Thermal Interface Device for PCI Express M.2 Printed Circuit Assemblies

Abstract

In some embodiments, a device includes an integrated circuit module and a printed circuit board, the integrated circuit module including: two thermal interface material layers; a printed circuit assembly, the printed circuit assembly arranged between the two thermal interface material layers and including a plurality of integrated circuits arranged on both sides of the circuit board, wherein at least one of the integrated circuits is thermally coupled to one of the thermal interface material layers; and two heat spreaders, the two heat spreaders are adapted to be removably retained to each other and adapted to encapsulate and thermally couple the two thermal interface material layers when retained to each other, a connector is arranged on the printed circuit board, wherein a connector edge of the printed circuit assembly is arranged within the connector. In other embodiments, a frame is adapted to retain the two heat spreaders.

Description

Background Art

[0001] Modern computer systems generate a lot of heat. While some of this heat is generated by things like the power supply, most of it is typically generated by integrated circuits like processors and memory chips. To operate properly, these computer systems must be kept within a certain temperature range. Therefore, the heat generated by these processors and memory chips must be dissipated or otherwise removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The present disclosure is described in detail according to one or more different embodiments with reference to the following drawings. The drawings are provided for illustrative purposes only and depict only typical or example embodiments.

[0003] Figure 1 A PCI Express (high speed) M.2 printed circuit assembly is shown mounted on a PCI printed circuit board.

[0004] Figure 2 Describes a method for cooling Figure 1 PCI Express M.2 printed circuit assembly integrated circuit system.

[0005] Figure 3A and Figure 3B An integrated circuit module according to a first embodiment is shown.

[0006] Figure 4A and Figure 4B An integrated circuit module according to a second embodiment is shown.

[0007] Figure 5 An integrated circuit module is shown mounted on a PCI printed circuit board.

[0008] Fig. 6A A heat sink is shown mounted on a PCI circuit board and thermally coupled to an integrated circuit module.

[0009] Figure 6B An exploded view of an integrated circuit module and heat sink mounted on a PCI circuit board is shown.

[0010] Fig. 7A A heat sink is shown mounted on the underside of a PCI circuit board and thermally coupled to an integrated circuit module.

[0011] Figure 7B An exploded view of an integrated circuit module and heat sink mounted on a PCI circuit board is shown.

[0012] Figure 8 A process according to one embodiment is shown.

[0013] The drawings are not exhaustive and do not limit the disclosure to the precise forms disclosed. DETAILED DESCRIPTION

[0014] Printed circuit assemblies generate a lot of heat, especially in high-density configurations. One of the newer printed circuit assemblies is the Peripheral Component Interconnect Express M.2 printed circuit assembly (hereinafter referred to as the "PCIe M.2 printed circuit assembly (PCA)"). The PCIe M.2 printed circuit assembly is defined by the M.2 specification (formerly known as the Next Generation Form Factor (NGFF) specification). The M.2 specification defines an internally mounted computer expansion card and an associated connector. One of the computer bus interfaces provided by the M.2 connector is the PCIe bus interface.

[0015] In some cases, it can be difficult to properly cool a printed circuit assembly, such as a PCIe M.2 PCA. In particular, these PCAs generate much more heat than previous PCAs, while removing much less heat. These PCAs are characterized by very high component density, and the density continues to increase as new designs are introduced to support greater functionality. In addition, these PCAs are characterized by a double-sided layout with components mounted on both sides. As a result, the heat generated is approximately twice that of a single-sided board. In addition, the double-sided board does not have the cooling provided by the unpopulated side of the single-sided board. The result is that much more heat is generated, while much less heat is removed. Another difficulty in cooling these PCAs is caused by the thickness of the PCA board. As described below, previous attempts to cool these PCAs have resulted in board bending, causing components to separate from the board.

[0016] Thus, exemplary techniques for cooling a printed circuit assembly that address the difficulties noted above are disclosed herein. In particular, in the examples disclosed herein, a PCA is sandwiched between two thermal interface pads that flexibly conform to components mounted on both sides of the PCA and effectively conduct heat away from these components. In addition, the sandwich is encased in a rigid metal structure that provides both additional cooling by conducting heat away from the thermal interface pads and structural rigidity to prevent flexing of the PCA board.

[0017] Figure 1 A PCIe M.2 PCA mounted on a PCI printed circuit board (hereinafter referred to as "PCI PCB") is shown. However, although various embodiments are described in terms of a PCIe M.2 PCA and a PCI PCB, it should be understood that the disclosed technology can be applied to other PCAs and PCBs. Figure 1, the PCI PCB 102 includes an M.2 connector 104 mounted thereon. A PCIe M.2 PCA 106 is also shown. The PCIe M.2 PCA 106 is a double-sided printed circuit assembly having integrated circuits (generally shown at 108) mounted on both sides of a thin circuit board 114. An M.2 connector edge (generally shown at 110) of the PCIe M.2 PCA 106 is disposed within the M.2 connector 104 of the PCI PCB 102. The other end of the PCIe M.2 PCA 106 is secured to the PCI PCB 102 by a fastener 112.

[0018] Figure 2 Describes a method for cooling Figure 1 The invention relates to a method for passing the integrated circuit 108 of the PCIe M.2 PCA 106 of the PCIe M.2 PCA 106. According to the method, the thermal interface pad 202 is arranged between the PCIe M.2 PCA 106 and the PCI PCB 102. The method allows the heat generated by the PCIe M.2 PCA 106 to be transferred to the PCI PCB 102 and dissipated by it. However, because the circuit board 114 of the PCIe M.2 PCA 106 is very thin and is only fixed at each end, the pressure applied by the flexible thermal interface pad 202 to the integrated circuit 108 mounted on the lower side of the PCIe M.2 PCA 106 causes the PCI Express in the PCIe M.2 PCA 106 to bend upward. In some applications, the temperature difference in the PCA may be large enough to cause or increase such bending. Such bending may cause components (such as the integrated circuit 108) mounted on the PCIe M.2 PCA 106 to detach from the circuit board 114 of the PCIe M.2 PCA 106. Various embodiments disclosed herein address this problem by encapsulating the PCIe M.2 PCA 106 in a rigid metal structure that both dissipates the heat generated by the PCIe M.2 PCA 106 and prevents the PCIe M.2 PCA 106 from flexing through its rigidity and rapid and uniform heat dissipation.

[0019] Figure 3A and Figure 3B An integrated circuit module 300 according to a first embodiment is shown. Figure 3A 3 is a perspective view of the integrated circuit module 300 in its assembled state. Figure 3B The integrated circuit module 300 includes a PCIe M.2 PCA 302, such as Figure 1 PCIe M.2 PCA 106.

[0020] Reference Figure 3B, the integrated circuit module 300 also includes two thermal interface material layers 304a, 304b and two heat spreaders 306a, 306b. A common thermal interface material is a thermal gap pad. However, other thermal interface materials can be used. The heat spreaders 306a, 306b can be made of aluminum. However, other materials with sufficient rigidity and thermal conductivity can be used to form the heat spreaders 306a, 306b, such as stainless steel, etc.

[0021] The PCIe M.2 PCA 302 is arranged between two thermal interface material layers 304a, 304b such that the integrated circuit 108 is thermally coupled to one of the thermal interface material layers 304a, 304b. As used herein, two objects are "thermally coupled" when they are either in direct contact with each other or they are in direct contact with one or more thermally conductive intermediates that form a thermally conductive path between the two objects. As used herein, if the material forming the object is "thermally conductive", then an object comprising a continuum of the same material will be considered "thermally conductive". As used herein, a material has a thermal conductivity equal to or greater than 1 W·m at any temperature between 0°C and 100°C. -1 ·K -1 A material is "thermally conductive" if it has a thermal conductivity (usually expressed as k, λ or κ) of 1.0. As used herein, a body as a whole, comprising a plurality of distinct bodies (which may be made of different materials), has a heat transfer coefficient equal to or greater than 10 W·m from one end of the body to the other end of the body at any temperature between 0°C and 100°C. -2 ·K -1 , then the object is considered to be "thermally conductive". An example of a thermally conductive object comprising multiple different bodies is a heat pipe. The two heat spreaders 306a, 306b are adapted to be removably retained to each other and are adapted to encapsulate and thermally couple the two thermal interface material layers 304a, 304b when retained to each other.

[0022] In the embodiment of FIG. 3 , one heat diffuser 306a includes four tabs 308a, 308b, 308c, 308d and the other heat diffuser 306b includes four corresponding voids 310a, 310b, 310c, 310d. In the embodiment of FIG. 3 , the heat diffusers 306a, 306b have a C-shaped cross-section. However, in other embodiments, other cross-sectional shapes may be used. The heat diffusers 306a, 306b may snap together so that when the tabs 308a, 308b, 308c, 308d are arranged in the corresponding voids 310a, 310b, 310c, 310d, the heat diffusers 306a, 306b are retained to each other. When assembled, as shown in FIG. Figure 3AAs shown, the integrated circuit module 300 not only dissipates the heat generated by the PCIe M.2 PCA 302, but also provides a rigid structure to prevent the PCIe M.2 PCA 302 from flexing. Figure 2 In the solution, the pressure applied to one side of the PCIe M.2 PCA 302 by one thermal interface material layer 304 a is balanced by the pressure applied to the other side of the PCIe M.2 PCA 302 by another thermal interface material layer 304 b.

[0023] Figure 4A and Figure 4B An integrated circuit module 400 according to a second embodiment is shown. Figure 4A 4 is a perspective view of the integrated circuit module 400 in its assembled state. Figure 4B The integrated circuit module 400 includes a PCIe M.2 PCA 302, such as Figure 1 PCIe M.2 PCA 106.

[0024] Reference Figure 4B , the exemplary integrated circuit module 400 also includes two thermal interface material layers 304a, 304b, two heat spreaders 406a, 406b, and a frame 412. A common thermal interface material is a thermal gap pad. However, other thermal interface materials can be used. The heat spreaders 406a, 406b can be made of aluminum. However, other materials can be used to form the heat spreaders 406a, 406b, such as stainless steel, etc. The frame 412 can be made of any suitable material, such as plastic, etc.

[0025] The PCIe M.2 PCA 402 is disposed between the two thermal interface material layers 304 a , 304 b such that the integrated circuit 108 is thermally coupled to one of the thermal interface material layers 304 a , 304 b .

[0026] The frame 412 is adapted to removably retain the two heat spreaders 406a, 406b so that the two heat spreaders 406a, 406b encapsulate and thermally couple the two thermal interface material layers 304a, 304b. The frame 412 may include a groove 416 for receiving an edge of the PCIe M.2 PCA 302. The frame 412 may include an opening 414 for receiving an M.2 connector edge 420 of the PCIe M.2 PCA 302.

[0027] In the embodiment of FIG. 4 , the heat spreaders 406a, 406b together include eight tabs 408a, 408b, 408c, 408d, 408e, 408f, 408g, 408h, and the frame 412 includes eight corresponding voids 410a, 410b, 410c, 410d, 410e, 410f, 410g, 410h. In the embodiment of FIG. 4 , the heat spreaders 406a, 406b have a C-shaped cross-section. However, in other embodiments, other cross-sectional shapes may be used. The heat spreaders 406a, 406b and the frame 412 may snap together so that when the tabs 408a, 408b, 408c, 408d, 408e, 408f, 408g, 408h are arranged in the corresponding voids 410a, 410b, 410c, 410d, 410e, 410f, 410g, 410h, the frame 412 holds the heat spreaders 406a, 406b. Figure 4A As shown, the integrated circuit module 400 both dissipates heat generated by the PCIe M.2 PCA 302 and provides a rigid structure that prevents flexing of the PCIe M.2 PCA 302. Although this example illustrates eight tabs 408a, 408b, 408c, 408d, 408e, 408f, 408g, 408h and eight corresponding voids 410a, 410b, 410c, 410d, 410e, 410f, 410g, 410h, in other embodiments, other numbers of tabs and corresponding voids may be used.

[0028] Figure 5 An integrated circuit module 502 is shown mounted on a PCI PCB 506. The integrated circuit module 502 may be implemented as Figure 3A , Figure 3B The integrated circuit module 300 or Figure 4A , Figure 4B The integrated circuit module 400 is provided with an M.2 connector 504 mounted on the PCI PCB 506. The M.2 connector edge 420 of the integrated circuit module 502 is arranged within the M.2 connector 504. The opposite end of the integrated circuit module 502 can be mechanically coupled to the PCI PCB 506 by any fasteners (e.g., screws, bolts, etc.). For example, an extension provided on either the heat spreader 306a, 306b or 406a, 406b, or the frame 412 can be fixed with a screw or a locking tab, and the release tab is located on the PCI PCB 506.

[0029] exist Figure 5In the depicted embodiment, the PCI PCB 506 includes a through hole 508 for accommodating the thickness of the integrated circuit module 502. In other embodiments, the integrated circuit module 502 is mounted on the PCI PCB 506 and thermally coupled thereto. In such embodiments, the PCI PCB 506 dissipates the heat generated by the integrated circuit. In some embodiments, the PCI PCB 506 may include a metal layer or other thermal interface material thermally coupled to the PCI PCB 506. In such embodiments, the metal layer dissipates the heat generated by the integrated circuit. The metal layer may be made of copper or the like.

[0030] Some embodiments include a heat sink. Figure 6B An exploded view is shown with integrated circuit module 502 mounted on PCI PCB 506 and heat sink 620. Any suitable heat sink may be used. Fig. 6A A heat sink 620 is shown mounted on the PCI PCB 506 and thermally coupled to the integrated circuit module 502. The heat sink 620 may be mechanically attached to the PCI PCB 506 using any suitable fastener, such as Fig. 6A , Figure 6B Screws 612a, 612b, 612c, 612d are shown. In some embodiments, a thermal interface material is disposed between the heat sink 620 and the integrated circuit module 602. Any suitable thermal interface material, such as thermal grease, may be used. The heat sink 620 not only dissipates the heat generated by the integrated circuit, but also provides additional rigidity to the integrated circuit module 502.

[0031] Some embodiments include a second heat sink mounted to a second side of the PCI PCB. Figure 7B An exploded view is shown with integrated circuit module 502 mounted on PCI PCB 506 and heat sink 720. Any suitable heat sink may be used. Fig. 7A A heat sink 720 is shown mounted on the underside of the PCI PCB 506 and thermally coupled to the integrated circuit module 502. The heat sink 722 can be mechanically attached to the underside of the PCI PCB 506 using any suitable fasteners, such as the screws 712a, 712b, 712c, 712d shown in FIG. 7. In some embodiments, a thermal interface material is disposed between the heat sink 720 and the integrated circuit module 702. Any suitable thermal interface material, such as thermal grease, can be used. The heat sink 720 not only dissipates the heat generated by the integrated circuit, but also provides additional rigidity to the integrated circuit module 502.

[0032] Figure 8A process 800 according to one embodiment is shown. Although the steps of the process are shown in a particular order, some or all of the steps may be performed in other orders, in parallel, or in a combination thereof. Some of these steps may be omitted. Figure 8 At 802 , process 800 includes providing two layers of thermal interface material.

[0033] At 804, process 800 includes placing a PCIe M.2 PCA between two thermal interface material layers such that at least one integrated circuit disposed on the PCIe M.2 PCA is thermally coupled to one of the thermal interface material layers. Any thermal interface material may be used, such as a thermal gap pad.

[0034] At 806, process 800 includes removably encapsulating the PCIe M.2 PCA and the two thermal interface material layers within two heat spreaders such that the heat spreaders are thermally coupled to the two thermal interface material layers. The heat spreaders can be made of aluminum. However, other materials can be used to form the heat spreaders, such as stainless steel, etc.

[0035] At 808, process 800 includes providing a PCI PCB having a PCI Express M.2 connector disposed thereon. At 810, process 800 includes arranging a connector edge of a printed circuit assembly within the connector. Process 800 may also include thermally coupling one of the heat spreaders to the PCI PCB. Process 800 may also include thermally coupling a metal layer to the PCI PCB. Process 800 may also include thermally coupling a heat sink to one or both of the heat spreaders. Process 800 may also include arranging an integrated circuit module in a through hole of the PCI PCB, mechanically attaching a first heat sink to a first side of the PCI PCB, and mechanically attaching a second heat sink to a second side of the PCI PCB.

[0036] Embodiments of the present invention provide many benefits. As mentioned above, the disclosed technology provides enhanced heat dissipation. In addition, compared to other approaches, the disclosed embodiments provide thermal interface surfaces for both sides of the M.2 PCA. These benefits allow the use of higher power and faster M.2 modules than before.

[0037] The disclosed technology provides strength and rigidity to the PCIe M.2 PCA, which can reduce mechanical failures during shock and vibration testing. In addition, as mentioned above, this rigidity prevents flexing of the PCIe M.2 PCA, thereby preventing separation of the PCIe M.2 circuit board from the components mounted thereon.

[0038] The disclosed embodiments are compatible with several current M.2 designs. The disclosed embodiments are tool-free, as the heat spreader can be snapped together manually.

[0039] Currently, many M.2 module developers in the industry loosely follow or even violate the PCI Express design specifications. As a result, it may be difficult for manufacturers of computing devices to provide cost-effective heat dissipation solutions for M.2 modules from different M.2 manufacturers, because the computing device manufacturer may need to design a unique solution for each variant of the M.2 module, which increases the cost and complexity of the manufacturing process. Therefore, another benefit of the examples disclosed herein is that they are essentially universal, which means that they can be used with almost any variant of the M.2 module (even if it deviates from the M.2 specification). In particular, in the examples disclosed herein, the TIM on the other side of the M.2 module can provide some flexibility or tolerance, which allows variations in the height of the integrated circuit 108 above the board 114, variations in the layout of the integrated circuit 108, variations in the thickness of the board 114, etc. In addition, M.2 modules of different lengths can be accommodated in the heat spreaders 306a, 306b and 406a, 406b, and the heat spreaders 306a, 306b and 406a, 406b can be sized to allow for variations in the width of the M.2 modules. This universal mounting and thermal solution eliminates the need for unique heat sink designs for different M.2 modules, thereby reducing the inventory types and factory spare parts that must be stocked.

[0040] In common usage, the term "or" can have an inclusive meaning or an exclusive meaning. As used herein, the term "or" should always be interpreted with an inclusive meaning, unless the exclusive meaning is specifically pointed out or is logically necessary. For example, when the term "or" is paired with the term "either", such as in "either A or B", the exclusive meaning of "or" is specifically pointed out. As another example, the exclusive meaning can also be specifically pointed out by appending "exclusive" or "but not both" after the list of items, such as in "A or B, exclusive" and "A or B but not both". Moreover, the description of resources, operations or structures in the singular form should not be understood to exclude the plural. Unless otherwise specifically provided, or otherwise understood in the environment as used, conditional language (among others, such as "may", "can", "can" or "can") is generally intended to convey that certain embodiments include (while other embodiments do not include) certain features, elements and / or steps.

[0041] Unless expressly stated otherwise, the terms and phrases used in this document and variations thereof should be interpreted as open ended and not restrictive. Adjectives such as "conventional," "traditional," "normal," "standard," "known," and terms of similar meaning should not be interpreted as limiting the items described to items available for a given time period or at a given time, but should be understood to encompass conventional, traditional, normal, or standard technology that may be available or known at any time now or in the future. In certain instances, the presence of broad words and phrases such as "one or more," "at least," "but not limited to," or other similar phrases should not be understood to mean that a narrower case is intended or required where such broad phrases may not be present.

Claims

1. A device comprising: An integrated circuit module comprising Two thermal interface material layers, a printed circuit assembly disposed between the two thermal interface material layers, and comprising a plurality of integrated circuits disposed on both sides of the circuit board, wherein at least one of the integrated circuits is thermally coupled to one of the thermal interface material layers, and two heat spreaders adapted to be removably retained to one another and to encapsulate and thermally couple to the two thermal interface material layers when retained to one another; and a heat sink thermally coupled to a first one of the heat spreaders; and A printed circuit board includes a connector disposed thereon, wherein a connector edge of the printed circuit assembly is disposed within the connector.

2. The device of claim 1, wherein: The printed circuit assembly is a PCI Express M.2 printed circuit assembly; The connector is a PCI Express M.2 connector; and The printed circuit board is a PCI printed circuit board.

3. The device of claim 1, wherein: A first one of the heat spreaders is thermally coupled to the printed circuit board.

4. The apparatus of claim 1, further comprising: An additional heat sink is thermally coupled to a second one of the heat spreaders.

5. The device of claim 4, wherein: The integrated circuit module is arranged in a through hole of the printed circuit board; The heat sink is mechanically attached to the first side of the printed circuit board; and The further heat sink is mechanically attached to the second side of the printed circuit board.

6. The device of claim 1, wherein: A first one of the heat spreaders comprises at least one tab; and A second heat diffuser of the heat diffusers comprises at least one gap; wherein the heat spreaders are retained to one another when the tabs are arranged within the voids.

7. A device comprising: An integrated circuit module comprising Two thermal interface material layers, a printed circuit assembly disposed between the two thermal interface material layers, and comprising a plurality of integrated circuits disposed on both sides of the circuit board, wherein at least one of the integrated circuits is thermally coupled to one of the thermal interface material layers, Two heat spreaders, and a frame for removably holding the two heat spreaders so that the two heat spreaders encapsulate the two thermal interface material layers and are thermally coupled to the two thermal interface material layers; and a heat sink thermally coupled to a first one of the heat spreaders; and A printed circuit board includes a connector disposed thereon, wherein a connector edge of the printed circuit assembly is disposed within the connector.

8. The apparatus of claim 7, wherein: The printed circuit assembly is a PCI Express M.2 printed circuit assembly; The connector is a PCI Express M.2 connector; and The printed circuit board is a PCI printed circuit board.

9. The apparatus of claim 7, wherein: A first one of the heat spreaders is thermally coupled to the printed circuit board.

10. The apparatus of claim 7, further comprising: An additional heat sink is thermally coupled to a second one of the heat spreaders.

11. The apparatus of claim 10, wherein: The integrated circuit module is arranged in a through hole of the printed circuit board; The heat sink is mechanically attached to the first side of the printed circuit board; and The further heat sink is mechanically attached to the second side of the printed circuit board.

12. The apparatus of claim 7, wherein: Each of the heat spreaders comprises at least one tab; and The frame includes at least one void; wherein the frame retains the heat diffuser when the tab is disposed within the void.

13. A method comprising: Provide integrated circuit modules, including Provides two thermal interface material layers, placing a printed circuit assembly between the two thermal interface material layers such that at least one integrated circuit disposed on the printed circuit assembly is thermally coupled to one of the thermal interface material layers, and removably enclosing the printed circuit assembly and the two thermal interface material layers within two heat spreaders such that the heat spreaders are thermally coupled to the two thermal interface material layers; thermally coupling a heat sink to a first one of the heat spreaders; providing a printed circuit board including a connector disposed thereon; as well as A connector edge of the printed circuit assembly is disposed within the connector.

14. The method of claim 13, wherein: The printed circuit assembly is a PCI Express M.2 printed circuit assembly; The connector is a PCI Express M.2 connector; and The printed circuit board is a PCI printed circuit board.

15. The method of claim 13, wherein: A first one of the heat spreaders is thermally coupled to the printed circuit board.

16. The method of claim 13, further comprising: An additional heat sink is thermally coupled to a second one of the heat spreaders.

17. The method of claim 16, wherein: placing the integrated circuit module in a through hole of the printed circuit board; mechanically attaching the heat sink to a first side of the printed circuit board; as well as The additional heat sink is mechanically attached to the second side of the printed circuit board.

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