the exposed longer first portion of the inner conductor.
Embodiment 2 is the electrical cable of Embodiment 1, wherein the shorter second portion has a zero length.
Embodiment 3 is the electrical cable of Embodiment 1, wherein the at least one insulated conductor extends along the length direction of the cable between opposite ends of the at least one insulated conductor, the exposed longer first portion of the inner conductor of the at least one insulated conductor comprising one of the ends.
Embodiment 4 is the electrical cable of Embodiment 1, wherein the exposed longer first portion of the inner conductor of the at least one insulated conductor is at least 0.5 mm long.
Embodiment 5 is the electrical cable of Embodiment 1, wherein the exposed longer first portion of the inner conductor of the at least one insulated conductor is at least 1 mm long.
Embodiment 6 is the electrical cable of Embodiment 1, wherein the exposed longer first portion fully overlaps the exposed shorter second portion.
Embodiment 7 is the electrical cable of Embodiment 1, wherein the at least one insulated conductor extends along the length direction of the cable between a first end of the at least one insulated conductor at a same first end of the cable and an opposite second end of the at least one insulated conductor at a same opposite second end of the cable.
Embodiment 8 is the electrical cable of Embodiment 7, wherein the exposed longer first portion of the inner conductor of the at least one insulated conductor comprises the first end of the at least one insulated conductor.
Embodiment 9 is the electrical cable of Embodiment 1, further comprising an electrically conductive shield substantially co-extensive with the plurality of substantially parallel insulated conductors.
Embodiment 10 is the electrical cable of Embodiment 9, wherein at least 70% of a periphery of each insulated conductor is encompassed by the electrically conductive shield.
Embodiment 11 is the electrical cable of Embodiment 10, wherein each insulated conductor is surrounded by the electrically conductive shield.
Embodiment 12 is an electrical cable comprising a plurality of substantially parallel insulated conductors extending along a length direction of the cable, each insulated conductor comprising an electrically conductive inner conductor covered with an insulating layer, at least 70% of a periphery of each insulated conductor encompassed by a substantially co-extensive electrically conductive shield, such that when the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for each insulated conductor, portions of the insulating layer and the conductive shield are removed from the top side of the cable to expose a portion of the inner conductor of the insulated conductor, such that from a top plan view, an average lateral width of the exposed portion of the inner conductor is less than an average lateral width of the inner conductor, the exposed portion of the inner conductor comprising a first end of the inner conductor on a same first end of the cable, the insulated conductor adapted to mate with an electrically conductive mating conductor at the exposed portion of the inner conductor.
Embodiment 13 is the electrical cable of Embodiment 12, wherein the exposed portion of the inner conductor is at least 0.5 mm long.
Embodiment 14 is the electrical cable of Embodiment 12, wherein the exposed portion of the inner conductor is at least 1 mm long.
Embodiment 15 is an electrical cable comprising a plurality of substantially parallel insulated conductors extending along a length direction of the cable, each insulated conductor comprising an electrically conductive inner conductor co-extensive and covered with an insulating layer, and an electrically conductive shield substantially co-extensive with and surrounding each insulated conductor, such that when the electrical cable is laid flat defining opposing major top and bottom sides of the cable, for each insulated conductor, portions of the insulating layer and the conductive shield are removed from the top side of the cable to expose a portion of the inner conductor of the insulated conductor, such that from a top plan view, an average lateral width of the exposed portion of the inner conductor is less than an average lateral width of the inner conductor, the exposed portion of the inner conductor comprising a first end of the inner conductor on a same first end of the cable, the insulated conductor adapted to mate with an electrically conductive mating conductor at the exposed portion of the inner conductor.
Embodiment 16 is the electrical cable of Embodiment 15, wherein the exposed portion of the inner conductor is at least 0.5 mm long.
Embodiment 17 is the electrical cable of Embodiment 15, wherein the exposed portion of the inner conductor is at least 1 mm long.
Embodiment 18 is an electrical cable assembly, comprising:
a circuit board comprising a plurality of contact pads disposed on a major surface of the circuit board; and the electrical cable of any one of Embodiments 1 to 11, wherein the exposed longer first portion of the inner conductor of each insulated conductor is attached to a corresponding contact pad of the circuit board at an attachment area, and wherein the unremoved portions of the conductive shield at least partially shield the attachment area.
Embodiment 19 is the electrical cable assembly of Embodiment 18, further comprising:
a frame having an upper portion disposed over the electrical cable and at least one side portion extending from the upper portion towards the circuit board and attached to the circuit board; and
at least one feature disposed between the upper portion of the frame and the electrical cable, the at least one feature adapted to attach the exposed longer first portion of the inner conductor of each insulated conductor to the corresponding contact pad of the circuit board by applying pressure to the electrical cable opposite the corresponding contact pad.
Embodiment 20 is the electrical cable assembly of Embodiment 19, wherein the at least one feature comprises at least one compliant feature.
Embodiment 21 is an electrical cable assembly, comprising:
a circuit board comprising a plurality of contact pads disposed on a major surface of the circuit board; and
the electrical cable of any one of Embodiments 12 to 17, wherein the exposed portion of the inner conductor of each insulated conductor is attached to a corresponding contact pad of the circuit board at an attachment area, and wherein the unremoved portions of the conductive shield at least partially shield the attachment area.
Embodiment 22 is the electrical cable assembly of Embodiment 21, further comprising:
a frame having an upper portion disposed over the electrical cable and at least one side portion extending from the upper portion towards the circuit board and attached to the circuit board; and
at least one feature disposed between the upper portion of the frame and the electrical cable, the at least one feature adapted to attach the exposed portion of the inner conductor of each insulated conductor to the corresponding contact pad of the circuit board by applying pressure to the electrical cable opposite the corresponding contact pad.
Embodiment 23 is the electrical cable assembly of Embodiment 22, wherein the at least one feature comprises at least one compliant feature.
Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.
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WO2018/022379 | 2/1/2018 | WO | A |
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