CN107896421B - PCB capable of fast radiating - Google Patents

Abstract

The invention relates to the technical field of circuit boards, and discloses a PCB capable of quickly dissipating heat, which comprises a stepped groove and a heat dissipation substrate; the stepped groove comprises a through groove and a groove, and the through groove is used for accommodating a high-power component; the heat dissipation substrate is arranged in the groove; and an electric and heat conducting bonding sheet is arranged between the heat dissipation substrate and the metal layer adjacent to the upper surface of the heat dissipation substrate. According to the invention, the groove is formed in the PCB, the heat dissipation substrate in contact with the high-power component and the electric and heat conduction bonding sheet in direct contact with the heat dissipation substrate are embedded in the groove, so that heat generated by the high-power component can be transmitted out in time through the heat dissipation substrate and the electric and heat conduction bonding sheet, and the heat dissipation performance of the PCB is improved.

Description

PCB capable of fast radiating

Technical Field

The invention relates to the technical field of circuit boards, in particular to a PCB capable of quickly dissipating heat.

Background

Pcb (printed Circuit board), i.e. printed Circuit board, is a provider of electrical connections for electronic components. The multilayer PCB is manufactured by laminating a core board and a prepreg. With the development of electronic product technology, the surface mounting and miniaturization trends of components are more and more obvious, the density of products is continuously increased, the dominant frequency of the components is continuously improved, and the power consumption of a single component is gradually increased, so that the heat flux density is sharply improved. Therefore, in order to ensure the service life of the electronic equipment, the heat dissipation problem of the high-power components must be solved.

A large amount of heat generated by the mounting position of the high-power component can assist the component in heat dissipation through a special heat dissipation structure. For example, the prior art provides a heat dissipation PCB, which has a metal layer, an insulating layer and a heat dissipation layer sequentially arranged from top to bottom, wherein a heat dissipation pit is formed at the bottom of the heat dissipation layer for rapidly dissipating heat. The tree-shaped heat dissipation core made of copper is arranged in the insulating layer and the heat dissipation layer and comprises core branches, a core rod and a core root, wherein the core branches and the core root are umbrella-shaped and are symmetrically distributed at the upper end and the lower end of the core rod. The core branches and the core roots are respectively buried in the insulating layer and the heat dissipation layer. The heat dissipation pit is located under the core root. However, this technique has the following drawbacks:

1) firstly, the heat dissipation core is made of copper and cannot be directly contacted with the metal layer, and the heat conductivity of the insulating layer is poor, so that the heat on the electronic element is difficult to be transferred to the heat dissipation core through the insulating layer, and therefore, the heat dissipation performance cannot be obviously improved although the heat dissipation core is added into the PCB;

2) secondly, even if insulating heat conduction materials are selected as prepregs, such as heat dissipation silicone grease, heat conduction silicone sheets and the like, the use method of the prepreg is different from that of the traditional prepreg method, so that the laminating difficulty is increased;

3) thirdly, the tree-shaped radiating core can be embedded in the insulating layer and the radiating layer only by a series of processing and shaping, the preparation process is very complex, and the mass production rate is low.

Therefore, a PCB with fast heat dissipation is needed to solve the above-mentioned drawbacks and to solve the heat dissipation problem of electronic components.

Disclosure of Invention

The invention aims to provide a PCB capable of quickly dissipating heat, which can solve the problem that the existing PCB is low in heat dissipation performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

a PCB capable of rapidly dissipating heat comprises a stepped groove, wherein the stepped groove comprises a through groove and a groove, and the through groove is used for accommodating a high-power component; the heat dissipation substrate is arranged in the groove; and an electric and heat conducting bonding sheet is arranged between the heat dissipation substrate and the metal layer adjacent to the upper surface of the heat dissipation substrate.

The purpose of arranging the electric and heat conducting bonding sheet is to enable heat generated by the high-power component to be transferred to the heat dissipation substrate and the metal layer connected with the heat dissipation substrate as soon as possible through the electric and heat conducting bonding sheet.

Preferably, solder paste is arranged between the high-power component and the electric and heat conducting bonding sheet, between the metal layers adjacent to the upper surface of the heat dissipation substrate and between the high-power component and the heat dissipation substrate.

The solder paste is selected because the melting point of the solder paste is about 150-220 ℃, the solder paste is easy to melt, high-power components are convenient to fix, and meanwhile, the heat generated by the high-power components does not exceed the melting point of the solder paste, so that the solder paste is not melted in the using process, and the solder paste has good electric conduction and heat conduction performance and low cost.

Preferably, the upper surface of the heat dissipation substrate is provided with a concave portion, and the concave portion accommodates the bottom of the high-power component.

Set up the concave part at the upper surface of heat dissipation substrate, bottom and partial lateral wall that can guarantee high power components and parts on the one hand set up in the concave part to increased the area of contact of high power components and parts and base plate with heat dissipation, on the other hand is that high power components and parts set up in concave part and logical inslot, compare in the prior art at the surface mounting of PCB or place the product of high power components and parts, reduced PCB surface components's occupation space, make PCB's structural dimension diminish, thereby the integrated level of components and parts on the PCB has been improved.

In addition, because the top metal layer of the PCB is provided with the bonding pads for mounting the pins of the high-power component, the pins of the high-power component are not allowed to be short-circuited, and therefore, the filling amount of the solder paste is not higher than that of the top metal layer of the PCB, and the short-circuit of the high-power component is prevented.

Preferably, the heat dissipation substrate is made of copper. The main body of the heat dissipation substrate is made of copper, and the copper has good heat conduction and electric conduction performance, so that heat can be quickly conducted to the heat dissipation plate to be dissipated.

Preferably, the heat dissipation substrate is embedded in the stepped groove. After the prepreg is thermalized, the radiating substrate is embedded into the groove, so that other process modes or materials for fixing the radiating substrate can be omitted, and the manufacturing cost is saved; and the fixing of the heat dissipation substrate is completed simultaneously in the core plate and prepreg laminating process, so that the working efficiency is improved, and the phenomenon of inaccurate alignment or increased alignment errors caused by multiple positioning is avoided.

Preferably, the bottom surface of the heat dissipation substrate is flush with one surface of the PCB. The structure arrangement can ensure that the radiating substrate is fixed inside the PCB in an embedded mode, reduces the overall structure size of the PCB and enables the structure of the PCB to be more compact, thereby ensuring the integrity of the PCB, facilitating the processing and installation of the PCB, facilitating the covering of a copper layer outside the PCB and being more beautiful; on the other hand, heat can be rapidly dissipated from the bottom surface of the heat dissipation substrate. In addition, compared with the product of pasting or placing the heat dissipation substrate on the surface of the PCB in the prior art, the PCB of the invention has greatly reduced overall thickness and more compact structure.

Furthermore, the bottom surface of the heat dissipation substrate and the one surface of the PCB are coated with copper layers.

The purpose of covering the copper layer is to increase the heat dissipation area, so that the heat in the heat dissipation substrate can be quickly dissipated at the bottom metal layer of the PCB, and the overall structural strength of the PCB is enhanced.

Preferably, the bottom surface of the copper layer is provided with a heat sink. The purpose of setting up the fin is can increase the area of contact of heat and air, accelerates the effluvium of heat.

Preferably, the PCB further comprises a via hole. The conducting hole belongs to an electroplating through hole, is formed after copper deposition and electroplating, has one function of heat dissipation, can transfer heat in a metal layer inside the PCB to the conducting hole, and dissipates the heat to the air through the conducting hole to play a role in assisting heat dissipation; another function of the via hole is to electrically conduct different metal layers for connecting copper foil wiring between two or more layers of the PCB.

Preferably, the heat sink covers the via hole. This setting has also played supplementary radiating effect, and the heat in the through hole has increased heat radiating area after the fin in other words, accelerates the heat effluvium in the through hole, prevents that PCB is inside overheated, causes the destruction to PCB.

The PCB capable of dissipating heat quickly has the beneficial effects that:

1) a quick heat dissipation structure of a PCB is designed, a groove is formed in the PCB, a heat dissipation substrate in contact with a high-power component and an electric conduction and heat conduction bonding sheet in direct contact with the heat dissipation substrate are embedded in the groove, heat generated by the high-power component can be transmitted out through the heat dissipation substrate and the electric conduction and heat conduction bonding sheet in time, and the heat dissipation performance of the PCB is improved;

2) the high-power component is contacted with the metal layer in the PCB through the solder paste, and the PCB is provided with the via hole, so that part of heat generated by the high-power component can be transferred to the via hole through the metal layer, and the high-power component has the function of auxiliary heat dissipation;

3) the high-power components are arranged in the through grooves and the concave parts, and compared with a structure that the high-power components are arranged on the surface of the PCB, the occupied space of the components on the surface of the PCB is reduced, the overall structure size of the PCB is reduced, and therefore the overall structure of the PCB is more compact.

Drawings

Fig. 1 is a cross-sectional view of a PCB with rapid heat dissipation (metal blocks and components are not shown) according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a PCB with fast heat dissipation according to one embodiment of the present invention;

fig. 3 is a schematic diagram of a high power component transferring heat through a high thermal conductive metal block according to a second embodiment of the present invention;

fig. 4 is a schematic diagram of a medium-high power component conducting heat through a metal layer according to a second embodiment of the present invention;

fig. 5 is a cross-sectional view of a PCB with fast heat dissipation according to a third embodiment of the present invention.

In the figure:

1. a stepped groove; 10. a metal layer; 11. a through groove; 12. a groove; 2. a high thermal conductivity metal block; 3. a high-power component; 4. an electrically and thermally conductive adhesive sheet; 5. tin paste; 6. a heat sink; 7. and a via hole.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The terms of orientation such as "upper", "lower", "top" and "bottom" used in the embodiments of the present invention are defined in the case of the structure as in the drawings of the PCB providing rapid heat dissipation provided in the embodiments, and "upper", "lower", "top" and "bottom" refer to upper, lower, top and bottom of the structure of the PCB itself. These directional terms are used for ease of understanding and are not intended to limit the scope of the present invention.

Example one

Referring to fig. 1-2, the present embodiment provides a PCB with fast heat dissipation, which is formed by laminating three core boards, but the number of the core boards is not limited thereto. The schematic diagram of the groove on the PCB is shown in fig. 1, the PCB is provided with a non-metalized steppedgroove 1, which includes a throughgroove 11 located at the upper part of the PCB and agroove 12 located at the lower part of the PCB, and the through groove and the groove form a convex steppedgroove 1. Referring to fig. 2, the PCB further includes a heat dissipation substrate, which may be a high thermalconductive metal block 2. The throughgroove 11 is used for accommodating the high-power component 3, the electrically and thermallyconductive bonding sheet 4 is arranged between the high-thermal-conductivity metal block 2 and themetal layer 10 adjacent to the upper surface of the high-thermal-conductivity metal block, and thesolder paste 5 is arranged between the high-power component 3 and the electrically and thermallyconductive bonding sheet 4, between themetal layer 10 adjacent to the upper surface of the high-thermal-conductivity metal block 2, and between themetal layer 10 adjacent to the upper surface of the high-thermal-conductivity metal block 2. The material of the high thermalconductive metal block 2 in this embodiment is preferably copper. The main body of the high heatconduction metal block 2 is made of copper, and the copper has good heat conduction and electric conduction performance, so that heat can be quickly conducted to the radiatingfins 6 to be dissipated.

The material of thegold block 2 with high thermal conductivity in this embodiment may also be aluminum, silver, or tin.

Themetal block 2 with high thermal conductivity in this embodiment is embedded in thegroove 12, and the bottom surface of themetal block 2 with high thermal conductivity is flush with one surface (i.e. the bottom surface) of the PCB. The structure arrangement can ensure that the high-heat-conductivity metal block 2 is fixed in the PCB in a buried mode, the overall structure size of the PCB is reduced, and the structure of the PCB is more compact, so that the integrity of the PCB is ensured, the PCB is convenient to process and install, a copper layer is convenient to cover outside the PCB, and the PCB is more attractive; on the other hand, heat can be rapidly dissipated from the bottom surface of the high heat-conductingmetal block 2. In addition, compared with the product of the prior art in which the high-heat-conductivity metal block 2 is pasted or placed on the surface of the PCB, the whole thickness of the PCB is greatly reduced, and the structure is more compact.

In the embodiment, the high-thermal-conductivity metal block 2 is embedded in thegroove 12, and the high-thermal-conductivity metal block 2 is fixed in thegroove 12 through the heated prepreg, so that other process modes or materials can be omitted for fixing the high-thermal-conductivity metal block 2, and the manufacturing cost is saved; and the core plate and the prepreg are simultaneously fixed in the pressing process, so that the working efficiency is improved, and the phenomenon of inaccurate alignment or increased alignment errors caused by multiple positioning is avoided.

As can be seen from fig. 2, the bottom surface of themetal block 2 with high thermal conductivity and the surface of the PCB flush with themetal block 2 with high thermal conductivity are both coated with copper layers. After the copper layer is covered, the metal layer and the copper layer on the lower surface of the PCB form a bottom metal layer of the PCB, the copper layer is covered to increase the heat dissipation area, so that heat transferred from the high-power component 3 to the high-heat-conduction metal block 2 can be quickly dissipated at the bottom metal layer of the PCB, and meanwhile, the overall structural strength of the PCB is also enhanced.

Theheat sink 6 is provided on the bottom surface of the PCB, i.e., the bottom surface covered with the copper layer, in order to increase the contact area between heat and air and accelerate the heat dissipation.

The PCB with the rapid heat dissipation function in the embodiment further comprises a viahole 7, wherein the viahole 7 belongs to an electroplating via hole and is formed after copper deposition and electroplating, one function of the via hole is used for heat dissipation, heat in a metal layer inside the PCB can be transferred to the viahole 7, and the heat is dissipated into air through the viahole 7 to play a role in assisting heat dissipation; another function of the viahole 7 is to electrically conduct different metal layers for connecting copper foil wiring between two or more layers of the PCB.

Further, theheat sink 6 covers the viahole 7. This setting has also played supplementary radiating effect, and the heat in the viahole 7 has increased heat radiating area after 6 fin, accelerates the heat effluvium in the viahole 7, prevents that the inside overheat of PCB from causing the destruction to PCB.

Example two

As shown in fig. 3 to 4, the present embodiment is different from the first embodiment in that a concave portion is provided on the upper surface of the high thermalconductive metal block 2, the concave portion is used for accommodating the bottom portion of thehigh power component 3, thehigh power component 3 is provided with asolder paste 5 between the electrically and thermally conductiveadhesive sheet 4 and between the metal layers 10 adjacent to the upper surface of the electrically and thermally conductiveadhesive sheet 4, and thesolder paste 5 is also provided between thehigh power component 3 and the concave portion of the high thermalconductive metal block 2.

As shown in fig. 3, heat generated by the high-power component 3 is mainly transferred by the high-thermal-conductivity metal block 2, and the heat transfer path is a main heat dissipation path of the high-power component 3. Specifically, a part of heat generated by the high-power component 3 is conducted to the high-heat-conduction metal block 2 through the bottom of the high-power component 3, and because the high-power component 3 is fixed in the concave portion of the high-heat-conduction metal block 2 through thesolder paste 5 and the side wall of the high-power component 3 is also fixed with the electric-heat-conduction bonding sheet 4 through thesolder paste 5, a part of heat generated by the high-power component 3 is simultaneously transmitted to the side wall of the concave portion of the high-heat-conduction metal block 2 and the electric-heat-conduction bonding sheet 4 through the side wall of the; further, a part of the heat transferred to the electrically and thermally conductiveadhesive sheet 4 is also transferred into the thermallyconductive metal block 2, and finally the heat of the thermallyconductive metal block 2 is dissipated into the air mainly in the form of thermal conduction and thermal convection through theheat sink 6.

As shown in fig. 4, a part of the heat transferred to the conductive and thermaladhesive sheet 4 is transferred to themetal layer 10 adjacent thereto through the conductive and thermaladhesive sheet 4, the heat is conducted in themetal layer 10, and a part of the heat in themetal layer 10 is transferred to the inner wall of the viahole 7, so as to exchange heat with the air in the viahole 7; the other part of heat is transferred to the top metal layer and the bottom metal layer of the PCB through the inner wall of the viahole 7, the heat of the top metal layer can be directly diffused into the air, and the heat of the bottom metal layer is diffused into the air through theheat sink 6. The heat transfer path is a secondary heat dissipation path of the high-power component 3. It should be noted that the heat dissipation processes of fig. 3 and fig. 4 occur simultaneously, without any priority.

EXAMPLE III

As shown in fig. 5, the difference between the second embodiment and the second embodiment is that the PCB for fast heat dissipation in the second embodiment is formed by laminating four core boards.

The difference from the second embodiment is that the throughgroove 11 penetrates through the upper core plate, thegroove 12 penetrates through the lower core plates and the prepregs adjacent to the lower core plates, and the high-thermal-conductivity metal block 2 is arranged in thegroove 12.

The applicant declares that the present invention is exemplarily described by the above embodiments, and it is obvious that the specific implementation of the present invention is not limited by the above manner, and it is within the protection scope of the present invention as long as various insubstantial modifications are made by using the concept and technical scheme of the present invention, or the concept and technical scheme of the present invention are directly applied to other occasions without modifications.

Claims (7)

1. A PCB for rapid heat dissipation, comprising:

the stepped groove (1) comprises a through groove (11) and a groove (12), wherein the through groove (11) is used for accommodating the high-power component (3);

a heat-dissipating substrate disposed in the groove (12);

an electric and heat conducting bonding sheet (4) is arranged between the heat dissipation substrate and the metal layer (10) adjacent to the upper surface of the heat dissipation substrate;

copper layers are coated on the bottom surface of the heat dissipation substrate and one surface of the PCB;

the conductive through hole is characterized by also comprising a through hole (7), wherein the through hole (7) is an electroplating through hole;

and solder pastes (5) are arranged between the high-power component (3) and the electric-conduction and heat-conduction bonding sheet (4), between metal layers (10) adjacent to the upper surface of the heat-dissipation substrate and between the high-power component and the heat-dissipation substrate.

2. The PCB for rapid heat dissipation according to claim 1, wherein the upper surface of the heat-dissipating substrate is provided with a recess which accommodates the bottom of the high-power component (3).

3. The PCB of claim 1, wherein the heat-dissipating substrate is made of copper.

4. The PCB for rapid heat dissipation according to claim 1, wherein the heat-dissipating substrate is buried in the groove (12).

5. The PCB of claim 1, wherein the bottom surface of the heat-dissipating substrate is flush with a face of the PCB.

6. The PCB for rapid heat dissipation according to claim 1, wherein the bottom surface of the copper layer is provided with a heat sink (6).

7. The PCB for rapid heat dissipation according to claim 6, wherein the heat sink (6) covers the via hole (7).

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