SPLIT FLEX CABLE
A cable assembly for interconnecting a plurality of circuit boards together by using a connector assembly connected to each of the circuit boards. The cable assembly includes a first cable having a first end part and a second cable having a second end part. A first periphery of the first end part has a plurality of first half vias that collectively form a column along a width direction of the connector assembly. A second periphery of the second end part has a plurality of second half vias that collectively form a column along the width direction of the connector assembly. The first and second end parts are coupled together to form a connecting unit, such that the first half vias and the second half vias are joined together to form full vias.
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This is a division of application Ser. No. 13/326,845, filed on Dec. 15, 2011, which was, in turn, a division of application Ser. No. 12/244,216, filed on Oct. 2, 2008 (issued on Jan. 31, 2012 as U.S. Pat. No. 8,106,300), the entire disclosures of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates to a flex cable for interconnecting together a plurality of printed circuit boards through a connector assembly, and in particular, to a split flex cable that is coupled to the connector assembly, thereby providing an increased electrical performance and enhanced mechanical flexibility.
2. Background Information
Cables typically are coupled with an electronic connector assembly at opposing ends that are matable with a printed circuit board of electronic devices. Such a cable connector assembly is well known in the connector assembly art and includes a universal serial bus (USB)-type connector assembly, a parallel connector assembly, a serial connector assembly, a VHDM (very high density metric) connector assembly, and the like. The VHDM connector assembly may be used for a high-density connection between electronic devices.
In computer systems, for example, flex cables having connector assemblies at each end are utilized for a high-speed interconnection between a first circuit board assembly and a second circuit board assembly. However, when a single flex cable interconnects more than two circuit boards, the end of the flex cable should be understood to mean each portion of the flex cable that is connected to each printed circuit board through the VHDM connector assembly.
Each column of signal pins is separated from adjacent columns of signal pins by ground shield GS. Each ground shields GS has a predetermined number of ground shield solder tails or ground pins (not shown) that are arranged along the width direction W of the connector assembly 12. The connector assembly with eight-row signal pins conventionally has seven rows of ground pins shown as dotted circles in
The signal pins and ground pins of the connector are inserted into corresponding vias of the flex cable that are arranged in a pattern that the pins of the VHDM connector assembly 12 can be inserted into to the vias.
Each connecting portion 110 and 120 of the flex cable 10 has a plurality of signal vias and a plurality of ground vias. For example, as shown in
Conventionally, a VHDM connector assembly is connected to only one single connecting portion of a flex cable that extends and integrally formed in its length direction L.
In case of a complex system, more pins are required in the VHDM connector assembly, and a large number of vias and a large length of signal wirings are required in the flex cable, resulting a significant increase in the width of the flex cable or in the number of layers on a flex cable.
For example, if four busses B1 to B4 of signal lines are required to interconnect the two circuit boards 14 and 16 as shown in
Alternatively, the bus lines B1 to B4 of the flex cable 10 may be disposed on two or more separate signal layers of the flex cable based on the signal amounts and the constraint for the overall width of cable. However, this configuration also requires increased number of layers in a single flex cable. A higher number of layers on flex cables increase cost, negatively affect manufacturability and reliability, and result in more stiff cables that do not meet flexibility or other mechanical packaging requirements.
A flex cables that is split along a length direction, e.g., designated by an arrow L in
However, when the connecting portion of the flex cable is split in its length direction that is perpendicular to its width direction, each split part of the connecting portion of the flex cable has the same length in the length direction of the connector assembly to which each split part is connected. Thus, each split part should be formed as an integrated element that has the same length as an unsplit connecting portion of the flex cable, thereby limiting design flexibility.
In addition, the conventional VHDM connector assembly 12 is, e.g., on a 2.0×2.25 mm pitch. Accordingly, the vias of the corresponding flex cable 10 has a pitch PL (see
Moreover, such a flex cable split in its length direction does not give any solution to the layer number increase in the flex cable for connecting a multi-drawer system.
SUMMARY OF THE INVENTIONAccording to one aspect of the invention, a cable assembly including a split connecting unit is provided. The connecting unit is split into two separate parts, including a first connecting part and a second connecting part. The first connecting part is a portion of a first cable, and the second connecting part is a portion of the second cable. The first cable further includes a main cable portion and another connecting part. The second cable further includes a main cable portion and another connecting part. The first and second cables jointly connect two circuit boards through a connector assembly. The connector assembly may be a VHDM connector assembly. The first and second connecting parts jointly form the connecting unit connected to the connector assembly.
In another exemplary aspect of the invention, the number of buses in the first cable may be the same as or different from the number of buses in the second cable, on condition that the first and second cables jointly include the required total number of buses for the interconnection between the two circuit boards. The buses of each cable may be disposed on the same layer so as to reduce a thickness of each cable, or may be disposed on a plurality of layers so as to meet a width restraint of each cable. Thus, the numbers of layers of the first cable may be the same as or different from that of the second cable. The width of the first cable may be the same as that of the second cable. Further, the main cable portions of the first and second cables can be stacked together in a thickness direction of the cable, so as to reduce a width of the combined cables.
In a further exemplary aspect of the invention, the connecting unit has a split line disposed between the two connecting parts. The split line extends along a width direction of the connecting unit which is the same as the width direction of the connector assembly, and passes through the center of ground vias of one of the ground columns of the connecting unit.
In a further exemplary aspect of the invention, the cable assembly may be configured to run signals to extend from one connecting part to the other connecting part, crossing over the split line e.g., through vias on the split line. The vias may be tied together with solder and disposed in areas without connector assemblies.
In a further exemplary aspect of the invention, the split line may be in a step shape, a zigzag shape, or other suitable shapes. The step-shaped split line may include a first plurality of sub-lines extending along the width direction of the connector assembly and a second plurality of sub-lines extending along the length direction of the connector assembly. The first sub-lines collectively divide the connecting unit of the cable assembly into two separate connecting parts in the width direction. The second sub-lines respectively connect two adjacent first sub-lines. Further, some of the sub-lines may pass through centers of the signal vias, while the remaining sub-lines pass through centers of the ground vias.
The invention will now be described in more detail by way of example with reference to the embodiments shown in the accompanying figures. It should be kept in mind that the following described embodiments are only presented by way of example and should not be construed as limiting the inventive concept to any particular physical configuration.
Further, if used and unless otherwise stated, the terms “upper”, “lower”, “front”, “back”, “over”, “under”, and similar such terms are not to be construed as limiting the invention to a particular orientation. Instead, these terms are used only on a relative basis.
Because the two connecting parts 62a and 64a are separated from each other, each connecting part may be formed as a portion of a separate cable. As shown in
As shown in
Four buses are required to connect the two circuit boards 14 and 16, as shown in
Because each cable 62 and 64 has two buses, each cable 62 and 64 may have a reduced width WC2 (see
By connecting two systems with multiple cables, each cable may have a reduced number of buses and a reduced width. Further, compared with the conventional cables that may be required to have an increased number of layers to meet the minimum width constraint of the cable, each cable of the invention may have a reduced number of layers. Accordingly, the cable of the invention is more flexible. In addition, each cable may be formed as a modular cable, which is easier to manufacture, thereby improving yields and reducing the manufacturing cost.
Each connecting part 62a and 64a has semicircular half vias 620 and 640 (see
If two buses are required so as to interconnect two circuit boards in the three-drawer system, each cable has two buses (B11, B12), (B13, 14) and (B15, B16), as shown in
Next, a method for fabricating the cable assembly of the invention will be described. The cable assembly may be fabricated by using a flex cable that generally includes signal lines, frame ground domains and logic ground domains. When the flex cable is split into two parts, one part may form the first connecting part 62a of the first cable 62, and the other part may form the second connecting part 64a of the second cable 64, as shown in
First, the signal lines of the flex cable are wired out of the area of the flex cable to be split.
Second, the frame ground or power domains are pulled back from the edge of the area to be split. These frame grounds are pulled back so that they are not exposed at the split line SL (see
Third, the logic ground domains are pulled back from the edge or the split line SL of the area to be split, or they can extend past the edge of the routed cable leaving exposed ground planes in the split zone. When the half vias of the two connecting parts 62a and 64a are soldered together later, the logic ground domains of the two connecting part are interconnected together. In this case, the logic ground domains of each connecting parts could extend to the half vias of each connecting parts 62a and 64a.
Fourth, the flex cable is cut or split into two or more separate parts through at least one split line that passes through centers of vias, thereby forming, e.g., the first connecting parts 62a and the second connecting parts 64a, each having half vias at each outer periphery. The vias may be ground vias, and accordingly the half vias may be ground half vias. However, the vias may be power vias connected to the power domains or signal vias connected to the signal lines, and thus the half vias may be power half vias or signal half vias.
Fifth, the two or more split separate parts are joined together by aligning. During the joining, the split parts may be laminated onto an FR-4 stiffener.
Finally, the VHDM connector assemblies are attached to the joined separate parts by using conventional processes.
The cable assembly of the invention enables a customized volume design. Because the connecting unit of the invention can be divided into a plurality of connecting parts, it is possible to set ID bits of the connecting unit or fix a defected area in the connecting unit based on each divided connecting part, without treating the entire connecting unit. As shown in
As shown in
As shown in
Further, the connecting unit may have an irregular split line SL2. The split line SL2 include sub-lines SL2a to SL2e that collectively form a step shape. However, the split line may be a zigzag shape or other shapes. The sub-lines SL2a, SL2c and SL2e extend along the width direction W of the connector assembly, and collectively divide the connecting unit of the cable assembly into two separate connecting parts with respect to the width direction W. The horizontal sub-lines SL2b and SL2d respectively connect two adjacent vertical sub-lines (SL2a, SL2c) and (SL2c, SL2e), and may extend along the length direction L of the connector assembly.
Further, the split line is not limited to pass through centers of the ground vias. In
Further, the split line may have an angle other than 180 degree in the vias. In
According to another exemplary embodiment of the invention, a circuit board connected to the connector assembly may be split into two or more segments.
It should be understood, however, that the invention is not necessarily limited to the specific arrangement and components shown and described above, but may be susceptible to numerous variations within the scope of the invention.
It will be apparent to one skilled in the art that the manner of making and using the claimed invention has been adequately disclosed in the above-written description of the preferred embodiments taken together with the drawings. It will be understood that the above description of the preferred embodiments of the present invention are susceptible to various modifications, changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
Claims
1. A method for manufacturing a flex cable assembly including a flex cable and a connector assembly connected to the flex cable, the method comprising:
- providing a plurality of split parts, wherein each of the plurality of split parts forms an end part of a cable to be connected to the connector assembly and has a plurality of partial vias;
- aligning the plurality of split parts so that the partial vias are joined together to form full vias; and
- attaching the connector assembly to the plurality of split parts.
2. The method of claim 1, wherein the plurality of split parts include a first split part having a plurality of first partial vias and a second split part having a plurality of second partial vias.
3. The method of claim 1, wherein the plurality of partial vias include semi-circle shaped vias.
4. The method of claim 1, wherein the plurality of partial vias include quarter-circle shaped vias.
5. The method of claim 1, wherein the plurality of partial vias include three-quarter-circle shaped vias.
6. The method of claim 1, wherein the plurality of split parts include at least three split parts.
Type: Application
Filed: Apr 10, 2015
Publication Date: Aug 6, 2015
Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION (Armonk, NY)
Inventors: David J. Braun (St. Charles, MN), Mark G. Clark (Rochester, MN), John R. Dangler (Rochester, MN), Matthew S. Doyle (Rochester, MN), Thomas D. Kidd (Stewartville, MN), Jason T. Stoll (Fort Collins, CO)
Application Number: 14/683,995