Patent Application
20220223317
Electrical cables for transmission of electrical signals are well known. One common type of electrical cable is a coaxial cable. Coaxial cables generally include an electrically conductive wire surrounded by an insulating material. The wire and insulator are surrounded by a shield, and the wire, insulator, and shield are surrounded by a jacket. Another common type of electrical cable is a shielded electrical cable that includes one or more insulated signal conductors surrounded by a shielding layer formed, for example, by a metal foil.
In some aspects of the present description, a ribbon cable is provided, including a plurality of conductors extending along a length of the cable; and a structured insulative tape including a plurality of spaced apart supports forming alternating first and second groups of supports disposed on a major surface thereof. Each first group of supports includes at least one taller first support, and each second group of supports includes at least one shorter second support. The insulative tape is helically wrapped around the conductors along the length of the cable such that each first group of supports is disposed between and maintains a minimum separation between two adjacent conductors, and each of the two adjacent conductors makes contact with a side of the taller first support. Each second group of supports is disposed around one or more conductors, such that each of the conductors makes contact with a top of the at least one shorter support.
In some aspects of the present description, a conductor set is provided, including a plurality of conductors, a structured insulative tape including a plurality of spaced apart supports forming alternating first and second groups of supports disposed on a major surface thereof, and an electrically conductive shield substantially surrounding the plurality of conductors and the structured insulative tape. Each first group of supports includes at least one taller first support, and each second group of supports includes at least one shorter second support. The insulative tape is helically wrapped around the conductors along the length of the cable such that each first group of supports is disposed between and maintains a minimum separation between two adjacent conductors, and each of the two adjacent conductors makes contact with a side of the taller first support. Each second group of supports is disposed around one or more conductors, such that each of the conductors makes contact with a top of the at least one shorter support.
In some aspects of the present description, a shielded electrical cable is provided, including a plurality of spaced apart, substantially parallel conductor sets extending along a length of the cable and arranged along a width of the cable. Each conductor set includes two substantially parallel conductors extending along the length of the cable and arranged along the width of the cable, and a structured insulative tape helically wrapped around the conductors of each conductor set along the length of the cable. The structured insulative tape includes a plurality of spaced apart first and second supports disposed on an inner major surface thereof facing the two conductors. Each first support is taller than each second support, and each first and second support extend substantially from a first lateral edge of the structured insulative tape to an opposite second lateral edge of the structured insulative tape. The first supports are disposed between and maintain a minimum separation between the two conductors, such that the two conductors make contact with opposite sides of the first supports, the second supports disposed around the two conductors and maintaining a minimum separation between the two conductors and the inner major surface of the structured insulative tape, the two conductors making contact with tops of the second supports.
In some aspects of the present description, a ribbon cable is provided, including a plurality of spaced apart, substantially parallel uninsulated conductors extending along a length of the cable and arranged along a width of the cable, a structured insulative tape including a plurality of spaced apart supports of equal heights integrally formed on a major surface thereof, and a spacer disposed and maintaining a minimum separation between each pair of adjacent uninsulated conductors along the length of the cable. The insulative tape is helically wrapped around the plurality of the uninsulated conductors along the length of the cable such that, for each helical wrap, each uninsulated conductor makes contact with a top of at least one support. The spacer makes contact with both uninsulated conductors and is not integrally formed with the insulative tape or either one of the uninsulated conductors.
In some aspects of the present description, a ribbon cable is provided, including a plurality of spaced apart, substantially parallel uninsulated conductors extending along a length of the cable and arranged along a width of the cable, an insulative tape helically wrapped around the uninsulated conductors along the length of the cable, and a spacer disposed and maintaining a minimum separation between each pair of adjacent uninsulated conductors along the length of the cable. For each helical wrap, each uninsulated conductor makes contact with the insulative tape. The spacer makes contact with both uninsulated conductors and is not integrally formed with the insulative tape or either one of the uninsulated conductors.
In the following description, reference is made to the accompanying drawings that form 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 description. The following detailed description, therefore, is not to be taken in a limiting sense.
According to some aspects of the present description, electrical cables incorporating the structures described herein have been found to provide improved performance over conventional cables. For example, the electrical cables may have one or more of a reduced impedance variation along the cable length, lower skew, lower propagation delay, lower insertion loss, increased crush resistance, reduced cable size, increased conductor density, and improved bend performance compared to conventional cables.
In some embodiments, an electrical cable is constructed by creating a planar three-dimensional (3D) structured dielectric and then wrapping the structured dielectric helically around two or more signal conductors. The structured dielectric may be an insulative tape featuring a series of supports of varying heights. When the structured dielectric is wrapped around two or more conductors, the supports may provide precise spacing between adjacent conductors, as well as precise spacing between the conductors and a shielding film placed around the conductors, incorporating air into the cable as well as providing crush resistance. The supports may have a low effective dielectric constant and/or a low dielectric loss (e.g., low effective loss tangent). For example, the supports may have a high air (or other low dielectric constant material) content to provide the low effective dielectric constant. The supports may be a porous material with air in the voids. In some embodiments, the air content of the supports may be greater than 40%.
In some embodiments, each of the supports may have a dielectric constant of less than about 2, or less than about 1.7, or less than about 1.6, or less than about 1.5, or less than about 1.4, or less than about 1.3, or less than about 1.2. In some embodiments, an dielectric constant of the cable for at least one pair of adjacent conductors driven with differential signals of equal amplitude and opposite polarities is less than about 2.5, or less than about 2.2, or less than about 2, or less than 1.7, or less than about 1.6, or less than about 1.5, or less than about 1.4, or less than about 1.3, or less than about 1.2. The dielectric constant of the supports may be in any of the specified ranges when determined at an operating frequency of the cable and/or when determined at a frequency of 100 MHz, 1 GHz, or 10 GHz, for example.
The conductors may include any suitable conductive material, such as an elemental metal or a metal alloy (e.g., copper or a copper alloy), and may have a variety of cross sectional shapes and sizes. For example, in cross section, the conductors may be circular, oval, rectangular or any other shape. One or more conductors in a cable may have one shape and/or size that differs from other one or more conductors in the cable. The conductors may be solid or stranded wires. All the conductors in a cable may be stranded, all may be solid, or some may be stranded and some solid. Stranded conductors and/or ground wires may take on different sizes and/or shapes. The conductors may be coated or plated with various metals and/or metallic materials, including gold, silver, tin, and/or other materials.
In some embodiments, the supports may be adhered to the insulative tape of the structured dielectric. The supports may be placed such that, when the structured dielectric is helically wrapped around two or more conductors, a first subset of the supports is disposed between and maintains a minimum separation between adjacent conductors, and a second subset of the supports is disposed between each conductor and a surrounding shielding film. In some embodiments, the first subset of supports may be taller than the second subset of supports.
In some embodiments, one or more separate spacers may be used to separate adjacent conductors in addition to the supports of the structured dielectric. The spacers may be separately formed from the structured dielectric, and may be held in place by the conductors. In some embodiments, the spacers may be placed between adjacent conductors and then adhered to a structured dielectric which is helically wrapped around the conductors in the process of forming the electrical cable. In some embodiments, a spacer may be used in place of supports to separate adjacent conductors. The spacers may be made of a material which has a low effective dielectric constant and/or a low dielectric loss. For example, the spacers may have a high air content to provide the low effective dielectric constant.
In some embodiments, the cable can be produced with high uniformity to maintain a constant impedance, and related data transmission performance along a single transmission path or among cables of the same design manufactured at different times. In some embodiments, the spacing between conductors (e.g., center-to-center spacing) in the cable can be different (e.g., smaller) than the spacing in a direction orthogonal to the plane of the conductors between the shields included in the cables. This can allow for a high density of conductors in the cable, for example, which is highly desirable in some cases.
In some embodiments, the conductors of the cable are insulated with a dielectric layer. In some embodiments, incorporating low effective dielectric constant materials or structures in the insulative layer(s) of the cable allows the thickness of the dielectric layer to be smaller than that of conventional cables while providing a desired cable impedance (e.g., a differential impedance in a range of 70 ohms to 110 ohms). For example, conventional cables typically have a ratio of a diameter of the insulated conductor to the diameter of the conductor of the insulated conductor substantially greater than 2 (e.g., about 2.8 or higher), while this ratio for cables of the present description having the same impedance can be less than about 2 in some embodiments.
In some embodiments, an electrically conductive shield may be wrapped or otherwise placed around the conductors and structured dielectric. The shield may include an electrically conductive shielding layer disposed on an electrically insulative substrate layer. In some embodiments, the shield may include a first shield disposed on a top side of the electrical cable and a second shield disposed on a bottom side of the electrical cable. The shield may include cover portions and pinched portions, such that the cover portions create a channel or pocket which substantially surround and contain the conductors and structured dielectric, and the pinched portions are portions where the first and second shields are pushed together or nearly together and which may not contain conductors and structured dielectric.
When the structured insulative tape 20 is wrapped helically around conductors 10, as illustrated in
As described elsewhere, one or more taller first supports 30a extend up between and maintain a precise separation between adjacent conductors 10, and one or more shorter second supports 30b are positioned such that they provide support for conductors 10 and maintain a precise separation between conductors 10 and conductive shield 60. The structured insulative tape 20 has a defined width W and a projected width W′ along the length of the cable and is wrapped around the conductors 10 at a pitch P, where P is defined as the distance from a lateral edge 22 of one wrap of the structured insulative tape 20 to the same lateral edge 22′ of the immediately successive (adjacent) wrap of the structured insulative tape 20. The structured insulative tape 20 is helically wrapped around conductors 10 such that a difference between the projected width W′ and pitch P defines a helical gap G between adjacent wraps of the structured insulative tape 20. In various embodiments, the width W and pitch P can be varied to create different helical gaps G. By increasing the helical gap G, it may be possible to increase the air content of ribbon cable 100 (i.e., create a lower effective dielectric constant and/or a lower dielectric loss). In an embodiment, the helical gap G may be greater than or equal to two times the width W of structured insulative tape 20. In some embodiments, the helical gap G may be greater than the projected width W′ by at least a factor of 2. In another embodiment, helical gap G may be less than equal to zero (i.e., the pitch P may be adjusted such that successive adjacent wraps of structured insulative tape 20 touch or overlap each other, greatly reducing or eliminating helical gap G. Any appropriate width W, pitch P, and gap G may be used, depending on the desired electrical and physical properties of the ribbon cable 100.
In some embodiments, the heights of second supports 30b may be substantially equal throughout the length of structured insulative tape 20, such that a consistent spacing is maintained between conductors 10 and outer conductive shield 60. In other embodiments, the heights of second supports 30b may be varied over the length of structured insulative tape 20, such that the spacing between a first subset of the conductors 10 and the conductive shield 60 is different than the spacing between a second subset of the conductors 10 and the conductive shield 60. For example, in the four-conductor example of
Although the examples presented herein discuss varying the heights of or eliminating second supports 30b, the same principles may be applied to taller first supports 30a, as well. Various embodiments may use any number of sizes or shapes of supports 30 (including taller first supports 30a and shorter second supports 30b) to meet different ribbon cable design requirements. Supports 30 may be any appropriate shape, including, but not limited to, cylindrical, rectangular, pyramidal, spherical, hemispherical, and cross-shaped. Supports 30 may be solid forms or hollow to increase air content in the structures. In one embodiment, the heights of taller first supports 30a may be such that the tops of supports 30a extend up from the structured insulative tape 20 to a point past the conductors it is between. In another embodiment, the heights of taller first supports 30a may only extend up through a fraction of the diameter of the conductors, such as 10%, 25%, 50%, 75%, or 90% of the diameter of the conductors, or any other appropriate percentage of the diameter of the conductors. In an embodiment, the height of taller first supports 30a may be substantially equal to the height of shorter second supports 30b.
Turning to
This spacer 90 is initially a separate component which may in some embodiments be held in place by the conductors and pressure from the surrounding structured insulative tape 20 without requiring additional adhesion to the conductors 10 or tape 20. In other embodiments, the spacer 90 may be placed in between conductors 10 and adhered to conductors 10, structured insulative tape 20, and/or supports 30 in a separate process. The spacers may be made of a material which has a low effective dielectric constant and/or a low dielectric loss. For example, the spacers may have a high air content to provide the low effective dielectric constant.
In the embodiment of
In some embodiments, the length L of spacer 90 of
In the embodiment of
In some embodiments, spacer 90 may be held in place by contact with conductors 10 and/or insulative tape 20c, which may be wrapped helically around conductors 10. In some embodiments, an outer conductive shield and/or a cable jacket (not shown) may surround and contain conductors 10, spacer 90, and insulative tape 20c. In other embodiments, an adhesive may be applied between spacer 90 and insulative tape 20c and/or conductors 10 to hold ribbon cable 100 together.
As illustrated in
In some embodiments, the conductive shield 60 may be longitudinally wrapped around ribbon cable 100. In other embodiments, conductive shield 60 may be helically wrapped around ribbon cable 100. In still other embodiments, conductive shield 60 may include a first and second shield layer disposed respectively on top and bottom sides of ribbon cable 100.
The conductive shielding layer 76 may include any suitable conductive material, including but not limited to copper, silver, aluminum, gold, and alloys thereof. The electrically insulative substrate layer 78 may be an electromagnetic interference (EMI) absorbing layer. For example, electrically insulative substrate layer 78 may include EMI absorbing filler material (e.g., ferrite materials). Alternatively, or in addition, in some embodiments, one or more separate EMI absorbing layers are included. The conductive shielding layer 76 and electrically insulative substrate layer 78 may have a thickness in the range of 0.01 mm to 0.05 mm and the overall thickness of the cable may be less than 2 mm or less than 1 mm.
Shield layers 60a and 60b are disposed on respective top and bottom sides of ribbon cable 100 such that they include cover portions 72 and pinched portions 74. Cover portions 72 of first shield layer 60a and second shield layer 60b are aligned or otherwise arranged with respect to each other such that, in combination, they surround ribbon cable 100. Similarly, pinched portions 74 of first shield layer 60a and second shield layer 60b are aligned or otherwise arranged to form pinched portions 74 in shield 60, substantially enclosing and isolating conductors 10 and structured insulative tape 20. In some embodiments, an adhesive may be used between the pinched portions 74 of first shield layer 60a and second shield layer 60b. One or more taller first supports 30a extend up from structured insulative tape 20, maintaining precise spacing between conductors 10, and one or more shorter second supports 30b provide and maintain spacing between conductors 10 and shield 60.
In an embodiment, two or more conductor sets 40 share a common shield 60. The shield 60 includes a first shield layer 60a and a second shield 60b, disposed on respective top and bottom sides of conductor sets 40. Each shield layer 60a and 60b includes an electrically conductive shielding layer 76 disposed on an electrically insulative substrate layer 78. Shield layers 60a and 60b are disposed on respective top and bottom sides of ribbon cable 100 such that they include cover portions 72 and pinched portions 74. Cover portions 72 of first shield layer 60a and second shield layer 60b are aligned or otherwise arranged with respect to each other such that, in combination, they surround a conductor set 40. Similarly, pinched portions 74 of first shield layer 60a and second shield layer 60b are aligned or otherwise arranged to form pinched portions 74 in shield 60, substantially surrounding and isolating each conductor set 40 in ribbon cable 100. In some embodiments, an adhesive may be used between the pinched portions 74 of first shield layer 60a and second shield layer 60b.
In some embodiments, shield 60 includes first and second shields 60a and 60b disposed on respective top and bottom sides of the ribbon cable 100 and includes cover portions 72 and pinched portions 74 arranged such that, in cross-section, the cover portions 72 of the first and second shields 60a and 60b, in combination, substantially surround the ribbon cable 100, and the pinched portions 74 of the first and second shields 60a and 60b, in combination, form pinched portions of the conductor set on at least one side of the ribbon cable 100. In some embodiments, the pinched portions 74 of the first and second shields 60a and 60b, in combination, form the pinched portions 74 of the conductor set 40 on each side of the ribbon cable 100. In some embodiments, the pinched portions 74 of the first and second shields 60a and 60b, in combination, form the pinched portions of the conductor set 40 only on one side of the ribbon cable 100.
Although the example of
It should be noted that, for simplicity's sake, the examples provided do not show shorter second supports or conductive shielding. The intent of
Finally,
In example structured insulative tape 20q, supports 30a are substantially equal in size and placed at regular intervals along major surface 21. Supports 30a extend from surface 21 between conductors 10, but do not extend past conductors 10. In example structured insulative tape 20r, supports 30a are similarly spaced as those in tape 20q, but are longer, extending past conductors 10. Longer supports 30a such as these may be used to provide additional structure to the ribbon cable, providing support for an outer wrap such as a conductive shield or cable jacket. In example structured insulative tape 20s, supports 30a vary in both height and width throughout the length of the resulting ribbon cable. This may be done as required to balance trade-offs such as additional structural support (for example, additional crush resistance) and a lower dielectric constant. Finally, in example structured insulative tape 20t, supports 30a are broad, such that supports 30a span the width of major surface 21. As can be appreciated by one skilled in the art, any appropriate size, shape, and number or supports 30a may be used to achieve the desired properties in an electrical cable.
Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1.1, and that the value could be 1.
Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned.
All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.
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.
This application is a divisional filing of U.S. application Ser. No. 17/259,053, filed Jan. 8, 2021, now allowed, which is a national stage filing under 35 C.F.R. 371 of PCT/IB2019/055836, filed Jul. 9, 2019, which claims the benefit of U.S. Provisional Application No. 62/696,501, filed Jul. 11, 2018, the disclosures of which are incorporated by reference in their entireties herein.
| Number | Date | Country | |
|---|---|---|---|
| 62696501 | Jul 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17259053 | Jan 2021 | US |
| Child | 17711138 | US |
