Flattening circuit board assemblies using vacuum pressure

Abstract

An example method of flattening a circuit board assembly includes attaching the circuit board assembly to a structure having dimensions that partially enclose a space, where attaching the circuit board assembly to the structure forms a hermetic seal over the space, and where the structure has at least one port in fluid communication with the space. The method further includes applying a vacuum pressure to the space via the at least one port, wherein the vacuum pressure urges at least a portion of the circuit board assembly toward the space; and selectively dispensing a thermal interface material onto a portion of the circuit board assembly while the vacuum pressure is applied.

Description

Technical Field

[0001] This specification describes examples of systems for leveling circuit board assemblies using vacuum pressure. Background Art

[0002] The circuit board assembly may bend or buckle during the manufacturing process. For example, the center or middle of the circuit board assembly may be higher than all or part of the sides of the circuit board assembly. Such bending or buckling may have an adverse effect on operations performed during the manufacturing process involving the circuit board assembly. Summary of the invention

[0003] An example method of flattening a circuit board assembly includes attaching the circuit board assembly to a structure having dimensions that partially enclose a space, wherein attaching the circuit board assembly to the structure forms an airtight seal over the space, and wherein the structure has at least one port in fluid communication with the space. The method also includes applying vacuum pressure to the space via the at least one port, wherein the vacuum pressure pushes at least a portion of the circuit board assembly toward the space; and selectively dispensing a thermal interface material onto a portion of the circuit board assembly while applying the vacuum pressure. The method may include one or more of the following features, either individually or in combination.

[0004] The portion of the circuit board assembly may include a component on the surface of the circuit board assembly. The thermal interface material may be dispensed onto the surface of the component. Applying vacuum pressure may reduce the height deviation of the stack including the circuit board assembly and the structure in the vertical dimension. In some examples, the thermal interface material may not be dispensed onto all or some areas of the circuit board assembly that do not include the component.

[0005] In the absence of the vacuum, the circuit board assembly at least partially flexes relative to the structure. The vacuum pressure may be applied in a sufficient amount and for a sufficient duration to reduce or eliminate flexure of the circuit board assembly relative to the structure. The vacuum pressure may be applied in a sufficient amount and for a sufficient duration to flatten the circuit board assembly.

[0006] The structure may include a gasket that forms the airtight seal over the space between the circuit board assembly and the structure. The structure may include a rib within the space. The position of the rib may correspond to the position of the circuit board assembly that does not include a component. The rib may be configured to allow fluid communication with the at least one port throughout the space.

[0007] The structure may include an alignment pin. Attaching the circuit board assembly to the structure may include aligning the alignment pin of the structure with a corresponding hole in the circuit board assembly. Aligning the alignment pin may reduce a mechanical tolerance of a stack including the circuit board assembly and the structure in a horizontal dimension. The mechanical tolerance may be related to a position of the circuit board assembly within a system for performing the method.

[0008] The method may be performed using a machine that supplies the vacuum pressure. The structure and the circuit board assembly may be at an oblique angle relative to a generally rectangular surface of the machine. The method may include contacting the portion of the circuit board assembly to which the thermal interface material is dispensed with a hot plate. The method may also include removing the structure from the circuit board assembly. The hot plate may be or include a cooling plate.

[0009] An example system for leveling a circuit board assembly includes a structure having dimensions of an enclosed space such that attachment of the circuit board assembly to the structure forms an airtight seal over the space. The structure has at least one port in fluid communication with the space. The system includes a vacuum source for applying vacuum pressure to the space via the at least one port. The vacuum pressure has a sufficient magnitude and duration to push at least a portion of the circuit board assembly toward the space. The system also includes a robot for selectively dispensing thermal interface material onto portions of the circuit board assembly while applying the vacuum pressure. The system may include one or more of the following features, either singly or in combination.

[0010] The portion of the circuit board assembly may include a component on a surface of the circuit board assembly. The robot may be controlled to dispense the thermal interface material onto the surface of the component. The robot may be controlled not to dispense the thermal interface material onto an area of ​​the circuit board assembly that does not include the component.

[0011] In the absence of vacuum, the circuit board assembly at least partially flexes relative to the structure. The vacuum source can be controlled to apply the vacuum pressure with a sufficient magnitude and for a sufficient duration to reduce or eliminate flexure of the circuit board assembly relative to the structure. The vacuum source can be controlled to apply the vacuum pressure with a sufficient magnitude and for a sufficient duration to flatten the circuit board assembly.

[0012] The structure may include a gasket that forms the airtight seal over the space between the circuit board assembly and the structure. The structure may include a rib within the space. The position of the rib may correspond to the position of the circuit board assembly that does not include a component. The rib may be configured to allow fluid communication with the at least one port throughout the space. The structure may include an alignment pin located at a position corresponding to the position of a hole in the circuit board assembly.

[0013] The system may include a machine having a generally rectangular surface for holding the structure. The machine may include the vacuum source. The structure and the circuit board assembly may be at an oblique angle relative to the generally rectangular surface of the machine.

[0014] Any two or more of the features described in this specification (including this summary) may be combined to form implementations not specifically described in this specification.

[0015] The various systems described herein, or portions thereof, may be controlled at least in part via a computer program product that includes instructions stored on one or more non-transitory machine-readable storage media and executable on one or more processing devices (e.g., microprocessors, application specific integrated circuits, programming logic such as field programmable gate arrays, etc.). The systems described herein, or portions thereof, may be implemented as one or more apparatuses or methods and may include one or more processing devices and a computer memory storing executable instructions for implementing control of various functions. The devices, systems, and / or components described herein may be configured, for example, by design, construction, arrangement, placement, programming, operation, activation, deactivation, and / or control.

[0016] The details of one or more implementations are set forth in the accompanying drawings and the detailed description that follows. Other features and advantages will be apparent from the detailed description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a top view of an example structure for leveling a circuit board assembly.

[0018] Figure 2 yes Figure 1 A side perspective view of an example structure.

[0019] Figure 3 is a top view of an example circuit board assembly.

[0020] Figure 4 yes Figure 3 A side perspective view of an example circuit board assembly.

[0021] Figure 5 is a top view of another example structure for leveling a circuit board assembly.

[0022] Figure 6 is a top view of another example structure for leveling a circuit board assembly oriented at an oblique angle.

[0023] Figure 7 A gasket is installed on it Figure 1 A side perspective view of an example structure.

[0024] Figure 8 is a block diagram of a system for leveling a circuit board assembly and for adding thermal interface material to components of the circuit board assembly.

[0025] Fig. 9 is a flow chart illustrating an example process for manufacturing an apparatus, such as a testing instrument, that includes flattening a circuit board assembly.

[0026] Fig.10 is a block diagram showing how a cold plate is combined with an assembly including a circuit board assembly and a structure for leveling the circuit board assembly.

[0027] Fig.11 is a block diagram illustrating the combination of a cold plate, an assembly including a circuit board assembly, and a structure for leveling the circuit board assembly.

[0028] Like reference numbers in different drawings indicate similar elements. DETAILED DESCRIPTION

[0029] An example implementation of a system and method for flattening a circuit board assembly using vacuum pressure is described herein. An example of this system includes a structure having dimensions that partially enclose a space / volume. The attachment of the circuit board assembly to the structure forms an airtight seal above the space. The structure includes at least one port in fluid communication with the space. A vacuum source is connected to the port to apply vacuum pressure to the space. The vacuum pressure has a sufficient magnitude and duration to push a curved or flexed portion of the circuit board assembly toward the space, thereby flattening the circuit board assembly so that all portions of the circuit board assembly are in substantially the same plane. A robot is configured to selectively dispense a thermal interface material (TIM) onto portions of the circuit board assembly while applying the vacuum pressure. Assuming that the circuit board assembly is flat, the robot is controlled to deposit the TIM. The bend or flexure in the circuit board assembly may cause the robot to deposit the TIM at an incorrect location on the circuit board assembly. However, because the circuit board assembly has been flattened by the vacuum pressure, the robot is more likely to deposit the TIM at an intended location on the circuit board assembly, thereby potentially reducing manufacturing errors.

[0030] Figure 1 shows an example top view of an example structure 10 of the type described above; and Figure 2A side perspective view thereof is shown. Structure 10 is rectangular in shape; however, any suitable shape may be used. For example, structure 10 may be square, trapezoidal, or irregular in shape. Structure 10 includes a bottom surface 12 and side walls 14, 15, 16, and 17. Surface 12 and side walls 14 to 17 together partially enclose a volume or space 20. In the example described herein, space 20 is enclosed on five sides, with the top open, as shown. As described below, structure 10 is configured (e.g., sized and shaped) so that a circuit board assembly, such as a printed circuit board assembly (PCBA), is mounted above its top 21, thereby enclosing space 20. In some embodiments, the opening at the top 21 of structure 10 has the same size (e.g., area) and shape as the opening of the circuit board assembly mounted above the top of the structure.

[0031] The structure 10 also includes one or more ribs 22a to 22e within the space. The ribs include walls having a height that is the same or substantially the same as the height of the side walls 14 to 17. In this article, "substantially the same as..." covers manufacturing variations or slight irregularities in the height of the ribs and / or side walls. The ribs provide stability and support the circuit board assembly. The ribs are located within the space based on the location of the structure included on the circuit board assembly mounted above the top of the structure 10. In one example, the ribs are located at a location corresponding to a location on the circuit board assembly that does not include a component.

[0032] refer to Figure 3 and Figure 4 , such as a circuit board assembly 25 ( Figure 4 The circuit board assembly components are omitted) may include a substrate that holds components and conductive traces and / or layers. The circuit board assembly includes two surfaces, namely its mounting surface 27 and its bottom 28. The mounting surface 27 is where components 26 such as active electronic devices and passive electronic devices (e.g., programmable logic 26a, memory 26b, resistors 26c, and other types of components) can be mounted and electrically connected to the circuit board assembly. The bottom 28 typically does not include components, but in some specific implementations, the bottom of the circuit board assembly can include components. The bottom can be where the circuit board assembly is electrically, mechanically, or both electrically and mechanically connected to another structure. For Figure 3 and Figure 4 In the example of FIG. 1 , there are no components on the mounting surface or bottom surface of circuit board assembly 25 along locations 30a to 30e, which correspond to ribs 22a to 22e on structure 10. This reduces the likelihood that the ribs will damage any components when circuit board assembly 25 is attached to structure 10 and when a vacuum source is applied.

[0033] Return to reference Figure 1 and Figure 2, the ribs are arranged to enable fluid communication throughout the space 20. That is, the ribs may include holes, openings, or passages through which air can reach or leave all locations within the space 20. In this example, there is an opening 32 between ribs 22c and 22d through which air can reach the subspace 33. There is also an opening 34 between ribs 22a and 22b through which air can pass. In this article, a subspace includes one or more areas of a space (such as space 20) that are partially enclosed by one or more ribs in the ribs.

[0034] Figure 5 Another example structure 40 is shown having the same function as structure 10, but with a different rib configuration. Here, ribs 42a and 42b include openings 41 through which air flows between subspaces 40a and 40b.

[0035] Return to reference Figure 1 , the structure 10 includes at least one / one or more air ports 35a, 35b in fluid communication with the space 20. Ports where air can reach or leave all areas of the space 20. The port is configured (e.g., sized, shaped, and airtight) to be connected to a vacuum source 37, such as a compressor, an air pump, or the like, or a component thereof, to create a vacuum, thereby drawing air from the space 20, or in some cases introducing air into the space 20. In one example, the vacuum source 37 may include or be connected to one or more hoses 37a, 37b. The ports 35a, 35b may also be configured to be connected to respective hoses 37a, 37b, through which pressure, including vacuum pressure, is applied to the space 20.

[0036] In some implementations, the hose may be located in a position where it is difficult or inconvenient to connect to the port. Figure 6 As shown, structure 50, which is a variation of structures 10 and 40, can be disposed on a machine 51 having a generally rectangular surface for holding the structure during processing using the techniques described herein. Machine 51 is connected to or includes a vacuum source (not shown). Machine 51 holds the structure (and the circuit board assembly on the structure) at an oblique angle 52 (e.g., an angle that is not a right angle or a multiple of a right angle) relative to the generally rectangular surface of the machine. Holding the structure at the oblique angle facilitates and enables connection between hoses 53a, 53b and corresponding ports 54a, 54b on structure 50. That is, in this example, the hoses do not need to be flexed or extended to connect to the ports on the structure.

[0037] Return to reference Figure 1 and Figure 2, mounting the circuit board assembly on top of the structure 10 closes the space 20. When closed, the space 20 is airtight and will prevent air from entering or escaping. If a small amount of air enters or escapes the space, the space 20 can still be considered airtight, wherein those small amounts of air that escape or enter will not prevent or significantly interfere with the use of vacuum pressure to level the circuit board assembly as described herein. Also refer to Figure 7 In some implementations, to improve or facilitate an airtight seal between the circuit board assembly 25 and the structure 10, a gasket 56 may be placed on top of the structure along all or part of the periphery of the structure 10. The gasket 56 may be made of rubber, plastic, or other pliable or soft material that is capable of forming an airtight seal between the circuit board assembly, the gasket, and the structure when the circuit board assembly is placed on the gasket. In some implementations, the gasket may be part of the structure. For purposes described herein, a circuit board assembly “on” a structure may include a circuit board assembly placed directly on the structure without a gasket, or a circuit board assembly placed on a gasket that is placed on or partially on the structure.

[0038] Return to reference Figure 1 and Figure 2 The structure 10 may also include two or more alignment pins 58 and 59. The alignment pins 58 and 59 are aligned with corresponding holes 61 and 62 ( Figure 3 Thus, when the circuit board assembly 25 is assembled to the structure 10, the alignment pins 58, 59 fit into the corresponding holes 61, 60, thereby ensuring that the circuit board assembly 25 is in the proper or intended position on the structure 10.

[0039] refer to Figure 8 , the structure 10 is part of a system 65 for manufacturing a device such as a test instrument, the device including the structure 10 / circuit board assembly 25 on the gasket 56, and at least temporarily leveled using the techniques described herein. The system 65 includes a vacuum source 37 (such as those described above) to provide a vacuum to the structure 10 via ports 35a, 35b ( Figure 1 ) vacuum pressure is applied to the airtight space 20 enclosed by the structure 10 and the circuit board assembly 25. The vacuum pressure has a sufficient magnitude and duration to push the curved or bent portion of the circuit board into the space, thereby flattening the circuit board assembly. In one example, the vacuum pressure is higher than 20 inches of mercury, such as 20 inches to 24 inches of mercury. However, the vacuum pressure is not limited to these values.

[0040] The system 65 also includes a robot 66 mounted on a stage 67 and configured to move in an X dimension 68, a Y dimension 69, and a Z dimension 70 relative to the circuit board assembly 25. For example, the robot 66 can be mounted on a track 70 and move along the track 70 in the X dimension 68. The track 70 can be mounted to a track 71 and move in the Y dimension 69 to also move the robot in the Y dimension. The robot 66 can include an actuator or the like to move its TIM dispenser 72 closer to the component 26a in the Z dimension. Alternatively, the robot 66 can be mounted close enough to the component on the mounting surface 27 so that no Z dimension movement is required. The robot 66 is configured to selectively dispense the TIM onto the component and / or the portion of the surface of the circuit board assembly that does not include the component while applying vacuum pressure. Although one robot is shown, the system 65 can include multiple robots for depositing the TIM.

[0041] As explained above, mounting surface 27 of circuit board assembly 25 includes components. Some of these components generate heat. Examples of components that generate heat include, but are not limited to, programmable logic such as field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), memory such as random access memory (RAM), and resistors. Heat buildup may adversely affect the operation of the circuit board assembly. Therefore, a cold plate 75 ( Fig. 9 ) to conduct heat from components on the circuit board assembly. The cold plate 75 can be made of metal or other thermally conductive materials and can be temperature controlled, for example, by a control system as described herein using a refrigerant or other cooling mechanism to maintain a certain temperature, such as 70 degrees Fahrenheit (℉) or below, 60℉ or below, 50℉ or below, or a lower temperature. Components on the circuit board assembly and / or portions of the circuit board assembly that do not include the components (e.g., the board substrate) can be brought into thermal contact with the cold plate, resulting in heat from the components and / or the circuit board assembly being transferred to the cold plate.

[0042] Thermal contact between the cold plate and the portion of the component and / or circuit board assembly that does not include the component can be achieved through the TIM. That is, all or some of the components and / or portions of the portion of the component and / or circuit board assembly that does not include the component can be in physical contact with the TIM, and the TIM can be in physical contact with the cold plate. In some implementations, the TIM can be made of any compliant, thermally conductive and electrically insulating material. For example, the TIM can be or include, for example, paraffin and / or silicone-based materials.

[0043] The TIM may be deposited in a semi-solid or gel-like form onto the portion of the component and / or circuit board assembly that does not have the component by the robot 66. The cold plate is then brought into contact with the TIM, thereby forming a thermal path through the TIM between the cold plate and the portion of the component and / or board surface that includes the TIM. In some implementations, the TIM is allowed to cure or harden prior to contacting the cold plate, resulting in the TIM being sufficiently pliable, deformable, and soft to form a thermal interface between the cold plate and the portion of the component and / or circuit board assembly that includes the TIM.

[0044] The robot 66 can be controlled by the control system to move to preprogrammed positions above the mounting surface 27 of the circuit board assembly 25 and deposit a preprogrammed amount of TIM at each preprogrammed position. The preprogrammed positions can correspond to the positions of components (such as 26a, 26f) that generate heat (such as those described above) and / or positions on the circuit board assembly itself that require thermal control (e.g., cooling). That is, the TIM is applied to the surface of such components. The preprogrammed amount can be based on the area to be covered. For example, for components with a larger surface area, a larger amount of TIM may be required; while for components with a smaller surface area, a smaller amount of TIM may be required. The thickness of the deposited TIM layer can be based on the type of material, the heat, the location of the TIM deposition, and / or the fragility of the circuit board assembly and / or the components. For example, a thicker TIM layer can be used for more fragile components to reduce potential damage to these components when the circuit board assembly contacts the cold plate. For example, a thicker TIM layer can be used for portions of the board that do not include components to achieve contact between these TIM layers and the cold plate, because the height of the components may interfere with this contact. Figure 8 The example of FIG. 6 shows the robot 66 depositing TIM 29 on component 26f before moving to another component 26a. Note that for simplicity, only two components of the circuit board assembly 25 are shown. Figure 3 As shown, for example, circuit board assembly 25 includes more than two components.

[0045] like Figure 8 As shown, the control system 76 may include one or more processing devices 77, examples of which are described herein. The control system 76 also includes a memory 78 storing computer code or instructions 79 that can be executed by the one or more processing devices to perform at least a portion of the processes described herein for controlling the operation of the vacuum source 37, the operation of the robot 66, and any other suitable automated functions described herein.

[0046] As described above, the robot 66 is controlled to move in position above the mounting surface and to deposit the TIM at pre-programmed locations on the surface of the component and / or the circuit board assembly itself. However, the pre-programmed positions are defined relative to a flat circuit board assembly; that is, relative to a circuit board assembly having a planar or substantially planar shape of the substrate (e.g., whose planarity / surface height does not vary by more than 5%, 4%, 3%, 2%, or 1%). However, as described above, the substrate and, therefore, the circuit board assembly may bend or flex. This may be the result of heat, humidity, or other environmental factors. The flexing or flexing may lift portions of the circuit board assembly and, therefore, affect the position of the component to be deposited with the TIM and / or the portion of the circuit board assembly where the component is not present. This may result in errors in the TIM deposition. Therefore, using the techniques described herein and the following description of the TIM deposition method, the TIM deposition method may be used to determine the position of the component to be deposited and / or the portion of the circuit board assembly where the component is not present. Fig. 9 The process 80 described is used to flatten the circuit board assembly before applying the TIM so that when the TIM is applied by the robot, all parts of the circuit board assembly are in substantially the same plane. This flattening can reduce the possibility that the robot deposits the TIM in the wrong location.

[0047] According to process 80, circuit board assembly 25 is placed (80a) over structure 10 and in contact with gasket 56 on structure 10. This configuration Figure 8 The placement can be performed manually or automatically (e.g., using a robot—not shown), and the holes in the circuit board assembly 25 can be aligned with the corresponding alignment pins of the structure 10. The circuit board assembly 25 is also placed against the gasket 56, with the mounting side facing up, using sufficient force to form an airtight seal or a substantially airtight seal between the circuit board assembly 25 and the gasket / structure 10.

[0048] Before, during or after placement (80a) of the circuit board assembly, a vacuum source 37 is connected to ports 35a, 35b on the structure 10 via hoses 37a, 37b ( Figure 1). The hose may be part of a structure, a vacuum source, or another machine. In any case, the control system 76 controls the vacuum source to apply (80b) vacuum pressure to the space 20, which is airtight and enclosed by the circuit board assembly 25. The vacuum pressure has a sufficient magnitude and duration to push or pull the bent or flexed portion of the circuit board assembly 25 toward the space and thereby flatten the circuit board assembly so that the substrate of the circuit board assembly is substantially planar. Applying the vacuum pressure can reduce the height deviation of the stack / assembly 81 including the circuit board assembly 25, the gasket 56, and the structure 10 in the vertical dimension. The magnitude and duration of the vacuum pressure required to push or pull the bent or flexed portion of the circuit board assembly toward the space may depend on, for example, the size of the space, the size of the circuit board assembly, and / or the amount of bending or flexing. In one example, the magnitude of the vacuum pressure is greater than 20 inches of mercury or 20 inches to 24 inches of mercury. The duration of the vacuum pressure may be the entire time that the robot applies the TIM and the cooling plate 75 contacts the TIM.

[0049] In this regard, after applying (80b) vacuum pressure to flatten the circuit board assembly and while continuing to apply vacuum pressure, the robot 66 is controlled by the control system 76 to selectively deposit (80c) the TIM onto the surface of the portion of the component and / or circuit board assembly that does not include the component. The robot selectively applies the TIM in the sense that the robot applies the TIM to a preprogrammed location, which can leave portions of the substrate, conductive traces, and / or one or more components free of TIM; that is, without TIM present thereon. However, in some cases, the entire mounting surface 27 of all components and the circuit board assembly can be covered with TIM.

[0050] After all of the TIMs have been applied, the resulting assembly (i.e., structure 10, gasket 56, circuit board assembly 25, and TIM 29) is partially disassembled as structure 10 is removed (80d). For example, air may be introduced into space 20, such as by reversing operation of vacuum source 37 to force structure 10 and circuit board assembly 25 apart or weaken their connection. Structure 10 may then be removed from the assembly, either manually or using a robot (not shown). The remaining parts (circuit board assembly 25 and TIM 29) are then moved, either manually or using a robot (not shown), to a compression system where they are combined with the structure (which may be structure 10 and gasket 56) and with the cold plate 75 (80f). This combination is achieved without the use of vacuum pressure or other fastening mechanisms. For example, referring to Fig.10 , the structure 10 , the gasket 56 , the circuit board assembly 25 including the TIM 29 , and the cold plate 75 may be combined by placing them in a stack. Fig.11The resulting stack assembly 81 shown in FIG. 8 is inserted into a compression mechanism (not shown). The compression mechanism applies a force in the direction of arrows 90a, 90b to force the cold plate into thermal contact with the TIM.

[0051] Specifically, the cold plate contacts the TIM on the portion of the component and / or circuit board assembly that does not include the component, thereby forming a thermal path between the cold plate and the portion of the component and / or circuit board assembly that does not include the component via the TIM. The cold plate, circuit board assembly, and structure can be contacted manually or automatically using a robot (not shown). In some specific implementations, the cold plate 76 can also include holes 83, 84 to align with the alignment pins 58, 59 of the structure 10 to ensure proper placement of the cold plate. That is, the alignment pins 58, 59 can protrude through the holes 61, 60 in the circuit board assembly 25 so that they can engage the corresponding holes 83, 84 in the cold plate. The amount of pressure applied to contact the cold plate, circuit board assembly, and structure can be large enough to enable heat conduction between the cold plate and all or part of the circuit board assembly via the TIM, but it will not be so large as to damage the circuit board assembly (including the components mounted thereon).

[0052] After compressing the assembly and cold plate, the combined assembly 81 is removed (80g) from the compression system, either manually or using a robot (not shown). The circuit board assembly and cold plate may be fastened (80h) together using screws or other types of fasteners. Thereafter, the structure 10 including the gasket 56 may be removed (80i) from the remainder of the combined assembly. For example, the structure 10 including the gasket 56 may then be removed from the cold plate / TIM / circuit board assembly, either manually or using a robot (not shown). The resulting combined circuit board assembly and cold plate (minus the structure 10 and gasket 56) may be used in a system such as a test system. For example, the resulting assembly may be a test instrument for a test system or a portion of the test instrument for a test system.

[0053] An example test instrument is a hardware device configured to send a test signal to OUT. The test signal may include a stimulus, such as a voltage or a current, to induce a reaction in OUT. The test instrument may also be configured to receive signals from OUT (including response signals to the test signals), and analyze these signals from OUT to determine whether OUT has passed a failed test, such as whether the response to the stimulus is its expected response. For example, the test instrument may compare the response signal with one or more predetermined thresholds, and determine whether the DUT has passed a failed test based on the comparison. Examples of types of test instruments that may use the resulting components include, but are not limited to, radio frequency (RF) test instruments, digital test instruments, and parametric test instruments.

[0054] An example test system may include multiple test instruments (e.g., one, two, three, four, or more) that may be configured to perform one or more types of tests, such as RF testing, digital testing, parametric testing, etc. The test system also includes a control system that may be part of, or distributed across, or separate from, one or more test instruments. The control system may include one or more processing devices, examples of which are described herein. The control system includes a memory storing computer code or instructions that may be executed by one or more processing devices to control testing by executing one or more test programs and sending instructions to one or more of the test instruments.

[0055] All or part of the systems and methods described in this specification, and various modifications thereof, may be configured or controlled, at least in part, by one or more computers, such as control system 76, using one or more computer programs tangibly embodied in one or more information carriers, such as in one or more non-transitory machine-readable storage media. Computer programs may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including as stand-alone programs or as modules, parts, subroutines, or other units suitable for use in a computing environment. Computer programs may be deployed to execute on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a network.

[0056] The actions associated with configuring or controlling the test systems and methods described herein may be performed by one or more programmable processors executing one or more computer programs to control or perform all or some of the operations described herein. All or part of the test systems and methods may be configured or controlled by dedicated logic circuitry such as an FPGA (field programmable gate array) and / or an ASIC (application specific integrated circuit) or an embedded microprocessor localized to instrument hardware.

[0057] Processors suitable for computer program execution include, for example, both general-purpose and special-purpose microprocessors, and any one or more processors of any kind of digital computer. Typically, the processor will receive instructions and data from a read-only storage area or a random access storage area or both. The elements of a computer include one or more processors for executing instructions and one or more storage area devices for storing instructions and data. Generally speaking, a computer will also include one or more machine-readable storage media or one or more machine-readable storage media operatively connected to receive data from it or transmit data to it or both, the one or more machine-readable storage media such as a mass storage device for storing data, such as a magnetic disk, a magneto-optical disk, or an optical disk. Non-transitory machine-readable storage media suitable for embodying computer program instructions and data include all forms of non-volatile storage areas, including, for example, semiconductor storage area devices, such as EPROM (erasable programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), and flash storage area devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROMs (compact disk read-only memory) and DVD-ROMs (digital versatile disk read-only memory).

[0058] The elements of the different implementations described may be combined together to form other implementations not specifically described above. Elements may be omitted from a previously described system without generally adversely affecting its operation or the operation of the system. In addition, individual elements may be combined into one or more single elements to perform the functions described in this specification.

[0059] Other implementations not specifically described in this specification are also within the scope of the following claims.

Claims

1. A method, comprising: attaching a circuit board assembly to a structure having dimensions to partially enclose a space, wherein attaching the circuit board assembly to the structure forms a hermetic seal over the space, the structure having at least one port in fluid communication with the space; applying vacuum pressure to the space via the at least one port, the vacuum pressure pushing at least a portion of the circuit board assembly toward the space; as well as Thermal interface material is selectively dispensed onto portions of the circuit board assembly while the vacuum pressure is applied.

2. The method of claim 1 , wherein the portion of the circuit board assembly comprises a component on a surface of the circuit board assembly; and The thermal interface material is dispensed onto a surface of the component. 3 . The method of claim 1 , wherein applying vacuum pressure reduces height deviation of a stack including the circuit board assembly and the structure in a vertical dimension. 4 . The method of claim 2 , wherein the thermal interface material is not dispensed onto areas of the circuit board assembly that do not include the component.

5. The method of claim 1 , wherein the circuit board assembly is at least partially bent relative to the structure in the absence of a vacuum; and The vacuum pressure is applied in a sufficient amount and for a sufficient duration to reduce or eliminate bending of the circuit board assembly relative to the structure.

6. The method of claim 5, wherein the vacuum pressure is applied in a sufficient amount and for a sufficient duration to flatten the circuit board assembly.

7. The method of claim 1, wherein the structure includes a gasket that forms the hermetic seal over the space between the circuit board assembly and the structure.

8. The method of claim 1, wherein the structure comprises a rib within the space, wherein a location of the rib corresponds to a location of the circuit board assembly that does not include a component.

9. The method of claim 8, wherein the rib is configured to allow fluid communication with the at least one port throughout the space.

10. The method of claim 1, wherein the structure includes alignment pins; and wherein attaching the circuit board assembly to the structure includes aligning the alignment pins of the structure with corresponding holes in the circuit board assembly.

11. The method of claim 10, wherein aligning the alignment pins reduces mechanical tolerances in a stackup comprising the circuit board assembly and the structure in a horizontal dimension, the mechanical tolerances being related to a position of the circuit board assembly within a system for performing the method.

12. The method of claim 1, wherein the method is performed using a machine that supplies the vacuum pressure; and Wherein the structure and the circuit board assembly are at an oblique angle relative to a generally rectangular surface of the machine.

13. The method according to claim 1, further comprising: contacting the portion of the circuit board assembly on which the thermal interface material is dispensed with a thermal plate; as well as The structure is removed from the circuit board assembly. The method of claim 13 , wherein the thermal plate comprises a cooling plate.

15. A system, comprising: a structure having a size enclosing a space such that attachment of the circuit board assembly to the structure forms a hermetic seal over the space, the structure having at least one port in fluid communication with the space; a vacuum source for applying a vacuum pressure to the space via the at least one port, the vacuum pressure having a sufficient magnitude and duration to urge at least a portion of the circuit board assembly toward the space; and A robot is provided for selectively dispensing thermal interface material onto portions of the circuit board assembly while applying the vacuum pressure.

16. The system of claim 15, wherein the portion of the circuit board assembly comprises a component on a surface of the circuit board assembly; and wherein the robot is controlled to dispense the thermal interface material onto the surface of the component.

17. The system of claim 15, wherein the robot is controlled to not dispense thermal interface material onto areas of the circuit board assembly that do not include the component.

18. The system of claim 15, wherein in the absence of a vacuum, the circuit board assembly at least partially flexes relative to the structure; and The vacuum source is controlled to apply the vacuum pressure in a sufficient amount and for a sufficient duration to reduce or eliminate bending of the circuit board assembly relative to the structure.

19. The system of claim 18, wherein the vacuum source is controlled to apply the vacuum pressure with a sufficient magnitude and for a sufficient duration to flatten the circuit board assembly.

20. The system of claim 15, wherein the structure includes a gasket that forms the hermetic seal over the space between the circuit board assembly and the structure.

21. The system of claim 15, wherein the structure includes a rib within the space, wherein a location of the rib corresponds to a location of the circuit board assembly that does not include a component.

22. The system of claim 21, wherein the rib is configured to allow fluid communication with the at least one port throughout the space.

23. The system of claim 15, wherein the structure includes alignment pins located at locations corresponding to locations of holes in the circuit board assembly.

24. The system of claim 15, further comprising: a machine having a generally rectangular surface for holding said structure, said machine including said vacuum source; Wherein the structure and the circuit board assembly are at an oblique angle relative to a generally rectangular surface of the machine.

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