CN107896421A - A fast heat dissipation PCB - 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

A fast heat dissipation PCB

technical field

The invention relates to the technical field of circuit boards, in particular to a PCB with rapid heat dissipation.

Background technique

PCB (Printed Circuit Board), that is, a printed circuit board, is a provider of electrical connections for electronic components. The multi-layer PCB is made by pressing the core board and the prepreg. With the development of electronic product technology, the trend of surface mount and miniaturization of components is becoming more and more obvious, the density of products is increasing, the main frequency of components is increasing, and the power consumption of individual components is gradually increasing, resulting in the increase of heat flux density. sharply increased. Therefore, in order to ensure the service life of electronic equipment, it is necessary to solve the problem of heat dissipation of high-power components.

A large amount of heat generated by the mounting position of high-power components can be used to assist the device to dissipate heat through a special heat dissipation structure. For example, the prior art provides a heat-dissipating PCB. The PCB is arranged with a metal layer, an insulating layer, and a heat-dissipating layer in order from top to bottom. A heat-dissipating pit is provided at the bottom of the heat-dissipating layer for rapidly dissipating heat. The insulating layer and the heat dissipation layer have a tree-shaped heat dissipation core made of copper, which is composed of core branches, core rods and core roots. The core branches and core roots are umbrella-shaped and symmetrically distributed at the upper and lower ends of the core rod. The core branch and the core root are buried in the insulating layer and the heat dissipation layer respectively. The cooling pit is located directly below the core root. However, this technique has the following drawbacks:

1) First of all, the heat dissipation core is made of copper and cannot directly contact the metal layer, and the thermal conductivity of the insulating layer is poor, so it is difficult for the heat on the electronic components to be transferred to the heat dissipation core through the insulation layer. Therefore, although the PCB is added Heat dissipation core, its heat dissipation can not be significantly improved;

2) Secondly, even if an insulating heat-conducting material is selected as the prepreg, such as heat-dissipating silicone grease, heat-conducting silicone sheet, etc., because its use method is different from the traditional prepreg method, it will increase the difficulty of lamination;

3) Thirdly, the tree-shaped heat dissipation core needs a series of processing and shaping to be embedded in the insulating layer and the heat dissipation layer. The preparation process is very complicated, and the mass production rate is low.

Therefore, a PCB with rapid heat dissipation is needed to solve the above-mentioned defects, so as to solve the problem of heat dissipation of electronic components.

Contents of the invention

The object of the present invention is to provide a PCB with rapid heat dissipation, which can solve the problem of low heat dissipation performance of existing PCBs.

For reaching this purpose, the present invention adopts following technical scheme:

A PCB for rapid heat dissipation, comprising stepped grooves, which include through grooves and grooves, and the through grooves are used to accommodate high-power components; a heat dissipation substrate, which is arranged in the groove; the heat dissipation substrate and the A conductive and thermally conductive adhesive sheet is arranged between adjacent metal layers on the upper surface of the heat dissipation substrate.

The purpose of providing the conductive and thermally conductive adhesive sheet is to transfer the heat generated by the high-power components to the heat dissipation substrate and the metal layer connected thereto as quickly as possible through the electrically conductive and thermally conductive adhesive sheet.

Preferably, solder paste is provided between the high-power component and the thermally conductive adhesive sheet, between the metal layer adjacent to the upper surface of the heat dissipation substrate, and between the heat dissipation substrate.

Solder paste is selected because the melting point of the solder paste is about 150°C-220°C, it is easy to melt, and it is convenient to fix high-power components. At the same time, the heat generated by high-power components will not exceed the melting point of the solder paste, so the solder paste will not It will melt, and the solder paste has good electrical and thermal conductivity and low cost.

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

A recess is provided on the upper surface of the heat dissipation substrate. On the one hand, it can ensure that the bottom and part of the side walls of the high-power components are arranged in the recess, thereby increasing the contact area between the high-power components and the heat dissipation substrate. On the other hand, the high-power components It is arranged in the concave part and the through groove. Compared with the products of mounting or placing high-power components on the surface of the PCB in the prior art, the occupied space of the components on the surface of the PCB is reduced, and the structural size of the PCB is reduced, thereby The integration of components on the PCB is improved.

In addition, since the top metal layer of the PCB is provided with pads for mounting the pins of high-power components, short circuits are not allowed between the pins of high-power components, so the filling amount of the solder paste should not be higher than the top of the PCB The metal layer is to prevent short-circuiting of high-power components.

Preferably, the heat dissipation substrate is made of copper. The main body of the heat dissipation substrate is made of copper, mainly because copper has good thermal conductivity and electrical conductivity, and can quickly conduct heat to the heat sink for dissipation.

Preferably, the heat dissipation substrate is buried in the stepped groove. After the prepreg is thermalized, the heat dissipation substrate is embedded in the groove, which saves the need to use other processes or materials to fix the heat dissipation substrate, which saves production costs; and the core board and the prepreg are pressed during the same time. The fixing of the heat dissipation base plate improves the work efficiency, and at the same time avoids misalignment or increase of alignment error caused by multiple positioning.

Preferably, the bottom surface of the heat dissipation substrate is flush with one side of the PCB. On the one hand, this structural setting can ensure that the heat dissipation substrate is fixed inside the PCB in the form of embedding, which reduces the overall structural size of the PCB and makes the structure of the PCB more compact, thereby ensuring the integrity of the PCB and facilitating the processing and installation of the PCB. It is convenient to cover the copper layer on the outside of the PCB, and it is also more beautiful; on the other hand, it can quickly dissipate heat from the bottom surface of the heat dissipation substrate. In addition, compared with products in the prior art that mount or place heat dissipation substrates on the surface of the PCB, the overall thickness of the PCB of the present invention is greatly reduced, and the structure is more compact.

Further, the bottom surface of the heat dissipation substrate and the one side of the PCB are covered with a copper layer.

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 at the same time enhance the overall structural strength of the PCB.

Preferably, a heat sink is provided on the bottom surface of the copper layer. The purpose of setting the heat sink is to increase the contact area between the heat and the air, so as to accelerate the dissipation of heat.

Preferably, the PCB further includes via holes. The via hole is a kind of electroplated through hole, which is formed after sinking copper and electroplating. One of its functions is to dissipate heat. It can transfer the heat in the metal layer inside the PCB to the via hole, and the heat is dissipated through the via hole. Out into the air, it plays the role of auxiliary heat dissipation; the other function of the via hole is to electrically conduct different metal layers, and to connect the copper foil lines between two or more layers of the PCB.

Preferably, the heat sink covers the via hole. This setting also plays the role of auxiliary heat dissipation. After the heat in the via hole passes through the heat sink, it is equivalent to increasing the heat dissipation area, accelerating the heat dissipation in the via hole, and preventing the PCB from overheating and causing damage to the PCB.

The beneficial effect of the PCB of rapid heat dissipation in the present invention is:

1) A rapid heat dissipation structure of PCB is designed. A heat dissipation substrate in contact with high-power components and a conductive and heat-conducting adhesive sheet directly in contact with the heat dissipation substrate are embedded in the PCB, and the heat generated by the high-power components themselves The heat can be transferred out in time through the heat dissipation substrate and the conductive and heat-conducting adhesive sheet, which improves the heat dissipation performance of the PCB;

2) High-power components are in contact with the metal layer inside the PCB through solder paste, and a via hole is opened on the PCB. Therefore, part of the heat generated by the high-power component can be transferred to the via hole through the metal layer, which has auxiliary The role of heat dissipation;

3) The high-power components are arranged in the through groove and the concave part, compared with the structure of setting high-power components on the surface of the PCB, the occupied space of the PCB surface components is reduced, and the overall structure size of the PCB is reduced, thereby Make the overall structure of PCB more compact.

Description of drawings

Fig. 1 is the cross-sectional view (not showing metal blocks and components) of the PCB of rapid heat dissipation in Embodiment 1 of the present invention;

Fig. 2 is a cross-sectional view of a PCB that dissipates heat quickly in Embodiment 1 of the present invention;

3 is a schematic diagram of heat transfer of high-power components through a high-thermal-conductivity metal block in Embodiment 2 of the present invention;

4 is a schematic diagram of heat transfer of high-power components through a metal layer in Embodiment 2 of the present invention;

FIG. 5 is a cross-sectional view of a PCB with rapid heat dissipation in Embodiment 3 of the present invention.

In the picture:

1. Step groove; 10. Metal layer; 11. Through groove; 12. Groove; 2. High thermal conductivity metal block; 3. High power components; 4. Conductive and thermal conductive adhesive sheet; 5. Solder paste; 6. Heat dissipation 7. Via hole.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

The orientation words used in the embodiments of the present invention such as "upper", "lower", "top" and "bottom" are defined in the case of the structure of the rapid heat dissipation PCB provided in this embodiment, as shown in the accompanying drawings, " Up, down, top, and bottom refer to the top, bottom, top, and bottom of the PCB itself. These orientation words are adopted for ease of understanding, and thus do not constitute a limitation of the protection scope of the present invention.

Embodiment one

Referring to Fig. 1-2, this embodiment provides a PCB with rapid heat dissipation, which is formed by pressing three core boards, but the number is not limited thereto. The schematic diagram of slotting on the PCB is shown in Figure 1. The PCB is provided with a non-metallized stepped slot 1, which includes a through slot 11 on the upper part of the PCB and a groove 12 on the lower part. The two form a convex stepped slot. 1. Referring to FIG. 2 , the PCB also includes a heat dissipation substrate, which may be a metal block 2 with high thermal conductivity. Wherein, the through groove 11 is used for accommodating high-power components 3, and a conductive and thermally conductive adhesive sheet 4 is arranged between the high thermally conductive metal block 2 and the metal layer 10 adjacent to its upper surface, and the high-power component 3 is bonded to the conductive and thermally conductive Solder paste 5 is provided between the sheets 4 , between the metal layers 10 adjacent to the upper surface of the high thermal conductivity metal block 2 , and between the upper surface of the high thermal conductivity metal block 2 . In this embodiment, the material of the high thermal conductivity metal block 2 is preferably copper. The main body of the high thermal conductivity metal block 2 is made of copper, mainly because copper has good thermal conductivity and electrical conductivity, and can quickly conduct heat to the heat sink 6 for dissipation.

The material of the high thermal conductivity gold nugget 2 in this embodiment can also be selected from aluminum, silver, and tin.

In this embodiment, the metal block 2 with high thermal conductivity is embedded in the groove 12 , and the bottom surface of the metal block 2 with high thermal conductivity is flush with one side (ie, the bottom surface) of the PCB. On the one hand, this structural setting can ensure that the high thermal conductivity metal block 2 is fixed inside the PCB in the form of embedding, which reduces the overall structural size of the PCB and makes the structure of the PCB more compact, thereby ensuring the integrity of the PCB and facilitating PCB installation. It is easy to process and install and cover the copper layer on the outside of the PCB, and it is also more beautiful; on the other hand, it can quickly dissipate heat from the bottom surface of the high thermal conductivity metal block 2 . In addition, compared with the products in the prior art that mount or place the high thermal conductivity metal block 2 on the surface of the PCB, the overall thickness of the PCB of the present invention is greatly reduced, and the structure is more compact.

In this embodiment, the high thermal conductivity metal block 2 is buried in the groove 12, and the high thermal conductivity metal block 2 is fixed in the groove 12 through the thermalized prepreg, which can save the use of other process methods or materials for high The heat-conducting metal block 2 is fixed again, thereby saving the production cost; and the fixing of the high-heat-conducting metal block 2 is completed at the same time during the pressing process of the core board and the prepreg, which improves the work efficiency and avoids damage caused by multiple positioning. Misalignment or increased alignment error.

It can be seen from FIG. 2 that the bottom surface of the high thermal conductivity metal block 2 and the side of the PCB that is flush with the high thermal conductivity metal block 2 are covered with a copper layer. After the copper layer is covered, the metal layer and the copper layer on the lower surface of the PCB form the bottom metal layer of the PCB. The purpose of covering the copper layer is to increase the heat dissipation area so that the high-power components 3 can be transferred to the metal block 2 with high thermal conductivity. The heat can be dissipated quickly at the bottom metal layer of the PCB, which also enhances the overall structural strength of the PCB.

A heat sink 6 is arranged on the bottom surface of the PCB, that is, the bottom surface covered with a copper layer, the purpose of which is to increase the contact area between heat and air and accelerate heat dissipation.

The PCB with rapid heat dissipation in this embodiment also includes a via hole 7, which belongs to a kind of plated through hole, which is formed after sinking copper and electroplating. One of its functions is to dissipate heat. The heat in the layer is transferred to the via hole 7, and the heat is dissipated into the air through the via hole 7, which plays the role of auxiliary heat dissipation; the other function of the via hole 7 is to electrically conduct different metal layers for Connects copper foil lines between two or more layers of a PCB.

Further, the heat sink 6 covers the aforementioned via hole 7 . This setting also plays the role of auxiliary heat dissipation. After the heat in the via hole 7 passes through the heat sink 6, it is equivalent to increasing the heat dissipation area, accelerating the heat dissipation in the via hole 7, and preventing the PCB from overheating and causing damage to the PCB. .

Embodiment two

As shown in Figures 3-4, this embodiment differs from the above embodiment one on the basis of the above embodiment one in that a recess is provided on the upper surface of the above-mentioned high thermal conductivity metal block 2, and the above-mentioned recess is used to accommodate At the bottom of the high-power component 3, the high-power component 3 is provided with solder paste 5 except between the conductive and thermally conductive adhesive sheet 4 and between the metal layer 10 adjacent to the upper surface of the conductive and thermally conductive adhesive sheet 4. Solder paste 5 is also provided between the components 3 and the concave portion of the high thermal conductivity metal block 2 .

As shown in FIG. 3 , the heat generated by the high-power components 3 is mainly transferred through the high-thermal-conductivity metal block 2 , and this heat transfer path is the main heat dissipation path of the high-power components 3 . Specifically, part of the heat generated by the high-power components 3 is conducted to the high-thermal-conduction metal block 2 through the bottom of the high-power components 3 . The sidewall of the power component 3 is also fixed with the conductive and heat-conducting adhesive sheet 4 through the solder paste 5, therefore, part of the heat generated by the high-power component 3 is simultaneously transferred to the concave part of the high-thermal-conduction metal block 2 through the sidewall of the high-power component 3 The side wall and the conductive and thermally conductive adhesive sheet 4; furthermore, part of the heat transferred to the conductive and thermally conductive adhesive sheet 4 is also transferred to the high thermally conductive metal block 2, and finally the heat of the high thermally conductive metal block 2 is mainly passed through heat conduction through the heat sink 6 Dissipate into the air in the form of heat convection.

As shown in Figure 4, part of the heat transferred to the conductive and thermally conductive adhesive sheet 4 is transferred to the metal layer 10 adjacent to it through the conductive and thermally conductive adhesive sheet 4, and the heat conducts heat in the metal layer 10, and the heat in the metal layer 10 Part of the heat will be conducted to the inner wall of the via hole 7, thereby exchanging heat with the air in the via hole 7; the other part of the heat will be transferred to the top and bottom metal layers of the PCB through the inner wall of the via hole 7, and the top metal layer The heat of the metal layer can be directly dissipated into the air, and the heat of the bottom metal layer is dissipated into the air through the heat sink 6 . The above-mentioned heat transfer path is a secondary heat dissipation path for the high-power components 3 . It is worth noting that the heat dissipation processes in Fig. 3 and Fig. 4 will occur at the same time, and there is no sequence.

Embodiment Three

As shown in FIG. 5 , on the basis of the second embodiment, this embodiment differs from the second embodiment above in that the rapid heat dissipation PCB in this embodiment is formed by pressing four core boards.

The difference from the above-mentioned second embodiment is that the through groove 11 runs through the upper core board, the groove 12 runs through the lower three core boards and the prepregs adjacent to the lower three core boards, and the high thermal conductivity metal block 2 is arranged in the concave in slot 12.

The applicant declares that the present invention has been exemplarily described through the above-mentioned embodiments. Obviously, the specific implementation of the present invention is not limited by the above-mentioned methods. Or directly applying the conception and technical solutions of the present invention to other occasions without improvement are all within the protection scope of the present invention.

Claims (10)

1. A fast heat dissipation PCB is characterized in that, comprising: A stepped groove (1) comprising a through groove (11) and a groove (12), the through groove (11) being used for accommodating high power components (3); a heat dissipation substrate, which is arranged in the groove (12); A conductive and thermally conductive adhesive sheet (4) is arranged between the heat dissipation substrate and the metal layer (10) adjacent to the upper surface of the heat dissipation substrate. 2. The PCB with rapid heat dissipation according to claim 1, characterized in that, between the high-power components (3) and the conductive and heat-conducting adhesive sheet (4), and in contact with the upper surface of the heat-dissipating substrate Solder paste (5) is arranged between adjacent metal layers (10) and between the heat dissipation substrate. 3. The PCB with rapid heat dissipation according to claim 1, characterized in that, the upper surface of the heat dissipation substrate is provided with a recess, and the recess accommodates the bottom of the high-power component (3). 4. The rapid heat dissipation PCB according to claim 1, wherein the material of the heat dissipation substrate is copper. 5. The PCB with rapid heat dissipation according to claim 1, characterized in that, the heat dissipation substrate is buried in the groove (12). 6 . The PCB with rapid heat dissipation according to claim 1 , wherein the bottom surface of the heat dissipation substrate is flush with one side of the PCB. 7 . 7. The PCB with rapid heat dissipation according to claim 6, wherein the bottom surface of the heat dissipation substrate and the one side of the PCB are covered with a copper layer. 8. The PCB with rapid heat dissipation according to claim 7, characterized in that a heat sink (6) is provided on the bottom surface of the copper layer. 9. The PCB with rapid heat dissipation according to claim 8, further comprising via holes (7). 10. The PCB with rapid heat dissipation according to claim 9, characterized in that, the heat sink (6) covers the via hole (7).