Header assembly for mounting to a circuit substrate

Abstract: A header (10) assembly is mounted to a backplane and receives a complementary electrical connector. The header (10) assembly has an insulating shroud having a base with backplane and connector sides and a primary edge, and differential signal pin pairs, ground shields (26), and ground pins mounted to the base. The signal pin pairs (24) are arranged into rows extending in a first direction along the base and along the base primary edge, and columns extending in a perpendicular second direction along the base. The signal pins (24) in each pair are adjacently arranged into a sub-row extending in the first direction. Each signal pin in a pair has an inner side facing the other pin in the pair, an opposing outer side, and primary and non-primary sides facing toward and away from the base primary edge, respectively. One ground shield is associated with each signal pin. Each ground shield extends through the base between the connector side and the backplane side, and includes first and second attached wings arranged at right angles. The first wing extends along the first direction adjacent and along either the primary or non-primary side of the associated signal pin, and the second wing extends along the second direction adjacent and along the outer side of the associated signal pin. The ground shields in combination substantially electromagnetically isolate within the base each signal pin pair from all others. Each ground pin (28) electrically contacts at least one ground shield (26) at the second wing thereof.

Description: The present invention relates to a header system of the kind referred to in the preamble portion of patent claim 1. Such a header system is known, for example, from EP 0 907 225 A2. In particular, the present invention is for a high density header system for use in, for example, a motherboard in a backplane/back panel application. In a typical electrical interconnection system, a first removably insertable circuit board includes a complementary electrical connector that is to be mated with a header system which is mounted to a second circuit board. As should be understood, when the first circuit board is coupled to the second circuit board by way of the electrical connector and header and when the first circuit board is in operation, a number of signals enter or leave the first circuit board through conductive paths defined by the electrical connector on the first circuit board and the header on the second circuit board. In many instances, the second circuit board has other circuit boards coupled thereto by other respective headers and complementary electrical connectors, and the aforementioned signals can originate form or be destined for such other circuit boards. Of course, the aforementioned signals can also originate from or be destined for other locations remote from the second circuit board by way of appropriate interconnections. If it is desirable to suppress signal noise and/or crosstalk, it is known that a signal may be transmitted over a pair of differential (positive and negative) signal lines that travel together in close proximity. Typically, in such pair of differential lines, the signal itself (+V) is transmitted on the positive line, and the negation of the signal (-V) is transmitted on the negative line. Since both lines travel together in close proximity, any noise encountered by the lines should appear in a generally identical form on both liens. Accordingly, the subtraction (by appropriate circuitry or other means) of the negative line (-V + noise) from the positive line (+V + noise) should cancel out such noise ((+V + noise)-(-V + noise) = 2 V), thus leaving the original signal, perhaps with a different amplitude. Oftentimes, in a high frequency environment, most every signal passing to and from a circuit board travels as a pair of differential signals on a pair of differential signal lines. Accordingly, the electrical connector on the circuit board and the header on the backplane must accommodate all such pairs of differential signal lines. Moreover, with increased contact density on a circuit board, there has been a corresponding increase in signal lines associated with such circuit board. As a result, the number of individual lines running through the electrical connector of the circuit board and the associated header can be quite large. At the same time, since it is desirable to increase the number of circuit boards that can be coupled to the backplane, the 'real estate' on the backplane used by the header must be kept small. Therefore, the 'density' of individual signals that pass through the electrical connector and header must be increased. With such increased density, however, the issue of susceptibility to noise and/or crosstalk again arises, even in electrical connectors and headers that transmit pairs of differential signals. To combat such density-based noise, the header in particular has been modified to include ground shielding which substantially electromagnetically isolates within the header each pair of differential signal lines from every other pair of differentially signal lines. EP 0 907 225 A2 discloses a header system mountable to a backplane having first and second opposed sides, comprising: a first header positionable on said first side of said backplane and including: a body; a plurality of ground shields in said body; and a plurality of apertures in said body; and a second header positionable on said second side of said circuit substrate and including a body and in said body a plurality of ground shields; a plurality of intermediate ground shields, each corresponding to and contacting at least one of said ground shields; and a plurality of apertures; and a plurality of ground pins, each extending through a corresponding one of said apertures in said first and second header bodies and contacting at least one of said ground shields in said first header and said intermediate ground shield in said second header and adapted to pass through said circuit substrate, to directly interface a circuit board mounted to the primary header through the backplane to another circuit board mounted to the secondary header. WO 94/16477 describes a connector with improved shielding. Its electrical contacts are shielded by square wave shaped shielding elements which are grounded together. Accordingly, it is the object of the present invention to improve a header system as known from EP 0 907 225 A2 such that it can have multiple differential signal pairs in relatively high density, a backplane can directly be sandwiched between headers such that a circuit board mounted to a primary header can be directly interfaced through the backplane to another circuit board mounted to a secondary header, and that the header system has ground shielding for the signal pins, where the header is practical and relatively easily manufactured. The present invention accomplishes the aforementioned object by providing a header system as claimed. Dependent claims are directed on features of preferred embodiments of the invention. The following detailed description of preferred embodiments of the present invention will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. As should be understood, however, the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: Fig. 1 is a perspective view of a portion of the pins and ground shields of the header, with the shroud removed for clarity, wherein primary and secondary headers share common pins and sandwich the backplane therebetween; Fig. 2A is an exploded perspective view showing the primary header, backplane, and secondary header of Fig. 1; and Fig. 2B is a perspective view showing a securing contact employed in connection with the secondary header of Fig. 1. Certain terminology may be used in the following description for convenience only and is not considered to be limiting. The words "left", "right", "upper", and "lower" designate directions in the drawings to which reference is made. The words "inwardly" and "outwardly" are further directions toward and away from, respectively, the geometric center of the referenced object. The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. Referring to the drawings in detail, wherein like numerals are used to indicate like elements throughout, there is shown in Fig. 1 an embodiment of the present invention. A primary header 10a has pairs 24p of signal pins 24a, 24b and ground pins 28 that extend a relatively long distance beyond the backplane 12. In addition, a secondary header 10b is positioned on the other side of the backplane 12 and generally opposite the primary header 10a such that the secondary header 10b receives and includes the extended portions of the pairs 24p of signal pins 24a, 24b. Accordingly, the backplane 12 is sandwiched between the primary and secondary headers 10a, 10b, each header 10a, 10b shares the pairs 24p of signal pins 24a, 24b and the ground pins 28, and a circuit board mounted to the primary header 10a is directly interfaced through the backplane 12 to another circuit board mounted to the secondary header 10b. Each header 10a, 10b has its own ground shields 26 (the ground shields 26 for the primary header 10a are not shown in Fig. 1). Unlike the primary header 10a, the secondary header 10b includes a plurality of securing contacts 50, where each securing contact 50 electrically contacts a respective ground pin 28 and secures such ground pin 28 to such header 10b. As seen, each securing contact 50 also electrically contacts at least one ground shield 26 within the secondary header 10b through bumps 38b, thereby electrically connecting the contacted ground shield(s) 26 with the contacted ground pin 28. In particular, the primary header 10a of Fig. 1 has pairs 24p of signal pins 24a, 24b and ground pins 28 that extend a relatively long distance to allow for rear plug-up. In the primary header 10a of Fig. 1 such pins 24a, 24b, 28 extend about 19 mm through and beyond the backplane 12. Preferably, each pin 24a, 24b, 28 is formed such that the distal end thereof (i.e., the end associated with the secondary header 10b) is substantially identical to the proximal end thereof (i.e., the end associated with the primary header 10a). Accordingly, the secondary header 10b is instantiated by way of a second shroud 14 substantially identical to the shroud 14 of the primary header 10a, where the second shroud 14 is slipped over the distal end of each pin 24a, 24b, 28 (Fig. 2A) after such pins are inserted through the backplane 12. As should be understood, the second shroud 14 is then moved toward the backplane 12 until the base 16 of such second shroud 14 is generally parallel to and in contact with such backplane 12. As viewed from their respective connector sides 20, then, the primary header 10a and the secondary header 10b each present substantially the same profile, pin arrangement, and 'footprint'. In fact, it is preferable that the primary header 10a and the secondary header 10b each be able to receive the same type of complementary electrical connector in their respective wells. Preferably, the primary edge 23 of the secondary header 10b is directly opposite the primary edge 23 of the primary header 10a, with respect to the backplane 12. As was discussed above, each ground pin 28 in the primary header 10a includes a generally planar fin 40 that generally resides within the base 16 of the shroud 14 of the primary header 10a and that extends generally laterally from the main body of the ground pin 28. As seen, each fin 40 has generally opposing planar sides such that each ground shield 26 in the primary header 10a is electrically contacted by a ground pin 28 at a planar side of the fin 40 of such ground pin 28. As was also discussed above, each ground pin 28 is preferably inserted into the shroud 14 of the primary header 10a such that the fin 40 maintains an interference fit therewith. However, and as should be understood, the insertion of each ground pin 28 through the backplane 12 prevents such ground pin 28 from having a second fin on the distal end thereof. Accordingly, and as was discussed above, it is preferable that the secondary header 10b include a plurality of securing contacts 50, where each securing contact 50 contacts a respective ground pin 28, secures such ground pin 28 to such header 10b, electrically connects such ground pin 28 to at least one ground shield 26 (through bumps 38b), and in effect performs the same function as a fin 40. In particular, it is preferable that, prior to being mounted to the backplane 12 and the pins 24a, 24b, 28, the second shroud 14 be fitted with a plurality of conductive securing contacts 50, where one contact 50 is in each space in the base 16 of the second shroud 14 where a second fin of a ground pin 28 would otherwise reside. The insertion of contacts 50 is generally similar to the insertion of shields 26 into the base 16. As seen in Fig. 2B, each such securing contact 50 has generally opposing planar sides, and as positioned in the second shroud 14 of the secondary header 10b is electrically contacted on at least one side by a ground shield 26 in the secondary header 10b at a planar side of such securing contact 50. When the second shroud 14 is slipped over the distal end of each pin 24a, 24b, 28 and moved toward the backplane 12, then, each securing contact 50 in such second shroud 14 securingly electrically contacts the side of a respective ground pin 28 and maintains an interference fit therewith. Preferably, each securing contact 50 includes a compliant or spring portion 52 in facing relation to the side of the respective ground pin 28 to assist in securingly electrically contacting the respective ground pin 28 and maintaining the interference fit therewith. As with the fin 40, each securing contact 50 engages bumps 38b on the contacted-to-ground shields 26. However, any other appropriate mechanism may be employed to perform such functions without departing from the spirit and scope of the present invention. With such securing contacts 50, the ground shields 26 in the second shroud 14 are electrically coupled to the ground pins 28. In addition, the entire second shroud 14 is secured to the backplane 12. The interference fit between the securing contacts 50 and the ground pins 28 secures the second shroud 14 to the backplane 12. In the foregoing description, it can be seen that the present invention comprises a new and useful header 10 for being mounted to a circuit substrate such as a backplane 12. The header 10 can have multiple differential signal pairs 24p in relatively high density, and ground shields 26 for each pair 24p such that each pair 24p of signal pins 24a, 24b is shielded from every other pair 24p of signal pins 24a, 24b by such ground shields 26. Moreover, the header is practical and relatively easily manufactured. It should be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the scope of the present invention as defined by the appended claims.

Claims: A header system (Fig. 6) mountable to a backplane (12) having first and second opposed sides, comprising: a first header (10a) positionable on said first side of said backplane (12) and including: a body; a plurality of ground shields (26) in said body (16); and a plurality of apertures in said body; and a second header (10b) positionable on said second side of said circuit substrate and including a body (16) and in said body (16) a plurality of ground shields (26); a plurality of intermediate ground shields, each corresponding to and contacting at least one of said ground shields; and a plurality of apertures; and a plurality of ground pins (28), each extending through a corresponding one of said apertures in said first and second header bodies and contacting at least one of said ground shields (26) in said first header (10a) and said intermediate ground shield in said second header (10b) and adapted to pass through said circuit substrate (12), to directly interface a circuit board mounted to the primary header (10a) through the backplane (12) to another circuit board mounted to the secondary header (10b); characterized in that the backplane (12) is sandwiched between the primary and secondary headers (10a, 10b), each header (10a, 10b) shares the pairs (24p) of signal pins (24a, 24b) and the ground pins (28), each header (10a, 10b) has its own ground shields (26), unlike the primary header (10a), the secondary header (10b) includes a plurality of securing contacts (50), where each securing contact (50) electrically contacts a respective ground pin (28) and secures such ground pin (28) to such header (10b), each ground pin (28) in the primary header (10a) includes a generally planar fin (40) that generally resides within the base (16) of the shroud (14) of the primary header (10a) and that extends generally laterally from the main body of the ground pin (28); each fin (40) has generally opposing planar sides such that each ground shield (26) in the primary header (10a) is electrically contacted by a ground pin (28) at a planar side of the fin (40) of such ground pin (28); each ground pin (28) is preferably inserted into the shroud (14) of the primary header (10a) such that the fin (40) maintains an interference fit therewith. The header system as recited in claim 1, characterized in that said signal pins (24) are arranged in columns, said ground shields (26) are arranged in columns and said columns of said ground shields (26) are positioned between adjacent columns of said signal pins (24). The header system as recited in claim 2, characterized in that two columns of signal pins (24) flank each side of two columns of ground shields (26). The header system as recited in claim 1, characterized in that each of said adjacent ground shields (26) has a projection extending towards the other adjacent ground shield (26). The header system as recited in claim 4, characterized in that the projection is a protuberance on a surface of said ground shield (26). The header system as recited in claim 4, characterized in that the projection is a tab (36a) extending from said ground shield (26). The header system as recited in claim 1, characterized by a plurality of intermediate ground shields (26), each of said intermediate ground shields disposed between said adjacent ground shields (26). The header system as recited in claim 1, characterized in that adjacent ground shields (26) are arranged in mirror image. The header system as recited in claim 2, characterized in that two columns of said signal pins (24) are flanked on both sides by two columns of said ground shields (16). The header system as recited in claim 1, characterized in that at least some of said ground pins (28) correspond to two ground shields (26). The header system as recited in claim 10, characterized in that said ground pins (28) are interstitially arranged relative to said signal pins (24). The header system as recited in claim 10, characterized in that two adjacent ground shields (26) each have a projection extending towards the other ground shield (26).

Inventors: ORTEGA JOSE L, RAISTRICK ALAN, STONER STUART C, ORTEGA, JOSE L., RAISTRICK, ALAN, STONER, STUART C.
Applicants: FRAMATONE CONNECTORS INT, FCI
Application year: 2000
Main classification: H01R12
IPC codes: H01R13, H01R12