WO2017048287A1

WO2017048287A1 - Printed circuit board

Info

Publication number: WO2017048287A1
Application number: PCT/US2015/051006
Authority: WO
Inventors: Choon Pheng Tan; Kevin Conn; Chanh V Hua; Bharath RAMESH
Original assignee: Hewlett Packard Enterprise Development Lp
Priority date: 2015-09-18
Filing date: 2015-09-18
Publication date: 2017-03-23

Abstract

In one example, a printed circuit board assembly includes a printed circuit board including a first side and a second side. A backing member is mounted to the second side of the printed circuit board and a standoff extends from the backing member.

Description

PRINTED CIRCUIT BOARD BACKGROUND

[0001] Computing devices such as servers, network switches, notebook computers, personal computers, tablet computers, etc. may comprise a printed circuit board and a plurality of components mounted to the printed circuit board. A printed circuit board (PCB) is a board for connecting electronic components together. A PCB may include a main body formed of an insulating material, such as plastic or fiber glass, and conducting lines inside, or on a surface of, the board to conduct electricity. The conducting lines may, for example, be formed of copper or another conductor.

[0002] In some cases, components may be mounted on both an upper side and a lower side of the PCB. One type of connector for attaching a component to a PCB is an edge connector. An edge connector is an electrical connector that is to connect with an edge, rather than a face of, a component. A component to be connected to an edge connector may for example be a solid state disk (SSD), wireless communications module or other electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Figure 1 shows an example of a printed circuit board (PCB) with a component mounted on a first side and a backing member and standoff on the second side;

Figure 2 shows an example of a printed circuit board (PCB) with a component mounted on a first side and a backing member, standoff and an edge connector on the second side;

Figure 3 shows the example of Figure 2 with a module mounted between the standoff and the edge connector;

Figure 4 shows an example of a printed circuit board (PCB) with a metal plate and an edge connector mounted on one side and a connector projecting from the metal plate;

Figure 5 shows the example of Figure 4 with a module mounted between a first connector and a second connector;

Figure 6A is a perspective view of the example of Figure 5 without a module;

Figure 6B is a perspective view of the example of Figure 5 with the module;

Figure 7 shows an example of a printed circuit board (PCB) and a plurality of components mounted to the PCB as seen from a first side.

Figure 8 shows an example of the printed circuit board (PCB) of Figure 7 as seen from a second side.

Figure 9 shows an example of a backing member in more detail;

Figure 10 shows the example of Figure 8 with a plurality of components mounted to the second side of the PCB between an edge connector and standoffs of the backing member. DETAILED DESCRIPTION

[0004] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure. Throughout the present disclosure, the terms "a", "an" and "a number of are intended to denote at least one of a particular element. As used herein, the term "includes" means includes but not limited to, the term "including" means including but not limited to. The term "based on" means based at least in part on.

[0005] Figure 1 is a schematic diagram showing an example of a printed circuit board (PCB) assembly 1 , which may form part of a computing device. A PCB assembly is a PCB together with components mounted to the PCB. As shown in Figure 1 , the PCB assembly includes a PCB 10 which has a first side 1 1 and a second side 12 opposite the first side. The sides may, for example, be opposite faces of the PCB. A first component 20 is mounted to the first side 1 1 of the PCB. The first component 20 may for example be an electronic component such as, but not limited to, an application specific integrated chip (ASIC), central processing unit (CPU), field programmable gate array (FPGA), integrated chip, system on chip (SOC) or a processor. In other examples the first component 20 may be a heat sink, or other support structure, for an electronic component.

[0006] A backing member 30 is mounted to a second side of the PCB in a location approximately opposite the first component 20. In one example the backing member is a plate meaning it is substantially planar. In one example the backing member is formed of metal. The backing member 30 and first component 20 may have different shapes and sizes, but there should be some overlap between the extent of the backing member and first component, so that at least a portion of the backing member 30 is opposite a portion of the first component 20. The first component is secured to the PCB by a number of elongate members 40 extending through respective through-holes of the PCB. The backing member 30 is, likewise, secured to the PCB by the same elongate members 40. The elongate members mechanically connect the backing member and first component and help to secure the backing member and first component in place relative to the PCB.

[0007] There may be one elongate member, two elongate members as shown in Figure 1 , or more than two elongate members. Each elongate member 40 may be separate from the backing member and the first component, e.g. it may extend through or be received by an aperture of the backing member or the first component. The elongate member may for example be a screw, bolt or pin etc. In another example, the elongate member may be an integral part extending from either the backing member or the first component. For instance, the first component may have legs that extend through through-holes of the PCB and a through hole of the backing member, or vice versa.

[0008] In one example, the elongate members exert a compressive force on the first component. For example, a screw, nut or similar arrangement may be tightened to push the backing member and first component towards the PCB. This may help to secure electrical connections of the first component to the PCB; for instance if the first component is electrically connected to the PCB by a ball grid array, then the compressive force may help to prevent the ball grid array connection from being damaged by vibrations or mechanical shocks.

[0009] A standoff 50 extends from the backing member 30. A standoff is a member that extends outwardly from the PCB to create a spacing distance between the PCB and a component that is to be mounted to the PCB, or to create a spacing distance between the PCB and an external casing. The standoff may be integral with the backing plate, or the standoff may be a separate piece that is adhered, soldered or mechanically secured to the backing plate. In one example the standoff includes an aperture with a female screw thread into which a screw may be screwed. This may help the PCB to be secured to an external casing or help to secure a module to the standoff. [0010] It should be noted that in this example, the standoff does not extend into the PCB. This is in contrast to conventional standoffs, which are secured to a PCB by drilling a hole in the PCB and inserting one end of the standoff into the drilled hole. Rather, in this example, the standoff is mounted to, or forms an integral part of, the backing member. This provides more flexibility as the standoff can be located at any desired location on the backing member, without worrying about the internal circuit lines of the PCB. In contrast, if a standoff is mounted in a hole drilled in the PCB, then it may not be possible to place the standoff in certain locations as this might interfere with the internal circuits of the PCB.

[001 1] Figure 2 is the same as Figure 1 , but shows an edge connector 60 extending from the second side of the PCB and opposite to the standoff 50. In this way the edge connector 60 may act as a first connector and the standoff may act as a second connector. An electronic device or module may be mounted between the edge connector 60 and the standoff 50. An edge connector is an electrical connector that is to connect with an edge of, rather than a face of, a component. An edge connector may for example include an aperture or socket with a plurality of conductive pins for connecting with connectors of an electronic component. For instance, the component to be mounted may include a mini-PCB with a number of electrical signal lines that terminate at one end of the PCB and are to contact the pins of the edge connector. Examples of an edge connector include, but are not limited to, a M.2 connector, a PCI connector, Mini PCI or Mini PCI express.

[0012] Figure 3 shows the example of Figure 2 with an electronic component 70 or module mounted between the standoff 50 and the edge connector 60. The electronic component 70 may for example be a solid state disk (SSD), wireless communications module or other electronic device.

[0013] Figure 4 shows another example of a PCB assembly which may form part of a computing device. As in Figure 1 , the assembly includes a PCB 10 which has a first side 1 1 and a second side 12 opposite the first side. A metal back plate 30, which is one example of a backing member, is mounted to the second side of the PCB assembly. A first connector 60, which may for example be an edge connector, is mounted to and extends from the second side of the PCB.

[0014] A second connector 50 extends from the backing member 30. The second connector 50 may be integral with, or mounted to, the metal back plate 30. For instance, the second member may be clipped or screwed into the back plate. The second connector 50 may extend substantially perpendicular to a surface of the backing member 30 and the second side 12 of the PCB. The second connector 50 may include an engagement feature (not shown) such as a ridge to abut with an edge of a removable module that is to be mounted between the first connector and the second connector. The second connector may act as a standoff. In one example, the second connector includes an aperture with a female screw thread.

[0015] In the example of Figure 4, the metal back plate 30 is mounted to the PCB in a manner that does not require through holes extending through the PCB. For instance, the back plate 30 may be mounted to the second side 12 of the PCB by a mechanical fit, such as a clip or spring, or by adhesive or by soldering. In other examples, the back plate 30 may be mounted to the PCB by an elongate member extending through the PCB, as discussed above with respect to Figures 1 to 3.

[0016] Figure 5 shows an example of the PCB assembly of Figure 4, in which a module 70 has been mounted and secured between the first connector 60 and the second connector 50. The module 70 may be removable. The module 70 may be selected by the manufacturer, or may be a component that is chosen from among a plurality of possible components by an end user. The module 70 may for example be a solid state disk (SSD), wireless communications module or other electronic device. For clarity, Figure 5 shows the assembly in a different orientation to Figure 4, with the second side 12 of the PCB facing upwards. However, in use the assembly may have any appropriate orientation. One end of the module 70 may be inserted into an aperture of the first connector 60. In this way conductive contacts located at the end of the module 70 may connect with conductive pins (not shown) in the aperture of the first connector 60. The second connector 50 may include an aperture having a screw thread 55. A screw 90 may be screwed into the aperture so that a head of the screw 92 may abut against a second end of the module 70 and thus help to secure the module 70 in place. A similar arrangement may be used to secure the module 70 shown in Figure 4.

[0017] As the back plate 30 is formed of metal, it may act as an electrical ground for the module 70. In one example, the second connector 50 is formed of a metal and thus provides a conductive path from the second end of the module 70 to the back plate 30 which acts as a ground. In other examples, the second connector 50 may be formed of plastic or another non-conductive material. In that case, the screw 90 may act as the conductive path between the module 70 and the back plate 30. For instance, the screw shank 94 may abut with the back plate 30 to provide a conductive path. In one example (not shown), the back plate 30 may have a threaded aperture to receive the screw shank 94. The backing member 30 of Figures 1 to 3 may similarly act as a circuit ground, if it is made of metal, or another conductive material.

[0018] Figure 6A is a perspective view of the arrangement of Figure 5, before the module 70 is inserted to the edge connector 60. Figure 6B is a perspective view from above, after the module 70 has been mounted. The same reference numerals are used as in Figure 5. In Figure 6A, the pins 66 in the aperture or socket 64 of the edge connector are clearly shown. Further, as can be seen in Figure 6B, the head of the screw 92 abuts a recessed portion 72 of the module 70, which is shaped to receive the screw head.

[0019] Figures 7 and 8 show another example of a computing device according to the present disclosure. The computing device may for example be a server module, notebook computer, network switch, storage system or other computing device. The computing device includes a PCB assembly. The PCB 10 has a first side 1 1 and a second side 12 with components mounted on both sides.

[0020] Figure 7 is a perspective view from above of the first side 1 1 . Various components are mounted to the first side including two memory modules 1 10 and 120 and a heat sink 20 for a system on chip (SOC) package including a processor. The heat sink 20 may be mounted on top of a SOC package (not shown) which is mounted to the first side of the PCB. The heat sink 20 helps to dissipate heat generated by the SOC package. The heat sink 20 is secured to the PCB by a plurality of elongate members 40. In the illustrated example the elongate members 40 are screws, but the present disclosure is not limited thereto. The elongate members may extend through holes in the heat sink 20 and through-holes in the PCB 10, as discussed above with reference to Figures 1 to 3. While there are four elongate members in the example of Figure 7, in other examples there may be more or fewer elongate members. The location of the through holes and corresponding elongate members may be chosen so as to avoid interfering with circuitry of the PCB. As the SOC and heat sink is a major component of the PCB and generally secured with a back plate, the PCB circuitry may already have been designed to allow room for through holes to support the SOC and heat sink. In the example of Figure 7, the first side of the PCB is quite crowded and there is no room for mounting SSD modules with edge connectors. However, as described below, in this example there is room for such components on the second side of the PCB.

[0021] Figure 8 shows the PCB assembly as seen from the second side 12. Various components are mounted to the second side, including a further memory module 130. A backing member 30, which may for example be a metal back plate, is mounted to the second side 12. The back plate 30 is secured in place by the elongate members 40, which may be received by receiving parts 32 of the backing member. A plurality of standoffs 50A, 50B, 50C, 50D extend outwardly from the back plate 30. The standoffs may be located at any desired position on the back plate. As the standoffs do not necessarily extend into the PCB, they may be located at any position on the back plate. In the example of Figure 8, each standoff is located opposite a respective corresponding edge connector. Thus standoff 50A is located opposite edge connector 60A and standoff 50B is located opposite edge connector 60B. Edge connector 60C is opposite two standoffs 50C and 50D, the reason being to facilitate mounting of different lengths of module. A normal size module may be mounted between edge connector 60C and standoff 50D. If a larger size module is to be mounted then standoff 50D may be removed and the module mounted between standoff 50C and edge connector 60C. The edge connectors may be connected to conductive signal lines of the PCB so as to carry signals to and from the mounted module and other parts of the PCB assembly.

[0022] Figure 9 is a perspective view showing an example of the back plate 30 in more detail. The back plate is planar and may be formed of metal. In the illustrated example it has several large gaps 31 to allow room for other components or to reduce use of material. In other examples there may be no such gaps. There are standoffs 50 mounted to the back plate 30 at locations chosen for convenient mounting of a module, e.g. opposite corresponding edge connectors of the PCB. Such standoffs may be mounted anywhere on the back plate and need not extend into the PCB, thus providing flexibility in design and location of the standoffs. Receiving parts 32 are designed for connection to the elongate members 40. In one example, the receiving parts 32 may be projections with a threaded aperture that are to extend into through holes of the PCB. In that case the threaded apertures may receive an elongate member in the form of a screw to secure the back plate 30 to a component on the first side of the PCB. In other examples (not shown), the back plate may itself have elongate members that are to extend through through-holes of the PCB and be received by a component on the first side of the PCB.

[0023] The standoffs 50A to 50C and the receiving parts 32 may be integral to the back plate, or may be mounted to the back plate. For example they may be clipped, screwed or otherwise mechanically secured to the back plate, or adhered or soldered onto the back plate.

[0024] In still another example (not shown), the back plate 30 may not be connected to a component on the first side of the PCB, but may be secured directly to the PCB. For instance, the back plate 30 may have clips, springs or other connecting parts that mechanically secure the back plate to an aperture, or connecting feature, of the PCB. In still other examples the back plate 30 may be adhered or soldered to the PCB. In this respect, a mechanical connection whether by clip, spring, connecting part, or elongate members such as bolts, pins, screws etc. may be more secure than adhesive and may avoid exposing the PCB to the heat generated by soldering a large item such as a back plate. [0025] Figure 10 shows an example of the assembly of Figure 8 after a plurality of modules have been mounted to the PCB. Two memory modules 130 and 140 are mounted to the PCB. The memory module 140 may overlap slightly with a portion of the back plate 30. Further, a number of modules have been mounted between the edge connectors and standoffs. Specifically, a first module 70A is mounted between the edge connector 60A and the standoff 50A, a second module 70B is mounted between the edge connector 60B and the standoff 50B and a third module 70C is mounted between the edge connector 60C and the standoff 50C. In an example, a first end of each module 70A, 70B, 70C may be inserted to a respective edge connector, while a second end of each module may be held in place by a screw screwed into the respective standoff. The back plate 30 thus acts to support the standoffs and may also act as an electrical ground for the mounted modules. The modules may for example be a SSD, a wireless communications module for sending and receiving wireless signals such as WiFi or cellular telecommunication signals, or another electronic device.

[0026] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0027] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims

WHAT IS CLAIMED IS:

1 . A printed circuit board assembly comprising:

a printed circuit board including a first side and a second side;

a component mounted on the first side of the printed circuit board;

a backing member mounted to the second side of the printed circuit board, the backing member being secured to the second side of the printed circuit board by elongate members extending through the printed circuit board to the component on the first side; and

a standoff extending outwardly from the backing member, wherein the standoff does not extend into the main body of the printed circuit board.

2. The printed circuit board assembly of claim 1 wherein the standoff includes a threaded aperture to receive a screw.

3. The printed circuit board assembly of claim 1 wherein the backing member is formed of metal and the standoff is formed of metal.

4. The printed circuit board assembly of claim 1 , further comprising an edge connector mounted to the second side of the printed circuit board at a location opposite the standoff, whereby a module can be secured between the edge connector and the standoff.

5. The printed circuit board assembly of claim 4 comprising a plurality of standoffs extending from the backing member and a plurality of edge connectors mounted to the second side of the printed circuit board, each edge connector positioned opposite a respective one of the standoffs.

6. The printed circuit board of claim 1 wherein the component mounted on the first side includes a heat sink.

7. A computing device comprising: a printed circuit board assembly including a first side and a second side opposite the first side;

a metal plate mounted to the second side;

a first connector on the second side to connect with a first edge of a removable module;

a second connector to connect with a second edge of the removable module, the second connector extending from the metal plate on the second side of the printed circuit board assembly.

8. The computing device of claim 7 wherein the second connector is formed of metal.

9. The computing device of claim 7 wherein the first connector includes a female socket and a plurality of pins are located in the female socket

10. The computing device of claim 7 wherein the second connector extends substantially perpendicular to a surface of the metal plate and includes an engagement feature to abut a second edge of the removable module.

1 1 . The computing device of claim 7 wherein the metal plate is mechanically secured to the main body.

12. A computing device comprising:

a printed circuit board including a first face and a second face opposite the first face;

a component mounted on the first face of the printed circuit board;

a plate mounted to a second face of the printed circuit board at a location opposite the component;

a plurality of elongate members extending through the printed circuit board and securing the component and the plate in place;

a standoff projecting outwardly from a surface of the plate and extending outwardly from the plate, but not extending into the printed circuit board; and a module mounted on the second face of the printed circuit board, one end of the module contacting the standoff.

13. The computing device of claim 12 wherein the module is a solid state disk module or a wireless communications module.

14. The computing device of claim 12 wherein the plate acts as an electrical ground for the module.

15. The printed circuit board assembly of claim 12 wherein the standoff includes a threaded aperture to receive a screw and one end of the module is held in place by the screw and another end of the module contacts with an edge connector that is electrically connected to a signal line of the printed circuit board.