Electrical connector with a contact having at least two conductive paths

An electrical connector includes a carrier having opposite first and second sides. A plurality of contacts are held in the carrier. Each contact includes a first conductive element defining a first conductive path and a second conductive element defining a second conductive path separate from the first conductive path. The first and second conductive paths are configured to electrically connect an electrical component on one side of the carrier to an electrical component on the opposite side of the carrier.

BACKGROUND OF THE INVENTION

The invention relates generally to surface mounted connectors, and more specifically, to a connector that reduces the crosstalk added to signals passing through the connector.

The trend toward smaller, lighter, and higher performance electrical components and higher density electrical circuits led to the development of surface mount technology in the design of electrical systems. As is well understood in the art, surface mount packaging allows an electronic package to be attached to pads on the surface of a circuit board, either directly or through a surface mount connector, rather than by means of contacts or pins positioned in plated holes in the circuit board. Surface mount technology allows for an increased component density on a circuit board, thereby saving space on the circuit board.

In a connector, with the close proximity of contacts to one another there is a potential for crosstalk and the loss of signal integrity. As signal speeds have increased, crosstalk has become a serious issue. Some circuit boards that carry high speed signals incorporate transmission lines in the board design wherein the width of signal traces and the distance between signal and ground traces are controlled to reduce crosstalk. High speed signals propagate down a transmission line considerably better than down a stand alone trace. However, when the signal encounters a connector, the transmission line is disturbed. Typically, the benefits derived from the transmission line are not maintained as the signal moves through the connector.

A need exists for a connector that preserves signal integrity through the connector by reducing crosstalk in the connector.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, an electrical connector is provided. The connector includes a carrier having opposite first and second sides. A plurality of contacts are held in the carrier. Each contact includes a first conductive element defining a first conductive path and a second conductive element defining a second conductive path separate from the first conductive path. The first and second conductive paths are configured to electrically connect an electrical component on one side of the carrier to an electrical component on the opposite side of the carrier.

Optionally, a plurality of polymer columns are held by the carrier with each polymer column including a first end extending from the first side of the carrier and a second end extending from the second side of the carrier. Each contact includes opposite contact ends, and each contact end includes first and second contact tips. The first conductive element extends between the first contact tips and the second conductive element extends between the second contact tips. Each contact includes an insulative layer having opposite inner and outer sides. One of the conductive elements is formed on the outer side and the other of the conductive elements is formed on the inner side.

In another embodiment, an electrical connector includes a carrier having opposite first and second sides. A plurality of contacts are held in the carrier. Each contact includes a first conductive element configured to be signal carrying and a second conductive element configured to be a current carrying ground. The first and second conductive elements are positioned relative to one another such that the signal and ground on each contact are electromagnetically coupled to one another such that crosstalk between adjacent contacts is minimized.

In yet another embodiment, a contact for an electrical connector is provided. The contact includes a flexible layer of insulative material having opposite inner and outer sides. The flexible layer includes a body that extends between first and second contact ends. A first conductive element on the outer side of the flexible layer extends between a first contact tip at the first contact end to a first contact tip at the second contact end. A second conductive element on the inner side of the flexible layer extends between a second contact tip at the first contact end to a second contact tip at the second contact end. The first and second conductive elements define separate electrical paths between the first and second contact ends.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates an electronic assembly100including a connector110formed in accordance with an exemplary embodiment of the present invention. The connector110is mounted on a circuit board114and an electronic package120is loaded onto the connector110. When loaded onto the connector110, the electronic package120is electrically connected to the circuit board114. In one embodiment, the connector110may be a socket connector. The electronic package120may be a chip or module such as, but not limited to, a central processing unit (CPU), microprocessor, or an application specific integrated circuit (ASIC), or the like.

The connector110includes a dielectric housing116that is configured to be mounted on the circuit board114. The housing116holds an interconnect member124that includes a plurality of electrical contact assemblies126. The electronic package120has a mating surface130that engages the interconnect member124. The interconnect member124is interposed between contact pads (not shown) on the mating surface130of the electronic package120and corresponding contact pads (not shown) on the circuit board114to provide electrical paths to electrically connect the electronic package120to the circuit board114as will be described. It is to be understood, however, that such description is for illustrative purposes only and that no limitation is intended thereby. That is, the interconnect member124, in other embodiments, may be used to interconnect two electrical components such as two circuit boards or two electronic packages. Further, although the interconnect member124is described with reference to a purely compressive interconnect member, it is to be understood that the interconnect member124may also be used in applications where other connection methods, such as solder connections on one or both sides of the interconnect member124, are employed.

FIG. 2illustrates an enlarged perspective view of a portion of the interconnect member124which is formed in accordance with an exemplary embodiment of the present invention. The interconnect member124includes a carrier134upon which the contact assemblies126are arranged. In one embodiment, the contact assemblies126are arranged on opposite sides of a diagonal (not shown) that divides the contact assemblies126into two contact groups. The contact assemblies126on opposite sides of the diagonal face each other to neutralize frictional forces on the electronic package120(FIG. 1) that result from the compression of the contact assemblies126that would otherwise tend to push the electronic package120toward one corner of the connector110(FIG. 1). In some embodiments, the carrier134is positioned between compression stops136. In such embodiments, the compression stops136are provided to limit the compression of the contact assemblies126when the electronic package120is loaded into the connector110.

The carrier134has a first side140and an opposite second side142. Each contact assembly126includes a polymer column146and a contact150, both of which are held in the carrier134. The polymer columns146are positioned to align with contact pads (not shown) on the electronic package120(FIG. 1) and the circuit board114(FIG. 1). As illustrated, each of the contacts150spans two polymer columns146and is configured to electrically connect two contact pads on the electronic package120with two contact pads on the circuit board114as will be described.

With continued reference toFIG. 2,FIG. 3is a perspective view of a polymer column146. Each polymer column146includes a first end154that extends from the first side140of the carrier134and a second end156that extends from the second side142of the carrier134. The polymer columns146provide the desired mechanical properties including normal force and working range for the contact assemblies126. The polymer column146includes a primary column158and may also include one or more secondary support columns160. The secondary support columns160, when present, are provided to stabilize and control the direction of compression of the primary column158. The primary column158includes a first engagement end162that extends from the first side140of the carrier134and a second engagement end164that extends from the second side142of the carrier134. The polymer columns146may be formed from either a pure polymer or a mixed polymer selected to provide desired mechanical properties. In an exemplary embodiment, the polymer columns146may be molded directly onto the carrier134.

With continued reference toFIGS. 2 and 3,FIG. 4illustrates a perspective view of a contact150.FIG. 5illustrates an enlarged plan view of the outer side180of the contact150shown in a flat state.FIG. 6illustrates an enlarged plan view of the inner side188of the contact150shown in a flat state. Each contact150includes an elongated contact body170that extends between first and second opposite contact ends174and176respectively. The contact150includes an outer side180that has an outer or first conductive element182that defines a first conductive path between a first pair of contact tips184and an opposite inner side188that has an inner or second conductive element190that defines a second conductive path between a second pair of contact tips192. The second conductive element190and its associated conductive path are separate from the first conductive element182and its associated conductive path. Vias194are provided at the second contact tips192through which electrical connectivity is established from the second conductive element190to the outer side180of the contact150. Pad engagement elements196formed around the vias194on the outer side180of the contact150are provided for engagement with contact pads on the circuit board114(FIG. 1) and the electronic package120(FIG. 1).

The contact body170extends through the carrier134and includes a centrally located bend200that facilitates flexing of the contact body170when interposed and compressed between the electronic package120(FIG. 1) and the circuit board114(FIG. 1). The contact150includes bends204at each contact end174and176that orient the contact tips184and192for accurate registration with the contact pads (not shown inFIG. 4) on the circuit board114and the electronic package120. The contact150is positioned and dimensioned such that the first pair of contact tips184are proximate the engagement ends162and164of one polymer column146while the second pair of contact tips192are proximate the engagement ends162and164of a different polymer column146. Thusly arranged, the first conductive element182, between the first contact tips184, electrically connects a first pair of contact pads (not shown inFIG. 4), one on a first electrical component, i.e. the electronic package120and one on a second electrical component, i.e. the circuit board114, and the second conductive element190, between the second contact tips192, electrically connects a second separate pair of contact pads, again, one on the electronic package120and one on the circuit board114.

Turning now toFIGS. 5 and 6, the contact150includes a layer of a flexible insulative material300such as a polyimide material that includes the outer side180with the first conductive element182and the inner side188with the second conductive element190. The contact body170extends along a longitudinal axis302between the contact ends174and176. The contact body170includes a centrally located mounting portion that includes wings310with notches312. The wings310are configured to frictionally engage the carrier134while allowing some degree of movement between the contact body170and the carrier134. In an exemplary embodiment, the flexible layer300is fabricated from a flexible polyimide material. One such polyimide material is commonly known as Kaptons® which is available from E.I. du Pont de Nemours and Company. The conductive elements182and190may be formed from copper that may be etched or otherwise adhered to the flexible layer300. After application of the conductive elements182and190to the flexible layer300, the contacts150are formed to their final shape as shown inFIG. 4. Although the vias194are shown as extending through the flexible layer300, the contact tips192, and the pad engagement elements196, it is to be understood that it is only necessary that the vias194extend through the flexible layer300.

FIG. 7illustrates a top plan view of the carrier134. The carrier134includes a plurality of apertures320and slots322. The polymer columns146(FIG. 3) are molded onto the carrier134at the apertures320. In the illustrated embodiment, the apertures320are arranged in groups324that include three of the apertures320, with each group324defining a location of one polymer column146. It is to be understood however, that other arrangements of apertures320are possible including more or fewer apertures320. For instance, the apertures320in each group324may be replaced by a single aperture sized to retain one polymer column146. Further, the apertures320may take geometric shape other than the circular shapes shown.

With reference toFIG. 6, each slot322is configured to hold a contact150. Each slot322has a transverse width330that is sized to receive a transverse width332of the contact body170at the notches312while the wings310have a transverse width334that is greater than the width330of the slot322. When installed in the carrier134, the notches312of the contact body170fit within the slot322while the wings310engage the first and second sides140and142respectively of the carrier134so that the conductive elements182and190are isolated from the carrier134. In an exemplary embodiment, the carrier134may be fabricated from stainless steel. In other embodiments, the carrier134may be made from an insulative material such as FR4, which is commonly used for circuit boards, or a polyimide material.

With reference toFIG. 4,FIG. 8illustrates an enlarged side view of the contact assembly126in an uncompressed state.FIG. 9illustrates an enlarged side view of the contact assembly126in a compressed state. When the contacts150are loaded into the carrier134, the slots322in the carrier134provide clearance space for flexing of the contacts150. The wings310frictionally engage the first and second sides140and142of the carrier134sufficiently to prevent the contact ends174and176from becoming disengaged from the polymer columns146while permitting the contact body170to move in the direction of the arrow A within the slot322to flex in response to a compressive load on the contact assembly126. Coincident with the flexing of the contact150, the polymer column146, and particularly the primary column158, is compressed in response to the compressive load on the contact assembly126.

The flexible layer300of the contact150has a thickness340which represents a distance between the first conductive element182and the second conductive element190. At such distances, when one of the conductive elements182,190is signal carrying and the other is a ground, and particularly a current carrying ground, the signal and ground are very tightly electromagnetically coupled to one another rather than the signal being coupled to a signal carried in an adjacent contact150such that crosstalk introduced in the connector110is minimized even at high contact densities. In this manner, transmission line properties may be maintained through the connector110thereby preserving signal integrity through the connector110. It is to be understood, that the widths of the first and second conductive elements182and190respectively, as well as the thickness340of the flexible layer300may be varied to optimize the noise reducing characteristics, particularly crosstalk, in the connector110.

FIG. 10illustrates an enlarged plan view of an alternative contact350showing an outer side352in a flat state.FIG. 11is an enlarged plan view of an opposite inner side354of the contact350. The contact350is similar to the contact150previously described with the exception that the contact350includes an additional conductive element as described below.

The contact350includes a layer of a flexible insulative material360that includes the outer side352and the opposite inner side354. The contact350includes an elongated contact body370that extends between first and second opposite contact ends374and376respectively. The contact350includes first and second conductive elements380and382respectively, formed on the outer side352of the flexible layer360and a third conductive element384formed on the inner side354of the flexible layer360. The first and second conductive elements380and382define conductive paths between respective first and second pairs of contact tips390and392. The third conductive element384defines a third conductive path between a third pair of contact tips394. Vias396are provided at the third contact tips394through which electrical connectivity is established from the third conductive element384to the outer side352of the flexible layer360. Wings400with notches402are provided on the contact body370for retaining the contact350in a carrier such as the carrier134(FIG. 7) as previously described. After application of the conductive elements380,382, and384to the flexible layer360, the contacts350are formed to their final shape which is similar to that of the contact150as shown inFIG. 4.

With reference toFIG. 2, when loaded into a carrier, the contacts350are positioned such that the pairs of contact tips390,392, and394are proximate the engagement ends162,164(FIG. 3) of three different polymer columns146to thereby provide three separate electrical connections between two electrical components, such as the electronic package120on one side140of the carrier134and the circuit board114on the opposite side142of the carrier134.

In an exemplary embodiment, the conductive elements380and382may be signal carrying elements carrying differential signals and the conductive element384may be a ground element that may also be signal carrying. As previously described, the conductive elements380and382on the outer side352of the flexible layer360are separated from the conductive element384on the inner side354of the flexible layer360only by the thickness of the flexible layer360. Due to the close proximity of the signal carrying conductive elements380and382with the ground conductive element384, a tight electromagnetic coupling between the differential signals and ground exists such that crosstalk between the signals carried on adjacent contacts350is minimized.

The embodiments thus described provide a connector110that preserves signal integrity through the connector110by reducing crosstalk introduced in the connector110. The connector110includes contacts150having at least two independent conductive elements182,190on opposite sides180,188of a flexible layer300whereby the contacts150provide at least two separate electrical connections between two electrical components. The conductive elements182,190are separated by a thickness340of the flexible layer300such that when one conductive element is signal carrying and the other is a ground, a tight coupling between the signal and ground is achieved which minimizes the crosstalk between the signals carried on adjacent contacts150in the connector110.