Patent Description:
As electronic packaging density and dissipated power increase to achieve higher levels of electronic performance, the need for efficient thermal transport within electronic assemblies having electronic modules carrying printed circuit boards also increases. Even though electronic components are becoming smaller with greater processing capability, and operate at a much lower power, these two advantages may have a counterintuitive effect of increasing thermal density because circuit designers are expected to pack even more functionality into ever smaller circuit spaces, thus increasing heat generation and requiring more advanced cooling and thermal management.

Brute force heat transfer techniques may involve forced air, active liquid cooling, and similar heat transport mechanisms to transport heat from sensitive electronic components to heat sinks or similar heat spreading devices. Some heat transfer systems even use composite structures, for example, annealed pyrolytic graphite (APG) embedded within metallic skins or heat pipes connected to spreader plates.

A new industry standard, however, encourages the increased use of convection cooling to reduce dependence on conduction cooling using 3U and 6U circuit cards. The ANSI/VITA <NUM> mechanical form-factor standard leverages air-flow-through (AFT) cooling for chassis architectures to provide increased thermal performance while mitigating risk to electronic modules carrying different electronic components. The gas, normally air, is isolated to cooling paths adjacent the circuit board and the electronic components, where there are no foreign object debris (FOD), contaminants, or impingements to the airflow.

The VITA <NUM> AFT standard is directed to channeling airflow through plug-in module heat sinks that interface with a pressurized airflow manifold to reduce thermal resistances between the cooling medium and the heat-generating electronic components and provide a common framework for original equipment manufacturer (OEM) chassis and electronic module manufacturers. Designs that implement the VITA <NUM> AFT technology, however, may have technical drawbacks because of the complexity required in providing precision tapers on the plug-in electronic modules and the requirements for gaskets that interface components that cause binding. The gaskets may be compromised during insertion and extraction of the electronic modules.

Examples for electronic assemblies comprising chassis, sealing retainers and electronic modules, which are to be inserted into the chassis and/or sealing retainers, are disclosed by the documents <CIT>, <CIT>, <CIT> and <CIT>.

Generally, an electronic assembly comprises a chassis having a plurality of electronic module mounting positions. Each electronic module mounting position has a chassis cooling gas passageway. The electronic assembly also comprises a respective electronic module received in each electronic module mounting position and having a module cooling gas passageway. Each electronic module has a module glide surface. The electronic assembly further comprises a respective sealing retainer coupled between the chassis and each electronic module. The sealing retainer has a cooling gas passageway therethrough aligned with the chassis cooling gas passageway and the module cooling gas passageway. The sealing retainer comprises a retainer body having a retainer glide surface, and a gas sealing gasket carried by the retainer body. The module glide surface and the retainer glide surface have respective cooperating features so that the respective electronic module is maintained in spaced relation from the sealing gasket as the respective electronic module is slidably inserted into a seated position.

In embodiments according to the invention, one of the module glide surface and the retainer glide surface comprises a plurality of protrusions, and the other of the module glide surface and the retainer glide surface comprises a plurality of valleys. The plurality of valleys are aligned with the plurality of protrusions when the respective electronic module is in the seated position. The plurality of valleys are offset from the plurality of protrusions when the respective electronic module is not in the seated position. Optionally, each of the plurality of protrusions may comprise a roller device on an uppermost portion thereof.

Also, the module glide surface may comprise a tapered distal end. The sealing retainer may comprise a biasing member coupled between the retainer body and a respective electronic module mounting position. The sealing retainer may comprise a shoulder screw carried by the respective electronic module mounting position and extending through the retainer body. The chassis cooling gas passageway may comprise one of a chassis cooling gas inlet passageway and a chassis cooling gas outlet passageway. The electronic assembly may also comprise at least one cooling gas manifold coupled to the chassis. Each electronic module may comprise at least one circuit board having a cooling gas path associated therewith. Moreover, each electronic module may comprise a plurality of wedge lock style retainers adjacent the module glide surface, and a plurality of extraction levers for coupling to the electronic module mounting position.

Another aspect is directed to a method for mounting an electronic module in an electronic module mounting position of a chassis. Each electronic module mounting position has a chassis cooling gas passageway. The electronic module has a module cooling gas passageway, and a module glide surface. The method comprises coupling a sealing retainer between the chassis and the electronic module. The sealing retainer has a cooling gas passageway therethrough aligned with the chassis cooling gas passageway and the module cooling gas passageway. The sealing retainer comprises a retainer body having a retainer glide surface, and a gas sealing gasket carried by the retainer body. The module glide surface and the retainer glide surface have respective cooperating features so that the respective electronic module is maintained in spaced relation from the sealing gasket as the respective electronic module is slidably inserted into a seated position.

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings.

The VITA <NUM> AFT standard may not be widely adopted in the industry, and most designs may include shearing of seals when the electronic modules are inserted. Because of this, the existing approaches may not operate reliably since the damaged seals create openings/leaks in the cooling system. Moreover, the existing approach is wide, which creates SWaP issues.

Referring initially to <FIG>, an electronic assembly <NUM> according to the present disclosure is now described. The electronic assembly <NUM> includes a chassis <NUM> having a plurality of electronic module mounting positions 102a-102f. Each electronic module mounting position 102a-102f has opposing first and second chassis cooling gas passageways 103a-103f. As will be appreciated, only the first chassis cooling gas passageways 103a-103f are shown in <FIG>, but it should be appreciated that the second chassis cooling gas passageways are similarly constituted. Each chassis cooling gas passageway 103a-103f comprises one of a chassis cooling gas inlet passageway and a chassis cooling gas outlet passageway.

The electronic assembly <NUM> also comprises a respective electronic module <NUM> received in each electronic module mounting position 102a-102f and having a module cooling gas passageway <NUM>. For illustrative clarity, only one electronic module <NUM> is depicted. As shown in <FIG>, the respective electronic module <NUM> illustratively includes installation and extraction levers 106a-106b for assisting in overcoming the required seating forces and installing the electronic module to the proper depth when in a seated position. As shown in <FIG>, the module <NUM> illustratively includes wedge lock style retainers 118a and 118b for keeping the module <NUM> in the seated position. Each electronic module <NUM> comprises a circuit board <NUM> having a cooling gas path associated therewith, the cooling gas path extending between respective first and second chassis cooling gas passageways 103a-103f. For illustrative clarity, only one circuit board <NUM> is shown, but it should be appreciated that the electronic module may comprise a plurality of circuit boards. For example, the circuit board <NUM> may comprise an OpenVPX 3U circuit board format or an OpenVPX 6U circuit board format. Although not depicted for drawing clarity, the electronic assembly <NUM> includes a backplane circuit board receiving the respective circuit boards <NUM>.

The electronic assembly <NUM> comprises first and second cooling gas manifolds 109a-109b coupled to the chassis <NUM>. As will be appreciated, the first and second cooling gas manifolds 109a-109b respectively provide cool air into the chassis cooling gas inlet passageway, and receive warm air from the chassis cooling gas outlet passageway.

As perhaps best seen in <FIG>, each electronic module <NUM> has a module glide surface <NUM>. The electronic assembly <NUM> further comprises respective sealing retainers 110a-110b coupled between the chassis <NUM> and each electronic module <NUM>. The sealing retainer 110a-110b has a cooling gas passageway <NUM> therethrough aligned with the chassis cooling gas passageway 103a-103f and the module cooling gas passageway <NUM>.

The sealing retainer 110a-110b comprises a retainer body <NUM> having a retainer glide surface <NUM>, and a gas sealing gasket <NUM> carried by the retainer body. The gas sealing gasket <NUM> surrounds the cooling gas passageway <NUM> and ensures a tight seal (e.g. air tight or hermetic seal) for fluidly coupling to the first and second cooling gas manifolds 109a-109b. For example, the gas sealing gasket <NUM> may comprise a flexible material, such as rubber.

The retainer glide surface <NUM> comprises a plurality of protrusions 115a-115f, 116a-116f, and the module glide surface <NUM> comprises a plurality of valleys 117a-117f, 120a-120f. It should be appreciated that the arrangement of the plurality of protrusions 115a-115f, 116a-116f and the plurality of valleys 117a-117f, 120a-120f may be reversed on the retainer glide surface <NUM> and the module glide surface <NUM>.

Referring now to <FIG> & <FIG>, the module glide surface <NUM> and the retainer glide surface <NUM> have respective cooperating features so that the respective electronic module <NUM> is maintained in spaced relation from the gas sealing gasket <NUM> as the respective electronic module is slidably inserted into the seated position, as shown in <FIG> & <FIG>. The cooperating features comprise the plurality of protrusions 115a-115f, 116a-116f and the plurality of valleys 117a-117f, 120a-120f. As shown in <FIG>, the sealing retainer 110a-110b springs backward into the chassis <NUM> while the electronic module <NUM> is inserted. For example, the sealing retainer 110a-110b may retract a distance in the range of <NUM>-<NUM> mils. Advantageously, this may reduce wear on the gas sealing gasket <NUM> due to the electronic module <NUM> not rubbing (i.e. causing shear forces) on it during insertion and removal of the electronic module.

In particular, as shown in <FIG> & <FIG>, the plurality of valleys 117a-117f, 120a-120f is aligned with the plurality of protrusions 115a-115f, 116a-116f when the respective electronic module <NUM> is in the seated position. In other words, the plurality of valleys 117a-117f, 120a-120f is equally aligned onto the plurality of protrusions 115a-115f, 116a-116f so that respective protrusion fits into respective valleys, thereby positioning the gas sealing gasket <NUM> to be seated on and around the module cooling gas passageway <NUM>.

Alternatively, when the respective electronic module <NUM> is not in the seated position (i.e. the electronic module is being inserted into the respective electronic module mounting position 102a-102f of the chassis <NUM>), the plurality of valleys 117a-117f, 120a-120f are offset from the plurality of protrusions 115a-115f, 116a-116f. In other words, the plurality of valleys 117a-117f, 120a-120f are laterally spaced with respect to the plurality of protrusions 115a-115f, 116a-116f so that respective protrusion engages raised portions between respective valleys, thereby positioning the gas sealing gasket <NUM> to be spaced apart from the module cooling gas passageway <NUM>.

The respective cooperating features of the module glide surface <NUM> and the retainer glide surface <NUM> comprises first and second keyed surfaces. The first and second keyed surfaces would engage and maintain the spaced apart relation until the electronic module <NUM> is in the seated position. Once in the seated position, the first and second keyed surfaces would interface and abut each other (i.e. taking the seated position). The cooperating features may comprise protrusions having one or more of varying shapes, varying sizes, and varying laterally spacing therebetween so that no adjacent ones were identical, and avoiding premature seating of the retainer 110a-110b before the electronic module <NUM> is the seated position. The opposing side would include corresponding varying recesses. One or more of the plurality of protrusions 115a-115f, 116a-116f may comprise one or more roller devices (<FIG>).

As perhaps best seen in <FIG> & <FIG>, the electronic module <NUM> comprises first and second glide surface bodies 121a-121b defining a slotted opening <NUM> to be aligned with the cooling gas passageway <NUM> and the module cooling gas passageway <NUM>. The slotted opening is illustratively rectangular in shape. The glide surface body 121a-121b also defines a plurality of fastener receiving openings 122a-122b to receive fasteners 123a-123b (e.g. threaded screws) to couple the glide surface body to the electronic module <NUM>. The glide surface body 121a-121b has a first major surface to abut the electronic module <NUM>, and a second major surface opposite the first major surface and defining the module glide surface <NUM>.

The shown glide surface body 121a-121b is modular and coupled to a housing of the electronic module <NUM>. Alternatively, the glide surface body 121a-121b may be integral with a housing of the electronic module <NUM>. As perhaps best seen in <FIG>, the module glide surface <NUM> comprises a tapered distal end <NUM>, which helps guide the electronic module <NUM> during the insertion process. The glide surface body 121a-121b may comprise a polymer material having a low friction surface property.

As seen in <FIG>, the sealing retainer 110a-110b illustratively includes a biasing member <NUM> coupled between the retainer body <NUM> and a respective electronic module mounting position 102a-102f. The biasing member <NUM> may comprise a flexible foam material. The flexible foam material may lose needed flexibility at lower temperatures (e.g. -<NUM>). Optionally , the biasing member <NUM> includes one or more biasing devices, such as one or more coil springs or a leaf spring, and the flexible foam material is overmolded over the one or more biasing devices. The sealing retainer 110a-110b comprises first and second shoulder screws 126a-126b carried by the respective electronic module mounting position 102a-102f and extending through the retainer body <NUM>. As perhaps best seen in <FIG>, in cooperation with the biasing member <NUM> and the first and second shoulder screws 126a-126b, the sealing retainer 110a-110b is able to flexibly move as the respective cooperating features of the module glide surface <NUM> and the retainer glide surface <NUM> interact.

The electronic assembly <NUM> includes first and second sealing retainers 110a-110b on both sides of each electronic module mounting position 102a-102f. Also, the electronic module <NUM> includes first and second glide surface bodies 121a-121b cooperating with the first and second sealing retainers 110a-110b. Alternatively, these features may be limited to one side only (i.e. positive pressure cooling side).

Another aspect is directed to a method for mounting an electronic module <NUM> in an electronic module mounting position 102a-102f of a chassis <NUM>, each electronic module mounting position having a chassis cooling gas passageway 103a-103f. The electronic module <NUM> has a module cooling gas passageway <NUM>, and a module glide surface <NUM>. The method comprises coupling a sealing retainer 110a-110b between the chassis <NUM> and the electronic module <NUM>. The sealing retainer 110a-110b has a cooling gas passageway <NUM> therethrough aligned with the chassis cooling gas passageway 103a-103f and the module cooling gas passageway <NUM>. The sealing retainer 110a-110b comprises a retainer body <NUM> having a retainer glide surface <NUM>, and a gas sealing gasket <NUM> carried by the retainer body. The module glide surface <NUM> and the retainer glide surface <NUM> have respective cooperating features so that the respective electronic module <NUM> is maintained in spaced relation from the gas sealing gasket <NUM> as the respective electronic module is slidably inserted into a seated position.

Advantageously, the electronic assembly <NUM> may reduce seal shearing in VITA standards. Moreover, the approach disclosed herein may be durable and have a lifetime of up to <NUM> insertion cycles. Because the gas sealing gasket <NUM> is not subjected to seal shearing forces each insertion, the operation of the overall cooling system is not degraded. Moreover, the sealing retainer 110a-110b may be simple and less costly to produce. Indeed, the shown sealing retainer 110a-110b comprises the retainer body <NUM>, the gas sealing gasket <NUM>, and the biasing member <NUM>. Also, since the sealing retainer 110a-110b may be thin, as compared to typical approaches, the addition to the electronic assembly <NUM> is helpful for SWaP purposes.

Claim 1:
An electronic assembly (<NUM>) comprising:
a chassis (<NUM>) having a plurality of electronic module mounting positions (102a- 102f), each electronic module mounting position having a chassis cooling gas passageway (103a- 103f);
a respective electronic module (<NUM>) received in each electronic module mounting position and having a module cooling gas passageway (<NUM>), each electronic module having a module glide surface (<NUM>); and
a respective sealing retainer (110a - 110b) coupled between the chassis and each electronic module, the sealing retainer having a cooling gas passageway (<NUM>) therethrough aligned with the chassis cooling gas passageway and the module cooling gas passageway, the sealing retainer comprising
a retainer body (<NUM>) having a retainer glide surface (<NUM>), and
a gas sealing gasket (<NUM>) carried by the retainer body;
the module glide surface (<NUM>) and the retainer glide surface (<NUM>) having respective cooperating features so that the respective electronic module (<NUM>) is maintained in spaced relation from the sealing gasket (<NUM>) as the respective electronic module (<NUM>) is slidably inserted into a seated position,
wherein the electronic assembly (<NUM>) is characterized in that the cooperating features comprise a plurality of protrusions (115a - 115f, 116a - 116f) and a plurality of valleys (117a - 117f, 120a - 120f), and one of the module glide surface and the retainer glide surface comprises the plurality of protrusions, and the other of the module glide surface and the retainer glide surface comprises the plurality of valleys, wherein
the plurality of valleys is aligned with the plurality of protrusions when the electronic module is in the seated position so that respective protrusions fit into respective valleys, thereby positioning the gas sealing gasket to be seated on and around the module cooling gas passageway, and
when the electronic module is being inserted into the respective electronic module mounting position of the chassis, the plurality of valleys are offset from the plurality of protrusions so that respective protrusions engage raised portions between respective valleys, thereby positioning the gas sealing gasket to be spaced apart from the module cooling gas passageway.