Retention mechanism for shielded flex cable to improve EMI/RFI for high speed signaling

A retention apparatus for a shielded cable is described. In one embodiment, the apparatus comprises a substrate having a ground; a connector coupled to the substrate; a cable shielded with a conductive material and having an end connectable to the connector to electrically connect with the connector; an electrically conductive material coupled to the ground of the substrate; and a grounding retention mechanism to cause the electrically conductive material to electrically connect the cable to the ground of the substrate by applying a force to the cable shield.

FIELD OF THE INVENTION

Embodiments of the present invention relate to the field of high speed signaling in computing systems; more particularly, embodiments of the present invention relate to controlling electromagnetic interference (EMI) and/or radio-frequency interference (RFI) for internal cables of computing systems.

BACKGROUND OF THE INVENTION

Electromagnetic interference (EMI) or radio-frequency interference (RFI) are issues for internal cables of computing systems, such as desktops, All-in-Ones (AIOs), notebooks, tablets and smart phones. Because of this, shielded cables are recommended for use as internal cables for these computing systems. There are a number of shielded cables that are commonly used, including, for example, shielded u-coax cables, shielded flexible printed circuit (FPC) cables and shielded flexible flat cable (FFC) cables.

One solution to reduce EMI and RFI for the internal cables has been developed at Intel Corporation of Santa Clara, Calif. They developed a grounding mechanism that achieves low EMI/RFI by using a conductive material to attach a cable shield to a ground pad on printed circuit board (PCB) when the cable is connected to a connector attached to the PCB. In such cases grounding the shield properly can provide ˜20 dB noise reduction at ˜2.4 GHz in comparison to the case of floating shield.

One problem associated with the use of conductive tape in this EMI/RFI grounding mechanism is that once the cable is installed, it becomes very difficult to remove the cable. Therefore, rework is very challenging, and damage to the connector often occurs when peeling off the tape. As a result, although the RFI mitigation characteristics are good, the use of this approach is not expected to be prevalent.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Interconnection schemes and method for using the same are described herein. The interconnection schemes including several grounding retention mechanisms. In one embodiment, these retention mechanisms can be rework-friendly with still reliable electrical connection between cable shield and substrate (e.g., printed circuit board (PCB)) ground that ensures low EMI/RFI.

In one embodiment, the interconnect scheme disclosed herein includes the substrate (e.g., printed circuit board (PCB), having a first node (e.g., a ground node) (e.g., an exposed ground pad, a voltage reference node)), a connector that is coupled or otherwise attached to the substrate, a cable shielded with a conductive material and having an end that is attachable (e.g., insertable) to the connector to electrically connect the cable to the connector, an electrically conductive material coupled to the substrate ground, and a grounding retention mechanism to cause the electrically conductive material to electrically connect the cable to the ground of the substrate by applying a force to the cable shield.

In one embodiment, the grounding retention mechanism comprises a retention actuator. In one embodiment, the retention actuator is coupled to the connector to apply a retention force onto the shield of the cable when it is in a first position after the cable has been electrically connected to the connector. In one embodiment, the electrically conductive material is compressible and the retention force causes compression of the electrically connected material between the cable and the substrate of the material when the force is applied on the shield.

In one embodiment, EMI/RFI grounding retention mechanism is integrated into the actuator of the connector (e.g., a FPC/FFC connector). In such a case, the actuator that secures cable also applies a retention force to the cable shield with sufficient force to compress an electrical conductive material placed in between the shield and substrate (PCB) ground the cable shield. Therefore, the cable shield makes good electrical contact to substrate (e.g., PCB) ground.

FIGS. 1A and 1Billustrate an integrated EMI/RFI grounding retention mechanism that includes and actuator. In one embodiment, the actuator is connected to the connector. Referring toFIG. 1A, connector101(e.g., flexible flat cable (FFC), flexible printed circuit (FPC) connector, etc.) is coupled to a substrate, printed circuit board (PCB)102. Shielded cable103is then electrically connected to connector101. A conductive material104electrically connects shielded cable103to exposed ground pad105, which is on PCB102. In one embodiment, electrically conductive material104comprises an EMI gasket, direct metal (e.g., steel), solder, or other material that is compressible and electrically conductive. Also connected to connector101is a retention actuator106. InFIG. 1A, retention actuator106is in an open position.

FIG. 1Billustrates actuator106in a closed position. In the closed position, actuator106contacts shielded cable103and applies a force on shielded cable103to provide retention. The force on shielded cable103makes an electrical connection between shielded cable103and exposed ground pad105via conductive material104. In one embodiment, actuator106applies the force in response to manually moving actuator106.

In another embodiment, the grounding retention mechanism comprises a screw-type actuator. In such a case, the screw-type actuator includes one or more screw holes.FIGS. 2A and 2Billustrate an example of an integrated screw-type actuator for EMI/RFI grounding.

Referring toFIG. 2A, a connector201is attached to PCB202(or other substrate). PCB202includes a plated-through hole (PTH) (a voltage reference node (e.g., ground)) via208. Cable203(e.g., a FFC/FPC cable) electrically connects with connector201. An actuator with a screw hole206is positioned on top of cable203. Screw207is attached to PTH via208, thereby securing actuator206to apply a force to cable203by tightening screw207. While not shown inFIG. 2A or 2B, a conductive material is between cable203and an exposed ground pad on PCB202such that when actuator206is secured in place by screw207, an electrical connection occurs between shielded cable203and the exposed ground pad on PCB202via this conductive material.

FIG. 2Billustrates the top view of the PCB (or other substrate). Referring toFIG. 2B, two screw holes210are shown on opposite sides of actuator206. Screws207are attached via screw holes210to secure actuator206in place so that actuator206applies a force on to shielded cable203.

In another embodiment, the grounding retention mechanism comprises an integrated latch-type actuator for EMI/RFI grounding. Such a latch-type actuator includes a latch that latches to a substrate when a latch is in a particular position. The latch-type actuator may comprise a fork, a hook, or an eye-of-needle (EON) as part of the latch.

FIGS. 3A-3Cillustrate examples of an integrated latch-type actuator. Referring toFIG. 3A, connector301is attached to PCB (substrate)302. PCB302includes one or more of PTH vias308. Actuator306includes a latch on both sides. More specifically, latch306includes latches311(e.g., EON, fork, or hook-type). That is, there are two latches at the ends of the actuators. Therefore, the actuator can apply force more evenly to the cable. InFIG. 3A, the actuator is in the open position.

FIG. 3Billustrates a fork- or hook-type latch in the closed position. In the closed position, latches312(e.g., fork-type latch, hook-type latch, etc.) are inserted and electrically connect to PTH vias308. Actuator306is in electrical contact with shielded cable303(e.g., FFC/FPC cable). Latch306is in electrical contact with shielded cable303which is grounded to the connection of actuator306with PTH via308.

FIG. 3Cillustrates a closed position of an actuator with a latch that includes an EON-type latch313. In the closed position, actuator306is in electrical contact with shielded cable303and is electrically coupled with the ground (a voltage reference node) via PTH via308.

In one embodiment, the grounding retention mechanism comprises a lever-type or similar retention mechanism. When the lever is locked, it applies pressure to the cable and cable shield to achieve a good grounding connection to the PCB ground. The lever type retention mechanism can be a component separate from the connector or can be integrated as part of the connector.

FIGS. 4A-4Cillustrate an example of one embodiment of a lever-type retention mechanism.FIG. 4Aillustrates a front view of one embodiment of the retention mechanism. Referring toFIG. 4A, a connector401is attached to a PCB402. Electrically conductive material404is coupled to ground pad405on PCB402. Also coupled to conductive material404is shielded cable403when shielded cable403is electrically connected to connector401. A grounding retention mechanism406is coupled to PCB402and includes lever410. Lever410is shown in an open and closed positions. When lever410is in a closed position, a force is applied to shielded cable403to make electrical contact via conductive material404to ground pad405.

FIG. 4Billustrates a side view of the grounding retention mechanism406, andFIG. 4Cillustrates a top view of the grounding retention mechanism406.

In one embodiment, the grounding retention mechanism comprises a compressible material and an actuator. In one embodiment, the compressible material is coupled to the shielded cable on the opposite side of where an electrically conductive material contacts the cable shield. In other words, the compressible material is aligned with the cable shield and the electrically conductive material. The actuator makes contact with the top of the compressible material to cause the compressible material to become compressed when the actuator is positioned on top of the compressible material. The material being compressed causes a force to be applied to the cable shield, which in turn makes an electrical connection between the shielded material and a ground of the substrate (e.g., a PCB).FIG. 5illustrates one embodiment of an integrated grounding retention mechanism. Referring toFIG. 5, the connector501is attached to PCB502. PCB502includes an exposed ground pad505. A conductive material (e.g., an EMI gasket)504is electrically connected to ground pad505. Shielded cable503is electrically connected to connector501. Compressed material510is on top of shielded cable503and is attached to chassis511.

Chassis, or another type of actuator,511is positioned to make contact with compressed material510, causing compressed material510to become compressed. In one embodiment, this occurs when the chassis is installed. When compressed material510is compressed, a force is applied to shielded cable503which causes an electrical connection between shielded cable503and ground pad505via conductive material504. Thus, the compressed material applies a force to the cable shield and achieves the required grounding for low RFI.

In one embodiment, the grounding retention mechanism includes an extended latch for mechanical retention of the cable. In one embodiment, the latch engages one or more sides of the shield of the cable to secure the cable when an end of the cable is electrically connected with the connector.FIG. 6illustrates an example of an extended latch for mechanical retention.

Referring toFIG. 6, a connector601is coupled to PCB602. An end of cable603is electrically connected to connector601. A conductive material604is between a ground pad on PCB602and cable603. Extended latch611extends on both sides of cable603. In one embodiment, extended latch611includes a hole that secures an extension that protrudes off the sides of cable603. When cable603is connected to connector601, the extensions protruding from cable603extend into the hole of the extended latch611and are secured.

In another embodiment, grounding retention mechanism includes a conductive material that is integrated into a connector with spring areas that electrically connect with a cable when the cable is connected with the connector. In this case, the grounding retention mechanism comprise the one or more spring regions.FIG. 7illustrates one embodiment of an example of a conductive material having spring regions.

Referring toFIG. 7, a PCB702includes a connector701attached thereto. PCB702includes ground pad705(a voltage reference node). Electrically connected to ground pad705is grounding retention mechanism706which includes springs711. In one embodiment, the grounding retention mechanism706is electrically connected to ground705via surface mount technology; however, other connection schemes may be used. When a shielded cable (e.g., FFC/PFC cable) is electrically connected to connector701, springs711(which extend upward) make electrical contact with the conductive shield on cable, thereby causing the cable to be electrically connected to ground705and grounding the cable.

FIG. 8is a flow diagram of a process for using a grounding retention mechanism to ground a cable connected to a connector. Referring toFIG. 8, the process begins by electrically connecting an end of a cable (shielded with a conductive material) with a connector (processing block801). In one embodiment, the connector is coupled to a substrate having a ground and an electrically conductive material is coupled to the ground of the substrate (e.g., an exposed ground pad).

Next, the processing logic employs a grounding retention mechanism to cause the electrically conductive material to electrically connect the material to the substrate ground when the end of the cable is electrically connected to the connector by applying a force to the cable shield (processing block802). In one embodiment, employing the grounding mechanism includes moving at least a portion of the grounding retention mechanism to apply a retention force on the shield of the cable after the cable has been electrically connected to the connector. In one embodiment, the electrically conductive material is compressible and the retention force causes compression of the electrically conductive material between the cable and the substrate ground when the force is applied to the shield.

Unlike conductive tapes where the connection will degrade over time due to deterioration of the boding material, the techniques described herein provide a reliable connection between a cable shield and a substrate (e.g., PCB) ground for superior EMI/RFI reduction.

Furthermore, if replacement of an internal cable is needed, the techniques described herein provide an easy way to remove/uninstall the cable without damaging the connector. This resolves potential customer issues of destructive reworking and saves the cost of replacing damaged connector.

In a first example embodiment, an apparatus comprises a substrate having a first node, a connector coupled to the substrate, a cable shielded with a conductive material and having an end connectable to the connector to electrically connect with the connector, an electrically conductive material coupled to the first node of the substrate, and a retention mechanism (e.g., a grounding retention mechanism) to cause the electrically conductive material to electrically connect the cable to the first node of the substrate by applying a force to the cable shield.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the retention mechanism comprises a retention actuator coupled to the connector to apply a retention force on the shield of the cable when in a first position after the cable has been electrically connected to the connector, where the electrically conductive material is compressible and the force causes compression of the electrically conductive material between the cable and the first node of the substrate when applied on the shield.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the electrically conductive material is integrated into the connector and the retention mechanism comprises one or more spring regions included in the electrically conductive material.

In another example embodiment, the subject matter of the first example embodiment can optionally include a latch to engage with one or more sides of the shield of the cable to secure the cable when an end of the cable is electrically connected to the connector.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the retention mechanism comprises a screw-type actuator with a screw hole.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the grounding retention mechanism comprises a latch-type actuator that latches to the substrate when in a first position.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the latch-type actuator comprises a fork, a hook or an eye-of-needle (EON) as part of a latch coupled to the connector.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the substrate comprises a plated-through hole (PTH) via and the lever latches to the PTH via in the substrate.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the retention mechanism comprises a lever-type retention mechanism.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the retention mechanism comprises a compressible material coupled to the shielded cable on a side of the cable opposite where the electrically conductive material contacts the cable shield and an actuator to cause the compressible material to become compressed when the actuator is positioned on top of the compressible material, where the material is compressed causing a force to be applied to the cable shield.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the first node comprises an exposed ground pad, and the retention mechanism comprises a grounding retention mechanism.

In another example embodiment, the subject matter of the first example embodiment can optionally include that the electrically conductive material comprises an EMI gasket.

In a second example embodiment, an apparatus comprises a substrate having a reference node, a connector coupled to the substrate, an electrically conductive material coupled to the reference node of the substrate, and a retention mechanism to cause the electrically conductive material to electrically connect a cable shielded with a conductive material to the reference node of the substrate when an end of the cable is electrically connected to the connector by applying a force to the cable shield.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the retention mechanism comprises a retention actuator coupled to the connector to apply a retention force on the shield of the cable when in a first position after the cable has been electrically connected to the connector, where the electrically conductive material is compressible and the force causes compression of the electrically conductive material between the cable and the reference node of the substrate when applied on the shield.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the electrically conductive material is integrated into the connector and the retention mechanism comprises one or more spring regions included in the electrically conductive material.

In another example embodiment, the subject matter of the second example embodiment can optionally include a latch to engage with one or more sides of the shield of the cable to secure the cable when an end of the cable is electrically connected to the connector.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the retention mechanism comprises a latch-type actuator that latches to the substrate when in a first position.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the retention mechanism comprises a compressible material coupled to the shielded cable on a side of the cable opposite where the electrically conductive material contacts the cable shield, and an actuator coupled to the top of the compressible material to cause the compressible material to become compressed when the actuator is positioned on top of the compressible material, where the material is compressed causing a force to be applied to the cable shield.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the reference node comprises an exposed ground pad.

In another example embodiment, the subject matter of the second example embodiment can optionally include that the electrically conductive material comprises an EMI gasket.

In a third example embodiment, a method comprises: connecting an end of a cable shielded with a conductive material into a connector to electrically connected the cable to the connector, the connector coupled to a substrate having a first node, and wherein an electrically conductive material is coupled to the first node of the substrate; and employing a retention mechanism to cause the electrically conductive material to electrically contact the cable to the first node of the substrate when the end of the cable electrically connected to the connector by applying a force to conductive material of the cable shield.

In another example embodiment, the subject matter of the third example embodiment can optionally include that employing a retention mechanism comprises moving a retention actuator to apply a retention force on the shield of the cable after the cable has been electrically connected to the connector, the electrically conductive material being compressible, the retention force causing compression of the electrically conductive material between the cable and the first node of the substrate when the force is applied on the shield.

In another example embodiment, the subject matter of the third example embodiment can optionally include that the retention mechanism comprises a screw-type, latch-type or lever-type actuator, and wherein employing a retention mechanism comprises moving the actuator to maintain contact between the cable and the first node of the substrate when the actuator contacts the shield.

In another example embodiment, the subject matter of the third example embodiment can optionally include that the first node comprises an exposed ground pad.

In another example embodiment, the subject matter of the third example embodiment can optionally include that the electrically conductive material comprises an EMI gasket.