CN107734838A - A fast heat dissipation PCB - Google Patents

Abstract

The present invention relates to the field of circuit boards, and discloses a PCB with rapid heat dissipation, comprising a stepped groove, and a stepped high thermal conductivity metal block, which is arranged in the stepped groove, and solder paste is arranged between the top surface of the stepped high thermal conductivity metal block and the high-power components arranged on the surface of the PCB; solder paste is arranged between the shoulder of the stepped high thermal conductivity metal block and the metal layer adjacent to it. The present invention arranges a stepped groove inside the PCB and buries the stepped high thermal conductivity metal block, which can timely transfer the heat generated by the high-power components and the metal layer inside the PCB to the air through the stepped high thermal conductivity metal block, thereby improving the heat dissipation performance of the PCB, having a simple structure, and being more convenient to process and install.

Description

A fast heat dissipation PCB

technical field

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

Background technique

PCB (Printed Circuit Board), that is, printed circuit board, is the 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.

The heat dissipation problem at the mounting position of high-power components can be solved from two aspects. On the one hand, lower driving voltage is used, and the parasitic resistance/capacitance is smaller, so that the heat consumption of the device is reduced accordingly; on the other hand, A special heat dissipation structure is used to assist the heat dissipation of the device. 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) The heat dissipation core is a copper product, which cannot be directly in contact with 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 heat dissipation core is added to the PCB , its heat dissipation cannot be significantly improved;

2) 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) 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 fast heat dissipation is needed to solve the above-mentioned defects, so as to accelerate the 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 with rapid heat dissipation, comprising a stepped groove and a stepped metal block with high thermal conductivity, the stepped metal block with high thermal conductivity is arranged in the stepped groove, and solder paste is arranged between the top surface of the stepped metal block with high thermal conductivity and high-power components; Solder paste is arranged between the shoulder of the stepped metal block with high thermal conductivity and its adjacent metal layer.

Ladder grooves are set inside the PCB and a stepped metal block with high thermal conductivity is set. The high-power components in contact with the stepped high thermal conductivity metal block can quickly diffuse heat to the stepped metal block with high thermal conductivity. Therefore, the stepped high thermal conductivity metal block Played a rapid cooling effect.

Preferably, the stepped metal block with high thermal conductivity is made of copper. The use of copper as the main body of the stepped high thermal conductivity metal block utilizes the excellent thermal conductivity and electrical conductivity of copper. The stepped high thermal conductivity metal block made of copper can quickly transfer the heat from high-power components to the heat sink.

Preferably, the solder paste is solder paste. The selection of solder paste needs to ensure the adhesion, electrical conductivity and thermal conductivity between high-power components and stepped metal blocks with high thermal conductivity. In order to meet these requirements, solder paste is selected as the solder paste. Since the melting point of solder paste is about 150°C to 220°C, and the heat generation of high-power components is far below this temperature, it will not melt when solder paste is used as solder paste.

Preferably, the stepped metal block with high thermal conductivity is embedded in the stepped groove. Embed the stepped high thermal conductivity metal block into the stepped groove so that it can be fixed inside the PCB during the process of pressing the stepped high thermal conductivity metal block and the PCB, thus eliminating the need for steps between the stepped high thermal conductivity metal block and the PCB Additional fixing process between the grooves, also no additional bonding material is required.

Preferably, the top surface of the stepped metal block with high thermal conductivity is flush with the top surface of the PCB, and the bottom surface of the stepped metal block with high thermal conductivity is flush with the bottom surface of the PCB. This setting is convenient for the PCB to cover the copper layer and ensures the integrity of the PCB.

Preferably, the top surface of the stepped metal block with high thermal conductivity is covered with a copper layer, and the bottom surface of the stepped metal block with high thermal conductivity is covered with a copper layer. This setting encapsulates the stepped metal block with high thermal conductivity in the PCB, ensuring the structural strength of the PCB.

Preferably, a cooling fin is provided on the bottom surface of the bottom copper layer of the stepped metal block with high thermal conductivity. The purpose of setting the heat sink is to increase the contact area between the heat and the air, to achieve better temperature difference transfer, and to speed up the dissipation of heat.

Preferably, a via hole is further included, which is electrically connected to the metal layer. The via hole is a kind of plated through hole, and 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 transfer it to the outer surface of the PCB through the via hole to play a role The role of auxiliary heat dissipation; another function of the via hole is to connect the copper foil line 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. Since the via hole is relatively narrow, heat is not easily transferred from it. Therefore, a heat sink is installed at one end, which is equivalent to increasing the heat dissipation area, accelerating the heat dissipation in the via hole, and preventing PCB Overheating inside, 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 stepped groove is set inside the PCB and a stepped high thermal conductivity metal block is embedded, so that the heat generated by high power components and the internal metal layer of the PCB can be passed through the stepped high thermal conductivity metal block in time. Transfer to the air, improve the heat dissipation performance of PCB;

2) The present invention places the stepped metal block with high thermal conductivity in the stepped groove, which can save the external space of the PCB, reduce the overall size of the PCB, and make the overall structure of the PCB more compact.

Description of drawings

Fig. 1 is the cross-sectional view of the rapid heat dissipation PCB in Embodiment 1 of the present invention (not showing the stepped high thermal conductivity metal block and high power components);

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

FIG. 3 is a schematic diagram of heat transfer of high-power components through stepped metal blocks with high thermal conductivity in Embodiment 1 of the present invention;

Fig. 4 is a schematic diagram of heat transfer of the metal layer through a stepped metal block with high thermal conductivity in Embodiment 1 of the present invention;

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

6 is a cross-sectional view of a PCB that dissipates heat quickly in Embodiment 3 of the present invention;

FIG. 7 is a cross-sectional view of a rapid heat dissipation PCB in the present invention.

In the picture:

1. Step groove; 2. Metal layer; 3. Step-type high thermal conductivity metal block; 4. Solder paste; 5. High-power components; 6. Heat sink; 7. Via hole.

detailed description

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

Embodiment one:

This embodiment provides a PCB with rapid heat dissipation, wherein the PCB is formed by pressing three core boards (but the number is not limited thereto), and a schematic diagram of slotting on the PCB is shown in FIG. 1 . On the PCB, a stepped groove 1 is milled by a milling machine, and a via hole 7 is drilled by a drilling machine, wherein both are arranged along the thickness direction of the PCB, and the shoulder of the stepped groove 1 is connected to one of the metal layers 2 inside the PCB, etc. high. The via hole 7 is electrically connected to the metal layer 2 of the PCB, and is a metallized hole. In addition, the top surface of the PCB is pre-installed with high-power components 5 , and the opening position of the stepped groove 1 corresponds to the bottom position of the pre-installed high-power components 5 .

The via hole 7 is provided to transfer the heat in the metal layer 2 inside the PCB to the via hole 7 to play the role of auxiliary heat dissipation. The metallization of the hole wall can ensure that the various metal layers 2 of the PCB can conduct both electrical conduction and thermal conduction.

Referring to FIG. 2 , the stepped metal block 3 with high thermal conductivity is buried in the stepped groove 1 . The stepped high thermal conductivity metal block 3 is embedded in the stepped groove 1 so that it can be fixed inside the PCB during the process of pressing the stepped high thermal conductivity metal block 3 with the PCB, thus eliminating the need for the stepped high thermal conductivity metal block 3 The additional fixing process with the stepped groove of the PCB does not require additional bonding materials. A solder paste 4 is provided between the shoulder of the stepped metal block 3 with high thermal conductivity and the metal layer 2 adjacent thereto. After hot pressing, the solder paste 4 can flow to the neck of the stepped metal block 3 with high thermal conductivity. Specifically, in this embodiment, the stepped groove 1 and the stepped metal block 3 with high thermal conductivity are convex, and the high-power components 5 are fixedly connected to the convex portion of the stepped metal block 3 with high thermal conductivity. Since the high-power components 5 are installed on the top of the PCB, the heat in the high-power components 5 can be transferred smoothly only when the stepped metal block 3 with high thermal conductivity is in direct contact with the high-power components 5 or connected through a good thermal conductor. into the stepped high thermal conductivity metal block 3. Therefore, the high-power component 5 is fixedly connected to the convex portion of the stepped metal block with high thermal conductivity 3 through the solder paste 4 , the bottom surface area of the stepped metal block with high thermal conductivity 3 is larger, and the heat dissipation performance is better. Preferably, the top surface of the stepped high thermal conductivity metal block 3 is flush with the top surface of the PCB, and the bottom surface of the stepped high thermal conductivity metal block 3 is flush with the bottom surface of the PCB. This setting facilitates PCB copper pouring operation and ensures the integrity of PCB. Furthermore, the copper layer is coated on both the top surface and the bottom surface of the stepped metal block 3 with high thermal conductivity, so that the stepped metal block 3 with high thermal conductivity can be packaged into the PCB, ensuring the structural strength of the PCB.

In this embodiment, the solder paste 4 is preferably solder paste. The solder paste 4 ensures the adhesion, electrical conductivity and thermal conductivity between the high-power components 5 and the stepped high thermal conductivity metal block 3. In order to meet these requirements, the solder paste is selected. As solder paste 4, the main reasons are:

(1) The melting point of solder paste is about 150° C. to 220° C., but the heat generation of high-power components 5 is far below this temperature, so solder paste 4 is selected as conductive solder paste 4 without melting.

(2) The material of the solder paste is pure metal. Compared with other media, such as conductive adhesive sheets, the solder paste does not contain any non-metallic materials such as resin, which makes the thermal conductivity of the solder paste better.

Copper is used as the main body of the stepped high thermal conductivity metal block 3, which utilizes the excellent thermal conductivity and electrical conductivity of copper. The stepped high thermal conductivity metal block 3 made of copper can quickly transfer the heat from the high power components 5 to the heat sink 6 on.

In order to fix the stepped metal block 3 with high thermal conductivity and the PCB, a solder paste 4 is added between the two, which is bonded to the shoulder of the stepped groove 1 . By embedding the solder paste 4 in the PCB, the conduction of the inner layer of the PCB is realized, which has the following advantages:

(1) The conventional way to realize the electrical communication and thermal conduction between the metal layer 2 and the stepped high thermal conductivity metal block 3 is to drill holes on the PCB and the stepped high thermal conductivity metal block 3 and metallize the hole wall, and this One implementation method is difficult to process and has the problem of difficult electroplating. The above problems can be avoided by embedding the solder paste 4 .

(2) This process does not consume resin and electroplating potions, etc., which can save the cost of processing materials and related equipment costs.

(3) The process flow is simple and the processing cycle can be greatly shortened.

It can be seen from FIG. 2 that the top surface of the stepped metal block with high thermal conductivity 3 is covered with a copper layer, and the bottom surface is covered with a copper layer. The stepped metal block with high thermal conductivity is packaged in the PCB to ensure the structural strength of the PCB. The stepped metal block 3 with high thermal conductivity is at the same height as the PCB, and the bottom surface of the PCB is fixedly connected with a heat sink 6 . The first purpose of this setting is to ensure the integrity of the stepped metal block 3 with high thermal conductivity and the PCB, so that the stepped metal block 3 with high thermal conductivity is embedded inside the PCB, so that the PCB can be installed stably; The outer surface of the type high thermal conductivity metal block 3 is dissipated. Adding the heat sink 6 can increase the contact area between the heat and the air, and realize better temperature difference transfer.

In this embodiment, the heat sink 6 covers the stepped metal block 3 with high thermal conductivity and the via hole 7 on the PCB, so that heat can be transferred out of the PCB in time. Since the through hole 7 is relatively narrow, the heat is not easy to be transferred from it, so a heat sink 6 is provided at one end thereof, which can effectively transfer heat to the heat sink 6 .

Referring to FIG. 3 and FIG. 4 , it is a schematic diagram of heat transfer between the high-power components 5 and the metal layer 2 through the stepped metal block 3 with high thermal conductivity. FIG. 3 shows the heat transfer of the high-power components 5 through the stepped metal block 3 with high thermal conductivity, which is the main heat transfer path of the high-power components 5 . Since the bottom of the high-power component 5 is in contact with the stepped metal block 3 with high thermal conductivity through the solder paste 4 , and there is a temperature difference between the two, the heat can be transferred mainly through heat conduction. Most of the heat is transferred to the stepped metal block 3 with high thermal conductivity through the bottom of the high-power components 5 . In this way, since the side of the stepped metal block 3 with high thermal conductivity near the high-power components 5 has a high temperature and the other side has a low temperature, heat can be continuously transferred from the high-temperature side to the other side. The heat transferred to the lower temperature side of the stepped high thermal conductivity metal block 3 can be transferred to the heat sink 6 through heat conduction, and the heat sink 6 can dissipate heat into the air mainly through heat conduction and heat convection.

FIG. 4 shows the heat transfer of the metal layer 2 through the stepped metal block 3 with high thermal conductivity. In addition, the metal layer 2 can also conduct heat transfer through the via hole 7 . The metal layer 2 inside the PCB also generates a small amount of heat when it is in working condition. This part of heat can be transferred along the metal layer 2 into the solder paste 4 , and then transferred to the neck and shoulder of the stepped metal block 3 with high thermal conductivity. The temperature of the neck and shoulder of the stepped metal block 3 with high thermal conductivity is relatively high, and the temperature of the portion close to the heat sink 6 is relatively low. Therefore, heat can be continuously transferred from the side with high temperature to the other side. The heat transfer form after reaching the heat sink 6 is the same as that in FIG. 3 .

Embodiment two:

This embodiment provides another PCB with rapid heat dissipation. Its cross-sectional view is shown in FIG. 5 , and for the sake of simplicity, only the differences between Embodiment 2 and Embodiment 1 are described. The difference is:

In this embodiment, the structure of the stepped high thermal conductivity metal block 3 and the heat sink 6 is combined, that is, the sheet structure on the heat sink 6 is arranged on the stepped high thermal conductivity metal block 3, so that the stepped high thermal conductivity metal block 3 is Evenly distributed flake structure. Other structures are the same as those in Embodiment 1, and will not be repeated here.

Embodiment three:

This embodiment provides a PCB with rapid heat dissipation, and its cross-sectional view is shown in FIG. 6 . For the sake of simplicity, only the differences between the third embodiment and the first embodiment are described. The difference is:

The bottom surface of the stepped metal block 3 with high thermal conductivity protrudes from the bottom surface of the PCB, and the heat sink 6 is arranged close to the stepped metal block 3 with high thermal conductivity. Other structures are the same as those in Embodiment 1, and will not be repeated here.

In the known structure, after adopting the heat conduction metal layer 2, the heat is conducted to the air by the heat sink 6, however, the more media the generated heat passes through, the less heat the heat sink 6 dissipates. The medium of spreading scriptures will absorb most of the heat, but cannot dissipate it. Therefore, the structure in this embodiment can dissipate heat more quickly and directly.

In addition, the PCB can also be formed by laminating four core boards, and its specific structure is shown in FIG. 7 , which will not be repeated here. In all the embodiments of the present invention, each metal layer 2 is preferably copper, and may also be silver, aluminum, tungsten and other metallic conductive materials.

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 (9)

1. A kind of 1. PCB of quick heat radiating, it is characterised in that including：

   Step trough (1)；

   Stepped high-thermal conductive metal block (3), it is arranged in the step trough (1), the stepped high-thermal conductive metal block (3) Solder cream (4) is set between top surface and the high power component (5) for being arranged at the PCB surface；

   Solder cream (4) is set between the shoulder and metal level adjacent thereto (2) of the stepped high-thermal conductive metal block (3).
2. 2. the PCB of quick heat radiating according to claim 1, it is characterised in that the stepped high-thermal conductive metal block (3) Material is copper.
3. 3. the PCB of quick heat radiating according to claim 1, it is characterised in that the solder cream (4) is tin cream.
4. 4. the PCB of quick heat radiating according to claim 1, it is characterised in that the stepped high-thermal conductive metal block (3) is buried Enter in the step trough (1).
5. 5. the PCB of quick heat radiating according to claim 1, it is characterised in that the stepped high-thermal conductive metal block (3) The either flush of top surface and the PCB, and the bottom surface of the stepped high-thermal conductive metal block (3) is concordant with the bottom surface of the PCB.
6. 6. the PCB of quick heat radiating according to claim 1, it is characterised in that the stepped high-thermal conductive metal block (3) Top surface is covered with layers of copper, and the bottom surface of the stepped high-thermal conductive metal block (3) is covered with layers of copper.
7. 7. the PCB of quick heat radiating according to claim 6, it is characterised in that the bottom of the stepped high-thermal conductive metal block The bottom surface of face layers of copper is provided with fin (6).
8. 8. the PCB of quick heat radiating according to claim 7, it is characterised in that also including via hole (7), itself and the gold Category layer (2) conducts.
9. 9. the PCB of quick heat radiating according to claim 8, it is characterised in that the fin (6) covers the via hole (7)。