Patent Publication Number: US-2013252456-A1

Title: Securing a Field Replaceable Unit

Description:
TECHNICAL FIELD 
     The field of the invention relates generally to computer systems, and more specifically, to securing field replaceable units within computer systems. 
     BACKGROUND 
     A typical computer system used in the electronics industry today includes one or more field replaceable units (FRUs). An FRU may be a circuit board, part, or assembly. An FRU may be docked to a backplane or motherboard of a chassis or rack contained within a computer system such as a personal computer, server, or other piece of electronic equipment. Generally, FRUs can be quickly and easily removed from the computer system and replaced by the user or a technician without having to send the entire computer system to a repair facility. A common manufacturing strategy is to install the FRUs, conduct a test of the computer system, and then package it for shipping to a customer. 
     SUMMARY 
     According to embodiments of the invention, an assembly having first and second components may be provided. The first component may include a first electrical connector and a guide member. The second component may include a second electrical connector to couple with the first electrical connector, and a receptacle to receive the guide member in a mated position. The assembly may have an adhesive between the guide member and the receptacle to form a bond between the guide member and the receptacle. The bond may be reversed when the adhesive is heated above a threshold temperature. In one embodiment, a heating element to heat the adhesive may be provided. 
     According to other embodiments, a method may be provided for mating a first component with a second component. The first component may have a first electrical connector and a guide member. The second component may have a second electrical connector and a receptacle to receive the guide member. The method may include an operation of providing an adhesive between the outer surface of the guide member and the inner surface of the receptacle. In addition, the method may include an operation of heating the adhesive above a threshold temperature. Further, the method may include an operation of cooling the adhesive below the threshold temperature after the heating of the adhesive above the threshold temperature. This operation may include the adhesive forming a bond between the guide member and the receptacle. The bond may be reversible above the threshold temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side view of an assembly having first and second electronic components in accordance with various embodiments of the present invention. 
         FIG. 2  is a side view of a second electronic component having a heating system in accordance with an embodiment. 
         FIG. 3A  is a side view with a diagrammatic representation of the receptacle and heating system of  FIG. 2  showing a guide member mated with the receptacle. 
         FIG. 3B  is a sectional view of the receptacle and a heating element of  FIG. 3A  along section AA. 
         FIG. 4A  is a side view with a diagrammatic representation of the receptacle, a guide member, and a heating system according to an alternative embodiment. 
         FIG. 4B  is a sectional view of the guide member and heating system of  FIG. 4A  along section AB. 
         FIG. 5  is a side view with a diagrammatic representation of a receptacle and a heating system according to an alternative embodiment. 
         FIG. 6  is a flow chart of a method according to an embodiment of the present invention. 
         FIG. 7  is a side view of an assembly having first and second electronic components in accordance with various embodiments of the present invention. 
     
    
    
     In the drawings and the Detailed Description, like numbers generally refer to like components, parts, steps, and processes. 
     DETAILED DESCRIPTION 
     In the electronics industry, a computer system is often composed of a number of different units coupled together in a final assembly phase. A common manufacturing strategy is to install one or more FRUs on a backplane or motherboard, conduct a test of the system, and then package it for shipping to a customer. It is most desirable to leave the FRUs connected after testing, but vibration during shipping may cause the electrical contacts of any mating components, such as electrical connectors, to rub against each other, causing wear or separation that may result in a connection failure. Aspects of the present invention provide an apparatus and method for securing an FRU in a way that reduces or eliminates movement, and which may, therefore, reduce or eliminate wear of electrical connector materials. An embodiment of the apparatus may be considered a retainer for securing an FRU or a circuit board assembly. 
     With reference now to  FIG. 1 , an assembly  90  according to various embodiments of the invention is shown. The assembly  90  may be an element of a computer system such as a mainframe, server, or personal computer. The assembly  90  may include a first electronic component  100  and a second electronic component  106 . The first electronic component  100  may include: a circuit board  101 , an electrical connector  102  having one or more electrically conductive elements  103 , and a guide member  104 . The circuit board  101  may include electric circuits, integrated circuits, connectors, sockets, slots, and other electrical and electronic components. The circuit board  101  may be a motherboard, mothercard, backplane, chassis, or any other similar computer system component. In one embodiment, the electrical connector  102  may be a socket, such as a socket for a circuit board, DIMM, or SIMM. 
     The shown guide member  104  is cylindrical and has a conical tip  105 . Other embodiments of the guide member may have members of various shapes and sizes. For example, a guide member may be a rod with three or more flat sides. In addition, a guide member tip may be rounded or flat. In addition, a guide member may be of any suitable length or cross sectional area. In one embodiment, a guide member is 0.75 inches in length and has a cross-sectional area of 0.5 square inches. While only one guide member  104  is shown, two or more guide members may be provided on the first electronic component  100  in alternative embodiments. 
     The second electronic component  106  may include: a circuit board  107 , an electrical connector  108  having one or more electrically conductive elements  109 , and a receptacle  110  having an aperture  111  for mating with the guide member  104 . The circuit board  107  may be a daughter card, a blade, or any other similar computer system component. The circuit board  107  may include electric circuits, integrated circuits, connectors, sockets, slots, and other electrical and electronic components. In one embodiment, the electrical connector  108  may be adapted for insertion into a socket or other “female” connector, e.g., the electrical connector  108  may include a portion similar to the bottom edge of a DIMM or SIMM. Also, the shown aperture  111  is cylindrical and has a chamfered opening  112 . Other embodiments may have an aperture of various shapes and sizes. For example, an aperture may have three or more flat sides. Further, an aperture may be deeper than the length of a guide member. While only one receptacle  110  is shown, two or more receptacles may be provided in alternative embodiments. 
     Referring still to  FIG. 1 , a layer of thermally-reversible adhesive  113  may be provided on either an outer surface  114  of the guide member  104 , as exemplified by location  115 , or on an inner surface  116  of the receptacle  110 , as exemplified by location  117 , or on both surfaces  114  and  116 . The surfaces  114 ,  116  may have a roughened texture or they may contain grooves or threads to encourage adhesive flow and to strengthen the resulting bond. The cross-sectional area of the aperture  111  may be larger than the cross-sectional area of the guide member  104  by an amount sufficient to accommodate the thermally-reversible adhesive  113  and to facilitate mating. 
     The receptacle  110 , guide member  104 , and connectors  102 ,  108  may all be discrete components, and each may be placed within or on the first component  100  or the second component  106  in any suitable location. In some embodiments, the receptacle  110  or guide member  104  may be formed integrally with the circuit board  107  or circuit board  101 . Additionally, in some embodiments, the receptacle  110  or guide member  104  may be formed integrally with the connectors  102  or  108  as shown in  FIG. 7 . Moreover, the first component  100  and second component  106  may include a like number of guide members and guide member receptacles. 
       FIG. 2  is a side view of a second electronic component  200  having a receptacle  204  and a heating system  206  according to an embodiment of the invention. In this alternative embodiment, the second component  200  may include: a circuit board  201 , an electrical connector  202  having a plurality of electrically conductive elements  203 , and a receptacle  204  having an aperture  205  for mating with a guide member. The receptacle  204  includes an interior surface  208  within the aperture  205 . The surface  208  may contain one or more reservoirs or depressions where the thermally-reversible adhesive  113  may be provided. As one example, a reservoir or depression may be formed at location  210 . Alternatively, a layer of thermally-reversible adhesive  113  may be provided on an outer surface of a guide member (not shown). Moreover, one or more reservoirs or depressions (not shown) may be provided on a guide member for holding thermally-reversible adhesive  113 . 
     The second electronic component  200  may include a heating system  206  having a heater control module  214 , wires  216  and  218 , and a heating element  220 . The assembly  90  may be an element of a computer system and the heater control module  214  may be a circuit communicatively coupled with this computer system. The heater control module  214  may provide power to the heating element  220  upon receiving an activation signal. The activation signal may be generated by the computer system in response to a software or hardware command received from a user. In one alternative, a button or switch may be coupled with the module  214  and the activation signal may be generated in the heater control module  214 , such as in response to the button or switch being pushed or moved to a connect position. In one embodiment, the heater control module  214  may receive the activation signal from the first electronic component  100 . Additionally, the heater control  214  may receive electric current sufficient to power the heating element  220  from the first electronic component  100 . The heater control module  214  may receive the activation signal or the electric current providing power via the electrical connectors  102  and  202 , or via a dedicated connector. In one alternative, the heater control module  214  may include an internal power supply, such as a battery. 
     Any part of the heating system  206 , such as the control module  214  or heating element  220  may be placed within or on the first electronic component  100  or the second electronic component  106 ,  200  in any suitable location. Further, it is not critical that every part of the heating system  206  be provided on the same electronic component. Some parts may be on one electronic component while other parts are on another electronic component. A factor of component location may be that the heating element  220  and the thermally-reversible adhesive  113  are positioned so as to allow thermal communication between them. 
     As described below, one property of the thermally-reversible adhesive  113  is that when heated, it may melt and flow between one or more surfaces, and when cooled, it may form a bond between the surfaces. In addition, the thermally-reversible adhesive  113  generally permits bonded surfaces to be easily de-bonded at least one time by applying heat to the adhesive. Accordingly, one aspect of the present invention is the ability to bond a guide member, e.g., member  104  and a receptacle, e.g., receptacle  110 , by a first heating of the thermally-reversible adhesive  113 . An additional aspect is the ability to easily separate the guide member and receptacle one time by re-heating and re-melting the thermally-reversible adhesive  113 . In an alternative embodiment, the process of mating and separating the guide member and receptacle may be repeated two or more times. These features may allow a user to remove an FRU and service it, or may allow the user to replace an FRU with a similar component. 
       FIG. 3A  is a side view of the receptacle  204  and heating system  206  of  FIG. 2  showing an exemplary guide member  300  mated with the receptacle  204 . The heating system  206  may be activated at any desired time after the guide member  300  is seated in the aperture  205 . As mentioned, the heating system  206  may be activated in response to receipt of an activation signal by the heater control module  214 . In response to the activation signal, the heater control module  214  causes the heating element  220  to receive electric current through wires  216  and  218 . When the receptacle  204  is heated above a threshold temperature and the thermally-reversible adhesive  113  is sufficiently heated, the adhesive melts and flows throughout a space  307  between the outer surface of the guide member and the inner surface of the receptacle. The heating system  206  may be deactivated in response to receipt of a deactivation signal by the heater control module  214 . The heater control module  214  causes the heating element  220  to stop receiving electric current through wires  216  and  218  in response to the deactivation signal. The heating element  220  may be turned off after it is determined that adhesive has melted and flowed throughout the space  307 . The receptacle and adhesive may then be allowed to cool. The adhesive  113  creates a solid bond between the guide member  300  and the receptacle  204  after cooling, thereby holding a first electronic component and a second electronic component immovable with respect to one another when subject to many types of vibrations, such as those typically experienced during the shipping of a computer system. 
       FIG. 3B  is a sectional view of the receptacle and heating element of  FIG. 3A  along section AA. The guide member  300  is seated in the aperture  205  of the receptacle  204  after the guide member  300  and receptacle  204  have been mated. The thermally-reversible adhesive  113  is shown as a solid bond between the guide member  300  and the receptacle  204 , the bond having been formed following the above-described heating and cooling steps. 
     As mentioned, the assembly  90  may be an element of a computer system and the deactivation signal may be generated by this computer system. The computer system may include a software or hardware timer, and may generate the deactivation signal after a particular time has elapsed. In one alternative, the deactivation signal may be generated in the heater control module  214 , such as in response to pushing a button or moving a switch to a disconnect position, the button or switch being coupled with the module. In yet another alternative, a temperature sensor may be provided in a location near the receptacle  204 . The temperature sensor may be coupled with a computer system or the heater control module  214 . Sensed temperature data may be used to generate a deactivation signal when a particular temperature is sensed. 
     With reference to  FIGS. 4A and 4B , an alternative embodiment of a guide member and heating system is shown.  FIG. 4A  is a side view of a guide member  400 , showing the guide member  400  mated with the receptacle  204 , and the thermally-reversible adhesive  113 .  FIG. 4B  is a sectional view of the assembly of  FIG. 4A  along the section AB. The guide member  400  resides in the aperture  205  of the receptacle  204 . As shown in  FIG. 4B , the guide member  400  may include a cavity  404  for receiving a heating element  405 , which may be embedded in a compacted mass  406  of refractory insulating material, such as magnesium oxide. Alternatively, only the heating element  405  may be embedded in the guide member  400  if, for example, the member is made of a material that does not need an electrical insulator between the heating element and the guide member. 
     When activated, the heater control module  214  transmits an electric current through wires  408  and  409  to the heating element  405  within the guide member  400 . The guide member  400  is then heated, which in turn heats the thermally-reversible adhesive  113 . The embodiment shown in  FIGS. 4A and 4B  may be used for any operation described herein that requires heating of the thermally-reversible adhesive  113 . 
     In further aspects of the invention, a guide member according to the principles of the invention may be made from a metal, such as steel, nickel, or aluminum; or may be made from a plastic, such as an acetal. 
       FIG. 5  is a side view of a receptacle and a heating system according to an alternative embodiment. The receptacle  502  includes an aperture  504 . A layer of a thermally-reversible adhesive  113  may be provided on either an outer surface of a guide member or on an inner surface  506  of the receptacle  502 , as described herein. In this embodiment, a heating element  508  is provided within the receptacle  502 . The heating element  508  is coupled with the heater control module  214  via wires  510 ,  512 . The heating element  508  may be helical, surrounding the aperture  504 . In various alternatives, the heating element  508  may be provided within the receptacle  502  on one or more sides of the receptacle or on the end opposite the aperture  504 . The heating element  508  may be surrounded entirely by material or structure of the heating element, or may be partially or completely exposed above a surface of the heating element. 
     The receptacle  502  may be heated, which in turn heats the thermally-reversible adhesive  113 . The embodiment shown in  FIG. 5  may be used for any operation described herein that requires heating of the thermally-reversible adhesive  113 . 
     In further aspects of the invention, a receptacle according to the principles of the invention, e.g., receptacle  110 ,  204 , or  502 , may be made from a metal, such as steel, nickel, or aluminum; or may be made from a plastic, such as an acetal. 
     In other embodiments of the invention, a heat source that melts a thermally-reversible adhesive may be completely separate from a computer system. For example, the heating of a thermally-reversible adhesive may be done using a heat gun or other external heat source. 
     The thermally-reversible adhesive  113  has the ability to melt when heated a first time and solidify when cooled a first time forming a strong physical bond, and the ability to dissolve the bond at least once when heated a second time. In addition, the thermally-reversible adhesive  113  may have the ability to repeat the heating and cooling process one or more times without degrading the bond formed when cooled. The thermally-reversible adhesive  113  has a threshold or melting temperature, i.e., a temperature above which the adhesive  113  is a fluid and below which it is solid. The thermally-reversible adhesive  113  may be a hot-melt adhesive, an acetal-based epoxy thermoset, or an acrylic or silicone material employing reversible Diels-Alder crosslinks. The adhesive  113  may either be commercially available, e.g., Jet-melt™ adhesive from 3M (Minnesota Mining and Manufacturing) Company of St. Paul, Minn., or be capable of being tailored to exhibit, for example, a melting temperature between 140° F. (60° C.) (one common system operating temperature) and 455° F. (235° C.) (solder reflow temperature). For example, the adhesive  113  may be a thermoplastic resin having a melting temperature of 264° F. (129° C.), which is generally well above one common system operating temperature but generally well below the solder reflow temperature. In addition, the adhesive  113  may be a hot-melt adhesive having a melting temperature of 385° F. (196° C.), which is also within the above-mentioned exemplary temperature range. In another example, the adhesive  113  may be an acrylic or silicone employing reversible Diels-Alder crosslinks that has been synthesized such that it is crosslinked at all temperatures up to 266° F. (130° C.) at which point a retro Diels-Alder reaction occurs, breaking the crosslinks and rendering the silicone fluid like. 
     In one alternative, the thermally-reversible adhesive  113  may have a melting temperature below an expected operating temperature of the computer system. For example, the computer system may include a cooling device operable to maintain the receptacle and guide member at temperatures below the generally expected operating temperature of the computer system. As a second example, vibrations of the type typically experienced during the shipping of a computer system may not be expected after installation of the system at a fixed location. As such, an adhesive  113  may have a melting temperature below an expected system operating temperature, provided the melting temperature is above a maximum temperature expected during shipping. In this example, the adhesive  113  may serve to prevent electrical connector wear due to vibration during shipping even though the adhesive may melt during system operation. By way of example, an adhesive  113  may have a melting temperature of 110° F. (43° C.), 120° F. (49° C.), or 130° F. (54° C.), these melting temperatures being above maximum temperatures expected during particular shipping circumstances. In one embodiment, a guide member may be provided with a container or cup at its base for receiving an adhesive having a melting temperature below an expected system operating temperature but above a maximum temperature expected during shipping. 
       FIG. 6  illustrates a flow chart of a method  600  for securing a first electronic component to a second electronic component according to an embodiment of the invention. The method includes, in operation  602 , mating a first electronic component having a first electrical connector and a guide member with a second electronic component having a second electrical connector and a receptacle for the guide member. In operation  604  may include providing an adhesive between the outer surface of the guide member and the inner surface of the receptacle. In operation  606 , the thermally-reversible adhesive, e.g., adhesive  113 , may be heated until it reaches a temperature above its melting temperature. In operation  608 , the thermally-reversible adhesive is cooled until it reaches a temperature below its melting temperature. The operation  604  may be performed after the operation  606 . The thermally-reversible adhesive may form a bond between the guide member and receptacle in operation  608 . The method  600  may include optional operations  610  and  612  following the operation  608 . In operation  610 , the thermally-reversible adhesive  113  may be heated above its melting temperature. In operation  612 , the first electronic component and second electronic components may be separated. 
     In one embodiment, the method  600  may include an optional operation  614 . The operations  602 ,  604 ,  606 , and  608  may be repeated. Moreover, the method  600  may include an optional operation  616  in which the operations  610  and  612  may be repeated. 
       FIG. 7  is a side view of an assembly  700  having first  702  and second  704  electronic components according to an embodiment. The first electronic component  702  may include: a circuit board  706 , an electrical connector  708  having one or more electrically conductive elements  710 , and a guide member  712 . The second electronic component  704  may include: a circuit board  714 , an electrical connector  716  having one or more electrically conductive elements  718 , and a receptacle  720  having an aperture  722  for mating with the guide member  712 . A layer of thermally-reversible adhesive  113  may also be provided. This embodiment is an alternative where the guide member  712  and the receptacle  720  are formed integrally with the connectors  708  or  716 . The embodiment shown in  FIG. 7  may also include a heating system of the types shown in  FIG. 3 ,  4 , or  5 , or any similar heating system. 
     The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.