Electrical connector for mounting on a printed circuit board

Abstract: A right angle header connector (10) is disclosed for mounting on a surface of a printed circuit board (44) wherein the connector includes a dielectric housing (12) having a bottom mounting face (28), a forward mating face (24) and a rearward terminating face (26). A plurality of contact passages (36, 38) are provided in the housing and extending between the forward mating face and the rearward terminating face and defining top and bottom rows and vertical columns of passages, with at least a pair of passages in each column. A plurality of terminals (4) are secured in the passages and have contact sections (16) projecting from the forward mating face and terminating sections (18) projecting from the rearward terminating face connectable to corresponding circuit traces (42) on the printed circuit board. The terminating sections of the contacts in the bottom row (18b) thereof are formed at a first angle, and the terminating sections of the contacts in the top row thereof (18a) are formed at a relatively smaller angle for connection to corresponding rows of circuit traces on the printed circuit board spaced different distances from the rearward terminating face of the housing. The resultant configuration allows the terminals of both rows to have substantially equal electrical pathlengths and therefore eliminates signal delay in high speed applications. Furthermore, the rearward terminating face of the housing compensates for the relatively smaller bending moment of the top row of terminals by recessing the upper row of terminal passages thereby optimizing lead coplanarity.

Description: This invention generally relates to the art of electrical connectors and, particularly, to a right angle header connector according to the preamble of claim 1. Header connectors are used with IC packs or memory cards for interconnecting the semi-conductor circuit of the IC pack to an external circuit such as a main electronic unit. The IC pack is inserted into the header connector and is extracted therefrom as needed. Often, such header connectors are configured for mounting on a surface of a printed circuit board. The connector includes a dielectric housing having a forward mating face from which contact sections of a plurality of contacts project for interconnection with the contacts of the IC pack. The housing has a bottom mounting face for mounting the connector on the printed circuit board and a rearward terminating face from which terminating sections of the contacts project for connection to corresponding circuit traces on the printed circuit board. For instance, the terminating sections may have contact pads for soldering to the circuit traces. From document EP-A-0 147 039 it is known to provide a connector having at least two rows of through passages in a dielectrical housing with contact elements therein. The contact elements of each row have tail sections of varying lengths and of identical structural design extending outwardly from the housing for being soldered to traces on a circuit board. The terminating sections of the contacts project from the rearward terminating face of the dielectric housing at equal angles and different distances from the housing for soldering to the circuit traces on the printed circuit board which are in different arrays on the surface of the board. This contemplates differing overall terminal lengths and therefore the signal speed along the electrical paths of the terminals may vary. Such a variation in signal propagation can result in signal delay in high switching speed applications. The different overall lengths result in that the point of deflection of the terminating sections of the lower rows space closer to the rearward side of housing than the upper rows. This contemplates problems in providing sufficient flexibility for all of the terminating sections regardless of which row the respective contacts are located. If the vertical flexibility or bending moments of all leads are equalized, lead coplanarity of surface mounted connectors may be optimized. Other problems involve providing surfaces on the terminating sections, outside the dielectric housing, without interfering with the rearward terminating face of the housing during terminal insertion. In addition, problems are encountered in header connectors of the character described in affording visual observation of the condition of the printed circuit board termiantions. This invention is directed to solving the above problems in a header connector apparatus of the character described and to provide a new and improved electrical connector for mounting on a surface of a printed circuit board, such as the header connector for interconnection with IC packs or memory cards. An object, therefore, of the invention is to provide a new and improved electrical connector for mounting on a surface of a printed circuit board, such as a header connector for interconnection with IC packs or memory cards. As disclosed herein, the features of the invention are incorporated in an electrical connector which includes a dielectric housing having a bottom surface for mounting on a surface of a printed circuit board. The housing includes a forward mating face and a rearward terminating face. A plurality of contact passages are provided in the housing extending between the forward mating face and the rearward terminating face and defining top and bottom rows and vertical columns of passages, with at least a pair of passages in each column. A plurality of contacts are secured in the passages and have contact sections projecting from the forward mating face for interconnection with mating contacts of an appropriate IC pack or memory card. The contacts have terminating sections projecting from the rearward terminating face of the housing for connection to corresponding circuit traces on the printed circuit board, as by soldering. According to the invention, the terminating sections of the contacts in the bottom row thereof are formed toward the printed circuit board at a first angle for connection to corresponding circuit traces spaced a given distance from the rearward terminating face. The terminating sections of the contacts in the top row thereof are formed toward the printed circuit board at an angle smaller than the first angle for connection to corresponding circuit traces which are spaced closer to the rearward terminating face than the bottom row contacts. To prevent interference of terminals within a column, the terminating sections of each terminal must project from the rearward terminating face at separate vertical planes. Therefore, in an embodiment of the invention, the terminating sections of the top and bottom rows are offset from one another. In the preferred embodiment of the invention, the terminating sections of the contacts in the bottom rows thereof project from the rearward terminating face of the housing generally in the planes of the respective columns of contacts. The terminating sections of the contacts in the top and bottom row in the same vertical plane project from the rearward terminating face offset from the plane opposite from one another. The relative angles and positions of the terminating sections of the top and bottom rows of the terminals allows all terminals to have the same overall length. This is important where the switching speed of the electrical signal in the system is increased. If the electrical pathlengths of the terminals varies, propagation of the signal is not uniform and signal delays may result between adjacent terminals. The constant overall length in applicants' invention assures equal pathlength of high speed electrical signals and therefore minimizes signal delay. However, due to the angles at which the top row of the terminating sections connect to the printed circuit board, the relative bending moment of the terminating sections in the top row of terminals is less than that of the terminating sections in the bottom row. According to another embodiment of the invention, the housing has a stepped configuration in the rearward terminating face thereof from which the terminating sections of the top row of contacts project. This effects an increase in the vertical flexibility of the top row leads and substantially equalizes the bending moments of the two rows of terminals, thus improving the coplanarity of the leads. Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. Brief Description of the Drawings The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: FIGURE 1 is a perspective view of the mating end of the electrical connector of the invention; FIGURE 2 is a perspective view of the terminating end of the connector; FIGURE 3 is a fragmented perspective view of the left-hand portion of the connector as viewed in Figure 2, with some of the contacts about to be inserted into the connector housing, and with other of the contacts inserted into the housing and mounted to circuit traces on a printed circuit board; FIGURE 4 is a schematic illustration of a plurality of contacts, according to an alternate embodiment of the invention, surface mounted to circuit traces of an appropriate printed circuit board; and FIGURE 5 is a cross-sectional view of the electrical connector of the invention showing the stepped-configuration of the rearward terminating face. Detailed Description of the Preferred Embodiment Referring to the drawings in greater and detail, and first to Figures 1 and 2, the embodiment of the invention illustrated herein is incorporated in a header connector apparatus, generally designated 10, which includes a dielectric housing, generally designated 12, integrally molded of dielectric material such a plastic or the like. The housing mounts a plurality of high density contacts, generally designated 14, which include contact sections 16 and terminating sections 18. Contact sections 16 are provided for insertion into contact sockets of an IC pack or memory card (not shown) as is known in the art. Terminating sections 18 are adapted for connecting to corresponding circuit traces on a printed circuit board, as by soldering and as will be described hereinafter. Housing 12 has a pair of arms 20 defining tracks 22 for guiding a memory card into mating condition with an edge of the card inserted into a transverse receptacle 25 (Fig. 1) for mating of the contact sockets of the card with contact sections 16 of contacts 14 inserted into the contact sockets of the card. In addition, housing 12 has a forward mating face 24 (Fig. 1), a rearward terminating face 26 (Fig. 2) and a bottom mounting face 28. The bottom face is to be positioned on a surface of a printed circuit board, and means are provided for mounting the housing to the board. Specifically, the housing includes a plurality of integral mounting pegs 30 projecting from bottom face 28 for insertion into appropriate mounting holes in the printed circuit board. In addition, arms 20 of the housing have vertical through slots 32 into which locking clips are inserted to lock the housing to the board. In the drawings, bifurcated locking legs 34 of the locking clips are visible projecting from bottom face 28 in line with slots 32. As seen best in Figure 2, housing 12 has a plurality of contact passages 36 and 38 extending between forward mating face 24 and rearward terminating face 26. The contact passages define a top row (passages 36) and a bottom row (passages 38), with a pair of passages, one from each row, in a plurality of transverse columns. In other words, one passage 36 from the top row and a subjacent passage 38 from the bottom row are in a common vertical plane. Consequently, vertical pairs of contact sections 16 of terminals 14 are arranged in vertical pairs transversely of the housing and receptacle 25 therein. Referring to Figure 3, contacts 14 described in relation to Figure 1 have been designated with the reference numerals 14a and 14b to indicate the "top" contacts and the "bottom" contacts respectively, which have contact sections 16 for insertion into top passages 36 and bottom passages 38 respectively. Consequently, each top contact 14a has a terminating section 18a and each bottom contact 14b has a terminating section 18b. Each terminating section 18a and 18b has a distal end 40 which defines a contact area for engaging contact pads 42a and 42b on a printed circuit board 44 (Fig. 3). In addition, each contact 14a and 14b has a barbed section 46 which securely seats the contacts within passages 36 and 38. This is seen by the two pairs of contacts 14a and 14b shown in the cut away portion on the right side of Figure 3. As stated above, each vertical pair of passages 36 and 38 and each corresponding vertical pair of contact sections 18 of a vertical pair of contacts 14a and 14b, are arranged in a vertical plane. As seen most clearly, in Figure 3, terminating sections 18a of contacts 14a and terminating sections 18b of contacts 14b are disposed on respective opposite sides of the respective plane. In particular, taking any single pair of contacts shown in Figure 3, top contact 14a has a terminating section 18a to the right of the plane, and bottom contact 14b has a terminating section 18a to the left of the respective plane. This offsetting of the terminating sections results in offsetting pads 40 of the contacts for connection to the offset array of circuit traces 42a and 42b on the printed circuit board. In addition, by offsetting the terminating sections of the contacts, each contact has a transverse shoulder or surface 48a for contacts 14a and 48b for contacts 14b. These shoulders or surfaces provide means for appropriate tooling to abut and drive or insert the contacts into their respective passages. In addition, it can be seen by the two pairs of inserted contacts in Figure 3 and 5, that terminating sections 18b of bottom contacts 14b are formed toward the printed circuit board 44 at a relatively large first angle for connection to corresponding circuit traces 42b spaced a given distance from rearward terminating face 26 of housing 12. Terminating sections 18a of top contacts 14a are formed toward the printed circuit board 44 at a relatively smaller angle than terminating sections 18b for connection to circuit traces 42a spaced closer to terminating face 26 than terminating sections 18b of contacts 14b. The relative angles and positions of the terminating sections of the top and bottom rows of the terminals allows all terminals 14 to have the same overall length. This is important where the switching speed of the electrical signal in the system is increased. If the electrical pathlengths of the terminals varies, propagation of the signal is not uniform and signal delays may result. The constant overall length in applicants' invention assures equal pathlength of high speed electrical signals and therefore minimizes signal delay. However, due to the angles at which the top row of the terminating sections connect to the printed circuit board, the relative bending moment of the terminating sections in the top row of terminals is less than that of the terminating sections in the bottom row. Heretofore, it has been difficult to provide sufficient resiliency for the terminating sections of those contacts engaging circuit traces near the connector housing. Consequently, the terminating sections of those contacts had relatively smaller bending moments than those engaging circuit traces further from the housing. The flexibility of the leads and therefore the bending moments of the top row of terminals should be substantially equal to those of the bottom row in order to optimize the coplanarity of the leads. The invention contemplates means for solving this problem by providing a stepped configuration in the rearward terminating face of the housing which affords increased vertical flexibility for the smaller angled contacts. More particularly, as seen in Figures 3 and 5, an area 50 of rearward terminating face 26 of housing 12 is recessed, as defined by a step 52, so that the open ends of upper passages 36 are spaced inwardly from the open ends of bottom passages 38. By configuring the housing in such a way, the portions of top contacts 14a which project outwardly from housing 12 are made longer to provide greater vertical flexibility for terminating sections 18a of the top contacts effectively increasing the bending moment of the upper row of contacts. In addition, the stepped configuration of the housing provides additional spacing about shoulders 48a of top contacts 14a to accommodate the insertion tooling which is used to insert the contacts into the passages of the housing. Still further, by recessing the housing about the top passages, versus the bottom passages, an open area is provided along rearward terminating face 26 to afford greater visual observation of the interconnections between pads 40 of the terminating sections of the top contacts 14a with circuit traces 42a on the printed circuit board, thereby providing easier inspection of the interconnections. Figure 4 shows an alternate construction of the bottom contacts in relation to top contacts 14a. Specifically, bottom contacts, generally designated 56, in Figure 4 again include contact sections 16, contact pads 40 and terminating sections now designated 58, with the terminating sections being in the same plane as contact sections 16 of any given pair of top and bottom contacts. In essence, only top contacts 14a have offset terminating sections as shown in the drawing. This arrangement can accommodate circuit traces 42c and 42d which, may be staggered, with only terminating section 18a offset relative to the vertical plane of the contact sections while terminating sections 58 remain in the plane. It will be understood that the invention may be embodied in other specific forms without departing from the scope of the appended claims. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.

Claims: A right angle electrical connector (10) for mounting on a surface of a printed circuit board (44) wherein the connector includes a dielectric housing (12) having a bottom mounting face (28), a forward mating face (24) and rearward terminating face (26), a plurality of terminal passages (36, 38) in the housing and extending between the forward mating face (24) and the rearward terminating face (26) and defining top and bottom rows and vertical columns of passages with at least a pair of passages in each column, and a plurality of conductive terminals (14) secured in the passages, each having a contact section (16) projecting from said forward mating face (24) and a terminating section (18, 58) projecting from the rearward terminating face (26) including a board engaging end (40) connectable to corresponding circuit traces (42) on the printed circuit board (26), each terminating section (18) defining a mounting arm deflectable about a point generally defined between the contact section (16) and the terminating section (18) in response to a force applied to the board engaging end of the terminal by the printed circuit board (44), characterized in that the angle of the terminating sections of the top row (18a) to the board being greater than the angle of the terminating sections of the bottom row (18b, 58) to the board, that the conductive terminals of said top and bottom rows being of substantially the same overall length whereby an electrical signal travelling through each of said terminals will travel approximately the same distance in the same amount of time thereby eliminating signal delay. The right angle electrical connector (10) of claim 1 wherein the points of deflection of the mounting arms of the terminating sections in the top row (18a, 58) being offset from the points of deflection of the mounting arms of the terminating sections in the bottom row (18b) in the direction of the forward mating face (24) of the housing (12), whereby the bending moments of the mounting arms in the top row are substantially equal to the bending moments of the mounting arms in the bottom row. The electrical connector (10) of claim 1 or 2 wherein the points of deflection of the mounting arms of the terminating sections in the top and bottom rows are defined by the portion of the rearward terminating face superjacent the respective terminal passage. The electrical connector of claim 1, 2 or 3 wherein an area (50) of rearward terminating face (26) is recessed in a step-like manner (52), so that the open ends of upper passages (36) are spaced inwardly from the open ends of bottom passages (38). The electrical connector (10) as set forth in any of claims 1 to 4 wherein the terminating sections of the contacts in the bottom row (58) thereof project from the rearward terminating face (26) of the housing generally in the planes of the respective columns of contacts sections, and the terminating sections of the contacts in the top rows (18a) thereof project from the rearward terminating face (28) of the housing offset relative to said planes. The electrical connector (10) as set forth in any of claims 1 to 4 wherein the terminating sections of the contacts in the bottom row (18b) thereof project from the rearward terminating face (26) of the housing offset to one side of the planes of the respective columns of contacts sections, and the terminating sections of the contacts in the top row (18a) thereof project from the rearward terminating face (26) of the housing offset to the opposite side of said planes.

Inventors: ROCHE PETER G, ROCHE, PETER G.
Applicants: MOLEX INC, MOLEX INCORPORATED
Application year: 1992
Main classification: H01R23