Slotted rail mount for circuit boards

[0002] The present invention relates to methods and systems for mounting printed circuit boards within enclosures and, in particular, to a slotted rail mount for mounting printed circuit boards within spatially constrained enclosures.

[0003] Until recently, motherboards have been mounted into personal computers (“PCs”) and servers using screws and mounting assemblies that require significant design efforts, assembly time, and perhaps most importantly, a potentially time consuming and complex procedure for replacement of the motherboard mounted within a fully assembled PC or server. Common motherboard mounting techniques currently require large, parallel cable connections for connecting the motherboards to other components within the PC or server. Moreover, mounting techniques often vary from vendor to vendor, so that a motherboard prepared for mounting within a PC or server manufactured by one vendor may not be interchangeable with a motherboard manufactured by a different vendor.

[0004] In order to address the above-mentioned motherboard mounting problems, Intel® has developed a rail-mounting system for motherboards manufactured according to the NLX motherboard specification standard. FIG. 1 shows a detailed view of an NLX rail mounting assembly. Raised brackets 102-107, that together comprise a runner, are punched up through the surface 108 of an enclosure or chassis. A plastic rail 110 is affixed to the lower surface of the motherboard 112 via screws 114-116. In the interest of brevity, the numerical labels used in FIG. 1 will be used again in FIGS. 2 and 3 to label components shown in FIGS. 2 and 3 that are also shown in FIG. 1. FIG. 2 shows a rail positioned prior to mounting onto the runner. The front end of the rail 110 is angled, or tapered, to form a blunt point 202 that is positioned above a first pair of raised brackets 102-103 of the runner. Prior to mounting, the rail 110 is collinear with a central track 204 of the runner and the bottom surface of the rail 110 is coplanar with the surface of the enclosure from which the raised brackets of the runner are punched. The motherboard (not shown in FIGS. 2 and 3) is mounted to the enclosure by sliding the rail 110 affixed to the motherboard into the central track 204 of the runner, so that the rail 110 is held in place by the raised brackets 102-107. FIG. 3 illustrates a rail positioned within the central track of a runner following mounting.

[0005] FIGS. 4 and 5 illustrate the use of the NLX motherboard mounting system in a server enclosure. The numerical labels used in FIG. 4 are reused in FIG. 5, for components shown in both figures, for the sake of brevity and clarity. In FIG. 4, a motherboard 402 is positioned for mounting into a server enclosure 404. The server enclosure includes two runners 406 and 408 into which rails 410 and 412, affixed to the underside of the motherboard 402, are slid in order to mount the motherboard 402 securely to the enclosure 404. The motherboard 402 is fully mounted when conductive electrical connectors 414, arranged along the lower edge of the motherboard 402, are snugly fit into a connector receptacle 416.

[0006] FIG. 5 shows the motherboard of FIG. 4 mounted within the server enclosure. Once the motherboard 402 has been slid into position, a hinged panel 502 is rotated 90 degrees about two hinges 504 and 506 and snapped into position to form the top of the enclosure 404. This hinged top surface 502 is necessary because, prior to mounting, the motherboard 402 must be positioned, as shown in FIG. 4, with the lower edges of the rails 416 and 418 above the first sets of raised brackets 420 and 422, respectively. Prior to mounting, the top portion of the motherboard 402 extends above the plane of the top of the server enclosure 424-426.

[0007] While the NLX rail mounting system, described above in FIGS. 1-5, addresses the above-mentioned problems related to standardization, ease of mounting and replacement, and cableless connection, the necessity of the motherboard to be positioned above the top runner brackets prior to mounting requires either a hinged surface that can be opened to accommodate insertion of the motherboard, as shown in FIGS. 4 and 5, or requires server enclosures having at least once dimension significantly greater than the vertical dimension of the motherboard. However, designers and manufacturers of servers and PCs, in response to consumer demand, strive to keep the size of servers and PCs as small as possible, and strive to minimize manufacturing costs. Design of the hinged top surface of the server enclosure, as shown in FIGS. 4 and 5, adds additional parts and labor costs to the manufacture of the server or PC, and perhaps more importantly, may result in a weakening of the mechanical structure of the enclosure. For these reasons, designers and manufacturers of PCs and servers have recognized the need for a motherboard mounting system compatible with the NLX standard that does not require the motherboard to slide for a significant distance along runners, and that therefore does not require the motherboard to be initially positioned above the top of the runners prior to mounting, as illustrated in FIG. 4.

[0008] In one embodiment of the present invention, two slotted-rail mounting assemblies are employed to mount a motherboard within a server enclosure. Each slotted-rail mounting assembly comprises a runner piece, having raised brackets and guide posts that together form a runner and a slotted rail that slides through a control track of the runner. The slotted rails are affixed to the lower surface of the motherboard. The runners are affixed to a surface of the enclosure. Each slotted rail has two slots that allow the slotted rail to be positioned over corresponding raised brackets of the runner piece and against a surface of the enclosure within the central track of the runner. The slotted rail can then be translated along the central track of the runner for a distance of approximately ½ inch in order to lock the slotted rail underneath the runner brackets, thus mounting the motherboard securely to the surface of the enclosure to which the runners are affixed. Because mounting of the motherboard via the slotted-rail mounting assemblies does not require the motherboard to slide for many inches across the surface of the enclosure, the motherboard can be mounted within a compact enclosure, without requiring a hinged panel or an aperture through which the motherboard can be inserted.

[0009] FIG. 1 shows a detailed view of an NLX rail-mounting assembly.

[0010] FIG. 2 shows a rail positioned prior to mounting.

[0011] FIG. 3 illustrates a rail positioned within the central track of the runner following mounting.

[0012] FIGS. 4 and 5 illustrate the use of the NLX motherboard-mounting system in a server enclosure.

[0013] FIG. 6 is a detailed illustration of a single slotted rail initially positioned along a corresponding runner prior to mounting the slotted rail within the runner.

[0014] FIG. 7 shows a slotted rail in a mounted position underneath runner brackets.

[0015] FIG. 8 is an expanded view of the slotted-rail mounting assembly shown in FIGS. 6 and 7.

[0016] FIG. 9 shows a motherboard, with two attached slotted rails, positioned over two runners prior to mounting.

[0017] FIG. 10 shows a motherboard translated into a mounted position.

[0018] One embodiment of the present invention is a slotted-rail mounting assembly for mounting a motherboard within a PC or server enclosure. Two slotted rails are affixed to the lower surface of a motherboard. These slotted rails, along with the affixed motherboard, can be positioned directly over two corresponding runners affixed to the surface of a PC or server enclosure. The motherboard, and affixed rails, can then be translated along the runners for approximately ½ inch in order to securely mount the motherboard to the enclosure and snugly to fit electrical connectors along the lower edge of the motherboard into a connector receptacle. The small, ½ inch distance over which the motherboard slides along the runners allows the motherboard to be mounted within a relatively tight enclosure, without the need for special apertures through which the motherboard would otherwise need to be inserted and removed.

[0019] FIG. 6 is a detailed illustration of a single slotted rail initially positioned along a corresponding runner prior to mounting the slotted rail within the runner. The runner 602 is riveted to an inner surface of an enclosure 604. The runner 602 includes three raised brackets 606-608. The slotted rail 610 has two slots 612 and 614 that allow the slotted rail 610 to be placed over the two runner brackets 606 and 607 and positioned so that the inner edge of the slotted rail 616 is flush with the inner edge 618 of the runner 602 and so that the bottom surface of the slotted rail (obscured in FIG. 6) is flush with the surface of the enclosure 604. The slotted rail 610 has three inclined faces 620-622, or ramps, that are positioned parallel to the runner brackets 606-608 to allow the slotted rail 610 to be slid downward underneath the runner brackets 606-608. The slotted rail additionally has raised surface features 624 that include vertical stops 626-628 that will rest against the top edges of the runner brackets 606-608 when the slotted rail 610 is slid downward into a final mounted position. Three raised guideposts 630-632 form the right-hand side of a central track 634 within which the slotted rail is translated downward in order to lock the slotted rail into a mounted position. FIG. 7 shows a slotted rail in a mounted position underneath runner brackets.

[0020] FIG. 8 is an expanded view of the slotted-rail mounting assembly shown in FIGS. 6 and 7. Numerical labels used in FIG. 6 are reused in FIG. 8, where needed. The slotted rail 610 may be mounted to the motherboard 802 via screws 804-806. The three guideposts 630-632 are formed from the enclosure 604 by perforating the enclosure vertically, along both sides of the guideposts 630-632, and pressing, or stamping, the resulting vertical strips of enclosure material inward. The slotted rail 610 is molded from any number of different types of rigid plastic materials. The slotted rail 610 may also include a vertical mounting guide 808 that fits into an aperture 810 of the motherboard to allow for easy and accurate assembly.

[0021] FIG. 9 shows a motherboard, with two attached slotted rails, positioned over two runners prior to mounting. The motherboard 902 is positioned approximately ½ inch from the connector receptacle 904 into which the connectors 906 along the lower edge of the motherboard will be inserted. Because the motherboard 902 needs to be translated only ½ inch during the mounting process, there is no need for the top of the enclosure 908 to be hinged or to contain an aperture through which the motherboard is inserted. FIG. 10 shows a motherboard translated downward into a mounted position, with electrical connectors snugly fitted within an electrical connector receptacle.

[0022] Although the present invention has been described in terms of a particular embodiment, it is not intended that the invention be limited to this embodiment. Modifications within the spirit of the invention will be apparent to those skilled in the art. For example, the slotted rail portion of the slotted-rail mounting assembly may be manufactured from a variety of different materials, including molded plastics, metal, ceramic materials, or other such rigid materials. In the described embodiment, the slotted rails have dimensions approximately equivalent to the Intel® NLX standard for motherboard rail mounting assemblies. In alternate embodiments, the slotted rail mounting assemblies may have different dimensions as required for securely mounting different types and sizes of components to surfaces. The slotted rail mounting system may be employed to mount other types of printed circuit boards within server and PC enclosures, or, more generally, may be employed to mount any number of different types of objects with at least one flat surface to another flat surface. The slotted rails of the slotted rail mounting assembly may contain different numbers of slots to correspond to different numbers of runner brackets included on the corresponding runners. A variety of lengths of travel required to mount the slotted rails underneath the runner brackets can be obtained by varying the dimensions of the slots and of the vertical surface features that act as stops. Mounting of large or heavy objects may require more than two slotted-rail assemblies. The slotted rails may employ different attachment mechanisms, other than servers, for attaching to an object. The guideposts may be separate parts affixed to the surface bearing the runners, or may be a second, long, single-piece opposing runner piece.

[0023] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description; they are not intended to be exhaustive or to limit the invention to the precise forms disclosed, obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications and to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents: