Circuit board system

Abstract

According to one aspect of the present disclosure, there is provided a circuit board system comprising: a main board having a top side and a bottom side, where the main board has at least one cavity on its top side; a printed circuit board (PCB) having a top side and a bottom side; and at least one first electronic component disposed on the top side of the PCB and at least one second electronic component disposed on the bottom side of the PCB, where the PCB is disposed on the top side of the mainboard, and wherein the at least one second electronic component located on the bottom side of the PCB extends into the cavity on the top side of the motherboard.

Description

Technical Field

[0001] The present disclosure relates to a circuit board system. Background Art

[0002] Modular circuit board systems having electrically interconnected circuit boards are becoming increasingly popular, as the modularity of such arrangements allows for rapid adaptation to existing technologies. An exemplary circuit board system is described in US 2014 / 0063748 A1.

[0003] In many conventional circuit board systems, the connections between the individual circuit boards are implemented as plug-in connections. However, plug-in technology is expensive because it requires plugs and sockets. In addition to this, plug and socket technology takes up a lot of space on the circuit board. On the other hand, if solder connections are used instead of plug-in technology, the operating temperature of the system is limited in terms of range and / or cycle. In case of increased temperature and temperature cycles, the probability of failure is significantly higher than in systems using plug-in technology. At the same time, the size of the circuit board system needs to be maintained or reduced.

[0004] Therefore, there is a need for an improved circuit board system. Summary of the invention

[0005] The invention is defined in claim 1. Dependent claims recite selected optional features. In the following, each described system, device, apparatus, example and aspect that does not correspond exactly to the invention as defined in the claims is therefore not in accordance with the invention and, as with the entire description below, is presented merely for illustration purposes or to highlight a particular aspect or feature of the claims.

[0006] The present disclosure relates to a circuit board system having two or more electrically connected circuit boards, wherein one or more cavities are formed in one or more of the circuit boards. The cavity is arranged to accommodate an electronic component arranged on one of the circuit boards. The cavity enables the electronic component to be arranged on opposite surfaces of the circuit board and the cooling of the components on the opposite surfaces to be decoupled. The circuit boards can be electrically connected to each other via a land grid array (LGA) or a ball grid array (BGA).

[0007] According to a first aspect of the present disclosure, a circuit board system is provided, comprising: a main board having a top side and a bottom side, wherein the main board has at least one cavity on its top side; a printed circuit board PCB having a top side and a bottom side; and at least one first electronic component arranged on the top side of the PCB and at least one second electronic component arranged on the bottom side of the PCB, wherein the PCB is arranged on the top side of the main board, and wherein the at least one second electronic component located on the bottom side of the PCB extends into the cavity on the top side of the main board.

[0008] This arrangement enables the LGA module to be implemented as a double-sided assembly. Such an LGA module may have a system on chip (SoC) and one or more power management ICs (PMICs) on one side of a PCB, and a memory module (memory IC) arranged next to the SoC on the opposite side of the PCB. Passive electronic components may be placed below the SoC, on the same side of the PCB as the memory modules. These components (memory modules, passive components) may be received in openings in a mainboard electrically connected to the PCB via the LGA. The size and position of the openings are variable and may be determined based on the component size.

[0009] Compared to conventional LGA modules (implemented as a single-sided assembly, where the SoC, PMIC, memory, and power controller use a common heat sink), the double-sided assembly according to the embodiments of the present disclosure can decouple the heat sink for the SoC and / or PMIC on the one hand, and the heat sinks of other components such as the memory on the other hand. In other words, the SoC and / or PMIC and the memory can each be connected to their own heat sink. This decoupling of the heat sink is a significant improvement in coping with the increasing power consumption of the latest generation of SoCs.

[0010] The double-sided assembly according to the embodiments of the present disclosure enables the use of low temperature grade memories. Furthermore, removing / omitted components saves space on the SoC side of the PCB, thereby enabling an improved layout design. Furthermore, the assembly can be implemented as an LGA type module without the need for (expensive) connectors. Furthermore, due to the spatial isolation between the main heat sources (i.e., the SoC on one side and the memory on the other side), the heat sink design can be simplified.

[0011] In one embodiment, the at least one cavity extends from the top side of the mainboard through the mainboard to the bottom side of the mainboard. In other words, the at least one cavity is implemented as a through opening in the mainboard. Thus, electrical components on the bottom side of the PCB can extend through and beyond the bottom surface of the mainboard.

[0012] In one embodiment, the circuit board system includes: a plurality of the second electronic components arranged on the bottom side of the PCB; and a plurality of cavities located on the top side of the main board, wherein the cavities are arranged to match the positions of the second electronic components at the bottom of the PCB and receive the second electronic components. Thus, the main board can be customized to accommodate the electronic components at the bottom of the PCB while retaining a sufficiently large surface for LGA or BGA type electrical connections between the PCB and the main board.

[0013] In one embodiment, the circuit board system includes a plurality of the second electronic components arranged on the bottom side of the PCB, wherein one or more but not all of the second electronic components extend into one or more corresponding cavities of the at least one cavity. In other words, a cavity may be provided to accommodate selected ones of the electronic components arranged at the bottom side of the PCB. For example, some of the electronic components may have a larger vertical dimension (i.e., protrude further from the bottom surface of the PCB) than other electronic components. Cavities may be provided for those larger components, while there may already be enough space between the PCB and the mainboard to accommodate other (smaller) components.

[0014] In one embodiment, the PCB is connected to the mainboard via an LGA. An LGA type connection can be used to reduce the overall vertical size of the circuit board system.

[0015] In an alternative embodiment, the PCB is connected to the motherboard via a BGA. In a BGA type connection, there may be more space between the PCB and the motherboard. This space may be sufficient to accommodate some of the components at the bottom side of the PCB without leaving a corresponding cavity in the motherboard.

[0016] In one embodiment, the at least one first electronic component is attached to a heat sink at the top side of the PCB. Thus, the at least one first electronic component (e.g., SoC) has its own heat sink, which is isolated from the heat sink that may be provided for the electronic components (e.g., memory) disposed at the bottom side of the PCB.

[0017] In one embodiment, the at least one second electronic component is attached to a heat sink, heat spreader, chassis cover or sheet metal cover at the bottom side of the PCB. Therefore, the electronic component arranged at the bottom side of the PCB may (also) have its own heat sink, or heat dissipation may be provided in other ways, for example, by connecting to a chassis cover or sheet metal cover of a device for mounting the circuit board system. Therefore, existing components can be used for heat dissipation. The heat dissipation of such components may be lower than that of a dedicated heat sink, but this may be sufficient because the electronic component at the bottom side of the PCB generates less heat and is thermally decoupled from the electronic component (e.g., SoC) at the top side of the PCB that may generate more heat.

[0018] In one embodiment, the at least one second electronic component is attached to the heat sink, heat spreader, chassis cover or sheet metal cover by a thermally conductive molding compound or resin. Thus, the at least one second electronic component can be thermally coupled to components that are not directly adjacent (contacting) therewith.

[0019] In one embodiment, the at least one first electronic component includes a SoC. The at least one first electronic component may also include one or more PMICs. The at least one second electronic component may include one or more DRAMs and / or one or more multilayer ceramic chip capacitors MLCCs.

[0020] The at least one second electronic component may include one or more passive electronic components arranged on the bottom side of the PCB opposite to the SoC arranged on the top side of the PCB. Passive electronic components such as MLCCs do not generate additional heat and / or are sufficiently resistant to heat from the SoC and are therefore very suitable for arrangement below the SoC. This arrangement can effectively utilize the available PCB space.

[0021] In one embodiment, the PCB includes a plurality of the cavities in the mainboard and one or more bridges between the cavities. The bridges between the cavities increase the rigidity of the mainboard. In addition, the bridges can also be used to arrange pins, pads or balls thereon to connect the PCB to the mainboard. This arrangement can effectively utilize the available space for electrical connection between the mainboard and the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Example embodiments of the present disclosure will be described, by way of example only, with reference to the accompanying drawings, in which:

[0023] Figure 1 Schematically shows a top view of a main board PCB for a circuit board system according to an embodiment of the present disclosure;

[0024] Figure 2 Schematically illustrates a top view of a circuit board system according to an embodiment of the present disclosure;

[0025] Figure 3 Schematically shows the Figure 2 A cross section of a circuit board system;

[0026] Figure 4 Schematically shows a top view of another main board PCB for a circuit board system according to an embodiment of the present disclosure;

[0027] Figure 5 schematically illustrates a cross section through a circuit board system according to an embodiment of the present disclosure;

[0028] Figure 6 schematically illustrates a cross section through a circuit board system according to another embodiment of the present disclosure;

[0029] Figure 7 schematically illustrates a cross section through a circuit board system according to another embodiment of the present disclosure; and

[0030] Figure 8 A bottom view of a PCB for a circuit board system according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0031] Now, a detailed description of exemplary embodiments of the present disclosure will be given below, by way of example only. These examples are described with reference to the accompanying drawings identified above, which are included to provide further details and clarity. It should be understood that the examples described are not restrictive, and other examples that fall within the scope of the present disclosure can be envisioned.

[0032] Figure 1 A top view of a main board 10 for a circuit board system according to an embodiment of the present disclosure is schematically shown. The main board 10 includes a cavity 11 on the top surface. The cavity 11 may be formed by a groove or extend through the entire thickness of the main board 10. The cavity 11 is used to receive one or more electronic components arranged on the bottom surface of the PCB, as described below.

[0033] Figure 2 Schematically shows a top view of a circuit board system 20 according to an embodiment of the present disclosure. The circuit board system 20 includes a main board 10 and a PCB 21, wherein the PCB is arranged on the top surface of the main board 10 above the cavity 11, as shown in FIG. Figure 1 PCB 21 includes one or more first electronic components arranged on its top surface. For example, the first electronic components may include a system on chip (SoC) 22 and a PMIC 24. PCB 21 also includes one or more second electronic components arranged on its bottom surface. For example, the second electronic component may include a DRAM 23, as shown by the dotted line. It is worth noting that the present disclosure is not limited to any specific type, combination, or arrangement of electronic components on the top and bottom surfaces of PCB 21.

[0034] Figure 3 Schematically showing the line AA passing through Figure 2 PCB 21 has a second electronic component arranged on its bottom surface. In the illustrated embodiment, the second electronic component includes a DRAM 23 and a plurality of passive electronic components 30, such as MLCC (Multilayer Ceramic Chip Capacitors). The passive electronic components 30 are arranged opposite to the SoC 22 arranged on the top surface of the PCB 21.

[0035] Figure 3Also shown is the cavity 11 extending through the main board 10. The PCB 21 is arranged on the top surface of the main board 10 so that the second electronic components (DRAM 23 and MLCC) at the bottom of the PCB 21 extend into the cavity 21. Therefore, the circuit board system 20 according to the illustrated embodiment has a reduced overall thickness.

[0036] Figure 4 A top view of a main board 40 for a circuit board system according to another embodiment of the present disclosure is schematically shown. In this embodiment, the main board 40 includes three cavities 41, 42 and 43. However, the present disclosure is not limited thereto, and the main board may include any number and arrangement of cavities. In addition, the cavities may be formed by through openings or grooves or any combination thereof.

[0037] Between the cavities 41, 42 and 43, the main plate 40 includes bridges 44. Thus, in this embodiment, the main plate 40 does not have a single large cavity ( Figure 1 The motherboard 40 does not have a cavity 11, but has a plurality of cavities 41, 42 and 43 separated by bridges 44. The bridges 44 increase the rigidity and stability of the motherboard 40 and provide space for electrical connection, for example, space for electrical connection through solder balls or pads.

[0038] Figure 5 Schematically, a cross section through a circuit board system 20 according to an embodiment of the present disclosure is shown. In this embodiment, the circuit board system 20 includes a ball grid array (BGA) 50 for electrically connecting the PCB 21 to the motherboard 10. The vertical extension of the BGA 50 is higher than the vertical extension of the passive electronic components 30. Therefore, as shown in FIG. Figure 5 As shown in the lower part of the main board 10, the passive electronic component 30 is received in the space between the main board 10 and the PCB 21. In other words, in this embodiment, no cavity is provided in the main board 10 for accommodating the passive electronic component 30. On the other hand, the vertical extension of the BGA 50 is lower than the vertical dimension of the DRAM 23. In order to accommodate the DRAM 23, the main board 10 includes a cavity 51, one cavity for each DRAM 23. Therefore, although the DRAM 23 is arranged on the bottom side of the PCB 21 facing the main board 10, the overall vertical dimension of the circuit board system 20 can be maintained.

[0039] It is worth noting that any number of cavities 51 may be provided within the mainboard 10 to accommodate any type of active or passive electronic components arranged at the bottom side of the PCB 21 .

[0040] Figure 6A cross section through a circuit board system 20 according to another embodiment of the present disclosure is schematically shown. In this embodiment, the circuit board system 20 includes an LGA 60 instead of a BGA 50 for electrically connecting the PCB 21 to the motherboard 10. One difference between a BGA and an LGA is that the vertical dimension of the LGA is reduced. Therefore, the space between the PCB 21 and the motherboard 10 may not be sufficient to accommodate the passive electronic components 30. Therefore, in order to provide sufficient space, three cavities 61 (including an additional central cavity) are provided (with Figure 5 23 and passive electronic components 30. Note again that the present disclosure is not limited to the exemplary number and combination of electronic components and cavities shown. Rather, the present disclosure contemplates any number and arrangement of cavities in the motherboard 10 to accommodate any type of electronic components at the bottom of the PCB.

[0041] Figure 7 Schematically illustrates a cross section through a circuit board system 20 according to yet another embodiment of the present disclosure. Essentially, this embodiment combines Figure 5 and Figure 6 The present invention provides a feature of an embodiment in which the circuit board system 20 includes a BGA 70 and a central cavity 71 below the passive electronic component 30 located at the bottom of the PCB 21, as well as two cavities 71 for accommodating the DRAM 23. Although the central cavity 71 is not necessary for accommodating the passive electronic components, it is still advantageous because it also enables the motherboard 10 to be used in an LGA-based system. In other words, the motherboard is suitable for both BGA and LGA type assemblies. In addition, the central cavity 71 reduces the weight and material requirements of the motherboard 10. In addition, this embodiment is able to reduce the diameter of the ball of the BGA 70 to the extent that the passive electronic component 30 extends into the central cavity 71. In other words, this embodiment provides versatility in the implementation and use of the motherboard.

[0042] Note again that the present disclosure is not limited to the exemplary numbers and combinations of electronic components and cavities shown.

[0043] Figure 8 Schematically shows a bottom view of a PCB 21 for a circuit board system 20 according to an embodiment of the present disclosure. The printed circuit board 21 includes a BGA 80. The balls of the BGA 80 are arranged to cover most of the bottom side of the PCB 21, including a bridge 44 ( Figure 4 ) is formed on the top of the area 82. Alternatively, an LGA may be provided instead of the BGA 80.

Claims

1. A circuit board system, comprising: a main board having a top side and a bottom side, wherein the main board has at least one cavity on its top side; a printed circuit board PCB having a top side and a bottom side; as well as at least one first electronic component arranged on a top side of the PCB and at least one second electronic component arranged on the bottom side of the PCB, wherein the PCB is arranged on the top side of the main board, and Wherein the at least one second electronic component on the bottom side of the PCB extends into the cavity on the top side of the mainboard. 2 . The circuit board system of claim 1 , wherein the at least one cavity extends through the main board from the top side to the bottom side.

3. The circuit board system according to claim 1 or 2, comprising: a plurality of said second electronic components arranged on said bottom side of said PCB; as well as A plurality of cavities are located on the top side of the main board, wherein the cavities are arranged to match the position of the second electronic component at the bottom of the PCB and receive the second electronic component.

4. A circuit board system according to any preceding claim, comprising: A plurality of the second electronic components are arranged on the bottom side of the PCB, wherein one or more but not all of the second electronic components extend into one or more corresponding cavities of the at least one cavity.

5. A circuit board system according to any preceding claim, wherein the PCB is connected to the mainboard via a ball grid array (BGA).

6. The circuit board system according to any one of claims 1 to 4, wherein the PCB is connected to the mainboard via a land grid array (LGA).

7. A circuit board system according to any preceding claim, wherein the at least one first electronic component is attached to a heat sink at a top side of the PCB.

8. A circuit board system according to any preceding claim, wherein the at least one second electronic component is attached to a heat sink, heat spreader, chassis cover or sheet metal cover at the bottom side of the PCB.

9. The circuit board system of claim 8, wherein the at least one second electronic component is attached to the heat sink, heat spreader, chassis cover or sheet metal cover by a thermally conductive molding compound or resin.

10. A circuit board system according to any preceding claim, wherein the at least one first electronic component comprises a System on Chip (SoC).

11. The circuit board system of claim 10, wherein the at least one second electronic component comprises one or more passive electronic components arranged on the bottom side of the PCB opposite the SoC arranged on the top side of the PCB.

12. The circuit board system of any preceding claim, wherein the at least one second electronic component comprises one or more DRAMs and / or one or more multi-layer ceramic chip capacitors (MLCCs).

13. A circuit board system according to any preceding claim, wherein the PCB comprises a plurality of the cavities and one or more bridges between the cavities.

14. The circuit board system of claim 13, comprising a plurality of pins, pads or balls on the bridge for connecting the PCB to the main board.

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