WO2007009791A1

WO2007009791A1 - Connector assembly

Info

Publication number: WO2007009791A1
Application number: PCT/EP2006/007155
Authority: WO
Inventors: Timothy A. Lemke
Original assignee: Harting Electronics Gmbh & Co. Kg
Priority date: 2005-07-22
Filing date: 2006-07-20
Publication date: 2007-01-25

Abstract

A connector assembly comprises a header connector having an array of contact pairs. Each of the contact pairs has two dielectrically spaced signal contact pins. A mounting member is provided, which defines an array of recesses such that each of the recesses is configured to receive a corresponding one of the contact pairs so as to mate the header connector with the mounting member.

Description

Connector Assembly

The present invention generally relates to a connector assembly. More particularly, the present invention relates to a high speed backplane connector having a controlled impedance interface.

High speed backplane connectors have a number of interrelated mechanical and electrical performance requirements that they must meet. One of the most important performance requirements is that the impedance should be controlled along the signal path of the connector. This means that the geometry of the connector contacts relative to the dielectric materials provided in the connector must be carefully controlled. In connectors specifically designed for high speed differential pairs, the impedance is controlled by the material and spacing between the connector pins. As signal speeds and frequencies increase, control of impedance along the signal path becomes more important for maintaining the signal integrity along the length of the connector.

Many high speed connectors employ a header connector having square connector or contact pins. The contact pins in the header connector terminate at one end in compliant sections, each of which is then capable of being press-fitted into a circuit board, in plated through holes provided in the circuit board. The contact pins are mechanically staked at the other end into a plastic housing or mounting member.

The most difficult area of the connector to design is the mating area between the contact pin and the corresponding mating receptacle in the mounting member. The characteristic impedance of the connector should be relatively constant through this area, otherwise unwanted reflections can occur in the signal. One of the reasons this occurs is due to the transition between the two halves of the connector at the interface between the header connector and the mounting member. On one side of the interface the contact conductor is a square pin and on the other side of the interface (the contact provided in the mounting member) it is a spring material. The impedance is typically 100 Ohms The impedance of the signal contact pin also undergoes a change along its length. In a dielectric material of the type used in high speed backplane connectors, the characteristic impedance of the plated through hole in the circuit board is about 80-85 Ohms. The signal contact pin then extends into the housing, or mounting member, where it has an impedance of about 100 Ohms. However, when the pin emerges into air, its geometry is fixed and the impedance can be as high as 150 Ohms.

The impedance of the pins is most difficult to control in the area between the front face of the header connector and the point of contact where the pin mates with the mounting member. In this area, the pin is often in an air dielectric and the impedance is high at 150 Ohms. This can cause an unacceptable variation of impedance in this area.

Sometimes the signal contact pins and the mounting member are not completely mated. This allows a relatively large air gap to form between the face of the mounting member and the pin head. This mismatch can occur because of imperfections in the surrounding mounting hardware, which may prevent the connectors from mating fully or, more commonly, which causes the connectors to mate at an angle. The magnitude of the gap may be up to several millimeters, which is the same order of magnitude as the mating interface between the signal contact pins and the mounting member. At high signal transmission speeds, this can result in an impedance discontinuity.

The present invention has been devised with the foregoing in mind.

The present invention provides a connector assembly comprising a header connector having an array of contact pairs. Each of the contact pairs has two dielectrically spaced signal contact pins. A mounting member is provided, which defines an array of recesses such that each of the recesses is configured to receive a corresponding one of the contact pairs so as to mate the header connector with the mounting member. This provides the advantage that the impedance of the signal contact pins can be controlled at the mating interface between the header connector and the mounting member.

Preferably, at least a portion of the signal contact pins are spaced by a dielectric member having a dielectric constant higher than that of air. The connector assembly can also comprise an array of shielding members, such that each of the shielding members is associated with a corresponding one of the contact pairs. The shielding members can be arranged so that they at least partially surround a corresponding one of the contact pairs.

The shielding member can be provided at an interface between the contact pairs and the mounting member. Preferably, the mounting member further comprises an array of notches, such that each of the notches at least partially surrounds one of the recesses. In this way, the notches are configured to receive a corresponding one of the shielding members. Preferably, each of the shielding members and each of the notches is L-shaped. The dielectric member can also be provided between each of the contact pairs and a corresponding one of the shielding members.

Upon mating of the header connector with the mounting member, the assembly should be arranged so that the header connector projects from a first face of the mounting member. Preferably, the mounting member further comprises a guide member provided on a second face opposite the first face. The guide member can comprise a groove configured to receive a corresponding one of the contact pins. In this way, the groove can hold a corresponding contact pin more securely in the mounting member.

Each of the signal contact pins can be wider at a point that is held in a corresponding one of the recesses, upon mating of the header connector with the mounting member. This provides a more secure mating of the pin in the recess of the mounting member, and decreases the impedance of the signal contact pins.

Preferably each of said contact pairs is a differential pair. The pairs should be arranged on the header connector so that the distance between adjacent contact pairs is greater than the distance between each of the contact pins in a contact pair. The pairs can also be arranged on the header connector in rows and columns.

Thus the invention provides the advantage of a connector assembly that is simplified in mechanical design and which improves the mechanical mating characteristics of the connector, as well as the electrical performance. Further advantages and characteristics of the invention ensue from the description below of a preferred embodiment, and from the accompanying drawings, in which:

Figure 1 is a cross-sectional side view of a connector assembly according to the invention;

Figure 2 is a front view of a mounting member from a connector assembly according to the invention; and

Figure 3 is a back view of a mounting member from a connector assembly according to the invention.

The invention will now be described with reference to Figures 1 to 3. An electrical connector assembly 10 has a header connector with an array of signal contact pins 11 secured to, and extending outwardly of, the header connector. The signal contact pins 11 are arranged in a pattern of contact pairs 12. The contact pairs 12 are arranged in a pattern having rows and columns, such that the distance D1 between each adjacent contact pair 12 is greater than the distance D2 between the signal contact pins 11 in a single contact pair 12.

A mounting member 13 is provided with contact recesses 14 arranged in the front face of the mounting member 13 so that a single contact recess 14 corresponds to one contact pair 12; i.e., when the header connector is brought into contact with the mounting member 13, each contact pair 12 will be located in a single corresponding contact recess 14. Electrical contacts 15 made of a thin spring material are provided in each of the recesses 14 so that an electrical connection may be established between the signal contact pins 11 (i.e. the header connector) and the mounting member 13 when the header connector is connected to the mounting member 13. The pins 11 in the contact pair 12 are separated from each other by a dielectric material 20.

An L-shaped ground shield 16 can be provided to partially surround each contact pair 12, so as to isolate each of the contact pairs 12. Notches 17, having the same L-shaped configuration as each ground shield 16, can also be provided to define apertures in the front face of the mounting member 13, into which each ground shield 16 is received when the header connector is connected to the mounting member 13. However, the shield 16 may also be received in the same contact recess 14 as its associated contact pair 12.

Guide members 18 are formed as pillar-like structures on the back face of the mounting member 13 (the face opposite to the face onto which the header connector contacts the mounting member 13 when it is mated to the mounting member 13). The guide members 18 define grooves 19, each of which are configured to receive a signal contact pin 11. The guide members 18 are positioned on the back face of the mounting member 13 such that the grooves 19 correspond with the contact recesses 14. Thus when the contact pins 11 are inserted into corresponding contact recesses 14 and contact a corresponding one of the electrical contacts 15, they are also received in a corresponding groove 19.

It can be seen that one guide member 18 is provided for each contact pair 12.

The dielectric material 20 can be provided as a web between the contact signal pins 1 1 or, alternatively, also between the pins 1 1 and an adjacent shielding structure 16. It is only required to provide the dielectric material 20 at the mating interface between the header connector and the mounting member 13. This controls the impedance of the signal contact pins 1 1 in this section of the connector assembly, independently of whether or not the contact pins 1 1 are properly mated to the contact recesses 14 in the mounting member 13. The impedance of the pins 11 at the mating interface is then the same, or nearly the same, whether it is fully mated to the mounting member 13 or not. An additional benefit of the dielectric material 20 is that it provides mechanical stability to the contact pins 1 1. The mating face of the mounting member 13 is thus configured to accept the pair of contact pins 11 and their associated web of dielectric material 20. A single contact recess 14 can accept the pair of contact pins 11 or, alternatively, the pair of contact pins 1 1 and the associated shield 16, when no notches 17 are provided in the mounting member 13. The molds and parts of the connector assembly 10 can thus be simplified and more rugged in nature, as compared with conventional designs, which are provided with two holes for the signal contact pins.

When the header connector is mated with the mounting member 13, the initial guidance of the contact pins 11 in the mounting member 13 is accomplished using the external features of the shield 16 (if provided) in conjunction with the single corresponding contact recess 14 in the front mating face of the mounting member 13. The single opening in the recess 14 allows just a pair of contact pins 1 1 to be accommodated, or a pair of contact pins 1 1 with an associated shield 16, along with the dielectric material 20 spacing the contact pins 1 1. The contact pins 11 can also be wider at the point 21 where they mate with the mounting member 13, thus reducing the impedance of the pins 1 1. Such a mounting member 13 is capable of mating with free-standing contact pins, or contact pins separated by a dielectric member or having a widened base. This provides backward compatibility of the mounting member 13.

The guide member 18 can then provide further guidance of the contact pins

11. The grooves 19, corresponding to the shape of the signal contact pins 1 1 , project inwardly from the face of the mounting member 13 in a plane corresponding to a plane defined by the pairs of contact pins 1 1. The depth of the grooves 19 is less than the height or thickness of the contact pins 1 1 in the area where the contact pins 11 contact the grooves 19, thus allowing the mounting member 13 to make electrical contact with the contact pins 11 , via the electrical contacts 15, in the area of the guide member 18.

As well as guiding and supporting the contact pins 1 1 in the mating area between the header connector and the mounting member 13, the guide member 18 can cooperate with the electrical contacts 15 in the contact recesses 14, since the cantilever beams of the electrical contacts 15 can be preloaded on the structure, thus reducing the mating force between the contact pin 11 and the electrical contacts 15, by reducing the initial contact angle between the pin 11 and the electrical contact 15.

Although the invention has been described hereinabove with reference to a specific embodiment, it is not limited to this embodiment and no doubt alternatives will occur to the skilled person that lie within the scope of the invention as claimed.

Claims

1. A connector assembly, comprising:

a header connector having an array of contact pairs arranged thereon, each of said contact pairs being provided with two dielectrically spaced signal contact pins; and

a mounting member defining an array of recesses such that each of said recesses is configured to receive a corresponding one of said contact pairs so as to mate the header connector with the mounting member.

2. A connector assembly according to claim 1 , wherein at least a portion of said signal contact pins are spaced by a dielectric member having a dielectric constant higher than the dielectric constant of air.

3. A connector assembly according to claim 1 or claim 2, further comprising an array of shielding members, each of said shielding members being associated with a corresponding one of said contact pairs such that each of said shielding members at least partially surrounds a corresponding one of said contact pairs.

4. A connector assembly according to claim 3, wherein each of said shielding members is operable to be received in a corresponding one of said recesses.

5. A connector assembly according to claim 3, wherein the mounting member further comprises an array of notches such that each of said notches at least partially surrounds one of said recesses and is configured to receive a corresponding one of said shielding members.

6. A connector assembly according to any one of claims 3 to 5, wherein each of the shielding members is L-shaped.

7. A connector assembly according to any one of claims 3 to 6, wherein the dielectric member is additionally provided between each of said contact pairs and a corresponding one of said shielding members.

8. A connector assembly according to any one of claims 1 to 7, wherein upon mating of the header connector with the mounting member the header connector projects from a first face of the mounting member and the mounting member further comprises a guide member provided on a second face opposite the first face, the guide member comprising a groove configured to receive a corresponding one of said signal contact pins.

9. A connector assembly according to any one of claims 1 to 8, wherein each of said signal contact pins is configured to be wider at a portion that is operable to be held in a corresponding one of said recesses.

10. A connector assembly according to any one of claims 1 to 9, wherein each of said contact pairs is a differential pair.

11. A connector assembly according to any one of claims 1 to 10, wherein the distance between adjacent contact pairs is greater than the distance between each of said signal contact pins in a contact pair.