EP2435890A2 - Microtca device - Google Patents

Abstract

A MicroTC A shelf or the like has a backplane mounted to a chassis that includes a cover, bottom and sidewalls, where the backplane is mounted using a backplane holder assembly that can accommodate PCBs of different thicknesses and does not impinge on the backplane datum plane. The backplane holder engages cavities defined by edged flaps and the chassis walls. A grounding clip welded to the chassis encroaches on a power module slot to automatically physically contact and ground an inserted module. Cardguides are coupled to the chassis using visually verifiable means. Each cardguide has a plastic support defining AMC module channels and a metal grounding structure using a metal insert encased in the plastic support to rigidize the cardguide and ground inserted modules. Each AMC channel has an electrostatic dispersion (ESD) clip to automatically ground modules inserted in the channel. Each cardguide also has latches for locking AMC modules into backplane engagement. A cardguide latching post locks an AMC module's striker to lock the module in backplane operational engagement. The cardguide AMC channels use a stepped profile that matches an AMC module face plate. Hot swappable cooling units are coupled to the backplane using short header pin detection means and backplane locator pins that engage locator holes in the cooling unit. Each cooling unit has snap-in, vibration-dampened fans in a bracket.

Description

MICROTCA DEVICE MichaelJohn Franco, Richard A. Schulte

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U. S. C. § 119(e) and any other United States or other law of the following: U.S. Serial No. 61/181,891 (Atty. Docket No. 1303-p02p) filed May 28, 2009, entitled IMPROVED MICROTCA DEVICE, the entire disclosure of which is incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

Embodiments of the present invention relate generally to computer and telecommunications equipment and more specifically to embodiments of an improved device meeting MicroTCA specifications and providing electromechanical support for AMC cards.

BACKGROUND

Manufacturers and users of telecommunications and networking equipment, computer systems, and other types of electronic systems comprising computing and communications functions have proposed several non-proprietary standards to reduce costs, reduce time to market, and improve performance. Such non-proprietary standards, also known as open architecture standards, are believed to improve interoperability and increase reliability in products compliant with those standards. Open architecture standards for telecom and computing equipment may include, for example, thermal management schemes, mechanical dimensions of enclosures, racks, and electronic modules, connector styles and pin assignments and operating voltages and currents. Some examples of such standards include Advanced

Telecommunications Computing Architecture (ATCA), Micro Telecommunications Computing Architecture (MicroTCA) and Advanced Mezzanine Card (AMC), all of which are well known to those skilled in the art. More detailed discussions of background in this area are found in United States Publication No. 2008/0298014 Al, published December 4, 2008, and United States Publication No. 2008/0037218 Al, published February 14, 2008, both of which are incorporated by reference herein. The MicroTCA standard requires a backplane having high performance connectors into which AMC cards and other elements are plugged. MicroTCA carrier elements typically occupy one or more backplane slots. AMC backplane connectors bring the signals from the card edge connector into the backplane. Some connectors are optimized to carry high speed serial signals. Power module input connectors bring input power to power modules and power module output connectors carry high current power supply connections and control and management signals to the backplane from power modules. A mechanical support structure must hold the various components and backplane in correct alignment and secure it to the supporting "chassis" (or "frame"), which includes mounting holes, cardguides, electromagnetic interference (EMI) and electrostatic dispersion (ESD) control structures, and cooling units. Various additional mechanical elements include cooling and power unit mountings, cable guides, and brackets, typically are added to form the entire shelf, which often has a high power density. Cooling units (with fans or blowers, filters, and air plenums) remove heat from the electronics by directing large forced air flows through air paths between elements. MicroTCA shelves may use different cooling approaches, such as conductive cooling or natural convection. Systems, apparatus, methods and/or hardware that provide improved MicroTCA shelf construction, performance and other advantages would represent a significant advancement in the art.

SUMMARY The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings. Some embodiments of the present invention are described in this summary and include, but are not limited to, a shelf having a chassis to which a backplane is mounted. The chassis includes a cover, bottom and sidewalls and the backplane is mounted using a backplane holder assembly including a sheet metal backplane holder that permits telescopic assembly/disassembly with the chassis without disassembling the chassis. The backplane holder can use flanges having mating recesses engaging peripheral tabs on a printed circuit board backplane to hold the backplane in position and accommodate PCBs of different thicknesses. The backplane holder flanges do not impinge on the backplane datum plane and are configured to engage cavities defined by edged flaps (e.g., z-strips) and the chassis, thus securing the backplane holder assembly and backplane while also containing electromagnetic interference (EMI). Moreover, such embodiments provide a reduced- component tolerance chain based on the backplane front surface and allowing more precision in assembly and operation of such a shelf. Access points in a chassis sidewall allow for access to common signals, etc. A grounding clip can be welded to the chassis in position encroach on a power module slot or the like and is adapted to automatically physically contact and ground a module being inserted into the module slot.

One or more cardguides can be coupled to the chassis securely, in some cases using visually verifiable means, and each include a plastic support defining a plurality of AMC module channels and metal grounding structure using metal insert encased in the plastic support to rigidize the cardguide and ground inserted modules to the chassis. Each AMC channel includes an electrostatic dispersion (ESD) clip that automatically grounds AMC modules inserted in the channel. Each cardguide also include means for locking AMC modules into engagement with the backplane. Modules include a striker having a serrated engagement surface that locks to the cardguide using a cardguide latching post, which can be a bent metal tab having a rounded or beveled engagement edge to enhance AMC module locking without damaging the module striker and, in some instances, to allow visual confirmation of module cardguide latching. In some cases the cardguide AMC channels use a stepped profile that matches an AMC module face plate and/or elements to reduce unwanted module movement and/or disengagement when locked in the shelf.

One or more hot swappable cooling units can be coupled to the backplane securely, in some cases using a short header pin detection means to ensure proper electrical coupling prior to energizing a given cooling unit. EMI can be contained with EMI gaskets on each cooling unit. Backplane locator pins assist in locating cooling units by engaging locator holes on the leading surface of the cooling unit as it is inserted into the shelf. Each cooling unit itself can be a plurality of fans mounted to a bracket using snap-in mounting such as indents, dimples, tabs, etc. to permit easy fan replacement in a unit. Each fan can be mounted in the bracket with a vibration damping layer such as foam adhesive to reduce unwanted component vibration and resonant ringing at high fan speeds. Air filters in some cases have a rectangular frame and a plurality of support strips generally parallel to the direction of sliding the air filter assembly in and out of the shelf.

BRIEF DESCRIPTION OF DRAWINGS The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: Figs. 1-2 are perspective views of a IU MicroTCA shelf according to one or more embodiments of the present invention. Fig. 3 A is a perspective view of a 2U MicroTCA shelf according to one or more embodiments of the present invention. Fig. 3 B is a front view of the shelf of Fig. 3 A. Fig. 3C is a cross-section view of the shelf of Fig. 3B. Fig. 3D is a detail view of the shelf of Fig. 3 A. Figs. 4A-4C are a plurality of detailed views of a shelf sidewall according to one or more embodiments of the present invention. Figs. 5-6 are perspective and detail views, respectively, of a shelf according to one or more embodiments of the present. Fig. 7 is a flow diagram of a hot swap method for removing and replacing a shelf cooling unit. Figs. 8- 1OF are various views of power ground clip embodiments used with a MicroTCA shelf power unit/module. Figs. 11A-11B are perspective views of a IU MicroTCA shelf including backplane holder assembly according to one or more embodiments of the present invention. Fig. 12 A is an exploded view of backplane holder assembly embodiments. Fig. 12B is a top view of backplane holder assembly embodiments. Figs. 12C- 12D are side views of backplane holder assembly embodiments. Fig. 12E is a perspective view of backplane holder assembly embodiments. Fig. 13A is a side cross-section view of a backplane holder assembly and AMC connector according to one or more embodiments of the present invention. Fig. 13B is a side cross-section view of a backplane holder assembly and AMC connector according to an earlier device. Fig. 14 A is a top view of a shelf including one or more cooling unit embodiments. Figs. 14B-14E are detailed views of elements of Fig. 14A. Fig. 15 is a detailed view of short pin detection. Figs. 16A-16B are top and side views, respectively, of cooling unit embodiments. Figs. 16C, 16D and 16E are front, rear and cross- section views, respectively, of cooling unit embodiments. Fig. 17 is an exploded view of cooling unit embodiments. Figs. 18A-18B are views of embodiments of short pin detection and electrical coupling of cooling unit with a backplane. Figs. 19A-20I are various views of filter embodiments. Figs. 21 A and 22 are side and top views, respectively, of one or more cardguide embodiments. Figs. 21B-21C are detail views of the cardguide embodiments of Fig. 21A. Fig. 23 is a cross-section view of one or more cardguide embodiments. Figs. 24A-24B are detail views of the cardguide embodiments of Fig. 23. Figs. 25 A and 26A are perspective views of one or more cardguide embodiments. Figs. 25B and 26B are detail view of the cardguide embodiments of Figs. 25 A and 25B, respectively. Figs. 27A and 27B are side and end views, respectively, of one or more cardguide embodiments. Figs. 27C and 27D are detail views of the cardguide embodiments of Figs. 27A and 27B, respectively. Figs. 28A, 28B and 28C are side, cross-section and perspective views, respectively, of cardguide embodiments. Fig. 28D is a detail view of cardguide latching post embodiments of Fig. 28C. Fig. 29A is a cross-section view of one or more shelf embodiments. Figs. 29B-29C are detail views of the shelf embodiments of Fig. 29A. Fig. 30 is a detail view of one or more stepped cardguide profile embodiments. Fig. 31 A is a side view of one or more AMC module striker and cardguide latching post embodiments. Fig. 3 IB is a detail view of the mating of the latching post engagement edge and serrated striker engagement surface of Fig. 3 IA. Fig. 32 is a detail view of the mating of a prior art latching post engagement edge and serrated striker engagement surface.

DETAILED DESCRIPTION

The following detailed description will refer to one or more embodiments, but the present invention is not limited to such embodiments. Rather, the detailed description and any embodiment(s) presented are intended only to be illustrative. Those skilled in the art will readily appreciate that the detailed description given herein with respect to the Figures is provided for explanatory purposes as the invention extends beyond these limited embodiments. References in the specification to "embodiments," "some embodiments," "one embodiment," "an embodiment," etc. mean that a particular feature, structure or characteristic described in connection with such embodiment(s) is included in at least one embodiment of the present invention. Thus, the appearances of the noted phrases appearing in various places throughout the specification are not necessarily all referring to the same embodiment.

Certain terms are used throughout the description and claims to refer to particular system components. As one skilled in the art will appreciate, various companies, individuals, etc. may refer to components by different names. This disclosure does not intend to distinguish between components that differ insubstantially. Phrases such as "coupled to" and "connected to" and the like are used herein to describe a connection between two devices, elements and/or components and are intended to mean physically and/or electrically either coupled directly together, or coupled indirectly together, for example via one or more intervening elements or components or via a wireless connection, where appropriate. The term "system" refers broadly to a collection of two or more components and may be used to refer to an overall system (e.g., a computer system or a network of computers), a subsystem provided as part of a larger system (e.g., a subsystem within an individual computer), and/or a process or method pertaining to operation of such a system or subsystem. In this specification and the appended claims, the singular forms "a," "an," and "the" include plurals unless the context clearly dictates otherwise. Unless defined otherwise, technical and scientific terms used herein have the same meanings that are not inconsistent to one of ordinary skill in the art relevant subject matter disclosed and discussed herein. As illustrated in Figs. 1 and 2, a MicroTCA shelf 100 comprises a chassis 200 having a chassis cover 201, a chassis bottom 202, two cooling units 300, several combined cardguides 400/450 and rack mounting flanges 204. Chassis 200 has a plurality of ventilation holes 206 in sidewalls 208 that permit the flow of air through the device 100 for cooling internal components. Moreover, chassis 200 includes a removable backplane holder assembly 500 that affixes and holds a backplane (e.g., a printed circuit board (PCB)) 502, including one or more AMC card slots or connectors 504, in position at the back of shelf 100. Embodiments of MicroTCA shelf 100 shown in the Figures use an enclosure chassis 200, which can take a variety of shapes and sizes, depending on the anticipated use of the shelf 100 and its location. As noted above, in the embodiments of the present invention illustrated in the Figures, chassis 200 includes a chassis bottom 202 and an upper chassis cover 201. Although these can be made of plastic covered a conductive film, bottom 202 and cover 201 typically are made of sheet metal (e.g., bent or otherwise formed to appropriate sizes, shapes, etc.), offering an overlap (i.e., interlock) with backplane holder flanges 503 to contain electromagnetic interference (EMI). Some embodiments of the present invention provide new and/or improved features of the chassis 200 to provide improved performance, reliability and cost reductions over earlier MicroTCA shelves.

As shown in some embodiments, chassis top 201 and bottom 202 constitute a two-piece welded, screwless construction that can eliminate 8 or more screws that were part of earlier devices. Edged flaps along the back top and bottom likewise have eliminated 12 or more screws that were needed in earlier devices. These edged flaps can take the form of z-strips 210 seen in some of the Figures, or can be a number of lance and form flaps (cut or lanced material on 3 sides formed into a Z shape cut from the chassis to define grooves like the z-strips 210). Chassis cover 201 allows easy removal of backplane holder assembly 500 without having to disassemble the entire chassis 200, as required in earlier devices where the backplane assembly was screwed to a main chassis cover. As seen in Fig. 3C, some embodiments of removable backplane assembly 500 have a backplane cover 501 engaging several z-strips 210 fixed to the top and bottom of the interior of chassis 200, the z-strips 210 cooperating with the main chassis to create engagement slots for upper and lower edges of cover 501 and working cooperatively with chassis 200 to create slots to hold cardguides 400/450, as discussed in more detail below. Cover 201 can be bent at its front edge to form a hem 271 ; similarly bottom 202 can be bent to form a hem 272. Slots 209 cut in cover 301 and bottom 202 allow for mounting of one or more embodiments of cardguides used with MicroTC A shelves, providing reliable anchoring of each cardguide, visually verifiable mounting of such, and better structural integrity of the chassis 200 when the cardguides are so mounted (i.e., z-strips 210 and some cardguides help rigidize the chassis cover and bottom to prevent bending and/or bowing that could impair mounting relevant components). An alternate embodiment replaces the z-strips 210 with lance and form flaps cut from chassis cover 201 and bottom 202 defining grooves similar to z-strips to allow flanges 503 to hold backplane holder assembly 500 in place in chassis 200.

Air flow and cooling of shelf 100 is provided by a cooling hole configuration shown in Figs. 4A-4C, using hexagonal cooling holes 206, which permit a significant percentage of open area adjacent to cooling units 300 for good cooling performance. Holes 206 allow cooling units 300 to draw in cool air and to exhaust hot air using fans 306 mounted adjacent to each sidewall 208. Increasing open space in the sidewalls 208 is therefore highly advantageous. Hexagonal holes 206 provide structural integrity for sidewalls and excellent ventilating capability. Other structures similarly minimize metal and maximize opening for hot air exhaust (triangular, rectangular, hexagonal, etc.), while providing structural integrity for walls 208, especially where straight sides of geometric shaped are parallel, minimizing the amount of sidewall structure used to define the holes and support the shelf sidewall. Earlier shelves used optional screwed- on mounting ears having recesses; these recesses are eliminated in some embodiments by extending a flap of wall 208 as a mounting flange 204, providing improved strength in holding shelf 100 in its rack, and reducing the cost of shelf 100 by reducing materials and fabrication expense and complexity. Fig. 4B shows access points 222 in wall 208. Obtaining signals from a bus or clock in shelf circuitry was not simple or convenient in earlier devices because such signals were accessed either by disassembling the chassis or by extending a probe through air holes in a sidewall (so the shelf cooling unit could not be running). Some embodiments of the present invention ensure easy access to these signals without disassembling the shelf. Access points 222 are holes in wall 208 allowing probe testing of commonly used diagnostic signals (e.g., data signals, ground, clock signals, etc.). Holes 222 are adjacent one end of the PCB 502 in backplane holder assembly 500. As seen in Figs. 12A-12D, several contacts 561 reside at one or more edges of PCB 502. Contacts 561 can be wired to specific signals, ground, etc. (e.g., through PCB 502) to provide quick access to such signals, ground, etc. Some high vibration settings mandate further securing of a shelf in a rack or other mounting position. Figs. 5 and 6 show an embodiment of a shelf 100 secured to a rack bracket 281. In earlier mounting configurations, a planar connector bracket 282 was used to connect bracket 281 to side screw mounts 555 on the side of backplane holder assembly 500. In high vibration conditions, embodiments of shelf 100 are adapted for more secure mounting to bracket 281 with a C-shaped brace 284 secured to bracket 282 and to rear screw mounts 559 on the back surface of backplane holder assembly 500. As appreciated by those skilled in the art, this additional bracing significantly reduces or eliminates movement of a mounted shelf 100.

Power unit and/or other grounding are part of international codes for such shelves, though prior MicroTCA shelves often omitted power unit grounding. Figs. 8- 1OF show grounding clip embodiments in shelf 100, where a grounding clip 224 affixed to chassis 200 (e.g., by welding, screwing, etc.) is set on one side of the module slot through which power unit 802 (or any other module) is inserted into and removed from shelf 100. Clip 224 has welding tabs 227 that can be used to weld clip 224 to the chassis top 201 and/or bottom 202 (providing large grounding surface area) and clip 224 also has spring-like fingers 225 or other resilient members that automatically physically engage power unit 802 inserted into shelf 100 so that a user does not have to remember to or successfully connect power unit 802 to ground as a separate step. Using such embodiments, power unit 802 (or any other MicroTCA and/or AMC module) is automatically grounded whenever it is in operational contact with shelf 100. Chassis grounding is important and is done using a triangular array of holes 226 seen in the Figures, permitting vertical or horizontal grounding cable engagement.

Earlier devices required using more than 100 screws to assemble an entire shelf, each screw another shelf part and another fabrication step. Embodiments of shelf 100 use features (e.g., z-strips 210, cardguides 400, snap-in cooling fans 306, etc.) to reduce use of screws or other fasteners so that some embodiments use fewer than 40 screws (e.g., 36) for a finished shelf 100, significantly better than screw-reliant designs. Chassis 200 couples to backplane assembly 500 with fewer screws (or other connectors) than in earlier MicroTCA shelves. Per Figs. 3C and 13A, backplane assembly 500 telescopically engages (per arrow 211) the backs of chassis cover 201 and bottom 202 with minimal use of screws, etc. Chassis walls 208 have either 2 screws 555 in IU shelves or 3 screws 555 for 2U shelves per sidewall to anchor backplane assembly 500 to chassis 200, making removal of backplane assembly 500 much easier than earlier shelves. Also, the cost of fabricating and assembling such a MicroTCA shelf is reduced dramatically when screws, connectors and the like are eliminated.

The MicroTCA shelf backplane provides electrical connectivity between shelf modules (e.g., AMC cards, power modules) and other components with which modules interact. Figs. 12A-12D and 13A illustrate some backplane assembly 500 embodiments. Per above, backplane 502 can be a PCB providing electrical connectivity for components operating in shelf 100 and other components, systems, etc. to which shelf 100 connects directly or indirectly. Earlier devices (e.g., Fig. 13B backplane holder) used extruded aluminum backplane holders encroaching into a PCB's surface area, forcing the mounting of AMC slots 504, etc. inward on the PCB front surface plane. Earlier device 1500 in Fig. 13B has backplane holder 1501 secured to chassis 1201 using T-nut holes 1513 and screws/connectors 1515. PCB 1502 was held in place using an overhang/lip 1503 of holder 1501, meaning AMC connectors 504 were mounted farther inward (i.e., away from PCB edges, per arrow 1529), thus not in optimal position for accepting inserted AMC card 509. Insertion/withdrawal (arrow 517) led to flexing/bending of AMC cards 509 (per Fig. 13B) - this vertical misalignment caused damage, accelerated wear and electrical misconnection. Also, use of T-nut slots 1513 in devices 1500 on the back of holder 1501 (to permit screwing a backplane holder to the back of chassis 1201) increased the minimum thickness/depth of the backplane holder assembly in these devices. A comparison with embodiments of the present invention in Fig. 13A shows that inserted AMC card 509 does not flex as in Fig. 13B because top and bottom flanges 503 of holder 501 are perpendicular to and do not encroach into PCB 502's datum plane, allowing better AMC slot 504 placement (per Fig. 13A arrow 529, smaller displacement than Fig. 13B arrow 1529). Per above, PCB 502 (Fig. 13A) is not held by a lip/overhang in embodiments of backplane holders herein, but by tabs 506 in mating recesses 508, shortening backplane assembly 500 to reduce overall shelf depth.

Backplane holder 501 of Figs. 12A-12D is made of sheet metal, bent to create top and bottom flanges 503 and side flanges 507 that are generally 90° to the plane of PCB 502. Per Figs. 3C and 12A-12B, because flanges 503 are at a right angle to holder backwall 505 and PCB 502, those flanges 503 slide into and out of cavities defined by each edged flap (e.g., z-strip) and the chassis cover/bottom so that, unlike earlier devices, backplane holder 501 does not encroach into (i.e., reduce) usable surface of PCB 502 for mounting AMC connectors 504, etc. Expanded usable PCB surface permits proper mounting of AMC connectors 504 so that they are in the datum plane of AMC modules (e.g., AMC cards) inserted into shelf 100. Also, because PCB 502 is not screwed to the backplane holder, the backplane can "float" a small amount, further improving misalignment tolerance, etc. for AMC modules, cards, etc. Screws 557 are optional and can electrically ground the signal ground plane of PCB 502 to a chassis ground. The hole in PCB 502 is large enough to permit some backplane float, while allowing ground connection. If screws 557 are tightened down, PCB 502 will not float, but AMC modules will by then have found their positions, eliminating a need for PCB float. The 90° top and bottom flanges 503 also permit mounting of backplane assembly 500 to chassis 200 using z-strips 210, per Fig. 3C. Flanges 503 fit in a cavity defined by cover 201 or bottom 202 and a respective z- strip 210. Side flanges 507 are coupled to chassis walls 208 with screws 555. In some embodiments securing the backplane holder assembly 500 to the chassis 200 is adjustable. A crucial aspect of any MicroTCA shelf is the reliability of the placement of the backplane PCB 502 relative to a cardguide locking mechanism (e.g., posts 471 in some cardguide embodiments herein). In embodiments using tabs 506 and mating recesses 508, PCB 502 placement depends upon the PCB 502 pushing forward and abutting against the back edges of the z-strips 210, providing tolerance reference to the front surface of PCB 502. This means that embodiments can accommodate, with equal precision, PCBs 502 of different thicknesses (due to variations in PCB fabrication, different data/electrical requirements, etc.) without adjustment of the backplane holder assembly 500 or chassis 200, because it is the front face of the PCB 502 that establishes the PCB's position, not the backplane holder or other component. The tolerance chain defining the relationship of the latching post lock and the AMC connector/backplane position for such embodiments has fewer parts/components than in earlier devices and is defined by the cardguide latching post (cardguides can be tight tolerance injection molded parts), tight tolerance z-strips, and the backplane's front surface. In this type of configuration, side flanges 507 of backplane holder 501 can have slots that allow for such variation when screws 555 are secured (e.g., per Fig. 12E, holding backplane holder 501 by compressing sidewall 208 and a nutplate 598 inside each flange 507 to hold the backplane PCB 502 against the z-strips). Bracketing and backwall-mounted screws of earlier devices are eliminated by using flange/z-strip configurations, so total outside depth of shelf 100 is reduced as compared to earlier devices (e.g., from 200.1 mm to 195.0 mm).

PCB 502 is held in backplane holder 501 and against edges of z-strips 210 (when the backplane holder assembly 500 is secured to the chassis 200) using peripheral PCB tabs 506 engaging mating recesses 508 in flanges 503, which (laterally, two-dimensionally) locates PCB 502 accurately, supports PCB 502 to MicroTCA specified loads (e.g., 200 N), and eliminates backwall screws of earlier devices. Where holes are used in lieu of recesses 508, a screw used as a jack threading into tapped holes pries apart flanges 503 of holder 501 for insertion/removal of PCB 502. On tightening the screw, top and bottom flanges 503 separate, top and bottom tabs 506 fit into expanded flange 503 separation to permit installation of PCB 502, the screws then removed so flanges 503 return to original positions and hold PCB 502. The disclosed designs provide improved part geometry accuracy compared to extrusions or castings and improve shelf 100 while reducing fabrication/assembly cost and complexity. As will be appreciated in the art, compared to earlier devices, use of screws is also reduced by use of edged flaps such as z-strips 210. Top/bottom flanges 503 of backplane holder 501 are snuggly held in cavities between z- strips 210 and chassis walls 201, 202, eliminating a number of screws. "Screw-on" AMC connectors and stiffeners are replaced with automated SMT connectors that can be robotically placed and wave soldered on, again saving on assembly cost and complexity.

As is known in the art, two cooling units move cooler air into a shelf and move out heated air. Cooling unit embodiments in Figs. 14A-18B enhance cooling performance, ease of use, functionality, repair, etc., and slide in/out of shelf 100 adjacent to walls 208 using a handle 301. Each unit 300 has a latch 302, (e.g., an off-the-shelf latch replacing custom latches in earlier devices) that can be a spring-loaded slider with a cam tip or striker 358 engaging a slot 258 in chassis bottom 202 (Fig. 1 IA) to hold cooling unit 300 in operational engagement in shelf 100. In each unit 300 brackets 308 hold several fans 306 using formed snaps 307 that are indents (e.g., deformed dimples or punched through tabs) in the metal sheeting of brackets 308 (again eliminating screws and/or other connectors that made earlier fabrication, assembly, repair/replacement more complex and costly where, e.g., two screws (now eliminated by snap-in fans) held each fan in place). Brackets 308 can include beveled edges and/or lead-in surfaces to ease alignment with and insertion into a cooling unit bay in a shelf. Using snaps 307 engaging fan mounting holes 309 or directly clamping the fan's width, a fan 306 can be installed (e.g., as a replacement) reliably by "snapping" the fan into brackets 308. Fans in shelves reach high speeds that can cause significant vibration, noise, etc. Cooling unit embodiments include a vibration-damping layers 318 between each fan 306 and bracket 308. In some cases double- sided foam adhesive/tape functions as a shock absorber to isolate each fan's vibrations from the metal work and to reduce/eliminate noise (resonant ringing), damage, etc. otherwise caused by such vibration.

Electrical circuitry connects cooling unit 300 to a power source and any fan controls and/or control signals via PCB 502. Coupling a cooling unit to a shelf in earlier devices was done with push-button detectors and/or spring/compression tabs which were not reliable (e.g., spring/compression tabs broke or deformed, preventing proper contact). Some cooling unit embodiments herein use a two-piece connector with superior reliability. In older devices surface-to-surface spring contact had to be maintained (e.g., if a cooling unit release did not mate or locate correctly, there might be no compression and contact). Also, slight vertical or horizontal cooling unit movement or misalignment could break cooling unit/shelf contact.

Earlier cooling units needed clamps to tightly hold a cooling unit against PCB contacts; these clamps had to be loosened/removed each time a user accessed/removed a cooling unit. With enhanced positioning and electrical contact, embodiments herein use locator-pin-positioning of cooling units 300; clamps and add-ons are eliminated and damage to header pins, etc. reduced. Per Figs. 14A- 18, large cone-tipped locator pins 312 on backplane assembly 500 engage and mate with cooling unit holes 313 to (a) align cooling unit 300 and PCB 502 (even with worst case tolerances) when a cooling unit 300 is inserted into a cooling unit bay in the chassis (sliding the unit 300 along bay bottom and side walls) so that small PCB electrical header pins 314 connect correctly with cooling unit sockets 316 and (b) to lift the backplane-engaging end of cooling unit 300 slightly so that cooling unit components are not compressed when engaged with backplane 502. Thus locator pins 312 establish alignment in a plane parallel to PCB 502 while short-pin detection (i.e., electrical contact) sets proper depth perpendicular to PCB 502, replacing a cooling unit detector switch (mechanical contact) in earlier devices. Per detail in Fig. 15, one header pin 315 is shorter than other header pins to ensure proper depth between cooling unit 300 and PCB 502. If short pin 315 connects electrically with PCB 502, long pins 314 also must be connected electrically because they are longer, extending farther into unit 300 (giving -0.169" of position tolerance for unit 300 in some embodiments). Some cooling unit embodiments use one or more EMI gaskets 369 that are made of foam and metal and mate with the cooling unit bay walls to help contain EMI. Some cooling unit embodiments provide hot swap capability using hot swap button 320 and hot swap indicator light 322 on the face of unit 300 (triggering button 320 can be linked to latch 302 to prevent cooling unit removal without prior hot swap deactivation). Earlier devices needed the entire shelf turned off to remove a cooling unit for upkeep, repair, etc. After button 320 is pushed/triggered, status light 322 goes on to verify that cooling unit 300 is deactivated, so removal will not interfere with continued operation of modules, etc. running in shelf 100. Then once a cooling unit 300 is reinstalled and electrical connection verified (e.g., using short pin 315 detection to ensure that all pins 314 have engaged a reinstalled cooling unit 300 before powering up), the newly installed cooling unit 300 is energized and activated without having to push/trigger hot swap button 320 again or take any other action. This provides ergonomic cooling unit hot swap extraction/replacement. Fig. 7 shows method 380 in which a user pushes hot swap button 320 at 381 and checks hot swap light 322 at 382. If 322 is lit, the currently installed cooling unit is removed at 383; a cooling unit is reinstalled at 384, automatically powered up and operated without disturbing AMC modules or other devices operating in shelf 100. To reduce assembly time and make failed fan replacement easier, some embodiments use two-piece IDCs (insulation displacement connectors). The receptacles (connectors) can be crimped onto multi-conductor fan cable without stripping or soldering. There are a number of fan cables (e.g., 16 per cooling unit), and each is simply cut to the appropriate length, slid into the receptacle connector, then crimped. The cooling unit can then be readily assembled, quickly plugging each fan into the correct plug on the PCB assembly.

Air moving between the interior of shelf 100 and a cooling unit 300 is filtered per the MicroTCA specification with filters held in a filter holder 750 that is slidable in and out of shelf 100, per Figs. 19A-20I. Filter holder detector 591 (Figs. 12A- 12D) ensures that holder 750 is installed before operating an associated cooling unit 300. Holder 750 uses metal bracket 751 with a rectangular outer frame and fixed handle 752. Other than its outer frame "front" and "rear" members, bracket 751 has no vertical support strips or the like, which are common in earlier devices. Only horizontal supports 754 (i.e., generally linear and parallel to in and out holder movement) assist in retaining a filter within bracket 751. A filter typically has open cell polyurethane foam coated for fire retardation and fungi resistance and features deep loading, large dust holding capacity and low air resistance usable in widely varying environmental conditions. The foam is usually defined by pores per inch (e.g., 25 ppi). Using only horizontal supports 754 reduces snagging common with earlier devices' holders. To further reduce snagging and ease holder 750 insertion/ extraction, vertical edges 753 on bracket 751 have bends/bevels 757 to reduce snags. Earlier devices used ball detents in filter holder horizontal frame members. Lance and form units in some filter embodiments assist in locking filter holder 750 in operational position in shelf 100. A cantilevered, formed detent 756 on each horizontal member of the frame of bracket 751 engages a slot 256 in chassis bottom 202.

Some shelf embodiments use cardguides to assist in inserting AMC modules into operational connection with shelf 100. Exemplary 2U cardguides 400 and IU cardguides 450 in the Figures (various features of the exemplary IU cardguides 450 can be used in 2U cardguides 400, and vice versa) have a durable, low-cost plastic molding support 404 holding a metal insert 402 that is part of a metal grounding structure that acts as a conductive path for electrostatic discharge (ESD) and as a profiled fit for top AMC face plate guidance to stop AMC module movement that would allow an AMC latch to slip over a shelf cardguide latching post. Hybrid metal/plastic 2U cardguide 400 can be fabricated by molding plastic around a metal insert using well known molding techniques. Some embodiments of cardguides 400 in shelf 100 are generally vertical, ladder-like structures that internally span laterally from a front access area to backplane assembly 500 and vertically from chassis bottom 202 to cover 201. Metal insert 402 can be stainless steel, assisting in ruggedly holding an AMC or MicroTCA module, providing a strong latch post element, reducing/preventing module movement that affects latching, etc.

Some 2U cardguide embodiments (e.g., Figs. 3A-D, 21 A-27D) hold a vertical "stack" of four AMC cards, though the number and proportions of cardguides can be adjusted. Cardguide 400 in shelf 100 of Fig. 3 C (a) uses front anchor slots 406 to connect to front chassis cover hem 271 and bottom hem 272, and (b) back anchor slots 409 lodged in gaps in upper and lower z- strips 210 adjacent backplane assembly 500. In Figs. 23, 24A metal insert part 402A is exposed in upper front cardguide slot 406 and contacts hem 271 where cover 201 bends around spacer 212, thus conducting electricity between ESD clip 412 and ground. Front slot 406 holds hem 271 in contact with insert 402 A using plastic 404A underneath cover 201 to ensure a tight fit and conductivity between metal components (i.e., from AMC module face plate to clip 412 to button 418 to insert 402 to chassis 200). Also, in Figs. 23, 24B, insert 402 is exposed as fin 423 in lower cardguide slot 408 to contact hem 272 (again for electrical grounding). Hem slots 203 (per Figs. 1 IA, 14A) in hem 272 further assist to anchor cardguide 400 to chassis 200. The back ends of 2U cardguide 400 can be anchored in flap slots 207 (upper and lower) in z-strips 210 fixed to the back inner cover 201 and bottom 202 of chassis 200. In a IU shelf (Figs. 1, 2 and 28A-31) cardguides 450 typically can stack and guide two

AMC modules into shelf 100 to connectors 504 on PCB 502. The examples of cardguides 450 show metal insert 402 and plastic molding 404, but a different shelf anchoring than that shown with examples of 2U cardguides 400 above. Cardguide 450 has front fins 419 and rear fins 429 that are extensions of metal insert 402. Front fins 419 engage hems 271, 272 and slots 203 to anchor and ground cardguide 450. Likewise, rear fins 429 engage z-strips 210. Both front fins 419 and rear fins 429 can lie inside and be welded to slots 209 to further enhance grounding. Such configurations provide rigid support, good electrical grounding, a strong link to prevent chassis top/bottom separation, visually confirmable cardguide seating, etc.

ESD clips 412, also part of the cardguide metal grounding structure, snap onto cardguides (Figs. 26A-27D). Each cardguide 's AMC channel 414 has a plastic tab 416 and adjacent metal button 418 (another exposed part of metal insert 402). Each ESD clip 412 snaps onto a tab 416 so that clip 412 firmly contacts adj acent metal button 418 and so that clip 412 partially obstructs slot channel 414 (see end-on views of Fig. 27B and 27D where clip 412 encroaches into channel 414). As will be appreciated in the art, placement of clip 412 in slot channel 414 means that each AMC module's PCB contacts clip 412, ensuring immediate and safe discharge of static electricity as an AMC module is inserted into (and drawn out of) channel 414 of cardguide 400. Static electricity is conducted from an AMC module PCB through clip 412 to button 418. Because button 418 is part of metal insert 402, conductively connected to chassis 200 in cardguides 400/450, static electricity is conducted to a chassis ground. Such simple, reliable and inexpensive cardguide embodiments provide reliable AMC module guidance and reliable grounding of the AMC modules for ESD purposes. When a power unit, AMC module, etc. is inserted into a shelf, MicroTCA standards require that the module be locked into the shelf. Inserted modules have strikers that engage and are held by cardguide latch posts. Posts are usually made of stainless steel and strikers of die cast zinc or aluminum, leading to gouging of the striker's engagement edge by the harder engagement edges of earlier devices' posts, in turn leading to snagging of strikers on modules withdrawn from a shelf. Trying to mitigate this problem, MicroTCA was amended to require striker engagement surfaces to use rounded serrations, as seen in Figs. 31A-32. Despite the rounded serrations, posts still gouged strikers (see Fig. 32). Cardguide embodiments shown in Figs. 28B and 31 A show a rounded serration striker 471 and a cardguide post 473 featuring a rounded or beveled post engagement edge 475. Post 473 is another extension (e.g., a bent tab) of metal insert 402 of cardguides 400/450. Post engagement edge 475 is rounded to match or approximate (or beveled to approximate) the radius of curvature of each serration (radial increment) on the striker engagement edge 474 of striker 471 (e.g., serrations called out in the MicroTCA.l Rl .0 specification), thus distributing the locking force 478 of post 473 more evenly in a given serration curve as opposed to earlier devices wherein a sharp-edged latching post applied the force to a single point on the striker, gouging the striker surface, while being optimal for preventing the striker from sliding on the post. The post 473 is hard enough that striker 471 will not wear/round post edge 475 sufficiently to allow sliding disengagement of striker 471. Engagement of post 473 by strikers 471 has been further enhanced using cardguide embodiments as shown in Fig. 30, where the stepped profile of an AMC face plate is matched by a stepped cardguide slot profile 477. Thus the AMC module face plate matches and mates with cardguide channel 414 (including step 477) much more closely, thus providing a tighter fit of the AMC module in the cardguide and shelf and reducing/preventing undesirable movement and/or disconnection. Moreover, in each cardguide 400/450 adjacent each latching post 473, a window 494 is provided through which locking of a striker 471 against post 473 can be seen by a user. Making the striker 471 visible to a user allows the user to confirm proper insertion and engagement of an AMC module in a shelf. Thus cardguide embodiments address three AMC latching mechanism failures - (1) separation of striker and post allowing the striker to slip; (2) a striker sliding up a post due to insufficient friction/holding; and (3) unlatching problems due to the post cutting/gouging the striker.

The many features and advantages of the present invention are apparent from the written description, and thus, the appended claims are intended to cover all such features and advantages of the invention. Further, because numerous equivalent modifications and changes are apparent to those skilled in the art, the present invention is not limited to the exact construction and operation as illustrated and described. Therefore, the described embodiments should be taken as illustrative and not restrictive, and the invention should not be limited to the details given herein but should be defined by the following claims and their full scope of equivalents, whether foreseeable or unforeseeable now or in the future.

Claims

CLAIMS What is claimed is:

1. A MicroTCA shelf characterized by: a chassis adapted to accept a backplane holder assembly and comprising a pair of chassis sidewalls, a chassis cover having an internal top backplane flap and a chassis bottom having an internal bottom backplane flap; and the comprising a backplane held in a backplane holder, wherein the backplane holder comprises a back wall, a top flange, a bottom flange and two side flanges, wherein each flange is planar and is at a 90° angle to the back wall, wherein the backplane is held by the backplane holder generally parallel to the back wall and further wherein none of the flanges encroaches into a datum plane of the backplane; further wherein the backplane holder assembly is adapted to slide telescopically into and out of the chassis, wherein said backplane holder top flange is slidable in a cavity defined by the top backplane flap and chassis cover to create an interlock to position the backplane and contain EMI and the backplane holder bottom flange is slidable in a cavity defined by the bottom backplane flap and chassis bottom to create an interlock to position the backplane and contain EMI; further wherein two-dimensional positioning of the backplane in the backplane holder is maintained using a plurality of backplane periphery tabs that engage mating recesses on the backplane holder flanges.

2. The MicroTCA shelf of Claim 1 further characterized by: a plurality of cardguides mounted to the chassis, each cardguide comprising: a plastic support defining a plurality of AMC module channels and comprising a stepped profile adapted to match and mate with an AMC module faceplate profile to reduce movement of an AMC module in the AMC module channel; and a metal grounding structure comprising a sheet metal insert partially enclosed inside the plastic support and providing rigidity to the plastic support, the sheet metal insert comprising: a plurality of buttons extending out of the plastic support, each button adjacent to one of the AMC module channels, wherein each button is coupled to an electrostatic discharge (ESD) clip adapted to maintain contact with any module in the adjacent AMC module channel; and a latching post comprising a bent metal tab of the sheet metal insert adjacent each button and adapted to engage an AMC module striker to lock an AMC module inside the chassis for operational engagement with the backplane, wherein the latching post comprises a rounded post engagement edge adapted to engage an AMC module striker, wherein the AMC module striker comprises a striker engagement edge serrated in radial increments and further wherein the rounding of each latching post rounded post engagement edge matches a radial increment of the striker engagement edge; the cardguide further characterized by a window adjacent the latching post through which locking of the striker against the post can be visually verified.

3. The MicroTC A shelf of Claim 2 further characterized by: one or more cooling units electrically coupled to the backplane, each cooling unit comprising a plurality of fans mounted to a bracket using one or more bracket indents that hold the fan in the bracket, wherein each fan includes a vibration-damping layer between the fan and the bracket; and electrical circuitry configured to provide power and control signals to the fans.

4. The MicroTCA shelf of Claim 3 further characterized by: a module slot in a chassis front access area and comprising a grounding clip welded to the chassis, wherein the grounding clip encroaches on the module slot and is adapted to automatically physically contact a module being inserted into the module slot so that the inserted module is grounded during insertion into the shelf and during operational engagement within the shelf.

5. The MicroTCA shelf of Claim 2 or 4 further characterized by each cardguide being mounted to the chassis using at least one of the following: a plurality of mounting fins extending outside the plastic support, wherein each cardguide is adapted to be mounted inside the chassis by affixing in electrical contact two or more mounting fins to the chassis; a plurality of front mounting slots and a plurality of back mounting slots, wherein each front mounting slot is adapted to be secured to a hem in the chassis, further wherein each back mounting slot is adapted to be secured to an edged flap adjacent to the chassis, further wherein at least one of the front and back mounting slots is adapted to provide electrical contact between the metal grounding structure and the chassis.

6. The MicroTCA shelf of Claim 1, 2, 3 or 4 wherein the chassis comprises a plurality of screw holes and nutplates to which the backplane holder assembly is adjustably secured to hold a backplane front surface securely against the top and bottom backplane flap flaps.

7. The MicroTCA shelf of Claim 4 further characterized by the grounding clip comprising a plurality of fingers that flexibly contact the module during and after insertion into the shelf.

8. The MicroTCA shelf of Claim 1, 2, 3, 4 or 7 further characterized by: the backplane comprising one or more contacts providing access to at least one of the following: commonly used diagnostic signals, one or more bus signals, one or more clock signals, ground; wherein at least one chassis sidewall comprises one or more access points, each access point comprising a sidewall hole adapted for probe access to one or more of the backplane contacts without requiring removal or disassembly of any chassis component from its normal operational configuration.

9. The MicroTCA shelf of Claim 3, 4 or 7 wherein the mounting of the plurality of fans in each cooling unit using a plurality of bracket indents is not sufficiently secure to prevent vibration and noise, further wherein the vibration-damping layer between the fan and the bracket further secures the fan from movement and to prevent noise due to fan operation and vibration.

10. The MicroTCA shelf of Claim 3, 4 or 7 wherein each cooling unit is hot swappable.

11. A MicroTCA shelf comprising a chassis and a backplane holder assembly mounted to the chassis and comprising a PCB having a front surface, the shelf characterized by: the chassis comprising: a plurality of edged flaps on the inside surface of the chassis; a plurality of cardguides each comprising a cardguide slot having a latching post for locking an AMC module inside the chassis for operational engagement with the PCB, wherein each cardguide is secured to the chassis and to the plurality of edged flaps; wherein the backplane holder assembly holds the PCB front surface securely against edges of the plurality of edged flaps; further wherein the spacing between each latching post and the front surface of the PCB is defined by the dimensions of the cardguides and the edged flaps engaging the front surface of the PCB.

12. The MicroTCA shelf of Claim 11 wherein the spacing between each latching post and the front surface of the PCB is further defined by the chassis position at which the cardguide is secured and the chassis positions at which the edged flaps are located.

13. The MicroTCA shelf of Claim 11 or 12 further characterized by the backplane holder assembly comprising a backplane holder comprising a pair of mounting flanges each comprising a plurality of mating recesses; and the PCB comprising a plurality of tabs about the periphery of the PCB, wherein the tabs engage the mating recesses to located the PCB relative to the backplane holder; wherein the backplane holder assembly holds the PCB front surface securely against the edges of the plurality of edged flaps by securing the backplane holder assembly to the chassis.

14. The MicroTCA shelf of Claim 11 or 12 wherein the chassis comprises a plurality of screw holes and nutplates to which the backplane holder assembly is adjustably secured to hold the PCB front surface securely against the edges of the plurality of edged flaps.

15. A MicroTCA shelf characterized by: a chassis comprising a pair of chassis sidewalls, a chassis cover having an internal top backplane flap and a chassis bottom having an internal bottom backplane flap, the chassis defining a front access area and a back access area, the back access area being adapted to accept a backplane holder assembly; and the backplane holder assembly adapted to slide telescopically into and out of the chassis back access area and comprising a PCB held in a backplane holder, wherein the backplane holder comprises a top flange slidable in a cavity defined by the top backplane flap and chassis cover and a bottom flange slidable in a cavity defined by the bottom backplane flap and chassis bottom.

16. A MicroTCA shelf comprising a chassis and a backplane holder assembly, the backplane holder assembly characterized by a backplane holder having a PCB held thereby and being configured to slide into and out of the chassis, the backplane holder comprising a back wall, a top flange, a bottom flange and two side flanges, wherein each flange is planar and is at a 90° angle to the back wall, wherein the PCB is held by the backplane holder generally parallel to the back wall and further wherein none of the flanges encroaches into the datum plane of the PCB.

17. The MicroTCA shelf of Claim 15 wherein each backplane flap inside the chassis is one or more of: a z-strip secured to the interior surface of the chassis cover and/or chassis bottom; a rigid strip secured to the interior surface of the chassis cover and/or chassis bottom; a lance and form flap cut from the chassis cover and/or chassis bottom.

18. The MicroTCA shelf of Claim 15 or 16 wherein the chassis remains intact when the backplane holder assembly slides out of the chassis.

19. The MicroTCA shelf of Claim 15 wherein the top flange and chassis cover overlap to contain EMI, and further wherein the bottom flange and the chassis bottom overlap to contain EMI.

20. The MicroTCA shelf of Claim 15 or 16 wherein the PCB is held in the backplane holder using a plurality of tabs on the PCB periphery engaging a plurality of mating recesses on the backplane holder flanges to maintain two-dimensional positioning of the PCB relative to the backplane holder.

21. The MicroTCA shelf of at least one of Claims 15-20 wherein one or more AMC connectors are secured to the PCB without screws.

22. The MicroTCA shelf of Claim 21 wherein each AMC connector is connected to the PCB using automated SMT connectors.

23. The MicroTCA shelf of at least one of Claims 15-22 further characterized by the shelf comprising fewer than 40 screws.

24. A MicroTCA shelf characterized by: a chassis adapted to accept a backplane holder assembly and comprising a pair of chassis sidewalls, a chassis cover having an internal top backplane z-strip and a chassis bottom having an internal bottom backplane z-strip; and the backplane holder assembly adapted to slide telescopically into and out of the chassis and comprising a backplane held in a backplane holder, wherein the backplane holder comprises a top flange slidable in a cavity defined by the top backplane z-strip and chassis cover to create an interlock to position the backplane and contain EMI and a bottom flange slidable in a cavity defined by the bottom backplane z-strip and chassis bottom to create an interlock to position the backplane and contain EMI; wherein the backplane holder comprises sheet metal defining a back wall, the top flange, the bottom flange and two side flanges, wherein each flange is planar and is at a 90° angle to the back wall, wherein the backplane is held by the backplane holder generally parallel to the back wall and further wherein none of the flanges encroaches into the backplane datum plane; and further wherein two-dimensional positioning of the backplane is maintained in the backplane holder using a plurality of backplane periphery tabs that engage mating recesses on the backplane holder flanges.

25. A MicroTCA shelf comprising a metal chassis defining a front access area, the shelf characterized by a module slot in the front access area and comprising a grounding clip welded to the chassis, wherein the grounding clip encroaches on the module slot and is adapted to automatically physically contact a module being inserted into the module slot so that the inserted module is grounded during insertion into the shelf and during operational engagement within the shelf.

26. The MicroTCA shelf of Claim 25 further characterized by the grounding clip comprising a plurality of resilient members that flexibly contact the module during and after insertion into the shelf.

27. The MicroTCA shelf of Claim 26 wherein the plurality of resilient members comprises a plurality of fingers and further wherein the grounding clip is adapted to ground any inserted

AMC and/or MicroTCA module.

28. A MicroTCA shelf comprising a chassis defining a front access area, the shelf characterized by an AMC and/or MicroTCA module slot in the front access area and comprising a grounding clip secured to the chassis, wherein the grounding clip encroaches on the module slot to automatically contact a module inserted into the module slot so that the inserted module is grounded.

29. A MicroTCA shelf comprising a chassis comprising a pair of opposing sidewalls, a chassis cover and a chassis bottom, the shelf characterized by: a backplane coupled to the chassis and comprising one or more contacts providing access to at least one of the following: commonly used diagnostic signals, one or more bus signals, one or more clock signals, ground; wherein at least one sidewall comprises one or more access points, each access point comprising a sidewall hole adapted for probe access to one or more of the backplane contacts without requiring removal or disassembly of any chassis component from its normal operational configuration.

30. A MicroTCA shelf comprising a chassis and a backplane holder assembly comprising a backplane and being mounted to the chassis, the shelf characterized by: a plurality of cardguides mounted to the chassis, each cardguide comprising: a plastic support defining a plurality of AMC module channels; a metal grounding structure comprising a metal insert partially enclosed inside and providing rigidity to the plastic support, the metal insert comprising: a plurality of buttons extending out of the plastic support, each button adjacent each AMC module channel, wherein each button is coupled to an electrostatic discharge (ESD) clip adapted to maintain contact with any module in the adjacent AMC module channel; a plurality of front mounting slots, wherein each front mounting slot is adapted to be secured to a hem in the chassis; and a plurality of back mounting slots, wherein each back mounting slot is adapted to be secured to an edged flap adjacent to the chassis; wherein at least one of the front and back mounting slots is adapted to provide electrical contact between the metal grounding structure and the chassis.

31. A MicroTCA shelf comprising an electrically grounded chassis made at least in part of electrically conductive material, a backplane holder assembly comprising a backplane PCB, and a plurality of AMC cardguides, wherein each cardguide comprises: a support made of electrically non-conductive material secured to the chassis, the support configured to guide an AMC module when it is inserted into the chassis; a metal insert partially encased by the bracket, the metal insert comprising: an exposed portion in electrical contact with the chassis; and an AMC card contact configured to contact an AMC card as it is inserted into the chassis.

32. The MicroTCA shelf of Claim 31 wherein the support is plastic that is molded around a portion of the metal insert.

33. The MicroTCA shelf of Claim 31 or 32 wherein the AMC card contact is an electrically conductive snap-in clip, and further wherein the snap-in clip can be configured in different sizes and shapes to be adaptable to different AMC card types and sizes or other AMC modules.

34. The MicroTCA shelf of Claim 31, 32 or 33 wherein the metal insert is a sheet metal frame.

35. The MicroTCA shelf of Claim 31, 32, 33 or 34 wherein the cardguide support is secured to the chassis using at least one of the following: welding, soldering, snapping into a slot.

36. A MicroTCA shelf comprising a chassis and a backplane holder assembly comprising a backplane and being mounted to the chassis, the shelf characterized by: a plurality of cardguides mounted to the chassis, each cardguide comprising: a plastic support defining a plurality of AMC module channels; a metal insert partially enclosed inside and providing rigidity to the plastic support, the metal insert comprising: a plurality of buttons extending out of the plastic support, each button adjacent each AMC module channel, wherein each button is coupled to an electrostatic discharge (ESD) clip mounted to the plastic support and adapted to stay in contact with any module in the AMC module channel; a plurality of mounting fins extending outside the plastic support, wherein each cardguide is adapted to be mounted inside the chassis by affixing in electrical contact two or more mounting fins to the chassis; and a latching post comprising a bent metal tab adjacent each button and adapted to engage an AMC module striker to lock an AMC module inside the chassis for operational engagement with the backplane.

37. The MicroTCA shelf of Claim 36 further characterized by the plastic support having a stepped profile adapted to match and mate with an AMC module faceplate profile to reduce movement of an AMC module in the AMC module channel.

38. The MicroTCA shelf of Claim 36 further characterized by each latching post having a rounded or beveled post engagement edge adapted to engage the AMC module striker, wherein the AMC module striker comprises a striker engagement edge serrated in radial increments and further wherein the rounding or beveling, respectively, of each latching post rounded or beveled post engagement edge matches or approximates a radial increment of the striker engagement edge.

39. The MicroTCA shelf of Claim 36, 37 or 38 further characterized by the cardguide comprising a window adjacent the latching post through which locking of the striker against the post can be visually verified.

40. The MicroTCA shelf of Claim 36, 37, 38 or 39 further characterized by at least two mounting fins being adapted to securely engage at least one of the following: an edged flap on the interior of the chassis; a hem formed by the chassis.

41. The MicroTCA shelf of Claim 40 further characterized by flap slots in each edged flap and hem slots in each hem to accept the portion of the cardguide from which each mounting fin extends to provide additional support of the cardguide within the chassis.

42. A MicroTCA shelf comprising an electrically grounded chassis made at least in part of electrically conductive material, a backplane holder assembly mounted to the chassis and comprising a backplane PCB, and a plurality of AMC cardguides mounted in the chassis, wherein each cardguide comprises: an electrically non-conductive support secured to the chassis and adapted to support an

AMC module during insertion into and use within the chassis; a metal grounding structure partially encased by the support and comprising: an exposed portion in electrical contact with the chassis; and an AMC module contact adapted to contact an AMC module while it is inside the chassis.

43. The MicroTCA shelf of Claim 42 wherein the support is plastic molded around a portion of the metal insert.

44. The MicroTCA shelf of Claim 42 or 43 wherein the AMC module contact is an electrically conductive snap-in clip, and further wherein the snap-in clip can be configured in different sizes and shapes to adapt to different AMC modules.

45. The MicroTCA shelf of Claim 42, 43 or 44 wherein the metal insert is a sheet metal frame.

46. The MicroTCA shelf of Claim 42, 43, 44 or 45 wherein the cardguide is secured to the chassis using at least one of the following: welding, soldering, snapping into a chassis slot.

47. The MicroTCA shelf of Claim 45 further characterized by each cardguide comprising a plurality of AMC module latching posts, wherein each latching post is a bent tab of the sheet metal adjacent each AMC module contact and adapted to engage an AMC module striker to lock an AMC module inside the chassis for operational engagement with the backplane PCB.

48. A MicroTCA shelf comprising a chassis to which a plurality of cardguides are affixed, each cardguide comprising a plastic support defining a plurality of AMC module channels adapted to support an AMC module during insertion into and use within the chassis and further comprising a metal grounding structure partially enclosed inside the plastic support, each cardguide characterized by at least one of the following: the metal grounding structure comprising a plurality of mounting fins extending outside the plastic support, wherein each cardguide is adapted to be mounted inside the chassis by affixing in electrical contact two or more mounting fins to the chassis, by engaging at least one of the following: an edged flap on the interior of the chassis; a hem formed by the chassis; the metal grounding structure comprising a button extending out of the plastic support adjacent each AMC module channel, wherein each button is coupled to an electrostatic discharge (ESD) clip mounted to the plastic support and adapted to stay in contact with any module in the AMC module channel; the plastic support having a stepped profile adapted to match and mate with an AMC module faceplate profile to reduce movement of an AMC module in the AMC module channel; the metal grounding structure comprising a metal insert providing rigidizing support to the plastic support; the metal grounding structure comprising a sheet metal insert comprising a plurality of latching posts, each latching post comprising a bent tab of the sheet metal insert and adapted to engage an AMC module striker to lock an AMC module inside the chassis for operational engagement with a backplane; the metal grounding structure comprising a latching post having a rounded or beveled post engagement edge adapted to engage an AMC module striker, wherein the AMC module striker comprises a striker engagement edge serrated in radial increments and further wherein the rounding or beveling, respectively, of each latching post rounded or beveled post engagement edge matches or approximates a radial increment of the striker engagement edge; the cardguide comprising a window adjacent an AMC module latching post through which locking of an AMC striker against the latching post can be visually verified; the metal grounding structure being secured to the chassis using at least one of the following: welding, soldering, snapping into a chassis slot.

49. A MicroTCA shelf comprising a chassis, at least one cooling unit held in the chassis, a backplane holder assembly comprising a backplane, one or more cooling units electrically coupled to the backplane, a power module coupled to the backplane, and a plurality of AMC cardguides, wherein each cooling unit comprises: a plurality of fans mounted to a bracket, wherein each fan includes a vibration-damping layer between the fan and the bracket; and electrical circuitry configured to provide power and control signals to the fans.

50. The MicroTCA shelf of Claim 49 wherein the vibration-damping layer comprises double-sided foam adhesive sufficient to isolate fan vibration from the bracket and further sufficient to prevent resonant ringing.

51. A MicroTCA shelf comprising a chassis, at least one cooling unit held in the chassis, a backplane holder assembly comprising a backplane, a power module coupled to the backplane, and a plurality of AMC cardguides, each cooling unit characterized by a plurality of fans mounted to a bracket, wherein each fan is mounted to the bracket using one or more bracket indents that secure the fan in the bracket.

52. The MicroTCA shelf of Claim 49 wherein each bracket indent engages a fan mounting hole.

53. The MicroTCA shelf of Claim 51 or 52 wherein the mounting of the plurality of fans in each cooling unit using a plurality of bracket indents is not sufficiently secure to prevent vibration and noise, the cooling unit further characterized by each fan including a vibration- damping layer between the fan and the bracket to further secure the fan from movement and to prevent noise due to fan operation and vibration.

54. A MicroTCA shelf comprising a chassis, at least one cooling unit held in the chassis, a backplane holder assembly comprising a PCB, and a plurality of AMC cardguides, the MicroTCA shelf characterized by: an air filter assembly positioned between the cooling unit and the cardguides, the air filter assembly comprising a filter and a filter holder; wherein the filter holder comprises an outer, generally rectangular frame and a plurality of support strips; wherein the air filter assembly is slidable in and out of the MicroTCA shelf and further wherein each support strip is generally parallel to direction of sliding the air filter assembly in and out of the MicroTCA shelf.

55. A MicroTCA shelf comprising a chassis, at least one cooling unit held within the chassis, a backplane holder assembly comprising a backplane printed circuit board (PCB), and a plurality of AMC cardguides, the MicroTCA shelf further comprising: an air filter assembly positioned between the cooling unit and the cardguides, the air filter assembly comprising a filter and a filter holder; wherein the filter holder comprises an outer, generally rectangular frame; wherein the frame comprises a lance and form detent configured to holding the air filter assembly in place in the MicroTCA shelf when the air filter assembly is fully inserted into the shelf.

56. A MicroTCA shelf comprising a chassis, at least one cooling unit held within the chassis, a backplane holder assembly comprising a backplane printed circuit board (PCB), and a plurality of AMC cardguides, the MicroTCA shelf further comprising: an air filter assembly positioned between the cooling unit and the cardguides, the air filter assembly comprising a filter and a filter holder; wherein the filter holder comprises an outer, generally rectangular frame; wherein the frame comprises a plurality of supports that all have bent edges to facilitate sliding the air filter assembly into and out of the shelf without snagging.

57. A MicroTCA shelf comprising a chassis, at least one cooling unit held in the chassis, a backplane holder assembly comprising a backplane, a power module coupled to the backplane, and a plurality of AMC cardguides, wherein each cooling unit comprises: a plurality of fans mounted to a bracket; a handle mounted to the bracket; and electrical circuitry configured to provide power and control signals to the fans, wherein the electrical circuitry comprises hot swapping circuitry enabling hot swapping of each cooling unit.

58. The MicroTCA shelf of Claim 57 wherein hot swapping a cooling unit comprises: pushing a hot swap button on the cooling unit; the hot swapping circuitry deactivating the cooling unit; the cooling unit turning on a hot swap safe removal indicator light when the cooling unit is completely deactivated; removing the deactivated cooling unit; inserting the same cooling unit or a different cooling unit into the chassis; and the shelf energizing and activating the inserted cooling unit.

59. The MicroTCA shelf of Claim 57 or 58 wherein the cooling unit electrical circuitry is coupled to the backplane using one or more locator pins mounted to the backplane and a plurality of header pins mounted to the backplane.

60. The MicroTCA shelf of Claim 57 or 58 wherein at least one locator pin mounted to the backplane locates the cooling unit relative to the backplane.

61. The MicroTCA shelf of Claim 59 wherein at least one of the header pins is shorter than the other header pins and further wherein the shorter header pin is used to detect insertion of the cooling unit to a depth for operational engagement with the backplane.

62. The MicroTCA shelf of Claim 57, 58, 59, 60 or 61 wherein each cooling unit is held in the chassis using a standard latch.

63. The MicroTCA shelf of Claim 57, 58, 59, 60, 61 or 62 wherein no clamps are used to mount each cooling unit to the chassis.

64. The MicroTCA shelf of Claim 57, 58, 59, 60, 61, 62 or 63 wherein each fan is mounted to the bracket using at least one indent formed in the bracket.

65. The MicroTCA shelf of Claim 57, 58, 59, 60, 61, 62, 63 or 64 wherein each fan is electrically connected to the electrical circuitry using no-strip, no-solder connections.

66. A MicroTCA shelf having a chassis comprising at least one cooling unit and coupled to a backplane, the shelf characterized by each cooling unit engaging the backplane by: aligning the cooling unit for insertion into a cooling unit bay in the chassis; sliding the cooling unit into the cooling unit bay; mating an EMI gasket; engaging one or more locator pin tips with mating holes in the cooling unit; each locator pin lifting the inserted cooling unit; a short header pin on the backplane engaging an electrical socket on the cooling unit to confirm engagement of a plurality of long header pins with the electrical socket; activating the cooling unit; sliding a cooling unit striker cam from a standard latch over a cooling unit locking slot in the chassis; releasing the cooling unit striker to engage the cooling unit locking slot to lock the cooling unit in the chassis.

67. The MicroTCA shelf of Claim 66 further characterized by each cooling unit locked in the chassis being hot swappable by: pushing a hot swap button on the cooling unit; the hot swapping circuitry deactivating the cooling unit; the cooling unit turning on a hot swap safe removal indicator light when the cooling unit is completely deactivated; removing the deactivated cooling unit; inserting the same cooling unit or a different cooling unit into the chassis; and the shelf energizing and activating the inserted cooling unit.

68. A MicroTCA shelf comprising a chassis having a pair of opposing sidewalls, a chassis cover and a chassis bottom defining a front access area and a back access area; further comprising mounting flanges adjacent the front access area, wherein the mounting flanges are bent portions of the same sheet metal from the sidewalls.