Circuit board structure

A circuit board structure includes a circuit board, at least a through hole, and at least a heat dissipating structure. The circuit board has two opposite surfaces. A metal layer is disposed on each of the opposite surfaces of the circuit board. The through hole is disposed in the circuit board, and the through hole penetrates through the circuit board. The heat dissipating structure is disposed in the through hole. The heat dissipating structure includes a first metal block and a second metal block. The first metal block and the second metal block are joined together in the through hole and have an interface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application serial no. 109113855, filed on Apr. 24, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present invention relates to a circuit board, and particularly to a circuit board structure with a heat dissipation structure.

Description of Related Art

In recent years, in order to increase the application of printed circuit boards (PCBs), there are many current technologies that form the printed circuit board as a multi-layer circuit structure, in order to increase its internal space for circuit layouts. The manufacturing method of the multi-layer circuit board is to stack the laminated structure composed of copper foil and prepreg (PP) repeatedly, and laminate it on the core board, so as to increase the interior wiring space of the circuit board. The electroplating process is used to fill the through holes or blind holes of each laminated structure with conductive materials, so as to conduct each of the layers. In addition, many different types of components, such as chips, connectors, optoelectronic components or heat dissipating components, may also be disposed in the multi-layer circuit boards in accordance to requirements, so as to increase functions of the multi-layer circuit boards.

Taking high-power electronic components disposed in the circuit structure as an example, because high-power electronic components generate a lot of heat energy during operation, it will cause reliability problems to the circuit board. Therefore, how to improve the heat dissipating capability of the circuit board is an urgent problem to be solved in this field.

SUMMARY

The present invention provides a circuit board structure, which has a good heat dissipating capability, the manufacturing process is simple, and has good quality.

The circuit board structure of the present invention includes a circuit board, at least one through hole, and at least one heat dissipating structure. The circuit board has two opposite surfaces. A metal layer is disposed on each of the opposite surfaces of the circuit board. The through hole is disposed in the circuit board, and the through hole penetrates through the circuit board. The heat dissipating structure is disposed in the through hole. The heat dissipating structure includes a first metal block and a second metal block. The first metal block and the second metal block are joined in the through hole and have an interface.

In an embodiment of the present invention, the above-mentioned circuit board structure further includes an interface material. The interface material is filled in the through hole, and surrounding the heat dissipating structure. A gap is between the heat dissipating structure and an inner wall of the through hole. The interface material is disposed in the gap, so as to fix the heat dissipating structure in the circuit board.

In an embodiment of the present invention, a side surface of the at least one heat dissipating structure is a flat surface without protrusions.

In an embodiment of the invention, after the first metal block is joined to the second metal block, the heat dissipating structure is laterally deformed.

In an embodiment of the present invention, the interface is in between the first metal block and the second metal block. The crystal lattice of the first metal block on one side of the interface and the crystal lattice of the second metal block on an opposite side of the interface are discontinuously arranged.

In an embodiment of the present invention, a cross section of the interface is a complementary shaped surface between the first metal block and the second metal block.

In an embodiment of the present invention, the material of the first metal block and the second metal block includes metal materials or meal alloys selected from platinum, titanium, aluminum, copper, gold, silver, tin, and nickel.

In an embodiment of the present invention, the first metal block and the second metal block are respectively the same or different metal materials, or the same or different alloys.

In an embodiment of the present invention, the circuit board has an inner layer circuit board and a plurality of circuit build-up layers stacked on two opposite surfaces of the inner layer circuit board.

In an embodiment of the present invention, the above-mentioned circuit board structure further includes a first metal layer and a second metal layer. The first metal layer is disposed on the metal layer on a first surface of the circuit board. The second metal layer is disposed on the metal layer on a second surface of the circuit board opposite to the first surface. The first metal layer and the second metal layer overlap the heat dissipating structure.

In an embodiment of the present invention, the first metal block and the second metal block are porous metal blocks.

Based on the above, since the circuit board structure of an embodiment of the present invention has a heat dissipating structure penetrating through the circuit board, so as to quickly and efficiently transfer heat energy from one side of the circuit board to the other side. Therefore, the circuit board structure has good heat dissipating capability. In addition, the manufacturing process of the heat dissipating structure may be simple and may reduce the effect on tolerance. Therefore, the circuit board structure has the advantageous effect of reducing costs, and has good quality.

DESCRIPTION OF THE EMBODIMENTS

Some embodiments are provided hereinafter and described in detail with reference to figures. However, the embodiments provided are not intended to limit the scope of the invention. Moreover, the figures are only descriptive and are not drawn to scale. For ease of explanation, the same devices below are provided with the same reference symbols.

Moreover, terms such as “first” and “second” used herein do not represent order, and it should be understood that they are for differentiating devices or operations having the same technical terms.

Secondly, the terms “containing”, “including”, “having” and the like as used herein are all open-ended terms; i.e., including but not limited to.

Furthermore, the terms “in contact with”, “joined”, “bonded to” and the like, as used herein, may mean direct contact or indirect contact via other layers unless otherwise stated.

FIG. 1is a schematic cross-sectional view of a circuit board structure according to an embodiment of the invention.FIG. 2is a schematic top view of line A-A′ ofFIG. 1.FIG. 3is a schematic top view of a circuit board structure according to an embodiment of the invention. For the clarity of the drawings and the convenience of the description,FIG. 2andFIG. 3omit illustrating several layers or components from the figures. Please first refer toFIG. 1andFIG. 2. The circuit board structure10of the embodiment includes a circuit board100, at least one through hole130, and at least one heat dissipating structure200. The through hole130is disposed in the circuit board100, and the through hole130penetrates through the circuit board100. The heat dissipating structure200is disposed in the through hole130. Under the above configuration, the heat dissipating structure200may quickly and effectively transfer heat energy generated by the electronic components (not illustrated) from one side of the circuit board100to the other side, so that the circuit board structure10may have good heat dissipating capability.

Please refer toFIG. 1andFIG. 2, the circuit board structure10is, for example, a multilayer circuit board with a core board, which may have an application as a printed circuit board (PCB). The circuit board100of the circuit board structure10includes an inner layer circuit board110and a plurality of circuit build-up layers120stacked on two opposite surfaces of the inner circuit layer board110.

In detail, the inner layer circuit board110is, for example, a core board, which has a core layer111. The core layer111has an upper surface113and a lower surface115relative to the upper surface113. The inner layer circuit board110also has a first conductive layer112and a second conductive layer114. The first conductive layer112is disposed on the upper surface113. The second conductive layer114is disposed on the lower surface115. The first conductive layer112and the second conductive layer114are, for example, patterned conductive layers, but the invention is not limited thereto.

In the embodiment, the material of the core layer111is, for example, prepreg (PP) or other suitable dielectric materials. The materials of the first conductive layer112and the second conductive layer114include metal materials, metal nitrides, metal silicides, or combinations thereof, such as copper foil or other suitable conductive materials. In some embodiments, the above-mentioned metal materials may be, for example, platinum, titanium, aluminum, copper, gold, silver, tin, palladium or nickel, or alloys thereof, but the invention is not limited thereto. Therefore, the inner layer circuit board110may adopt a copper clad laminate (CCL) substrate or other substrates having the above-mentioned configurations. However, the present invention does not limit the type and formation method of the inner layer circuit board110.

As shown inFIG. 1, a plurality of circuit build-up layers120may be stacked on the upper surface113and the lower surface115of the core layer111. Specifically, the circuit build-up layer120includes a dielectric layer122and a conductive layer124. The dielectric layer122of the circuit build-up layer120near the core layer111is disposed on the upper surface113, or on the lower surface115. The outermost circuit build-up layer120away from the core layer111is disposed on the circuit build-up layer120close to the core layer111. In the embodiment, the conductive layer124may be a patterned conductive layer, and the conductive layers124of the circuit build-up layer120are stacked on each other, and may be electrically connected to each other. In addition, the conductive layer124may also be electrically connected to the first conductive layer112or the second conductive layer114of the inner layer circuit board110. As shown inFIG. 1, the circuit board100of the embodiment is, for example, a multi-layer circuit board having four layers of circuit build-up layer120, but the number of the circuit build-up layers120is not limited to that shown inFIG. 1. The number of layers may be increased or decreased based on requirements of the user.

In the embodiment, two of the circuit build-up layers120located farthest from the core layer111may respectively have the two opposite surfaces of the circuit board100, such as the first surface102and the second surface104of the circuit board100, which are opposite to each other. The conductive layer124may be disposed on the first surface102or the second surface104as metal layers on the two opposite surfaces of the circuit board100. In other words, the circuit board100with a multilayer circuit build-up layer120may also be a circuit board with metal layers only on both surfaces, such as cooper clad laminate (CCL), but the embodiment is not limited thereto.

In the embodiment, the material of the dielectric layer122is, for example, prepreg or other suitable dielectric materials. The material of the conductive layer124includes metal materials, metal nitrides, metal silicides or combinations thereof, such as copper foil, or other suitable conductive materials.

Please refer toFIG. 1andFIG. 2.FIG. 2is a top view of one of the circuit build-up layers120at line A-A′ inFIG. 1. In the embodiment, the through hole130is disposed in the circuit board100. The through hole130penetrates through the inner layer circuit board110of the circuit board100, and a plurality of circuit build-up layers120. The step of forming the through hole130may include a mechanical drilling process, a laser drilling process, or other suitable processes. The present invention does not limit the method of forming the through hole130.

In the embodiment, the inner wall133of the through hole130may encircle to form a circle (as shown inFIG. 2), but the present invention is not limited thereto. In some embodiments, the pattern of the through hole130may also be rectangular, polygonal, or irregular.

The heat dissipating structure200may be correspondingly disposed in the through hole130. In the embodiment, the heat dissipating structure200includes the first metal block220and the second metal block240. The first metal block220and the second metal block240are joined in the through hole130to form a heat dissipating structure200(eg. a heat dissipating copper pillar). The interface210between the first metal block220and the second metal block240is disposed in the through hole130. In the embodiment, the crystal lattice of the first metal block220on one side of the interface210and the crystal lattice of the second metal block240on the opposite side of the interface210are discontinuously arranged.

In the embodiment, the materials of the first metal block220and the second metal block240include metal materials or alloys selected from platinum, titanium, aluminum, copper, gold, silver, tin, or nickel, but the invention is not limited thereto. In the embodiment, the material of the first metal block220and the material of the second metal block240may be the same, such as copper. In other embodiments, the material of the first metal block220and the material of the second metal block240may respectively be the same or different metal materials, or the same or different alloys. In the embodiment, the cross section of the interface210between the first metal block220and the second metal block240is a plane surface, but the invention is not limited thereto.

It is worth noting that, the two outermost circuit build-up layers120of the circuit board100respectively have opposite first surface102and second surface104. The linear distance between the first surface102and the second surface104may define a height H of the circuit board100. The linear distance from the interface210to the top surface of the first metal block220close to the first surface102may define a first height H1 of the first metal block220. The linear distance from the interface210to the top surface of the second metal block240near the second surface104may define a second height H2 of the second metal block240. The sum of the first height H1 and the second height H2 may be greater than or equal to the height H of the circuit board100. In the embodiment, the first height H1 and the second height H2 are respectively 0.5 times of the height H (that is, the first height H1 is 0.5H, and the second height H2 is 0.5H), but the invention is not limited thereto. Under the above configuration, the heat dissipating structure200may penetrate through the circuit board100, and has the effect of improving the heat dissipating capability.

In the embodiment, the circuit board structure10further includes an interface material140filled in the through hole130. The interface material140surrounds the heat dissipating structure200in the through hole130. Generally speaking, in the conventional technical fields, the method of disposing the heat dissipating column in the circuit board mainly includes disposing bumps on the side surface of the heat dissipating column, so that the heat dissipating column may be fixed in the through hole by the bumps. It is worth noting that, in the embodiment, the interface material140may first be disposed between the first metal block220and the second metal block240, and then the first metal block220, the second metal block240and the interface material140are disposed together in the through hole130. Then, at a heated temperature, pressure is applied to end point of the first metal block220and end point of the second metal block240. Then, the first metal block220and the second metal block240are joined in the through hole130, and the interface210is formed in the through hole130. After the first metal block220and the second metal block240are joined, there is a gap132between the formed heat dissipating structure200and the inner wall133of the through hole130. The interface material140pressed by the first metal block220and the second metal block240may flow and be filled in the gap132. Therefore, the viscosity of the interface material140may keep the heat dissipating structure200in the through hole130. After the temperature is down, the interface material140may be solidified and disposed in the gap132, so as to fix the heat dissipating structure200in the through hole130of the circuit board100. Under the above configuration, the circuit board structure10of the present invention has the advantageous effect of simplifying manufacturing process and reducing costs.

Since the heat dissipating structure200of the embodiment is formed in the through hole130, the heat dissipating structure200may be directly fixed to the circuit board100by the interface material140. Therefore, the side surface202of the heat dissipating structure200may be a flat surface without any protrusion. Through this, as shown inFIG. 1andFIG. 2, the interface material140may surround the heat dissipating structure200and be configured in a ring shape in the through hole130. In this way, in addition to the simple manufacturing process of the heat dissipating structure200, the interface material140may also automatically fill up the gap132, and reduce the influence of the size tolerance on the heat dissipating structure200or on the through hole130during the manufacturing process. Therefore, the circuit board structure10may further have good quality.

In the embodiment, the material of the interface material140includes epoxy-based colloid, which has the characteristics of temperature controllable resin viscosity, but the invention is not limited thereto. In the embodiment, the volume of the interface material140disposed between the first metal block220and the second metal block240may be greater than or equal to the volume of the through hole130minus the volume of the heat dissipating structure200. Under the above configuration, the interface material140may be ensured to fill up the gap132, so that the circuit board structure10may have good reliability. In addition, the excess interface material140may flow out of the through hole130and remain on the first surface102or the second surface104of the circuit board100. In the embodiment, the remaining excessive interface material140may be removed by grinding or chemical-mechanical polishing (CMP), but the invention is not limited thereto.

In some embodiments, after the first metal block220is joined to the second metal block240, the first metal block220and the second metal block240are subjected to pressure from Z direction, so that the formed heat dissipating structure200may laterally deform in X and/or Y direction. In other words, the height H of the heat dissipating structure200may be reduced in the Z direction, and the width may be increased in the X direction and/or Y direction, resulting in a Poisson effect. Through this, the side surface202of the heat dissipating structure200may become close to or contact the inner wall133of the through hole130, so as to further enhance the bonding force of the heat dissipating structure200and the circuit board100. In this way, the reliability and quality of the circuit board structure10may be improved. In the embodiment, the X direction is perpendicular to the Y direction and the Z direction, and the Y direction is perpendicular to the Z direction.

Please refer toFIG. 1andFIG. 3, the circuit board structure10also has a first metal layer160and a second metal layer180. The first metal layer160is disposed on the conductive layer124of the first surface102of the circuit board100(e.g. the metal layer on one surface of the circuit board100). The second metal layer180is disposed on the conductive layer124of the second surface104of the circuit board100(e.g. the metal layer on the other surface of the circuit board100). In the embodiment, the first metal layer160and the second metal layer180are, for example, respectively disposed on both surfaces of the circuit board100(e.g. the first surface102and the second surface104). The first metal layer160and the second metal layer180are, for example, copper capping layers. In this way, the first metal layer160and the second metal layer180will cover and overlap the heat dissipating structure200(the through hole130and the heat dissipating structure200covered by the first metal layer160are in dotted lines as illustrated inFIG. 3).

In the embodiment, the materials of the first metal layer160and the second metal layer180include metal materials, metal nitrides, metal silicides, or combinations thereof, such as copper foil, or other suitable conductive materials. In some embodiments, the above-mentioned metal materials may be, for example, platinum, titanium, aluminum, copper, gold, silver, tin, palladium or nickel or alloys thereof, but the invention is not limited thereto. In this way, the circuit board structure10may be a double-layer copper foil circuit board, but the invention is not limited thereto.

In other embodiments, the material of the first metal layer160or the material of the second metal layer180may also be the same as or different from the material of the heat dissipating structure200. For example, the material of the heat dissipating structure200and the material of the first metal layer160or the second metal layer180may be copper. Or, the material of the heat dissipating structure200may be aluminum, and the material of the first metal layer160or the second metal layer180may be copper. Or, the material of the heat dissipating structure200may be titanium, and the material of the first metal layer160or the second metal layer180may be copper. However, the present invention is not limited thereto. Persons having ordinary skills in the art may select the appropriate materials of the heat dissipating structure200, the first metal layer160and the second metal layer180according to the actual applicable requirements.

In some embodiments, the materials of the first metal block220and the second metal block240may also specifically be porous metal blocks. Under the above configuration, when the first metal block220is being pressed to join the second metal block240, the first metal block220and the second metal block240may be deformed through the automatic compression of the pores (or holes) in the metal block to correspond to the size of the through hole130size. In this way, the size tolerance of the heat dissipating structure200or the through hole130may be further widened during the manufacturing process. Therefore, the accuracy requirements of the present invention in the manufacturing process may be reduced, which may facilitate the simplification of the manufacturing process. The yield and quality of the circuit board structure10may also be improved.

In addition, since the first metal block220and the second metal block240are porous metal blocks, the porous metal block has a larger heat dissipating surface area than solid metal block. Therefore, the first metal block220and the second metal block240may increase the heat dissipating surface area through these pores (or holes), thereby improving the heat dissipating efficiency of the circuit board structure10.

It should be noted that the reference symbols and a part of the contents in the previous embodiment are used in the following embodiments, in which identical reference symbols indicate identical or similar devices. The part of the description with the identical technical content omitted may refer to the foregoing embodiment, which is not repeated in the following description.

FIG. 4Ais a schematic cross-sectional view of a heat dissipating structure according to another embodiment of the invention. Please refer toFIG. 1andFIG. 4A. The heat dissipating structure200A of the embodiment is similar to the heat dissipating structure200ofFIG. 1. The main difference is that, in the embodiment, the cross section of the interface210A of the heat dissipating structure200A is a curved surface. Specifically, the first metal block220A has a convex curved surface at the interface210A, and the second metal block240A has a concave curved surface at the interface210A. Through this, the interface210A is a curved surface, and the same effect as that of the above embodiment may be obtained.

FIG. 4Bis a schematic cross-sectional view of a heat dissipating structure according to another embodiment of the invention. Please refer toFIG. 1andFIG. 4B. The heat dissipating structure200B of the embodiment is similar to the heat dissipating structure200ofFIG. 1. The main difference is that, in the embodiment, the cross section of the interface210B of the heat dissipating structure200B is a complementary shaped surface. Specifically, the first metal block220B has a convex contour at the interface210B, and the second metal block240B has a concave contour at the interface210B. Through this, the contour of the first metal block220B at the interface210B may complement the contour of the second metal block240B at the interface210B, and the same effect as that of the above embodiment may be obtained.

FIG. 4Cis a schematic cross-sectional view of a heat dissipating structure according to yet another embodiment of the invention. Please refer toFIG. 1andFIG. 4C. The heat dissipating structure200C of the embodiment is similar to the heat dissipating structure200ofFIG. 1. The main difference is that, in the embodiment, the cross section of the interface210C of the heat dissipating structure200C is a complementary shaped surface. Specifically, the first metal block220C has a bump at the interface210C, and the second metal block240C has a dimple at the interface210C. Through this, the bump of the first metal block220C at the interface210C may complement the dimple of the second metal block240C at the interface210C, and the same effect as that of the above embodiment may be obtained.

In other embodiments, while not deviate from the spirit and scope of the present invention, persons having ordinary skill in the art, should understand that any other shapes that are complementary to each other may be used as the shape of the interface between the first metal block and the second metal block. The shape of the interface is not limited to the drawings illustrated in the invention. For example, the shape of the interface between the first metal block and the second metal block may also be a complementary saw-tooth shape, a complementary wave shape, a complementary cog shape, or a complementary star shape, but the invention is not limited thereto.

FIG. 5is a schematic cross-sectional view of a circuit board structure according to another embodiment of the invention. Please refer toFIG. 1andFIG. 5. The circuit board structure50of the embodiment is similar to the circuit board structure10ofFIG. 1. The main difference is that. in the embodiment, the circuit board structure50is, for example, a double-layer circuit board.

In the embodiment, the circuit board structure50includes a circuit board100, and metal layers are respectively disposed on the two opposite surfaces of the circuit board100. Specifically, the circuit board100includes an inner layer circuit board110. The first conductive layer112(also referred to as the metal layer on one surface of the circuit board100) is disposed on the first surface102of the circuit board100(may also be referred to as the upper surface of the inner layer circuit board110). The second conductive layer114(also referred to as the metal layer on the other surface of the circuit board100) is disposed on the second surface104of the circuit board100(may also be referred to as the lower surface of the inner layer circuit board110). The through hole130is disposed in the circuit board100and penetrates through the circuit board100.

The first metal block220and the second metal block240are joined in the through hole130and have the interface210between the first metal block220and the second metal block240, so as to constitute the heat dissipating structure200. The interface material140fills up the gap132of the through hole130and surrounds the heat dissipating structure200. Through this, the heat dissipating structure200is fixed in the circuit board100.

The first metal layer160is disposed on the conductive layer124on the first surface102of the circuit board100. The second metal layer180is disposed on the conductive layer124on the second surface104of the circuit board100. Through this, the first metal layer160and the second metal layer180may be used as a copper capping layer disposed on both surfaces of the circuit board100(e.g. the first surface102and the second surface104). In this way, the first metal layer160and the second metal layer180will cover and overlap the heat dissipating structure200, and the same effect as that of the above embodiment may be obtained.

In summary, since the circuit board structure of an embodiment of the present invention has a heat dissipating structure penetrating through the circuit board, so as to quickly and efficiently transfer heat energy from one side of the circuit board to the other side. Therefore, the circuit board structure has good heat dissipating capability. In addition, the interface material may simply fill up the through hole and surround the heat dissipating structure, so as to fix the heat dissipating structure in the through hole of the circuit board. In this way, the surface of the heat dissipating structure may be flat, and the manufacturing process may be simplified. Therefore, the circuit board structure has the advantageous effect of reducing costs. In addition, the interface material may also automatically fill up the gap, and reduce the influence of the size tolerance on the heat dissipating structure or the through hole during the manufacturing process. Therefore, in addition to the simplified manufacturing process, the circuit board structure further has good quality. In addition, the first metal block and the second metal block of the circuit board structure of the present invention may also be porous metal blocks. In addition to improving the heat dissipating efficiency, the accuracy requirements in the manufacturing process may also be further reduced. Through this, the yield and quality of the circuit board structure of the embodiment may be further improved.