The invention relates to an electric interface, in particular an interposer, having a first connection plane with at least one first contact surface pair, each of which has a first and second contact surface, and a second connection plane with at least one second contact surface pair, each of which has a third and a fourth contact surface. For each of a first and second contact surface pair, a first electric connection electrically connects the first contact surface of the first connection plane to the third contact surface of the second connection plane, and a second electric connection electrically connects the second contact surface of the first connection plane to the fourth contact surface of the second connection plane. The first electric connection between the first and third contact surface has a specified first geometric length, and the second electric connection between the second and fourth contact surface has a specified second geometric length, the first and second geometric length being different.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrical interface, in particular an interposer, comprising a first connection plane with at least one first contact surface pair, each of which comprises a first and second contact surface, and a second connection plane with at least one second contact surface pair, each of which comprises a third and a fourth contact surface, wherein for each of a first and second contact surface pair, a first electric connection electrically connects the first contact surface of the first connection plane to the third contact surface of the second connection plane, and a second electric connection electrically connects the second contact surface of the first connection plane to the fourth contact surface of the second connection plane.

2. Description of Related Art

In large computer systems it is usual that several processor boards, each forming a server, in the form of populated printed circuit boards, also known as “blades”, are connected electrically and mechanically via plug-in slots with a so-called “backplane”, which is itself also a populated printed circuit board. For this purpose, angle connectors are provided which establish contact between plug connectors or connection points on the blades on the one hand and plug connectors or connection points on the backplane on the other hand in order to establish corresponding data transmission channels between the respective blade and the associated backplane.

However, the electrical connection via the angle connector gives rise to various different problems which affect the high-frequency signal transmission properties of the electrical connections. For example, the conductors in the printed circuit board plug connectors should all have an identical impedance of 85 Ohm.

However, due the geometrical circumstances, not all conductors in an angle plug connector have an identical geometric length, if these are arranged directly on the shortest paths running from the first plane to the second. However, phase differences in the transmission of high-frequency signals via the conductors of the angle connector need to be avoided, for which reason the conductors are frequently laid in a wavelike manner within the angle connectors, so that all conductors have an identical geometric length and thus also electric length. However, this has the disadvantage that the desired characteristic impedance of 85 Ohm is not present at each point between two adjacent conductors due to the distance changing in a wavelike manner. Since the conductors within a printed circuit board plug connector influence one another, for example during the differential transmission of high-frequency signals, this changing characteristic impedance over the course of the conductors leads to significant limitations in terms of the maximum transmittable bandwidth and bit rate.

SUMMARY OF THE INVENTION

The invention is based on the problem of improving an electrical interface of the aforementioned type such that high bandwidths and bit rates are achieved during the transmission of high-frequency signals.

According to the invention, this problem is solved through an electrical interface of the aforementioned type with the characterizing features of the independent claims. Advantageous embodiments of the invention are described in the further claims.

The above and other objects, which will be apparent to those skilled in the art, are achieved in the present invention which is directed to an electrical interface, in particular an interposer, comprising a first connection plane with at least one first contact surface pair, each of which comprises a first and second contact surface, and a second connection plane with at least one second contact surface pair, each of which comprises a third and fourth contact surface, wherein, for each of a first and second contact surface pair, a first electrical connection electrically connects the first contact surface of the first connection plane with the third contact surface of the second connection plane and a second electrical connection electrically connects the second contact surface of the first connection plane with the fourth contact surface of the second connection plane, wherein the first electrical connection between the first and third contact surface has a specified first geometric length and the second electrical connection between the second and fourth contact surface has a specified second geometric length, the first and second geometric lengths being different.

The electrical interface is designed to be interposed between a flat end surface of an electrical angle connector which has at least one conductor pair for the differential transmission of data signals and a connection point with contact surfaces on a printed circuit board.

The electrical interface may include two first and second contact surface pairs, wherein the first and second contact surfaces of the two first contact surface pairs on the first connection plane are arranged at the corners of a square such that a first and second contact surface of a first contact surface pair are in each case arranged diagonally opposite one another, wherein the third and fourth contact surfaces of the two second contact surface pairs on the second connection plane are arranged at the corners of a square such that a third and fourth contact surface of a second contact surface pair are in each case arranged diagonally opposite one another.

All first electrical connections are designed to have an identical geometric length relative to one another and that all second electrical connections have an identical geometric length relative to one another.

The first and second connection plane are preferably arranged parallel to one another.

The second electrical connection may be a through-connection running from the first to the second connection plane in a direction perpendicular to the connection planes. And the second and fourth contact surface of a first and second contact surface pair are arranged so as to align with one another in a direction perpendicular to the connection planes, wherein the first and third contact surface of a first and second contact surface pair are spaced apart from one another in a direction perpendicular to the connection planes.

A third plane may be included, which is arranged between the first and second connection plane, wherein the first electrical connection and the second electrical connection are formed in the third plane. The third plane may be formed parallel to the first and/or second connection plane.

The first electrical connection is designed as a flat conductor track which runs parallel to the first and/or second connection plane.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

According to the invention, in an electrical interface of the aforementioned type, the first electrical connection between the first and third contact surface has a specified first geometric length and the second electrical connection between the second and fourth contact surface has a specified second geometric length, the first and second geometric length being different.

This has the advantage that, with the electrical interface, runtime or phase differences, for example due to circuits adjacent the electrical interface, between a first electrical signal component which is transmitted via the first and third contact surface and a second electrical signal component which is transmitted via the second and fourth contact surface are deliberately influenced and in particular compensated to a difference of zero.

In order to compensate runtime or phase differences of signals which are transmitted via an electrical angle connector, the electrical interface is designed to be interposed between a flat end surface of an electrical angle connector which has at least one conductor pair for the differential transmission of data signals and a connection point with contact surfaces on a printed circuit board.

An arrangement of the contact surfaces in the manner of a star quad cable, or configured to make contact with end surfaces of a star quad cable, is achieved in that two first and second contact surface pairs are provided, wherein the first and second contact surfaces of the two first contact surface pairs on the first connection plane are arranged at the corners of a square such that a first and second contact surface of a first contact surface pair are in each case arranged diagonally opposite one another, wherein the third and fourth contact surfaces of the two second contact surface pairs on the second connection plane are arranged at the corners of a square such that a third and fourth contact surface of a second contact surface pair are in each case arranged diagonally opposite one another.

An identical compensation of runtime or phase differences for all conductors or contact surface pairs is achieved in that all first electrical connections have an identical geometric length relative to one another and that all second electrical connections have an identical geometric length relative to one another.

An electrical interface requiring little construction space is achieved in that the first and second connection plane are arranged parallel to one another.

A geometric length for the second electrical connection with a value of substantially zero is achieved in that the second electrical connection is a through-connection running from the first to the second connection plane in a direction perpendicular to the connection planes.

A particularly good impedance-controlled electrical interface is achieved in that the second and fourth contact surface of a first and second contact surface pair are arranged so as to align with one another in a direction perpendicular to the connection planes, wherein the first and third contact surface of a first and second contact surface pair are spaced apart from one another in a direction perpendicular to the connection planes.

A particularly electrically and mechanically simple and functionally reliable structure is achieved in that a third plane is formed which is arranged between the first and second connection plane, wherein the first electrical connection and the second electrical connection are formed in the third plane.

A compact structure which can be controlled well electrically, particularly in terms of impedance, is achieved in that the third plane is formed parallel to the first and/or second connection plane.

A particularly simple and electrically functionally reliable runtime or phase difference compensation is achieved in that the first electrical connection is designed as a flat conductor track which runs parallel to the first and/or second connection plane.

The invention is explained as follows with reference to the drawings.

The preferred embodiment of an electrical interface10illustrated inFIGS. 1 to 5has a first connection plane12, a second connection plane14and a third plane16which are all oriented parallel to one another, wherein the third plane16is arranged between the first and second connection plane12,14. Two first contact surface pairs19,19a, each with a first contact surface18,18aand a second contact surface20,20a, are arranged in the first connection plane12. Two second contact surface pairs23,23a, each with a third contact surface22,22aand a fourth contact surface24,24a, are arranged in the second connection plane14. In this context the term “plane” means a delimited level or flat surface considered as a two-dimensional object in three-dimensional space. In the exemplary embodiment described in the following, the “planes”12,14,16are flat (i.e. without curvature), square surfaces.

The first contact surface18of one first contact surface pair19in the first connection plane12is connected electrically with the third contact surface22of a second contact surface pair23in the second connection plane14via a first electrical connection26. The second contact surface20of the first contact surface pair19in the first connection plane12is connected electrically with the fourth contact surface24of a second contact surface pair23in the second connection plane14via a second electrical connection28.

The first contact surface18aof the other first contact surface pair19ain the first connection plane12is connected electrically with the third contact surface22aof the other second contact surface pair23ain the second connection plane14via a further first electrical connection26a. The second contact surface20aof the other first contact surface pair19ain the first connection plane12is connected electrically with the fourth contact surface24aof the other second contact surface pair23ain the second connection plane14via a further second electrical connection28a.

In other words, in the interface10, one first contact surface pair19in the first connection plane12is transposed to one second contact surface pair23in the second connection plane14and the other first contact surface pair19ain the first connection plane12is transposed to the other second contact surface pair23ain the second connection plane14.

The two first electrical connections26,26aare flat conductors which are arranged in the third plane16and run substantially parallel to the first and second connection plane12,14. The two second electrical connections28,28aare through-connections running from the first connection plane12, through the third plane16, to the second connection plane14and run substantially perpendicular to the three planes12,14,16. The geometric lengths of the first electrical connections26,26aare identical and at the same time longer than the geometric lengths of the respective second electrical connections28,28a. The geometric lengths of the second electrical connections28,28aare also identical to one another.

The first and second contact surfaces18,18a,20,20ain the first connection plane12are arranged at the corners of an imaginary square40(FIG. 4) in the first connection plane12such that the contact surfaces18,20or18a,20aof a contact surface pair19or19aare arranged diagonally opposite one another. Thus, in the illustrated embodiment, the first and second contact surface18,20of one first contact surface pair19are arranged diagonally opposite one another in relation to the imaginary square40(FIG. 4) and the first and second contact surface18a,20aof the other first contact surface pair19aare arranged diagonally opposite one another in relation to the imaginary square40(FIG. 4).

Analogously, in the second connection plane14the third and fourth contact surfaces22,24or22a,24aof the second contact surface pairs23or23aare arranged diagonally opposite one another at the corners of an imaginary square50(FIG. 5) in the second connection plane14. Thus, in the illustrated embodiment the third and fourth contact surface22,24of a second contact surface pair23are arranged diagonally opposite one another in relation to the imaginary square50(FIG. 5) and the third and fourth contact surface22a,24aof the other second contact surface pair23aare arranged diagonally opposite one another in relation to the imaginary square50(FIG. 5).

The arrangement or the so-called “footprint” of the first and second contact surfaces18,20and18a,20ain the first connection plane12described above is transposed via the invented interface10to the arrangement or “footprint” of the third and fourth contact surfaces22,24or22a,24ain the second connection plane14described above with identical dimensions and arrangement, but displaced in a direction perpendicular to the planes12,14,16. At the same time, by means of the first electrical connection26,26aproviding an electrical connection between a first contact surface18and18aand a third contact surface22,22a, the geometric paths and thus the electrical paths for a transmitted high-frequency signal are lengthened in comparison with the second electrical connections28,28abetween a second contact surface20,20aand a fourth contact surface24,24a.

The arrangement of the contact surfaces18/20,18a/20a,22/24,22a/24aof the contact surface pairs19,19a,23,23acorresponds to the arrangement of conductors in a so-called star quad transmission cable, which is in particular suitable for the differential transmission of high-frequency signals. The interface according to the invention hereby serves as an interposer between an angle connector30, as illustrated inFIG. 6, and a printed circuit board (not illustrated). As can be seen fromFIG. 7, the angle connector illustrated inFIG. 6contains two pairs of conductors32,34and32a,34a, which are arranged in the manner of a star quad cable, wherein in each cross section of the angle connector30the conductors are arranged at the corners of an imaginary square36, wherein two conductors32,34or32a,34aof a conductor pair are always arranged diagonally opposite one another in relation to the imaginary square36. In other words, on the one hand the conductors32,34are arranged diagonally opposite one another in relation to the imaginary square36and on the other hand the conductors32a,34aare arranged diagonally opposite one another in relation to the imaginary square36.

The angle connector30shown inFIG. 6has an angle of 90°, so that the conductors34,34ahave a shorter geometric length, from one end to the other end of the angle connector30, than the conductors32,32a, since the conductors34,34arun along an inside track and the conductors32,32arun along an outside track around the goo angle of the angle connector30. The interface10is arranged, as a so-called interposer, between the angle connector30and the (not illustrated) printed circuit board such that the conductors34,34awith the shorter geometrical paths in the angle connector30each meet on the two first contact surfaces18and18ain the first connection plane12, so that one first contact surface18makes electrical contact with the conductor34and the other first contact surface18amakes electrical contact with the conductor34a.

At the same time, the conductor32makes electrical contact with one second contact surface20and the conductor32amakes electrical contact with the other second contact surface20ain the first connection plane12. While the electrical signals transmitted via the conductors32and32aare transmitted directly from the second contact surfaces20,20aby means of the through-connections28,28a, by the shortest path through the interface10, to the fourth contact surfaces24,24ain the second connection plane14, the signals transmitted from the conductors34,34aare transmitted via the long first electrical connections26,26ato the third contact surfaces22,22a. The first electrical conductors26,26aare thereby so designed in terms of their geometric length that a phase or runtime shift relative to the signals transmitted on the other conductors32,32ais compensated. In other words, a phase or runtime shift between the geometrically shorter conductors34,34ain the angle connector30relative to the geometrically longer conductors32,32ain the angle connector30is compensated by means of the first electrical connection26,26a. The compensation in each case takes place for a conductor pair32,34or32a,34aarranged diagonally opposite one another in the angle connector30, so that the phase or runtime shift of a signal in the conductor34relative to the conductor32is compensated through one first electrical connection26and the phase or runtime shift of a signal in the conductor34arelative to the conductor32ais compensated through the other first electrical connection26a.

Each conductor32,34,32aand34ahas a copper wire42with a diameter of for example 0.3 mm as well as a coating44, for example made of Teflon. The four conductors32,34,32aand34aare embedded in a dielectric46, which for example has a diameter of 1.7 mm. The dielectric is for example manufactured from the material polyoxymethylene (abbreviation: POM).

The connection planes12,14are for example manufactured from an epoxy resin laminate with the designation NELCO® N4000-13 and have a thickness of for example 4 mm.