CN210489984U

CN210489984U - High-speed backplane connector

Info

Publication number: CN210489984U
Application number: CN201921878617.8U
Authority: CN
Inventors: 牛林
Original assignee: Shenzhen West Point Precision Technology Co Ltd
Current assignee: Shenzhen West Point Precision Technology Co Ltd
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2020-05-08
Anticipated expiration: 2029-11-04

Abstract

The utility model discloses a high-speed backplane connector relates to communication technology field. The plug comprises a plug assembly and a socket assembly, wherein a U-shaped metal sheet and metal pins are fixed on a first insulating shell on the plug assembly, a first interface terminal and a second interface terminal are electrically connected with a backboard circuit board, and two metal pins are arranged in an area surrounded by the U-shaped metal sheet; and a metal needle jack and metal sheet groups are fixed on a second insulating shell on the socket component, each metal sheet group comprises at least one first metal sheet and two second metal sheets, a third interface terminal, a fourth interface terminal and a fifth interface terminal are electrically connected with the single-board circuit board, the first metal sheets are contacted with the inner bottom wall of the U-shaped metal sheet, the two second metal sheets are respectively contacted with two inner side walls of the U-shaped metal sheet, and a metal needle is butted with the metal needle jack. Therefore, the problems that the reliability of the interconnection of the shielding plates of the plug and the socket of the high-speed backplane connector in the prior art is low and the shielding effect on the crosstalk of the differential pair signal pins is poor are solved.

Description

High-speed backplane connector

Technical Field

The utility model relates to the field of communication technology, more specifically say, relate to a high-speed backplane connector.

Background

The high-speed backplane connector is widely applied to communication technology, and is a type of connector commonly used for large-scale communication equipment, ultrahigh-performance servers, supercomputers, industrial computers and high-end storage equipment. With the continuous improvement of communication technology, the requirements for data transmission rate and storage are higher and higher, and therefore, the technical research on the high-speed backplane connector needs to be increased. Since the high-speed backplane connector transmits high-speed signals, it is necessary to reduce crosstalk between differential signals to the maximum extent, which requires good contact of the high-speed backplane connector to improve the grounding effect.

At present, the shielding piece of current high-speed backplane connector plug socket is single shell fragment contact usually, if shell fragment height discrepancy will appear virtual contact or even contactless problem, shielding piece ground protection inefficacy easily like this, the reliability is lower, leads to the requirement that the shielding performance of high-speed backplane connector can't satisfy 25G transmission rate and higher transmission rate connector, and this kind of single shell fragment contact structure is not good to the shielding effect of difference to signal needle crosstalk simultaneously.

Therefore, how to solve the problems of the prior art that the reliability of the interconnection of the shielding plates of the high-speed backplane connector plug jack is low and the shielding effect of the differential pair signal pin crosstalk is not good is an important technical problem to be solved by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a high-speed backplane connector is with the lower technical problem of reliability of the shielding piece interconnect who solves among the prior art high-speed backplane connector plug socket. The utility model provides a plurality of technical effects that preferred technical scheme among a great deal of technical scheme can produce see the explanation below in detail.

In order to achieve the above purpose, the utility model provides a following technical scheme:

the utility model provides a high-speed backplane connector, including the plug subassembly, the plug subassembly includes first insulation housing, fixes n U type sheetmetals and 2n metal pins that the cross section on the first insulation housing is the U type, fix in the first section of U type sheetmetal and be used for the first interface terminal that is connected with backplate circuit board electricity, fix in the first section of metal pin and be used for the second interface terminal that is connected with backplate circuit board electricity, every the second section of U type sheetmetal surrounds the region and all is provided with two side by side at the interval in the area;

the socket assembly is assembled with the plug assembly in an opposite insertion mode and comprises a second insulating shell, metal pin jacks which are arranged on the second insulating shell and are matched with the metal pins in a one-to-one correspondence mode, n groups of metal sheet groups, each group of metal sheet group comprises at least one first metal sheet and two second metal sheets, a third interface terminal which is fixedly connected to the first section of the first metal sheet and used for being electrically connected with a single-board circuit board, a fourth interface terminal which is fixedly connected to the first section of the second metal sheet and used for being electrically connected with the single-board circuit board, and a fifth interface terminal which is fixedly connected to the first section of the metal pin jack and used for being electrically connected with the single-board circuit board, wherein n is a positive integer greater than or equal to 1; the second section of the first metal sheet is in elastic interference contact with the inner bottom wall of the second section of the U-shaped metal sheet, the second sections of the second metal sheets are in elastic interference contact with the two inner side walls of the second section of the U-shaped metal sheet respectively, and the second section of the metal needle jack is in butt joint with the second section of the metal needle.

On the basis of the technical scheme, the utility model discloses can also do following improvement.

Furthermore, the first metal sheet, the second metal sheet and the position of U type sheetmetal inner wall elasticity interference contact all are provided with the arch.

Further, the number of the protrusions on each of the first metal sheet and the second metal sheet is at least one, and the shape of the protrusions is circular, oval or polygonal.

Further, the top of first sheetmetal is provided with first section of rolling over, the top of second sheetmetal is provided with the second section of rolling over, the bottom of second sheetmetal is provided with the third section of rolling over, the direction that first section of rolling over buckled with first sheetmetal with the inner wall of U type sheetmetal elasticity interference contact is kept away from mutually, the direction that the section of rolling over was buckled with the second sheetmetal with the inner wall of U type sheetmetal elasticity interference contact is kept away from mutually, the direction that the section of rolling over was buckled to the third with the direction that the section of rolling over was buckled to the second is the same.

Further, the number of the first metal sheets in elastic interference contact with the inner bottom wall of the U-shaped metal sheet is two.

Further, the height of the first metal sheet is larger than that of the second metal sheet.

Furthermore, the U-shaped metal sheet and the first interface terminal are of an integrated structure, the metal needle and the second interface terminal are of an integrated structure, the first metal sheet and the third interface terminal are of an integrated structure, the second metal sheet and the fourth interface terminal are of an integrated structure, and the metal needle jack and the fifth interface terminal are of an integrated structure.

Furthermore, the metal pin jack comprises a first elastic sheet and a second elastic sheet which are elastically abutted against each other, the parts of the first elastic sheet and the second elastic sheet which are elastically abutted against each other are both bending structures, and the bending directions of the first elastic sheet and the second elastic sheet are mutually far away.

Furthermore, the first insulating shell and the second insulating shell are made of plastic materials, and the U-shaped metal sheet, the metal needle, the first metal sheet, the second metal sheet and the metal needle jack are made of phosphor bronze materials.

Furthermore, the top of the second section of the metal needle is provided with a chamfer structure.

The technical scheme provided by the application comprises the following beneficial effects:

in the technical scheme provided by the utility model, high-speed back plate connector, including plug subassembly and socket subassembly, plug subassembly and socket subassembly are to inserting the assembly, be fixed with a plurality of cross sections for U type sheetmetal and a plurality of metal needle on the first insulating housing on the plug subassembly, first interface terminal is fixed in the first section of U type sheetmetal and is connected with backplate circuit board electricity, second interface terminal is fixed in the first section of metal needle and is connected with backplate circuit board electricity, two metal needles are all provided side by side at the interval in the region that the second section of every U type sheetmetal surrounds; the socket comprises a socket component and is characterized in that a second insulating shell on the socket component is fixedly provided with a metal needle jack and a plurality of groups of metal sheet groups, the metal needle jack and the metal sheet groups are matched with a metal needle in a one-to-one correspondence manner, each group of metal sheet group comprises at least one first metal sheet and two second metal sheets, a third interface terminal is fixedly connected to a first section of the first metal sheet and electrically connected with a single board circuit board, a fourth interface terminal is fixedly connected to a first section of the second metal sheet and electrically connected with the single board circuit board, a fifth interface terminal is fixedly connected to the first section of the metal needle jack and electrically connected with the single board circuit board, a second section of the first metal sheet is in elastic interference contact with an inner bottom wall of a second section of the U-shaped metal sheet, the second sections of the two second metal sheets are in elastic interference contact with two inner side walls of the. According to the arrangement, the first metal sheet on the socket assembly is in elastic interference contact with the inner bottom wall of the U-shaped metal sheet on the plug assembly, the two second metal sheets on the socket assembly are in elastic interference contact with the two inner side walls of the U-shaped metal sheet on the plug assembly respectively, a single contact formed by the contact of the single metal sheets of the contact point of the plug and the socket of the high-speed backplane connector is changed into a plurality of contacts formed by the contact of a plurality of metal sheets, the interconnection reliability of the shielding sheets of the plug and the socket is improved, meanwhile, the shielding sheet of the plug adopts the U-shaped metal sheet with the U-shaped cross section, and the shielding sheet of the U-shaped three-side surrounding structure better shields signal crosstalk between differential pair signal pins; therefore, the problems that the reliability of the interconnection of the shielding plates of the plug and the socket of the high-speed backplane connector in the prior art is low and the shielding effect on the crosstalk of the differential pair signal pins is poor are solved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of the whole high-speed backplane connector in the embodiment of the present invention;

fig. 2 is a schematic structural diagram of a plug assembly of a high-speed backplane connector according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a socket assembly of the high-speed backplane connector according to an embodiment of the present invention;

fig. 4 is a top view of the high-speed backplane connector in an embodiment of the invention;

fig. 5 is a partially enlarged schematic structural diagram of a socket assembly of the high-speed backplane connector according to an embodiment of the present invention.

Reference numerals:

1. a plug assembly; 2. a receptacle assembly; 3. a first insulating housing; 4. a U-shaped metal sheet; 5. a metal needle; 6. a first interface terminal; 7. a second interface terminal; 8. a second insulating housing; 9. a first metal sheet; 10. a second metal sheet; 11. a metal pin insertion hole; 12. a third interface terminal; 13. a fourth interface terminal; 14. a fifth interface terminal; 15. an inner bottom wall; 16. an inner sidewall; 17. a protrusion; 18. a first fold section; 19. a second folding section; 20. a third folding section; 21. a first spring plate; 22. a second elastic sheet; 23. and (6) chamfering.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The object of the present embodiment is to provide a high-speed backplane connector, wherein a first metal sheet on a receptacle assembly is in elastic interference contact with an inner bottom wall of a U-shaped metal sheet on a plug assembly, two second metal sheets on the receptacle assembly are in elastic interference contact with two inner side walls of the U-shaped metal sheet on the plug assembly, respectively, a single contact formed by a single metal sheet contacting a contact point of a plug and a receptacle of the high-speed backplane connector is changed into a plurality of contacts formed by a plurality of metal sheets contacting, so that the interconnection reliability of shielding sheets of the plug and the receptacle is improved, and meanwhile, the shielding sheet of the plug is a U-shaped metal sheet with a U-shaped cross section, which better shields signal crosstalk between differential pair signal pins; therefore, the problems that the reliability of the interconnection of the shielding plates of the plug and the socket of the high-speed backplane connector in the prior art is low and the shielding effect on the crosstalk of the differential pair signal pins is poor are solved.

Hereinafter, embodiments will be described with reference to the drawings. The embodiments described below do not limit the scope of the invention described in the claims. Further, the entire contents of the configurations shown in the following embodiments are not limited to those necessary as a solution of the invention described in the claims.

Referring to fig. 1-5, the present embodiment provides a high-speed backplane connector, which includes a plug assembly 1 and a receptacle assembly 2, the plug assembly 1 and the receptacle assembly 2 are assembled by inserting, the first insulating housing 3 on the plug assembly 1 is preferably made of plastic material, U-shaped metal sheets 4 and metal pins 5 are both vertically inserted into the first insulating housing 3, the number of the U-shaped metal sheets 4 and the position thereof on the first insulating housing 3 can be set according to specific use conditions, for example, the number of the U-shaped metal sheets 4 can be one or more, the specific arrangement position can be one row or multiple rows or multiple columns, two metal pins 5 are inserted into the area surrounded by each U-shaped metal sheet 4 and the two metal pins 5 are arranged side by side at intervals, the first interface terminal 6 and the U-shaped metal sheet 4 are of an integral structure, and the first interface terminal 6 is electrically connected to a ground circuit in a backplane circuit board, the second interface terminal 7 and the metal pin 5 are of an integrated structure, the second interface terminal 7 is electrically connected with a signal circuit in the backboard circuit board, the first interface terminal 6 and the second interface terminal 7 are preferably fisheye terminals, and the fisheye terminals only need to be pressed in plate holes on the circuit board without welding treatment, so that the operation is simple and convenient, and the connection is firm; the second insulating housing 8 on the socket assembly 2 is also preferably made of plastic material, the pin holes 11 and the metal plate groups are inserted into the second insulating housing 8, each metal plate group includes a first metal plate 9 and a second metal plate 10, in this embodiment, the number of the first metal plate 9 and the second metal plate 10 in each metal plate group is preferably two, the third interface terminal 12 and the first metal plate 9 are in an integral structure, and the middle portion of the third interface terminal is molded inside the second insulating housing 8 by in-mold injection molding, the fourth interface terminal 13 and the second metal plate 10 are in an integral structure, and the middle portion of the fourth interface terminal is molded inside the second insulating housing 8 by in-mold injection molding, the third interface terminal 12 and the fourth interface terminal 13 are electrically connected to the ground circuit in the single-board circuit board, the fifth interface terminal 14 and the pin holes 11 are in an integral structure, and the middle portion of the fifth interface terminal 14 and the pin holes 11 are molded inside the second insulating housing 8 by in-mold injection molding, the fifth interface terminal 14 is electrically connected with a signal circuit in the single board circuit board, and the third interface terminal 12, the fourth interface terminal 13 and the fifth interface terminal 14 are all preferably fisheye terminals; when the plug assembly 1 and the socket assembly 2 are assembled into a whole in an opposite-inserting mode, at the moment, the two first metal sheets 9 on the socket assembly 2 are in elastic interference contact with the inner bottom wall 15 of the U-shaped metal sheet 4 on the plug assembly 1, the two second metal sheets 10 on the socket assembly 2 are respectively in elastic interference contact with the two inner side walls 16 of the U-shaped metal sheet 4 on the plug assembly 1, and the metal pins 5 on the plug assembly 1 are connected with the metal pin insertion holes 11 on the socket assembly 2 in a clamping mode.

According to the arrangement, the two first metal sheets 9 on the socket component 2 are in elastic interference contact with the inner bottom wall 15 of the U-shaped metal sheet 4 on the plug component 1, the two second metal sheets 10 on the socket component 2 are in elastic interference contact with the two inner side walls 16 of the U-shaped metal sheet 4 on the plug component 1 respectively, multi-contact butt joint during plug-in assembly of a high-speed backplane connector plug and a socket is achieved, after a single contact formed by the contact of the original single metal sheets is changed into a plurality of contacts formed by the contact of a plurality of metal sheets, even if the condition that the height of a certain single metal sheet on the socket is out of tolerance with that of the plug metal sheets causes virtual contact or even non-contact, the rest metal sheets can still work independently to ensure good contact, and therefore the reliability of the interconnection of the shielding sheets of the plug and the socket is improved; meanwhile, the shielding sheet of the plug adopts a U-shaped metal sheet 4 with a U-shaped cross section, and the shielding sheet adopting the U-shaped three-side surrounding structure can better shield signal crosstalk between differential pair signal pins; therefore, the problems that the reliability of the interconnection of the shielding plates of the plug and the socket of the high-speed backplane connector in the prior art is low and the shielding effect on the crosstalk of the differential pair signal pins is poor are solved.

As an alternative embodiment, the first metal sheet 9 and the second metal sheet 10 are provided with protrusions 17 integrally formed by stamping at positions in elastic interference contact with the inner wall of the U-shaped metal sheet 4, the shape of the protrusions 17 formed by stamping can be set according to specific use conditions, for example, the shape of the protrusions 17 can be circular, oval or polygonal, and the like, and the provision of the protrusions 17 can further ensure the reliability of contact, thereby improving the problem of virtual connection caused by uneven contact surface or recess between the shielding sheets.

In more specific embodiments, the number of the projections 17 on each of the first metal sheets 9 and each of the second metal sheets 10 in the present embodiment is preferably one; by the arrangement, the problem of virtual connection caused by uneven contact surface or recess between the shielding sheets can be solved, and the difficulty of plug and socket assembly caused by excessive number of the protrusions 17 on each metal sheet can be avoided.

As an optional implementation manner, the first folding section 18 of the first metal sheet 9 and the second folding section 19 of the second metal sheet 10 are both bent towards a direction away from the inner wall in elastic interference contact with the U-shaped metal sheet 4, so that when the plug and the socket of the high-speed backplane connector are plugged together, the bending at the top of the first metal sheet 9 and the top of the second metal sheet 10 realize a guiding function, and it is ensured that the first metal sheet 9 and the second metal sheet 10 can be more easily in elastic interference contact with the inner wall of the U-shaped metal sheet 4; the bending direction of the third bending section 20 of the second metal sheet 10 is the same as the bending direction of the second bending section 19, so that when the plug and the socket of the high-speed backplane connector are assembled, the second metal sheet 10 is prevented from contacting with the outer wall of the U-shaped metal sheet 4.

In a more specific embodiment, the height of the first metal sheet 9 is greater than that of the second metal sheet 10, so that when a plug and a socket of the high-speed backplane connector are assembled, because the height of the first metal sheet 9 is greater than that of the second metal sheet 10, the first metal sheet 9 is firstly in elastic interference contact with an inner bottom wall 15 of the U-shaped metal sheet 4, and then the second metal sheet 10 is in elastic interference contact with an inner side wall 16 of the U-shaped metal sheet 4, and the design of the height difference between the first metal sheet 9 and the second metal sheet 10 well avoids the first metal sheet 9 and the second metal sheet 10 from being in elastic interference contact with the inner wall of the U-shaped metal sheet 4 at the same time, so that the friction resistance generated when the plug and the socket are assembled in an opposite insertion manner is reduced, and the effort of a user and the difficulty in assembling the plug and the socket are also reduced.

As an optional implementation manner, the metal pin jack 11 is composed of a first elastic sheet 21 and a second elastic sheet 22, and the top of the first elastic sheet 21 and the top of the second elastic sheet 22 are elastically abutted, so that the attaching force of the clamping connection part of the metal pin jack 11 and the metal pin 5 is enhanced, and the excellent contact performance of the metal pin jack and the metal pin 5 is ensured; the position that first shell fragment 21 and second shell fragment 22 elasticity offset is bending structure and the two direction of buckling and keeps away from each other, so sets up, and the effect of a direction has been realized to the bending structure of first shell fragment 21 and second shell fragment 22 in the metal needle jack 11, guarantees that metal needle 5 can be easier, insert inside metal needle jack 11 fast.

As an optional implementation mode, the U-shaped metal sheet 4, the metal needle 5, the first metal sheet 9, the second metal sheet 10, and the metal needle insertion hole 11 are preferably made of phosphor bronze, so that phosphor bronze is alloy copper, has good conductivity, is not prone to heat generation, ensures safety and has strong fatigue resistance, and the metal sheet made of phosphor bronze can ensure better contact, good elasticity and stable plugging.

As optional implementation mode, the top of the metal needle 5 is set to be in a chamfer 23 structure, so that the chamfer 23 at the top of the metal needle 5 is designed to be beneficial to uniformly dispersing pressure applied to the top of the metal needle 5 and the metal needle jack 11 during inserting assembly, the phenomenon that the top of the metal needle 5 is damaged due to repeated inserting and pulling of a plug and a socket is avoided, unnecessary collision between the metal needle 5 and the metal needle jack 11 is reduced, and the metal needle 5 is inserted into the metal needle jack 11 more easily is avoided.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A high-speed backplane connector, comprising:

the plug assembly (1) comprises a first insulating shell (3), n U-shaped metal sheets (4) and 2n metal needles (5) which are fixed on the first insulating shell (3) and have U-shaped cross sections, a first interface terminal (6) which is fixed on a first section of each U-shaped metal sheet (4) and is used for being electrically connected with a backboard circuit board, and a second interface terminal (7) which is fixed on a first section of each metal needle (5) and is used for being electrically connected with the backboard circuit board, wherein two metal needles (5) are arranged in parallel at intervals in an area surrounded by a second section of each U-shaped metal sheet (4);

the socket assembly (2) is assembled with the plug assembly (1) in an opposite insertion mode, the socket assembly (2) comprises a second insulating shell (8), metal pin jacks (11) which are arranged on the second insulating shell (8) and are matched with the metal pins (5) in a one-to-one correspondence mode, n groups of metal sheet groups, each metal sheet group comprises at least one first metal sheet (9) and two second metal sheets (10), a third interface terminal (12) which is fixedly connected to the first section of the first metal sheet (9) and used for being electrically connected with a single board circuit board, a fourth interface terminal (13) which is fixedly connected to the first section of the second metal sheet (10) and used for being electrically connected with the single board circuit board, and a fifth interface terminal (14) which is fixedly connected to the first section of the metal pin jacks (11) and used for being electrically connected with the single board circuit board, wherein n is a positive integer greater than or equal to 1; the second section of first sheetmetal (9) with interior diapire (15) elasticity interference contact of the second section of U type sheetmetal (4), two the second section of second sheetmetal (10) respectively with two inside wall (16) elasticity interference contact of the second section of U type sheetmetal (4), the second section of metal needle jack (11) with the second section butt joint of metal needle (5).

2. The high-speed backplane connector according to claim 1, wherein the first metal sheet (9) and the second metal sheet (10) are provided with protrusions (17) at positions in elastic interference contact with the inner wall of the U-shaped metal sheet (4).

3. A high-speed backplane connector according to claim 2, wherein the number of the projections (17) on each of the first metal sheet (9) and the second metal sheet (10) is at least one, and the projections (17) have a circular, elliptical or polygonal shape.

4. The high-speed backplane connector according to claim 1, wherein a first folding section (18) is disposed at a top of the first metal sheet (9), a second folding section (19) is disposed at a top of the second metal sheet (10), a third folding section (20) is disposed at a bottom of the second metal sheet (10), the first folding section (18) is folded in a direction away from an inner wall of the first metal sheet (9) and the U-shaped metal sheet (4) in elastic interference contact, the second folding section (19) is folded in a direction away from an inner wall of the second metal sheet (10) and the U-shaped metal sheet (4) in elastic interference contact, and the third folding section (20) is folded in a direction same as the second folding section (19).

5. A high-speed backplane connector according to claim 1, wherein the number of the first metal pieces (9) in elastic interference contact with the inner bottom wall (15) of the U-shaped metal piece (4) is two.

6. A high-speed backplane connector according to claim 1, wherein the first metal sheet (9) has a height greater than a height of the second metal sheet (10).

7. The high-speed backplane connector according to claim 1, wherein the U-shaped metal sheet (4) and the first interface terminal (6) are of an integral structure, the metal pins (5) and the second interface terminal (7) are of an integral structure, the first metal sheet (9) and the third interface terminal (12) are of an integral structure, the second metal sheet (10) and the fourth interface terminal (13) are of an integral structure, and the metal pin insertion holes (11) and the fifth interface terminal (14) are of an integral structure.

8. The high-speed backplane connector according to claim 1, wherein the metal pin jack (11) includes a first resilient piece (21) and a second resilient piece (22) that are resiliently abutted against each other, and both the resilient abutted portions of the first resilient piece (21) and the second resilient piece (22) are bent structures and the bending directions of the first resilient piece and the second resilient piece are away from each other.

9. The high-speed backplane connector according to claim 1, wherein the first and second insulating housings (3, 8) are each of a plastic material, and the U-shaped metal piece (4), the metal pins (5), the first metal piece (9), the second metal piece (10), and the metal pin insertion holes (11) are each of a phosphor bronze material.

10. A high-speed backplane connector according to claim 1, wherein the tops of the second sections of the metal pins (5) are provided in a chamfered (23) configuration.