Multi-layer PCB (Printed Circuit Board) structure with top-layer heat dissipation

Abstract

The utility model discloses a multilayer PCB structure with a top heat dissipation layer. The multilayer PCB structure comprises an aluminum substrate, a ceramic substrate, a multilayer PCB and a heat conduction column. The ceramic substrate is arranged on the aluminum substrate, the multi-layer PCB is arranged on the ceramic substrate, a plurality of copper-clad through holes are formed in the multi-layer PCB, the heat conduction columns penetrate through the copper-clad through holes, one ends of the heat conduction columns are connected to the top layer of the multi-layer PCB, and the other ends of the heat conduction columns are connected to the ceramic substrate. According to the multilayer PCB top-layer heat dissipation junction disclosed by the utility model, the heat conduction columns with higher heat conduction coefficients are added, and heat of the top-layer PCB is conducted to the ceramic substrate and the aluminum substrate at the bottom through the heat conduction columns, namely, the heat conduction performance between the top-layer PCB and the aluminum substrate at the bottom in the multilayer PCB is improved through adding the heat conduction columns, so that the heat dissipation efficiency of the top-layer PCB is accelerated, and the heat dissipation efficiency of the top-layer PCB is improved. Therefore, the reliability, the service life and the electrical performance of the electronic component are prevented from being reduced due to poor heat dissipation performance of the top-layer PCB.

Description

Technical Field

[0001] The utility model relates to the technical field of printed circuit board manufacturing, in particular to a multi-layer PCB structure with top-layer heat dissipation. Background Art

[0002] With the rapid development of electronic technology today, the design of thin and light electronic products has become more and more mainstream. For example, the size of power supplies is getting smaller and smaller, and the power density of power supplies is getting higher and higher. High-power and high-density modular power supplies are gradually becoming mainstream. In this modular power supply, multi-layer PCB boards are usually used for winding transformers or inductors, and power devices are mounted on the top layer. The heat generated by the power devices when working will cause the multi-layer PCB boards to heat up rapidly, thereby reducing the reliability, life and electrical performance of electronic components. To this end, technicians in this field install the multi-layer PCB on an aluminum substrate, and transfer the heat from the bottom layer of the PCB to the aluminum substrate by encapsulating thermal conductive silicone, thereby effectively dissipating heat; in addition, when mounting power devices, most of the heat-generating power devices will be installed on the PCB close to the side of the aluminum substrate. However, due to the limited space of the PCB near the aluminum substrate, some high-power heat-generating power devices also need to be installed on the PCB far from the aluminum substrate (hereinafter referred to as the top PCB), which makes the temperature of the top PCB rise faster; at the same time, since the thickness of the PCB is usually more than 4.3mm, and the copper foil layers of the PCB are isolated by an insulating layer, and the thermal conductivity of the insulating layer is poor, the heat of the top PCB (hereinafter referred to as the top PCB) cannot be effectively transferred to the aluminum substrate. Therefore, the heat of the top PCB is still difficult to be effectively transferred to the bottom layer of the PCB, which limits the heat dissipation through the aluminum substrate. Therefore, a multi-layer PCB structure with top-layer heat dissipation is proposed. Utility Model Content

[0003] The purpose of the utility model is to provide a multi-layer PCB structure with top-layer heat dissipation, so as to solve the technical problem that the heat of the top layer PCB in the multi-layer PCB is difficult to be effectively transferred to the bottom layer of the PCB, which limits the effect of heat dissipation of the top layer PCB through the aluminum substrate, thereby limiting the improvement of the power density of the module power supply.

[0004] To achieve this purpose, the utility model adopts the following technical solutions:

[0005] A multi-layer PCB structure with top-layer heat dissipation, comprising:

[0006] Aluminum substrate;

[0007] A ceramic substrate, disposed on the aluminum substrate;

[0008] A multi-layer PCB board is arranged on the ceramic substrate, and a plurality of copper-clad through holes are arranged on the multi-layer PCB board;

[0009] A heat-conducting column passes through the copper-clad through hole, one end of the heat-conducting column is connected to the top layer of the multi-layer PCB board, and the other end is connected to the ceramic substrate.

[0010] Optionally, the ceramic substrate is bonded to the aluminum substrate by means of a thermally conductive adhesive.

[0011] Optionally, a power device is disposed on the top layer of the multi-layer PCB board, and a plurality of the copper-clad through holes are equidistantly disposed around the power device.

[0012] Optionally, the power device forms a heat affected zone on the top layer of the multi-layer PCB board, and the plurality of copper-clad through holes form a through hole ring surrounding the power device, and the through hole ring at least covers half of an isotherm in the heat affected zone.

[0013] Optionally, the thermally conductive column is a copper column, and the length of the thermally conductive column is greater than the thickness of the multi-layer PCB board.

[0014] Optionally, one end of the heat-conducting column is connected to the top layer of the multi-layer PCB board by welding, and the other end of the heat-conducting column is connected to the ceramic substrate by welding.

[0015] Optionally, before the heat-conducting column is welded to the ceramic substrate, a welding pad corresponding to the copper-clad through hole is provided on the ceramic substrate.

[0016] Optionally, before the heat-conducting column is welded to the ceramic substrate, solder paste is coated on the welding pad.

[0017] Optionally, an insulating layer is coated on the outer circumference of the thermally conductive column.

[0018] Compared with the prior art, the utility model has the following beneficial effects: the power device in the top PCB of the multi-layer PCB generates heat during operation, and the heat is diffused with the heat-generating power device as the center. Most of the heat is diffused into the top PCB, and the top PCB transfers the heat to the heat-conducting column, which transfers the heat to the bottom ceramic substrate, and then the ceramic substrate transfers the heat to the aluminum substrate, thereby accelerating the heat dissipation of the top PCB. Compared with the existing multi-layer PCB board that relies on its own thermal conductivity to conduct the heat of the top layer to the bottom of the PCB, and then dissipates the heat through the aluminum substrate, the multi-layer PCB top layer heat dissipation junction disclosed by the utility model adds a heat-conducting column with a higher thermal conductivity coefficient, and conducts the heat of the top PCB to the bottom ceramic substrate and aluminum substrate through the heat-conducting column, that is, by adding the heat-conducting column, the thermal conductivity between the top PCB and the bottom aluminum substrate in the multi-layer PCB is improved, thereby accelerating the heat dissipation efficiency of the top PCB, thereby avoiding the reduction of the reliability, life and electrical performance of electronic components due to the poor heat dissipation of the top PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0021] Figure 1 A schematic diagram of a multi-layer PCB structure for top-layer heat dissipation of the present invention;

[0022] Figure 2 An exploded view of a multi-layer PCB structure for top-layer heat dissipation of the present invention.

[0023] Illustrations: 10, aluminum substrate; 20, ceramic substrate; 21, solder pad; 30, multi-layer PCB board; 31, copper-clad through hole; 40, thermal conductive column; 50, power device; 61, magnetic core. DETAILED DESCRIPTION

[0024] In order to make the purpose, features and advantages of the invention of the utility model more obvious and easy to understand, the technical scheme in the embodiment of the utility model will be clearly and completely described below in combination with the drawings in the embodiment of the utility model. Obviously, the embodiment described below is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0026] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0027] Reference Figure 1 to Figure 2 The embodiment of the utility model provides a multi-layer PCB structure with top-layer heat dissipation, comprising an aluminum substrate 10, a ceramic substrate 20, a multi-layer PCB board 30 and a heat-conducting column 40. The ceramic substrate 20 is arranged on the aluminum substrate 10, and the ceramic substrate 20 is bonded to the aluminum substrate 10 by a heat-conducting adhesive. The multi-layer PCB board 30 is arranged on the ceramic substrate 20, and a plurality of copper-clad through holes 31 are provided on the multi-layer PCB board 30. The heat-conducting column 40 passes through the copper-clad through holes 31, and one end of the heat-conducting column 40 is connected to the top layer of the multi-layer PCB board 30, and the other end is connected to the ceramic substrate 20. Optionally, the multi-layer PCB structure with top-layer heat dissipation further comprises a magnetic core 61 passing through the multi-layer PCB board 30 and the ceramic substrate 20, and the magnetic core 61 is used to handle electromagnetic interference, increase inductance, improve signal integrity, suppress radiation and resist external magnetic fields.

[0028] A power device 50 is disposed on the top layer of the multi-layer PCB board 30. The power device 50 is a high-power heat-generating electronic component. The power device 50 forms a heat-affected zone on the top layer of the multi-layer PCB board 30. The plurality of copper-clad through holes 31 form a through hole ring surrounding the power device 50. The through hole ring covers at least half of an isotherm in the heat-affected zone.

[0029] Specifically, when the power device 50 is working, the power device 50 generates heat, and the heat diffuses in the top PCB with the power device 50 as the center. For example, when the multi-layer PCB is in a non-working state, the temperature of the top PCB is 25°C; when the multi-layer PCB is in a working state, the power device 50 generates heat, and the temperature of the power device 50 reaches 80°C. At this time, the heat generated by the power device 50 diffuses to the top PCB with the power device 50 as the center, that is, the closer to the power device 50, the higher the temperature. The heat-affected zone is a zone with the power device 50 as the center and a temperature higher than 25°C. In the heat-affected zone, points with equal temperature are connected to form isotherms. The closer to the isotherms of the power device 50, the higher the corresponding temperature. The through hole ring is in the heat affected zone, and the distance between the isothermal line covered by the through hole ring and the power device 50 is 1 to 1.5 mm, that is, the distance between the copper-clad through hole 31 and the power device 50 is 1 to 1.5 mm, so that the heat generated by the power device 50 can be quickly conducted to the thermal conductive column 40.

[0030] By forming a through hole ring and a heat conduction ring around the power device 50, heat can be distributed more evenly, reducing the generation of local hot spots, which is beneficial to the stability of the entire heat dissipation system; at the same time, the thermal coupling between the heat dissipation components is effectively improved, which is beneficial to the balanced heat dissipation of the entire system.

[0031] Optionally, the thermally conductive column 40 is a copper column. The thermal conductivity of red copper is 386.4 W / mK, which can effectively improve the heat dissipation performance of the top PCB.

[0032] One end of the thermally conductive column 40 is connected to the top layer of the multi-layer PCB board 30 by welding, and the other end of the thermally conductive column 40 is connected to the ceramic substrate 20 by welding. Before the thermally conductive column 40 is welded to the ceramic substrate 20, a soldering pad 21 corresponding to the copper-clad through hole 31 is provided on the ceramic substrate 20, and solder paste is coated on the soldering pad 21 to facilitate the welding of the thermally conductive column 40.

[0033] The length of the heat-conducting column 40 is greater than the thickness of the multi-layer PCB board 30. Optionally, the length of the heat-conducting column 40 is 2 to 3 mm greater than the thickness of the multi-layer PCB board 30 to facilitate welding of both ends of the heat-conducting column 40.

[0034] In order to prevent the thermally conductive column 40 from penetrating through the copper-clad through hole 31 and causing conduction between the layers of the multi-layer PCB board 30 due to the conductivity of the thermally conductive column 40, an insulating layer is coated on the outer peripheral surface of the thermally conductive column 40 to ensure that there is no direct contact between the thermally conductive column 40 and the PCB board, thereby avoiding conduction between the layers of the PCB.

[0035] It should be noted that the heat-conducting column 40 can be connected not only to the top layer PCB, but also to the middle layer PCB. In addition, the pad for soldering the heat-conducting column 40 can be connected to the middle layer PCB. That is, the heat of the upper layer of the multi-layer PCB is transferred to the lower layer PCB by the heat-conducting column 40, and the lower layer PCB transfers the heat to the ceramic substrate 20, and then the ceramic substrate 20 transfers the heat to the aluminum substrate 10, thereby accelerating the heat dissipation of the upper layer PCB, which is within the protection scope of the present utility model.

[0036] During production and assembly, the ceramic substrate 20 is first coated with solder paste, and then the ceramic substrate 20 is placed on a reflow soldering fixture, and then the thermal conductive column 40 is placed on the solder paste-coated pad 21 of the ceramic substrate 20, and the ceramic substrate 20 and the thermal conductive column 40 are soldered by reflow soldering.

[0037] The aluminum substrate 10 is filled with potting thermal conductive glue, and the thickness of the thermal conductive glue is controlled to be between 0.2 and 0.3 mm. The ceramic substrate 20 is placed on the aluminum substrate 10, and the ceramic substrate 20 is pressed to make it close to the aluminum substrate 10 until the gap between the ceramic substrate 20 and the aluminum substrate 10 reaches less than 0.1 mm.

[0038] The multi-layer PCB board 30 is put on the copper pillar and the multi-layer PCB board 30 is fixed.

[0039] The top PCB is welded on the heat-conducting pillar 40. In order to facilitate welding, the aluminum substrate 10 is placed on a heating table for heating, and the temperature is controlled at about 125° C., and a high-power electric soldering iron is used to quickly complete the welding.

[0040] The utility model discloses a multi-layer PCB structure with top-layer heat dissipation, and the specific implementation method is as follows: the power device 50 in the top-layer PCB of the multi-layer PCB board 30 generates heat during operation, and the heat is diffused with the heat-generating power device 50 as the center. Most of the heat is diffused into the top-layer PCB, and the top-layer PCB transfers the heat to the heat-conducting column 40, which transfers the heat to the bottom-layer ceramic substrate 20, and then the ceramic substrate 20 transfers the heat to the aluminum substrate 10, thereby accelerating the heat dissipation of the top-layer PCB. Compared with the existing multi-layer PCB board 30 that relies on its own thermal conductivity to conduct the heat of the top layer to the bottom of the PCB and then dissipates the heat through the aluminum substrate 10, the multi-layer PCB top layer heat dissipation junction disclosed by the utility model adds a thermal conductive column 40 with a higher thermal conductivity coefficient. The heat of the top layer PCB is conducted to the bottom ceramic substrate 20 and the aluminum substrate 10 through the thermal conductive column 40. That is, by adding the thermal conductive column 40, the thermal conductivity between the top layer PCB and the bottom aluminum substrate 10 in the multi-layer PCB board 30 is improved, thereby accelerating the heat dissipation efficiency of the top layer PCB, thereby avoiding the reduction of the reliability, life and electrical performance of electronic components due to poor heat dissipation of the top layer PCB.

[0041] As described above, the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A multi-layer PCB structure with top-layer heat dissipation, characterized in that: include: Aluminum substrate (10); A ceramic substrate (20) disposed on the aluminum substrate (10); A multi-layer PCB board (30) is arranged on the ceramic substrate (20), and a plurality of copper-clad through holes (31) are provided on the multi-layer PCB board (30); A heat-conducting column (40) passes through the copper-clad through-hole (31); one end of the heat-conducting column (40) is connected to the top layer of the multi-layer PCB board (30), and the other end is connected to the ceramic substrate (20).

2. The multi-layer PCB structure with top-layer heat dissipation according to claim 1, characterized in that: The ceramic substrate (20) is bonded to the aluminum substrate (10) by means of a heat-conducting adhesive.

3. The multi-layer PCB structure with top-layer heat dissipation according to claim 1, characterized in that: A power device (50) is arranged on the top layer of the multi-layer PCB board (30), and a plurality of copper-clad through holes (31) are arranged at equal intervals around the power device (50).

4. The multi-layer PCB structure with top-layer heat dissipation according to claim 3, characterized in that: The power device (50) forms a heat-affected zone on the top layer of the multi-layer PCB board (30), and the plurality of copper-clad through holes (31) form a through hole ring surrounding the power device (50), wherein the through hole ring at least covers half of an isotherm in the heat-affected zone.

5. The multi-layer PCB structure with top-layer heat dissipation according to claim 1, characterized in that: The heat-conducting column (40) is a copper column, and the length of the heat-conducting column (40) is greater than the thickness of the multi-layer PCB board (30).

6. The multi-layer PCB structure with top-layer heat dissipation according to claim 1, characterized in that: One end of the heat-conducting column (40) is connected to the top layer of the multi-layer PCB board (30) by welding, and the other end of the heat-conducting column (40) is connected to the ceramic substrate (20) by welding.

7. The multi-layer PCB structure with top-layer heat dissipation according to claim 6, characterized in that: A soldering pad (21) corresponding to the copper-clad through hole (31) is provided on the ceramic substrate (20).

8. The multi-layer PCB structure with top-layer heat dissipation according to claim 7, characterized in that: Before the heat-conducting column (40) and the ceramic substrate (20) are welded, solder paste is coated on the welding pad (21).

9. The multi-layer PCB structure with top-layer heat dissipation according to claim 1, characterized in that: An insulating layer is coated on the outer peripheral surface of the heat-conducting column (40).

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