Electrical connector arrangement for the distribution of different levels of power to a printed circuit board.

The invention relates to an electrical connector arrangement for the distribution of different levels of power to a printed circuit board.

In processing units such as computers, it is necessary to supply widely varying power levels, such as high and lower current and data carrying signals, from a panel, typically a mother board, to an individual daughter board. In order to rationalise the board layout and facilitate assembly and disassembly of the daughter board with the mother board by a simple plugging action, it has been proposed to provide an array of different matable connectors which supply different power levels at a single location along one edge of a daughter board and on the face of the mother board.

French Patent Application 80-22655 discloses a connector arrangement for the distribution of different levels of power between printed circuit boards comprising first and second pairs of matable individual connectors having different power carrying characteristics, a first connector of each pair having a pluggable mating face located transversely of a board-engaging face and the second connector of each pair having a complementary pluggable mating face located opposite a board-engaging face so that the first connectors of each pair can be mounted in a row along one edge of a daughter board with the mating faces extending perpendicular to the plane of the board and the second individual connector of respective pairs can be mounted in a row along the face of a mother board with matable connectors of respective pairs located in corresponding positions and their mating faces extending parallel to the plane of the mother board whereby the daughter board can be releasably connected to the mother board for simultaneous distribution of different power levels thereto by mating of the connectors in a simple plugging action.

A disadvantage of the connector arrangement described in the above-mentioned document is that the relative positions of the different connector types are arranged only by fixing the connectors to the circuit boards, and dedication of the circuit boards to only a single connector arrangement to meet only a single power supply requirement is necessary at the time of manufacture of the boards. In addition, the alignment and assembly of the connectors on the boards can be relatively difficult and time-consuming.

According to one aspect of the invention, the connectors are modular, the first individual modules of respective pairs being provided with means to link them together with other mutually opposite faces of the first modules adjacent to form a first composite connector body, and the second individual connectors of respective first and second pairs being provided with means to link them together with other mutually opposite faces of the modules adjacent to form a second composite connector body, the relative positions of the first and second individual modules in the composite bodies being interchangeable.

As the first individual connector modules of the first pairs can be linked together in different relative positions to form a composite body or unit with corresponding rearrangement of the second individual connector modules of the second pairs, the composite bodies are programmable prior to application to the circuit boards to meet alternative mixed power requirements. Furthermore, they are readily adapted for automated assembly together to form the different composite connector bodies enabling the manufacturer to standardize circuit board layout.

Preferably, the board engaging faces of the modules have the same common dimensions, facilitating further standardisation of the circuit board manufacture to meet different combinations of power level requirement.

A programmable modular connector assembly is described in EP-A-85100178.4, but the modules must be retained in Juxtaposition by a separate frame or carrier and do not enable a daughter board to be plugged directly to a mother board to obtain the necessary supply of different power levels. Either frames of different sizes to accommodate different numbers of modules for different power supply requirements must be supplied, or a single frame oversize for many needs increasing the cost and unnecessary use of circuit board space. In addition, extra steps are required to complete the assembly of the modular connector to the printed circuit board.

A problem that is met in supplying higher current to printed circuit boards using terminals of small size is the formation of hot spots caused by uneven current flow through various locations in the terminal and at points of connection to the circuit board, with consequential risk of damage to the connectors' connections (particularly when soldered) and the circuit board.

According to another aspect of the invention, terminal posts which extend from the terminal at different locations and are for connection to the circuit board are of different resistivities, thereby to tend to equalise the current flow and avoid hot spots caused by high current concentrations.

A further problem that may be met is providing a compact polarising structure which can be readily changed to obtain different settings with simple tools.

An example of the invention will now be described with reference to the accompanying drawings in which: <ul id="ul0001" list-style="none"><li>Figure 1 is a perspective view of the modular connector assembly according to the invention;</li><li>Figure 2 is a perspective view of first connectors of the first and second connector pairs;</li><li>Figures 3A and 3B are fragmentary elevational views of the module;</li><li>Figures 4A and 4B are, respectively, perspective views of the matable current carrying contact terminals;</li><li>Figures 5A and 5B are sectional views in orthogonal planes showing a mated current carrying module with the contacts of Figures 4A and 4B;</li><li>Figure 5C is a perspective view of a cap utilized in the connector of Figures 5A and 5B;</li><li>Figures 6A and 6B are perspective views of the male and female versions of higher current carrying power contact terminals of the invention;</li><li>Figure 7 is a partly sectional view of a connector incorporating the contacts of Figures 6A and 6B;</li><li>Figures 8A and 8B are cross-sectional views of examples of polarising modules before and after mating;</li><li>Figures 9A and 9B are end views of the polarising modules shown in Figure 8; and</li><li>Figure 10 is a plan view of the mated polarising modules of Figure 8.</li></ul>

The modular connector assembly comprises first, second, and third pairs of matable individual connector modules 11,11ʹ; 12,12ʹ; and 13,13ʹ, respectively, each pair having contacts with different current-carrying characteristics. Each first connector module 11,12 or 13 of each pair has a board connecting face 17 located transversely of a pluggable mating face 18 and each second connector module 11ʹ,12ʹ or 13ʹ of each pair has a board-connecting portion 19 located opposite a pluggable mating face 21. The board-connecting portions have the same common dimensions. Each module is provided on respective other, mutually opposite, faces 24,24ʹ with latch means to link them together comprising a plurality of interengageable hooks and catches 25 and 26 which face in opposite rotational senses on respective faces 24 and 24ʹ. Each face is rectangular and the hooks and catches 25 and 26 are located on alternate corners equidistant from a central rotational axis at which is located a pivot pin on one face 24 and a socket on the other face 24ʹ. The hooks 25 are resilient and are formed with camming noses 27 such that they can flex to engage the catches 26 which are located in pockets 28 formed in the face during movement from the condition of Figure 3A to that of Figure 3B. Each face is formed with recesses 29,29ʹ opening at corresponding locations, which recesses are brought into registration to form cooling cavities 31 when the modules are rotated together to bring the hooks and catches into latching engagement.

It will be evident from the foregoing that individual first connector modules of different current-carrying types can be latched together to form a composite connector half mounted by means of end modules 30 having similar latching means and coding pins 31, projecting from mating faces without the need for further support, and such composite connector half mounted to extend along one edge of a daughter board 33 for plugging engagement with a similar composite connector half comprising individual second connector modules mounted (with complementary end modules 30ʹ) on the face of a mother board to form a modular connector assembly to distribute various different power inputs between the mother and daughter boards.

If desired, the composite connector half formed by the second individual connectors can be mounted in a bulkhead rather than on the mother board.

An advantage of the particular latching means is that the rotational movement needed for latching together individual modules precludes inadvertent unlatching.

It is envisaged that some modules may be adapted to carry fibre optic power supplies to the boards.

Referring now to Figures 4A, 4B, 5A and 5B, as shown, stamped and formed mating electrical terminals 60 and 80 are mounted in the insulating housings 61,61ʹ of modules 12 and 12ʹ to effect a medium level power connection therebetween, terminating respectively conductive paths 71 and 81 on boards 33 and 34ʹ. Terminal 60 includes a forwardly extending, inverted, channel-section body portion 62 which is relatively long and narrow and is formed with adjacent, longitudinally and transversely extending, stiffening embossments 65 and 64, respectively, defining a front mouth. A locking barb 66 extends outwardly rearwardly from the base of the channel and engages a projection or shoulder in the housing interior to secure the terminal 60 therewithin. The rear end is cut away to define catches 69 which project rearwardly and upwardly from the side walls to anchor an insulating cap, described below.

A row of three pairs of aligned posts 70 which are soldered or force fit in apertures in the daughter board connecting to pad 71 extend from the channel side walls adjacent the rear. Rearwardly spaced successive posts are of decreasing effective length with respect to their connection points to the daughter board to balance out the current flow through the terminals and posts, total resistance of the forward posts being larger than the rearward posts, so that current flowing through the terminal 60 from the mouth will be more evenly distributed through each post, thereby distributing the heat generated by current flow more evenly through the terminal posts and circuitry of the board.

Equalising the current flow by varying the length of the posts enables the posts to be of standard cross-sectional size, obviating any requirement for the provision of nonstandard conductive pads or paths on the circuit boards which would add to the cost. In addition, this enables the posts to be located in equally spaced-apart relation, providing both a stable mounting for the terminal and an evenly distributed current flow in the circuit board.

As shown in Figures 5A and 5B, the terminal may be made of dual thickness stock, the rear portion from which the posts extend being of thicker stock than the forward portion better to carry the high currents concentrated therein. In this case, the embossment 64 may be omitted.

As shown in Figure 4B, as stamped and formed male terminal 80 includes multiple posts 82 for connection to pad 81 and a like number of cantilever spring contact fingers 84 substantially evenly spaced from respective posts, extending rearwardly and forwardly from respective opposite edges of a planar body portion 85, providing conductive paths of equal length and resistance from the mother board 34ʹ to the mouth 67 of the mating terminal 60.

Alternate contact fingers 84 diverge from a planar body portion 85 in opposite senses and their free ends 86 are curved back towards each other facilitating mating with terminal 60 without stubbing and providing multiple evenly-spaced points of contact on the opposite sides of the terminal 60 for optimum current distribution. The male terminal is very inexpensive to manufacture yet provides an effective current carrying connection to paths 81 on the mother board 34ʹ.

As shown in Figures 5A, 5B and 5C, the terminals are recessed from the forward mating faces of the module housings to avoid shorting. The housing 61 is open at a rear end and integrally formed by moulding with a tubular mating portion 88 and a channel section rearward portion 89 with the channel mouth open to the circuit board. A plastic cap 90 is formed with fingers 92 by which it can be snap fitted into the rear of module 61 by the fingers engaging the projections 69 and the rearmost of the legs 70 of terminal 60. The cap 90 assures insulation of the terminals 60 while permitting the housing to be moulded in a simple straight-draw mould.

The contact combination of terminals 60 and 80 has a design rating in excess of fifteen amperes at 280 volts D.C. so that each module 12 has a design rating of thirty amperes or better. It should be noted that this relatively high current rating is achieved in a very narrow box-like configuration which minimises occupation of board space, such boards being very costly particularly with heavy gauge, high current, capacity.

Referring now to Figures 6A, 6B and 7, the higher current carrying modules 11 and 11ʹ include a female terminal 100 and a male terminal 120, respectively. Terminal 100 is similar to the previously described terminal and includes a tubular body 100 with a forward, mating receptacle portion of rectangular cross section, with a bevelled mouth 102 formed with longitudinal and transverse embossments 112 and 110, board connecting post pairs 104,106,108, and catches 104.

The male terminal 120 is stamped and formed from dual thickness stock and includes a series of cantilever spring contact fingers 122,124 extending generally coaxially forwardly and rearwardly, respectively, from aligned locations equally spaced around the periphery of a tubular body portion 121. The contact fingers 122 diverge radially outwardly as they extend towards their free ends which are bent inwardly to avoid stubbing on mating.

The housing of module 11ʹ is integrally moulded with centrally located, forwardly extending, tapering tubular projection 130, having a free end of further reduced diameter extending beyond the free ends of the terminal, the body portion and contact fingers of which are received in a recess defined between the projection 130 and an outer wall 136 of the module. The divergence maintains a separation between the projection 130 and contact portions of the contact finger adjacent the free ends, and avoids a rolling action on engagement with the housing of module 11.

In examples of polarising modules 230,232 shown in Figures 8A and BB, the plastics housing modules 234,236, respectively, are generally similar in overall shape to those 30,30ʹ shown schematically and are formed with respective hexagonal section cavities 238,240 receiving a polarising projection (not in Figure 1 version) and key 242,244, respectively, and intersected by bowed snap ring receiving slots 246,248, respectively. Access recesses 250,252 are formed with guiding abutment surfaces 254,256 for receipt of a lever release tool, such as the blade of a screwdriver receivable in an eye 247 provided in a tab 249 of the ring. Each snap ring 258 is formed with three radially inwardly protruding groove engaging lands 259,260,261 at a free end of each leg and at a central location, respectively. The end walls of the mating modules are provided with a resilient cantilever latching arm 264 having a latching eye 266 receiving a latching ramp 268 in known manner.

The polarising projection 242 is moulded of plastic material with a hexagonal section body with a snap ring receiving groove 270 at a rear end and an eccentrically located, axially longitudinally extending key receiving slot 272.

The cavity 240 of module 232 has a hexagonal section counterbore 274 at a rear end of smaller cross-sectional size than a front projection receiving portion 275 receiving a hexagonal section rear body portion 276 of the key 244 which is locked in position in a similar manner to projection 242. A forward mating portion 278 of the key is of semihexagonal section and projects through the front cavity portion 275 at an eccentric location. Both the mating portion 278 of the key and a forward portion of the projection protrude from the mating face beyond mating ends of the other modules and internest when mated, as shown in Figure 8B, beyond the opposed faces, avoiding a need for an excessively long projection for effective guiding which would arise if a projection from only one module were provided.

In summary, the modular concept permits intermating of several different kinds of modules in a way which fixes dimensions and allows a preassembly of modules prior to insertion in printed circuit boards, occupies relatively little board space, and provides several types of power terminals having themselves features to better assure distribution of current without hot spots, and a particular type of polarisation which allows considerable flexibility in adapting to electrical and electronic packaging.