Abstract:
A method for remanufacturing an electronic assembly allows the assembly to be disassembled, tested and reassembled despite certain components being permanently affixed to a housing of the assembly. The electronic assembly includes a circuit assembly within the housing. During remanufacture, a first portion of the housing is removed to expose a first side of the circuit assembly and a second portion of the housing is removed to expose a second side of the circuit assembly. When removing the second portion of the housing, one of the components of the circuit assembly may also be removed. During remanufacture a connector assembly including a replacement component substantially similar to the removed component, and including one or more pins connected to the replacement component and situated to mate with one or more empty sockets of the circuit assembly is used to facilitate testing of the assembly.

Description:
TECHNICAL FIELD 
     This patent disclosure relates generally to the remanufacture of electronic assemblies, and, more particularly, to a system for remanufacturing electronic assemblies wherein one or more electrical components of the assembly is removed prior to testing of the assembly. 
     BACKGROUND 
     With the advent of integrated electronics, electrical circuits have largely eliminated mechanical and electromechanical features in many applications, reducing the maintenance and adjustment chores associated with such applications. However, these electrical circuits as well as the mechanical aspects of the circuit housing, attachment points, and so on, may still occasionally require maintenance, adjustment, or even replacement. For example, power circuits may be exposed to excess heat and may be degraded. Vibration and other mechanical forces may affect the circuits and/or their housings or their connections to other circuit elements. 
     However, due to the relative permanence of integrated circuit assemblies, these assemblies are not often configured for easy disassembly, and disassembly may even require removal of one or more components from a board of the assembly. For example it is often advantageous to affix certain components to a housing or other nearby structure for purposes of heat transfer, mechanical support, and so on. However, by joining the board and housing in a semi-permanent manner, this practice can render one side of the board inaccessible, requiring removal of components to allow the remainder of the board to be accessed for inspection and repair. In such cases, the board no longer presents a fully functional device and it becomes difficult to test the remaining components. 
     Most of the testing solutions available today are directed to the testing of new boards being assembled rather than the testing of completed boards being disassembled for reconditioning, and thus are less than ideal for use in the context of remanufacturing and repair. For example, U.S. Pat. No. 6,486,686 to Fukasawa describes a bare-chip LSI mounting board test apparatus for testing a single chip (LSI) mounted on a board prior to mounting other components. The Fukasawa tester boards incorporate all other parts that will eventually be used on the LSI board and are interfaced to the LSI board via probes. In this state, a test signal is transmitted from a controller through the test boards to the LSI board to test the mounted LSI chip. However, this system requires that the board under test contain only a single chip (the LSI) which is generally not the case in the context of partial disassembly for remanufacture. In addition, rather than allowing the board under test to interface as it normally would, the board is forced to interface indirectly through the Fukasawa test boards, increasing complexity in the fixture and allowing additional avenues for inadvertent error. 
     SUMMARY 
     The disclosure describes, in one aspect, a method for remanufacturing an electronic assembly, the assembly including a housing having therein a circuit assembly comprising a plurality of components. In an example, the method comprises removing a first portion of the housing to expose a first side of the circuit assembly, removing a second portion of the housing to expose a second side of the circuit assembly, wherein removing the second portion of the housing includes removing at least one of the plurality of components, and placing the circuit assembly into a test fixture. The test fixture includes a test frame for receiving the circuit assembly, at least one connector assembly affixed to the test frame, the connector assembly including a replacement component substantially similar to the removed at least one of the plurality of components, and one or more pins connected to the replacement component and situated to mate with the one or more empty sockets of the circuit assembly when the circuit assembly is received in the test frame. Once the circuit assembly is placed in the fixture, the circuit assembly can be tested as if the at least one component had not been removed (e.g., a non-disassembled part). 
     In another aspect, the disclosure describes a test fixture for testing a partially disassembled circuit assembly. At least one component has been removed from the circuit assembly to create the partially disassembled circuit assembly, creating one or more empty sockets caused by the removal. In the described example, the test fixture comprises a test frame for having the partially disassembled circuit assembly affixed thereto. In addition, the test fixture comprises one or more connector assemblies affixed to the test frame, wherein each of the one or more connector assemblies comprises a replacement component similar in operation to the at least one removed component, and one or more pins connected to the replacement component and situated to mate with the one or more empty sockets of the partially disassembled circuit assembly when the partially disassembled circuit assembly is affixed to the test frame, whereby the partially disassembled circuit assembly can be tested as if the at least one component had not been removed. 
     In a further aspect, the disclosure describes a method for testing a partially disassembled circuit assembly that has had one or more components removed, so that the partially disassembled circuit assembly may be tested as if the one or more components had not been removed. The method comprises mounting the partially disassembled circuit assembly in a test frame, wherein the test frame comprises a one or more respective replacement components for each of the one or more removed components and a connector assembly for connecting the one or more respective replacement components to the circuit assembly at locations from which the one or more removed components were taken. Subsequently, the method comprises testing the partially disassembled circuit assembly as if the one or more removed components had not been removed from the circuit board. 
     Further features of various described embodiments will be appreciated from the remainder of this disclosure including the attached figures. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic overview of a remanufacturing process for an electronic assembly with circuit boards having one or more components affixed to a housing of the assembly; 
         FIG. 2  is a perspective front view of a circuit testing fixture for use in accordance with the principles disclosed herein; 
         FIG. 3  is a cross-sectional side view of a test frame and circuit under test for use in accordance with the principles disclosed herein, wherein the circuit under test is affixed to the test frame; 
         FIG. 4  is a cross-sectional side view of a test frame and circuit under test for use in accordance with the principles disclosed herein, wherein the circuit under test is released from the test frame; 
         FIG. 5  is a cross-sectional enlarged partial side view of a connector board and circuit under test for use in accordance with the principles disclosed herein; 
         FIG. 6  is a flow chart illustrating a method of testing a disassembled circuit in accordance with the principles disclosed herein; 
         FIG. 7  is a cross-sectional side view of an electronic assembly remanufacturable in accordance with the principles disclosed herein; and 
         FIG. 8  is a cross-sectional side view of a spring-loaded pin usable in accordance with the described principles. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates primarily to a system for remanufacturing circuit board assemblies and other electrical assemblies that require selective removal of one or more components from the assembly, e.g., for access to a portion of the assembly for repair or analysis. In general terms, the remanufacturing process with respect to a circuit assembly entails disassembly and testing of the assembly and/or portions thereof to identify remedial actions to be taken. The tested assembly is then reconditioned by adjustment or replacement of one or more parts or components pursuant to the testing or analysis performed, after which the part is reassembled and tested. 
     Typically, electronic assemblies such as ECUs that are intended for use in industrial or other demanding environments comprise an active portion, e.g., a printed circuit board, as well as a housing that protects the active portion from the ambient environment. Thus, this housing is typically removed to allow access to the active portion of the assembly for analysis, inspection, repair, and so on. However, in some cases, certain components of the active portion of the assembly may be affixed to a portion of the housing, so that the housing cannot be readily removed. For example, it is often advantageous to affix transistors, voltage regulators, and other power electronic components to the housing for purposes of heat transfer, mechanical support, and so on. Typically, a strong heat-conductive epoxy or other structural adhesive is used to attach the power electronic component to the housing. As such, it is difficult to mechanically separate the power electronic component from the housing to provide access to the board as a whole. In an illustrated embodiment, such components remain affixed to the housing and are instead detached from the board to allow access to the remainder of the board. 
     An example of such an arrangement is shown in the cross-sectional side view of an electronic assembly  78   FIG. 7 . A number of components  71 ,  72 ,  73  are attached to a top portion  74  of a clamshell type housing  79  that also comprises a mating bottom portion  75 . In this type of assembly, other components  76 ,  77  on the circuit assembly  70  are inaccessible for repair or replacement until the components  71 ,  72 ,  73  are desoldered so that the housing  74  (and components  71 ,  72 , and  73 ) may be lifted away from the board  70 . Typically the bottom portion  75  is removably held to the top portion  74  via screws, clamps, or other fastening means as will be appreciated by those of skill in the art. 
       FIG. 1  is a schematic overview of a remanufacturing process for electronic assemblies. At stage  1 , an electronic assembly such as an engine control unit (ECU) is provided for remanufacturing. For example, defective or outdated assemblies can be provided to a remanufacturing facility by a service facility. At stage  2 , the electronic assembly housing is opened. In the illustrated example, the electronic assembly comprises a clam shell housing such as illustrated in  FIG. 7  that is opened to access the circuit components of the assembly. In the case of an assembly wherein certain component are affixed to an upper portion of the clam shell housing, desoldering or other detachment of these components from the board at stage  3  allows the board to be separated from the upper portion of the clam shell housing, so that the other components on the board are no longer hidden by the upper portion of the clam shell housing and may be examined. 
     At stage  4  the board is tested to identify a defective component, which may then be replaced at stage  5 . Finally, the disassembled electronic assembly is reassembled at stage  6  to form a remanufactured electronic assembly. The unit is optionally tested again after reassembling to ensure proper operation before the unit is sold or otherwise placed back into service. 
     An example of a test fixture  11  in accordance with the principles disclosed herein is shown in the cross-sectional side view illustration of  FIG. 2 . The test fixture  11  comprises a number of components including a base  12  and one or more support arms  13 . The support arms  13  are adapted to bear pegs  14  that are connected to a test mount  15 . In this manner, the test mount  15  is rotatable within the fixture  11  and may be manipulated, e.g., via an arm  16  or other grip or lever. In an embodiment, the fixture  11  incorporates one or more set screws (not shown) or other means to prevent rotation of the test mount  15  within the fixture  11 . 
     The test mount  15  comprises a frame  17  that supports a number of further features of the fixture  11 . In the illustrated embodiment, the frame  17  supports one or more pads  18  for supporting a board under test (not shown in  FIG. 2 ) within the fixture  11  and one or more clamps  19  for holding the board under test against the pads  18 . The frame  17  further has mounted thereon one or more connector boards  20 . As will be described in greater detail later, the connector boards  20  include one or more chips or circuits (not visible in the top view of  FIG. 2 ) that are exposed to the board under test via a plurality of pins  21 . The pins may comprise a telescoping section operating along a common axis, that interact with the circuit under test via friction fit or otherwise. 
     The illustrated frame  17  embodies a centrally located opening  22  to allow access to the underside of the board under test when the board under test is clamped in the fixture  11 . The shape of the central opening  22  is not critical, but it preferably allows enough clearance so that all components or connections of interest are accessible to an operator. In an embodiment, the central opening  22  may be omitted. 
     The operation and further features of the fixture  11  and its use will be more fully appreciated from the cross-sectional side view of  FIG. 3 , which presents a cross-section of the test mount  15 . As can be seen from  FIG. 3 , a circuit board  30  is situated within the test mount  15  against the pads  18  of the frame  17 . The clamps  19  act to hold the board  30  in place positionally on the frame  17 . The clamps  19  may operate via spring tension, either downwardly or laterally against the board  30 , or may be moved into position via screws  31  or other means as will be appreciated by those of skill in the art. With the board under test  30  clamped in the frame  17 , the pins  21 , which pass through the opening  22  (not visible in  FIG. 3 ) in the frame  17 , are under longitudinal tension and are thus biased into contact with the board  30 . In an embodiment, the pins  21  comprise telescoping spring loaded assemblies that compress and/or are placed under tension when the board under test  30  is pressed against the frame  17 . An example of such a pin is described elsewhere herein in greater detail with reference to  FIG. 8 . 
     The pads  18  allow some degree of resilience to compensate for changing tolerances and slight loosening of components. In addition, the pads  18  also serve to electrically insulate the board under test  30  from the frame  17  so that the components of the board under test  30  do not short out against the frame  17  or otherwise have their operation affected by the fixture  11 . 
     The circuit board  30  comprises a nonconductive baseboard formed from a material such as glass, phenolic, fiberglass, plastic, fiber reinforced plastic, etc. For connecting various components to the board  30 , the board  30  typically comprises a number of metallic paths or “traces” adhered to one or both sides of the baseboard  30 . The circuit board  30  further comprises electrical components  32  mounted on a top surface of the board  30 . Such electrical components can include resistors, transistors, capacitors, inductors, switches, relays, connector blocks, integrated circuits, and any other electrical components whether discrete or integrated, active or inactive as needed to fulfill the requirements for the operation of the circuit board  30 . Typically, one or more of the electrical components comprise leads that extend through the board  30  to extend out the underside of the board  30 . 
     The traces by which components are attached to the circuit board  30  may be located on the top side of the board, e.g., the side whereupon the components  32  reside in the illustrated embodiment of  FIG. 3 , or may be located on the opposite side of the board  30 . In the illustrated example, the board under test  30  has been partially disassembled by the removal of four transistors having three leads each. Thus, the connector boards  20  have three replacement transistors  33  mounted thereon. For each transistor  33 , the three leads are connected to a respective three of the pins  21  exposed to the circuit board  30 . Thus, when the circuit board  30  resides in the fixture  11 , the missing transistors are effectively substituted by the replacement transistors  33  of the connector boards  20  so that the operation of the circuit board  30  may be fully tested. 
     To better appreciate the operation and functionality of the various components shown in  FIG. 3 , the cross-sectional side view of  FIG. 4  shows the circuit assembly  30  under test (i.e., “circuit under test”) removed from the frame  17 . As can be seen, the pins  21  have decompressed and are thus slightly extended compared to their compressed state. In the illustrated configuration, the board  30  has been removed to the extent that the pins  21 , although extended, no longer contact the board  30 . The clamps  19  are shown removed, although it is contemplated that hinged clamps that pivot without removal may alternatively be used. 
     A connector board  20  is illustrated in further detail in  FIG. 5 , which presents a cross-section of the connector board  20  and a portion of the circuit board under test  30 . It should be noted that although two connector boards  20  are employed in the illustrated embodiments and the illustrated connector boards  20  are symmetrical, there is no requirement that this be the case, and the connector boards  20  may alternatively be different in the configuration and number of boards  20  and/or components on the board(s)  20 . 
     As shown in  FIG. 5 , the connector assembly  20  (e.g., connector board) comprises a substrate  50 , which may be the same or similar nonconductive material as the baseboard of the circuit under test  30 , e.g., glass, phenolic, fiberglass, plastic, fiber reinforced plastic, etc. In the illustrated embodiment, the connector board  20  further comprises one or more replacement transistors  33 , which substitute for corresponding transistors removed from the circuit board under test  30  as indicated by outline  51 . The replacement transistors  33  comprise a mounting tab  52  which is attached to the substrate  50  via a screw  53  or other means. The replacement transistors  33  comprise three leads  54 , one of which can be seen in  FIG. 5 . Each lead of the one or more replacement transistors  33  is soldered or otherwise affixed to the base of a respective pin  21  so that at least the tip  55  of the pin  21  is in a conductive relationship with the respective lead of the associated replacement transistor  33 . 
     The circuit under test  30  comprises a socket  56  where the replaced transistor  51  was previously connected to the circuit under test  30 . As in the circuit prior to disassembly, the socket  56  is soldered or otherwise affixed to a metallic trace  57  on the board of the circuit under test  30 . In turn, the trace  57  remains linked to other circuitry, e.g., component  32 , on the board of the circuit under test  30  via soldered lead  58 . The component  32  may be further linked to other components (not shown) via another metallic trace  59 . 
     During use, as the circuit under test  30  is pressed into fixture  11 , the socket  56  compresses the pin  21  along its length, creating a spring-biased contact between the socket  56  and the pin  21 . This effectively brings the replacement transistor  33  into the circuit  30  in place of the removed transistor  51 . In an alternative embodiment, the socket  56  cooperates with the pin  21  in a frictional surrounding relationship rather than by compressing it. In this embodiment, the relative dimensions of the socket  56  and pin  21  are preferably coordinated to allow a relatively tight fit. If the fit between the socket  56  and pin  21  is overly loose, the necessary contact may be absent or intermittent, while if the fit is overly tight, the user may be unable to easily press the circuit  30  into the fixture  11 . 
     The fixture illustrated and discussed above enables a user to easily test a partially disassembled circuit without requiring the user to change the manner in which he or she connects other circuitry to the board and without requiring the user to reassemble the board. The flow chart of  FIG. 6  illustrates a process of using the fixture  11  according to an embodiment, although it is contemplated that other modes of usage will be apparent to those of skill in the art based on the foregoing disclosure. Referring to the process  60  of  FIG. 6 , a user or appliance removes one or more components from a circuit under test at stage  61 . This may be done for one or more of many reasons, including allowing access to the remainder of the circuit or isolating defects in the removed components from defects due to the remaining components and structure of the board. 
     At stage  62 , the user or appliance presses the partially disassembled board into a fixture such as that described above, and the board is optionally affixed to the fixture at stage  63 . The user or appliance then connects the board to a test facility in stage  64  in the same manner as would be used if the board had not been partially disassembled. For example, if the test protocol normally consists of connecting a 24-pin socket to a mating pin set on the board, then that is also how the partially disassembled board under test is connected in process  60 . 
     Finally, at stage  65 , the user or appliance executes a test process by sending a predetermined sequence of signals to the board via the connection made in stage  64 . Those of skill in the art will be aware of existing test sequences that may be sent to different types of boards to test them in the assembled state, and any such test sequences may be used in stage  65 . 
     Although any type of spring-loaded pin may be used as pin  21  in accordance with the described principle, an example pin  21  is illustrated in detail in the cross-sectional side view of  FIG. 8 . In the illustrated example, the pin  21  is cylindrical and comprises a tip  55  and a sheath  80 . The sheath  80 , which may be tubular, is configured to surround the pin  21  in a coaxial relationship. Although illustrated as electrically isolated for clarity, the tip  55  and sheath  80  are a least partially in electrical contact with one another. A shoulder  81  within the sheath  80  acts as an axial stop for spring  82 . The spring  82  biases the tip  55  in an upward direction, but is limited either by its relaxed length or a further stop so that the tip  21  and sheath  80  of the pin  21  remain connected even in the absence of external compression. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable to the remanufacture of electronic assemblies wherein one or more electrical components of the assembly is removed prior to testing and repair of the assembly. The electronic assembly may be of any type desired, but in an illustrated embodiment the electronic assembly is an Engine Control Unit (ECU) that comprises a plurality of transistors. The transistors may be glued or otherwise affixed to a housing of the ECU such that the components of the circuit board are largely inaccessible. 
     Such a configuration is shown in  FIG. 7 . In particular, as shown in  FIG. 7 , the transistors and other components  71 ,  72 ,  73  are attached to a top portion  74  of a clamshell type housing that also comprises a mating bottom portion  75 . In this type of assembly, other component  76 ,  77  on the board  70  are inaccessible for repair or replacement until the components  71 ,  72 ,  73  are decoupled from the board  70  so that the top portion  74  may be lifted away by elevating the part. Typically the bottom portion  75  of the housing is removably fixed to the top portion  74  via screws, clamps, or other fastening means as will be appreciated by those of skill in the art, allowing access to the inside of the housing to desolder or otherwise decouple the components to be removed. 
     The system described herein is advantageously capable of replicating a full circuit during remanufacture even though an electronic assembly may have been partially disassembled. The system disclosed herein further advantageously allows testing of the disassembled circuit in the same manner, e.g., via the same protocols and test sequences as would be used for the full circuit. 
     In the disclosed example, a test mount for use during remanufacture comprises a test frame rotatably mounted to allow access to the top and bottom of the circuit under test. The frame has a central opening to allow access, and comprises a plurality of clamps to retain the circuit under test during analysis as well as a plurality of pads to isolate the circuit from the frame. One or more connector boards affixed to the frame present a number of pins associated with replacement components on the connector boards so that the circuit under test will behave as a full circuit, and can be tested via the same protocols and test sequences as would be used for the full circuit. 
     It will be appreciated that the foregoing description provides examples of the disclosed system, structures, and techniques. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The term “plurality” is used to indicate more than one item, while the terms “at least one” and “one or more” are used to indicate one item or more than one item. 
     Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claim or claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.