WO2021209836A1

WO2021209836A1 - Electrical connector

Info

Publication number: WO2021209836A1
Application number: PCT/IB2021/052215
Authority: WO
Inventors: Yunlong Qiao; Saujit Bandhu; Kok Hoe LEE; Chin Hua Lim
Original assignee: 3M Innovative Properties Company
Priority date: 2020-04-15
Filing date: 2021-03-17
Publication date: 2021-10-21

Abstract

An elongated electrical connector includes an elongated base, a bottom tongue, and a top tongue extending forwardly from a front surface of the base. A substantially cuboid cavity is defined between opposing top and bottom surfaces of the bottom tongue. Electrical contacts are disposed on the top and bottom surfaces of the bottom tongue and on the top surface of the top tongue. A metal ground plate removably insertable in the cavity extends along its length across several of the top and bottom contacts including at least one top ground contact and at least one bottom ground contact respectively. The metal ground plate makes physical contact with at least one ground contact of one of the at least one top and at least one bottom ground contact, but not with any ground contact of the other one of the at least one top and at least one bottom ground contact.

Description

ELECTRICAL CONNECTOR

Technical field

The present disclosure generally relates to electrical connectors for mounting on printed circuit boards.

Background

Electrical cables facilitate transmission of electrical signals between devices. Cable connectors can be designed to provide interconnection between devices having a particular type of communications protocol, such as serially attached small computer interface system (SAS) and peripheral component interconnect express (PCIe). In view of the need for high speed interconnection between computers and peripheral devices, a continuing need exists for electrical cables that are capable of transmitting high speed signals without signal transmission issues, are mechanically robust, cost-effective, and can be used in a variety of applications.

Summary

Some aspects of the disclosure relate to an elongated electrical connector for mounting on a printed circuit board and mating with a mating connector along a mating direction. The connector includes an elongated base extending along a longitudinal direction perpendicular to the mating direction. A bottom tongue extends forwardly along the mating direction from a front surface of the base and defines a substantially cuboid cavity therein between opposing major top and bottom surfaces of the bottom tongue. The cuboid cavity has an open entrance at a back surface, opposite the front surface, of the elongated base. A top tongue extends forwardly along the mating direction from the front surface of the base and is spaced apart from the bottom tongue along a thickness direction perpendicular to the mating and longitudinal directions. The top tongue includes opposing major top and bottom surfaces. The major bottom surface of the top tongue faces the major top surface of the bottom tongue. A plurality of spaced apart top electrical contacts are disposed on the major top surface of the bottom tongue. A plurality of spaced apart bottom electrical contacts are disposed on the major bottom surface of the bottom tongue. A plurality of spaced apart auxiliary electrical contacts are disposed on the major top surface of the top tongue. A metal ground plate is removably inserted in the cuboid cavity from the open entrance thereof. The metal plate extends along its length along the longitudinal direction across several of the top contacts including at least one top ground contact and several of the bottom contacts including at least one bottom ground contact. The metal ground plate makes physical contact with at least one ground contact of one of the at least one top ground contact and the at least one bottom ground contact, but not with any ground contact of the other one of the at least one top ground contact and the at least one bottom ground contact. Some aspects of the disclosure relate to an electrical connector configured to mate with a mating connector along a mating direction. The connector includes a substrate portion defining a substantially cuboid cavity therein between, and substantially parallel to, opposing major top and bottom surfaces of the substrate. The cuboid cavity has an open end opposite a closed end. A plurality of alternating top ground contact and at least one top signal contact is disposed on the major top surface of the substrate. A plurality of alternating bottom ground contact and at least one bottom signal contact is disposed on the major bottom surface of the substrate. A metal ground plate is removably inserted in the cuboid cavity from the open end thereof. The metal ground plate includes a plurality of elongate through slots extending along the mating direction and is arranged along an orthogonal direction. Each slot continuously extends between opposing first and second closed ends of the slot. The metal plate extends along the orthogonal direction across a first group of the top contacts including at least one top signal contact and a second group of the bottom signal contacts including at least one bottom signal contact. In a plan top view, the metal ground plate covers less than about 60% of portions of the at least one top signal contact contacting the top surface of the substrate, and covers at least about 80% of portions of the at least one bottom signal contact contacting the bottom surface of the substrate. Removing the metal ground plate changes an impedance of each of the bottom signal contacts by no more than 10%.

These and other aspects of the present application will be apparent from the detailed description below. In no event, however, should the above summaries be construed as limitations on the claimed subject matter, which subject matter is defined solely by the attached claims.

Brief Description of Drawings

The various aspects of the disclosure will be discussed in greater detail with reference to the accompanying figures where,

Figs. 1-4 schematically show different views of an assembled connector in accordance with some embodiments;

Fig. 5 schematically shows a printed circuit board on which electrical connectors of some embodiments are mounted;

Fig. 6 schematically shows a mating connector for mating with the electrical connector according to some aspects of the disclosure;

Figs. 7-9 schematically show different views of the connector in accordance with some aspects;

Figs. 10-14 schematically show the assembly of a ground plate in the electrical connectors in accordance with some embodiments; Figs. 15-17 schematically show detailed views of the ground plate arrangement within the electrical connectors in accordance with some embodiments;

Fig. 18 schematically shows the ground plate design according to some embodiments;

Fig. 19 schematically shows the ground plate assembled with PCIe high speed signal pins according to some aspects;

Fig. 20 schematically shows the ground plate assembled with primary SAS/SATA high speed signal pins according to some aspects;

Figs. 21-24 schematically show additional views of the electrical connector and ground plate according to some embodiments;

Figs. 25-28 schematically show the top, bottom, and auxiliary electrical contacts of the connector in accordance with some embodiments; and

Fig. 29 graphically represents the contact impedance profile with and without the ground plate according to some embodiments.

The figures are not necessarily to scale. Fike numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

Detailed Description of Illustrative embodiments

In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration several specific embodiments. 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.

Electrical connectors are used in many applications such as to interconnect hard disk drives or solid state drives (SSD) to the motherboard of a computer. Serial advanced technology attachment (SATA) connectors and serial attachment small computer systems interface (SAS) connectors are common types of connectors used in hard disk drive interfaces. According to the Small Form Factor (SFF) specifications, SATA connectors have 22 contacts of which 15 contacts are used for power transmission and 7 contacts (primary signal contacts) are used for data signal transmission. In addition to the 22 contacts available in SATA connectors, SAS connectors have an additional 7 contacts (secondary signal contacts) for data signal transmission. Peripheral component internet express (PCIe) SAS connector is an interface based on the SATA/S AS form factor but running with PCIe signal. The PCIe SAS pin configuration is such that the primary SAS high speed signal contacts and the PCIe high speed signal contacts are close to each other. During operation, cross talk may occur between the primary SAS high speed signal contacts and the PCIe high speed signal contacts. The embodiments disclosed herein addresses these and other challenges. Some embodiments described herein are directed to an electrical connector for mounting on a PCB having a ground plate to shield the signal and to reduce or eliminate the cross talk between the PCIe and the primary high-speed SAS signals, without affecting the impedance. Some embodiments described herein are directed to connectors that use a printed circuit board itself to serve as the tongue interface of the plug connector. Embodiments are not limited to PCIe SAS connectors, but are applicable for any connector where balance between the impedance and crosstalk performance is desired. For instance, the connectors disclosed herein are useful for SATA connectors, SAS connectors, and PCIe SAS right angle plug connectors, among other connector types.

Some embodiments as illustrated in FIGS. 1-6 relate to an electrical connector (200) configured to mate with a mating connector (400) along a mating direction (y-axis). The electrical connector may be an elongated electrical connector (200) for mounting on a printed circuit board (PCB) (300). The elongated electrical connector (200) includes an elongated base (10) that extends along a longitudinal direction (x- axis) perpendicular to the mating direction (y-axis). First (70) and second (71) end walls extend forwardly along the mating direction (y-axis) from opposite longitudinal ends (13, 14) of the base (10). The connector (200) includes a substrate portion (20) having opposing major top (22) and bottom (23) surfaces. The substrate portion in some aspects is a bottom tongue (20) that extends forwardly along the mating direction (y-axis) from a front surface (11) of the base (10). The description henceforth will refer to the substrate as a bottom tongue, although these terms can be interchangeably used. The bottom tongue (20) may be disposed between and spaced apart from the first and second end walls (70, 71) in the longitudinal direction (x-axis).

In some aspects, a plurality of spaced apart top electrical contacts (50) are disposed on the major top surface (22) of the bottom tongue (20). The construction of each of the top electrical contact according to some embodiments is shown in Fig. 25. Each of the top contact (50) includes a mating portion (55a) for making contact with a corresponding contact (450) of the mating connector shown in Fig. 5. A mounting portion (55b) of each top contact (50) makes contact with a corresponding conductive pad (310) of the printed circuit board (300) shown in Fig. 6. In some aspects, the mating (55a) and mounting (55b) portions are substantially parallel to each other and to the mating direction (y-axis). The mating and mounting portion of each top contact (50) are joined with each other by a joining portion (55c) extending between the mating (55a) and mounting (55b) portions.

In some aspects, as best shown in Fig. 26, the mating portion (55a) of each of the top contact (50) is joined with the joining portion (55c) at a bent portion (58). At the bent portion, the mating portion (55a) of the top contact (50) defines a pair of substantially through cuts (58a, 58b) defining a middle portion (59a). The middle portion (59a) is disposed between, and isolated from, two side portions (59b, 59c). In some cases, the middle portion (59a), but not any of the side portions, may be bent so that the bent portion includes the middle portion (59a) but neither of the side portions (59b, 59c).

As depicted in Fig. 2, a plurality of spaced apart bottom electrical contacts (51) are disposed on the major bottom surface (23) of the bottom tongue (20). The construction of each of the bottom electrical contact according to some embodiments is shown in Fig. 27. Each of the bottom contact (51) includes a mating portion (56a) for making contact with a corresponding contact (451) of the mating connector shown in Fig. 5. A mounting portion (56b) of each bottom contact (51) makes contact with a corresponding conductive pad (310) of the printed circuit board (300) shown in Fig. 6. In some aspects, the mating (56a) and mounting (56b) portions are substantially parallel to each other and to the mating direction (y-axis). The mating and mounting portion of each bottom contact (51) are joined with each other by a joining portion (56c) extending between the mating (56a) and mounting (56b) portions. In some aspects, as best shown in Fig. 26, the mating portion (56a) of each of the bottom contact (51) is joined with the joining portion (56c) at a bent portion (58). At the bent portion, the mating portion (56a) of the bottom contact (51) defines a pair of substantially through cuts (58a, 58b) defining a middle portion (59a). The middle portion (59a) is disposed between, and isolated from, two side portions (59b, 59c). In some cases, the middle portion (59a), but not any of the side portions, may be bent so that the bent portion includes the middle portion (59a) but neither of the side portions (59b, 59c).

In some aspects, as best shown in Fig. 19, the connector (200) may include a plurality of alternating top ground contact (50b, 50c, 50d) and at least one top signal contact (53a, 53b) disposed on the major top surface (22) of the bottom tongue (20). A plurality of alternating bottom ground contact (51b, 51c, 5 Id, 51e) and at least one bottom signal contact (54a, 54b, 54c, 54d) may be disposed on the major bottom surface (23) of the bottom tongue (20) as shown in Fig. 20. In some other aspects, several of the top electrical contacts (50a) includes at least one top ground contact (50b-50d) and at least one top signal contact (53a, 53b). In other aspects, several of the bottom electrical contacts (51a) include at least one bottom ground contact (5 la-5 le) and at least one bottom signal contact (54a-54d).

In some embodiments, a top tongue (40) extends forwardly along the mating direction (y-axis) from the front surface (11) of the base (10). In some aspects, the top tongue (40) may be removably attached to the base (10). The top tongue (40) may be disposed between and spaced apart from the first and second end walls (70, 71) in the longitudinal direction (x-axis). The top tongue is also spaced apart from the bottom tongue (20) along a thickness direction (z-axis) perpendicular to the mating and longitudinal directions. The top tongue includes opposing major top (41) and bottom (42) surfaces as best seen in Fig. 4. The major bottom surface (42) of the top tongue (40) faces the major top surface (22) of the bottom tongue (20). In some aspects, the base (10), the top tongue (40) and the bottom tongue (20), and the first and second end walls (70, 71) may be formed unitarily. As shown in Fig. 4, a plurality of spaced apart auxiliary electrical contacts (52) may be disposed on the major top surface (41) of the top tongue (40). In some aspects, no electrical contact is disposed on the bottom surface (42) of the top tongue (40). The construction of each of the auxiliary electrical contact (52) according to some embodiments is shown in Fig. 28. Each of the auxiliary contact (52) includes a mating portion (57a) for making contact with a corresponding contact (452) of the mating connector (400) shown in Fig. 5. A mounting portion (57b) of each auxiliary contact (52) makes contact with a corresponding conductive pad (310) of the printed circuit board (300) shown in Fig. 6. In some aspects, the mating (57a) and mounting (57b) portions are substantially parallel to each other and to the mating direction (y-axis). The mating and mounting portion of each auxiliary contact (52) are joined with each other by a joining portion (57c) extending between the mating (57a) and mounting (57b) portions.

In some aspects, the top surface (22) of the bottom tongue (20) includes a surface portion (25). The surface portion (25) corresponds to and faces the bottom surface (42) of the top tongue (40). In some embodiments, no electrical contact is disposed on the surface portion (25).

With reference to Figs. 7-9 the dimensional relationship between the bottom and top tongues (20, 40) of the connector (200) will be explained herein. The bottom (20) and top (40) tongues have respective first (LI) and second (L2) lengths along the longitudinal direction (x-axis). In some aspects, the second length (L2) may be smaller than the first length (LI). The bottom tongue (20) has a uniform thickness (tl) along its length (LI) along the longitudinal direction (x-axis) and the top tongue (40) has a uniform thickness (t2) along its length (L2) along the longitudinal direction (x-axis). In some aspects, the top and bottom tongues have a same average thickness, such that, in some embodiments, t2 = tl . As shown in Fig. 9, the top (40) and bottom (20) tongues are separated along the thickness direction. In some instances, a separation (SI) between the top and bottom tongues along the thickness direction may be between about 0.1 mm to about 5 mm, or between 0.5 mm to 4.5 mm, or between 1 mm to 3.5 mm. In other aspects, as best seen in Fig. 8, the top (40) and bottom (20) tongues have substantially equal widths (W) along the mating direction measured from a front edge (40a, 20a) of the tongues (40, 20) to the front surface (11) of the base (10).

In an embodiment, the bottom tongue defines a substantially cuboid cavity (21) between the top (22) and bottom (23) surfaces of the bottom tongue (20). The different views of the cuboid cavity (21) formed in the bottom tongue (20) is best seen in Figs. 11-14. The cavity (21) may be formed to be substantially parallel to the top and bottom surfaces (22, 23) of the bottom tongue. As shown in Figs. 12 and 13, the cuboid cavity (21) has an open end (24) opposite a closed end (26). The open end (24) may be an open entrance (24) at a back surface (12) opposite the front surface (11) of the elongated base (10) and extends along a direction (x-axis) orthogonal to the mating direction (y-axis). In some embodiments, a metal ground plate (60) may be removably inserted in the cuboid cavity (21) from the open end/open entrance (24) thereof as illustrated in Figs. 10-16. The metal plate extends lengthwise in the longitudinal direction (x-axis) across a plurality of top and bottom contacts (50, 51) disposed on the top and bottom surfaces (22, 23) of the bottom tongue (20), as best seen in Fig. 15 and 16. For instance, in a PCIe/SAS electrical connector, the metal ground plate (60) may extend lengthwise across the 7 primary SAS high speed signal contacts and the PCIe high speed signal contacts.

In some aspects, referring specifically to Figs. 19 and 20, the metal plate (60) extends lengthwise along the longitudinal direction (x-axis) across several of the top contacts (50a) including at least one top ground contact (50b-50d) and several of the bottom contacts (51a) including at least one bottom ground contact (51b-51e). In some aspects, the metal ground plate extends lengthwise along the longitudinal direction (x-axis) and makes physical contact with at least one ground contact (50b, 50d) of one of the at least one top ground contact and the at least one bottom ground contact. The metal ground plate (60) does not make contact with any ground contact of the other one of the at least one top ground contact and the at least one bottom ground contact. For instance, the metal ground plate may make physical contact with at least one ground contact (50b, 50d) of the at least one top ground contact, but not with any ground contact of the at least one bottom ground contact (5 lb-5 le).

In other aspects, the metal plate (60) may extend along the orthogonal direction (x-axis) across a first group of the top contacts (50a) including at least one top signal contact (53a, 53b) and a second group of the bottom signal contacts (51a) including at least one bottom signal contact (54a-54d). In some cases, the first group of the top contacts (50a) includes at least one top ground contact (50b-50d) and the second group of the bottom signal contacts (5 la) includes at least one bottom ground contact (5 lb-5 le). The metal ground plate (60) makes physical contact with at least one ground contact (50b, 50d) of one of the at least one top ground contact and the at least one bottom ground contact, but not with any ground contact of the other one of the at least one top ground contact and the at least one bottom ground contact. For instance, the metal ground plate (60) may make physical contact with at least one ground contact (50b, 50d) of the at least one top ground contact, but not with any ground contact of the at least one bottom ground contact (51b-51e) as best shown in Figs. 21-22.

As shown in Fig. 18, the metal ground plate has a length L3 along the longitudinal direction (x- axis) and a width W3 along the mating direction (y-axis). In some instances, W 3 < L3. The metal ground plate, in some aspects, may include at least one metal spring member (63a, 63b) for making physical contact with the at least one (50b, 50d) of the at least one top ground contact, but not with any of the at least one bottom ground contact (51b-51e). In some instances, the metal ground plate (60) may include a pair of metal spring members (63a, 63b) spaced apart along the longitudinal direction. Each of the pair of metal spring members (63a, 63b) makes physical contact with a corresponding top (50b, 50d) ground contact, but not the bottom contact (5 lb-5 le). As shown in Figs. 23 and 24, in some aspects, the metal ground plate (60) may include cut off features. For instance, a plurality of elongate through slots (60a-60g) are formed on the metal ground plate

(60) extending along the mating direction (y-axis) and arranged along the longitudinal direction (x-axis). The plurality of elongate through slots may be spaced apart from each other in the longitudinal direction (x-axis), orthogonal to the mating direction (y-axis). Each slot (60a-60g) extends between opposing first

(61) and second (62) closed ends of the slot. In some instances, each slot may be continuous along the mating direction (y-axis). Each slot has a length (L4) along the mating direction (y-axis) and a width (W4) along the longitudinal direction (x-axis). In some cases, at least one first slot (60a) in the plurality of slots (60a-60g) has a constant width along the mating direction (y-axis) and at least one second slot (60b-60g) has a varying width along the mating direction (y-axis). In some aspects, at least one first slot (60a) in the plurality of slots has an average width greater than an average width of at least one other slot (60b-60g) in the plurality of slots.

In some aspects, several of the top contacts (50a) includes at least one top ground contact (50b- 50d) and at least one top signal contact (53a, 53b). The metal ground plate (60) may cover less than about 60% of portions of the at least one top signal contact (53a, 53b) contacting the top surface (22) of the bottom tongue (20) as seen in a plan top view. In some aspects, the metal ground plate may cover less than about 55%, or less than about 50%, or less than about 40% of portions of the at least one top signal contact (53a, 53b) contacting the top surface (22) of the bottom tongue (20) as seen in a plan top view. In some aspects, several of the bottom contacts (5 la) includes at least one bottom ground contact (5 la-5 le) and at least one bottom signal contact (54a-54d). The metal ground plate (60) may cover at least about 80% of portions of the at least one bottom signal contact (51a-51e) contacting the bottom surface (23) of the bottom tongue (20) as seen in a plan top view. In some aspects, the metal ground plate (60) may cover at least about 85- 90% of portions of the at least one bottom signal contact (51a-51e) contacting the bottom surface (23) of the bottom tongue (20) as seen in a plan top view.

In some cases, removing the metal ground plate (60) may change an impedance of each of the top signal contacts (53a, 53b) by no more than 10%. In some cases, removing the metal ground plate (60) may change an impedance of each of the bottom signal contacts (54a-54d) by no more than 10%.

The metal ground plate (60) extending lengthwise along the longitudinal direction (x-axis) across several of the top contacts (50a) and several of the bottom contacts (51a) reduces or eliminates the cross talk between the signal contacts without affecting the impedance of the connector. Fig. 29 shows the impedance profile of the connector with and without cut off features provided in the metal ground plate (60). In some embodiments, the cut off feature provided in the metal ground plate (60) in the form of plurality of elongate through slots (60a-60g) improves the impedance of the connector. 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.

Claims

1. An elongated electrical connector for mounting on a printed circuit board and mating with a mating connector along a mating direction, the connector comprising: an elongated base extending along a longitudinal direction perpendicular to the mating direction; a bottom tongue extending forwardly along the mating direction from a front surface of the base and defining a substantially cuboid cavity therein between opposing major top and bottom surfaces of the bottom tongue, the cuboid cavity having an open entrance at a back surface, opposite the front surface, of the elongated base; a top tongue extending forwardly along the mating direction from the front surface of the base and spaced apart from the bottom tongue along a thickness direction perpendicular to the mating and longitudinal directions, the top tongue comprising opposing major top and bottom surfaces, the major bottom surface of the top tongue facing the major top surface of the bottom tongue; a plurality of spaced apart top electrical contacts disposed on the major top surface of the bottom tongue; a plurality of spaced apart bottom electrical contacts disposed on the major bottom surface of the bottom tongue; a plurality of spaced apart auxiliary electrical contacts disposed on the major top surface of the top tongue; and a metal ground plate removably inserted in the cuboid cavity from the open entrance thereof, the metal plate extending along its length along the longitudinal direction across several of the top contacts comprising at least one top ground contact and several of the bottom contacts comprising at least one bottom ground contact, the metal ground plate making physical contact with at least one ground contact of one of the at least one top ground contact and the at least one bottom ground contact, but not with any ground contact of the other one of the at least one top ground contact and the at least one bottom ground contact.

2. The elongated electrical connector of claim 1 further comprising first and second end walls extending forwardly along the mating direction from opposite longitudinal ends of the base, wherein the bottom tongue is disposed between and spaced apart from the first and second end walls, wherein the top tongue is disposed between and spaced apart from the first and second end walls, and wherein the base, the top and the bottom tongues, and the first and second end walls form a unitary construction.

3. The elongated electrical connector of claim 1 , wherein the metal ground plate comprises a plurality of spaced apart elongate through slots extending along the mating direction and arranged along the longitudinal direction, each slot extending between opposing first and second closed ends of the slot, wherein each slot is continuous along the mating direction, wherein each slot has a length along the mating direction and a width along the longitudinal direction, wherein at least one first slot in the plurality of slots has a constant width along the mating direction, and at least one second slot has a varying width along the mating direction.

4. The elongated electrical connector of claim 1, wherein the metal ground plate makes physical contact with at least one ground contact of the at least one top ground contact, but not with any ground contact of the at least one bottom ground contact, wherein the metal ground plate comprises at least one metal spring member making physical contact with the at least one of the at least one top ground contact, but not with any of the at least one bottom ground contact.

5. The elongated electrical connector of claim 1 , wherein each of the top, bottom and auxiliary contact comprises: a mating portion for making contact with a corresponding contact of the mating connector; a mounting portion for making contact with a corresponding conductive pad of the printed circuit board; and a joining portion extending between and joining the mating and mounting portions, wherein the mating and mounting portions are substantially parallel to each other and to the mating direction, and wherein for at least one of the top and bottom electrical contacts, the mating portion is joined with the joining portion at a bent portion, wherein at the bent portion, the mating portion of the contact defines a pair of substantially through cuts defining a middle portion disposed between, and isolated from, two side portions, and wherein the middle portion, but not any of the side portions, is bent so that the bent portion comprises the middle portion but neither of the side portions.

6. An electrical connector configured to mate with a mating connector along a mating direction, the connector comprising: a substrate portion defining a substantially cuboid cavity therein between, and substantially parallel to, opposing major top and bottom surfaces of the substrate, the cuboid cavity having an open end opposite a closed end; a plurality of alternating top ground contact and at least one top signal contact disposed on the major top surface of the substrate; a plurality of alternating bottom ground contact and at least one bottom signal contact disposed on the major bottom surface of the substrate; and a metal ground plate removably inserted in the cuboid cavity from the open end thereof, the metal ground plate comprising a plurality of elongate through slots extending along the mating direction and arranged along an orthogonal direction, each slot continuously extending between opposing first and second closed ends of the slot, the metal plate extending along the orthogonal direction across a first group of the top contacts comprising at least one top signal contact and a second group of the bottom signal contacts comprising at least one bottom signal contact, such that in a plan top view, the metal ground plate covers less than about 60% of portions of the at least one top signal contact contacting the top surface of the substrate, and covers at least about 80% of portions of the at least one bottom signal contact contacting the bottom surface of the substrate, and wherein removing the metal ground plate changes an impedance of each of the bottom signal contacts by no more than 10%.

7. The electrical connector of claim 6, wherein the open end extends along the orthogonal direction.

8. The electrical connector of claim 6, wherein each slot has a length along the mating direction and a width along the orthogonal direction, wherein at least one first slot in the plurality of slots has a constant width along the mating direction, and at least one second slot has a varying width along the mating direction.

9. The electrical connector of claim 8, wherein at least one first slot in the plurality of slots has an average width greater than an average width of at least one other slot in the plurality of slots.

10. The electrical connector of claim 6, wherein the first group of the top contacts comprises at least one top ground contact and the second group of the bottom signal contacts comprising at least one bottom ground contact, and wherein the metal ground plate makes physical contact with at least one ground contact of one of the at least one top ground contact and the at least one bottom ground contact, but not with any ground contact of the other one of the at least one top ground contact and the at least one bottom ground contact.