CN110859027B

CN110859027B - Printed circuit board and method for manufacturing the same

Info

Publication number: CN110859027B
Application number: CN201810958890.5A
Authority: CN
Inventors: 李秉谚; 陈博政; 邓自强; 王赞钦; 石汉青; 吕政明
Original assignee: Tripod Wuxi Electronic Co Ltd
Current assignee: Tripod Wuxi Electronic Co Ltd
Priority date: 2018-08-22
Filing date: 2018-08-22
Publication date: 2022-05-17
Anticipated expiration: 2038-08-22
Also published as: CN110859027A

Abstract

The invention discloses a printed circuit board and a manufacturing method thereof, the manufacturing method of the printed circuit board comprises the steps of providing a circuit board base material, processing an opening on the circuit board base material, electroplating a first electroplated layer on the circuit board base material, pressing a copper block in the opening, flattening the surface of the circuit board base material to form a flattened circuit board surface, electroplating a second electroplated layer on the flattened circuit board surface, and forming a photosensitive film on the second electroplated layer.

Description

Printed circuit board and method for manufacturing the same

Technical Field

The present invention relates to a printed circuit board and a method for manufacturing the same, and more particularly, to a printed circuit board having a heat dissipation function and a method for manufacturing the same.

Background

At present, electronic products are developed toward high performance, high frequency, high speed, light weight, and thin, and various electronic related components are also developed toward multi-function, high speed, multi-power, and small volume. Under the condition that the functions of the electronic product are more and more, the consumed power is more and more, so that the electronic product generates much heat energy during operation, thereby increasing the temperature of the electronic product.

Printed Circuit Boards (PCBs) also face thermal control problems. Printed circuit boards are composed of substrate material connected within conductive insulating material between components and are not themselves good conductors of heat. Typically, a typical substrate material has a thermal conductivity λ of about 0.2W/mK, compared to copper, which has a high thermal conductivity of about 390W/mK. Therefore, in order to reduce the reliability problem of the electronic product caused by the over-high temperature, a copper block is usually embedded in the circuit board as a heat dissipation path of the electronic component.

However, in the heat dissipation method of embedding the copper block in the circuit board, the copper block is not always matched with the size of the opening between the circuit boards, for example, the side surface of the copper block is formed with a protrusion, so a gap is formed between the copper block and the circuit board, and the gap easily causes the solder paste and the heat-conducting paste in the circuit board manufacturing process to flow to the back surface of the circuit board, thereby affecting the performance of the electronic product.

Disclosure of Invention

In view of the above, the present invention provides a printed circuit board with heat dissipation function and a method for manufacturing the same to solve the above problems.

In some embodiments of the present invention, a method of manufacturing a printed circuit board includes the steps of providing a circuit board substrate, forming an opening in the circuit board substrate, plating a first plating layer on the circuit board substrate, pressing a copper block into the opening, planarizing the surface of the circuit board substrate to form a planarized circuit board surface, plating a second plating layer on the planarized circuit board surface, and forming a photosensitive film on the second plating layer.

In some embodiments of the present invention, the manufacturing method further includes patterning the photosensitive film to expose a plurality of grooves of the circuit board substrate, and the grooves include a plurality of gaps between the periphery of the copper block and the circuit board substrate.

In some embodiments of the present invention, the method further includes electroplating a third electroplating layer to fill the grooves of the substrate of the circuit board.

In some embodiments of the present invention, the first plating layer, the second plating layer, and the third plating layer are copper plating layers.

In some embodiments of the present invention, the method further comprises electrically connecting the first plating layer and the copper block.

In another embodiment of the present invention, a printed circuit board includes a substrate, a first plating layer, a copper block, a second plating layer, and a patterned photosensitive film. The circuit board substrate has an opening. The first electroplating layer is formed on the circuit board substrate. The copper block is disposed in the opening. The second plating layer is formed on the first plating layer. The patterned photosensitive film is formed on the second electroplated layer.

In some embodiments of the present invention, the circuit board substrate further includes a plurality of grooves, and the patterned photosensitive film is exposed out of the grooves, wherein the grooves include a plurality of gaps between the periphery of the copper block and the circuit board substrate.

In some embodiments of the present invention, the printed circuit board further includes a third plating layer filled in the grooves of the circuit board substrate.

In some embodiments of the present invention, the first plating layer is electrically connected to the copper block.

In view of the above, the printed circuit board and the manufacturing method thereof according to the present invention can achieve a good heat dissipation effect by performing the electroplating and planarization processes to form a photosensitive film and performing the patterning process to form the patterned photosensitive film, and during the planarization process, the ductility of copper itself can be used to help planarize the surface of the printed circuit board and improve the heat dissipation effect, so as to improve the problem that the solder paste and the thermal conductive paste in the circuit board manufacturing process flow to the back of the printed circuit board, thereby improving the performance of the electronic product.

The foregoing is merely illustrative of the problems, solutions to problems, and other aspects of the present invention, and the specific details of which are set forth in the following description and the associated drawings.

Drawings

FIG. 1 is a flow chart of a method for manufacturing a printed circuit board according to an embodiment of the present invention;

fig. 2A to 2G are schematic cross-sectional views illustrating steps of a method for manufacturing a printed circuit board according to an embodiment of the invention.

Description of the symbols

100: method for manufacturing printed circuit board

110. 120, 130, 140, 150, 160, 170, 180: step (ii) of

200: circuit board

210: circuit board base material

215: opening of the container

220: groove

220 a: at the gap

225: the first electroplated layer

230: copper block

235: planarizing the surface of a circuit board

240: second plating layer

245: patterned photosensitive film

250: third plating layer

Detailed Description

The following detailed description of the embodiments, taken in conjunction with the accompanying drawings, serve to better understand aspects of the present disclosure. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first element discussed below could be termed a second element without departing from the teachings of the present concepts. As used in this disclosure, the term "and/or" includes any and all combinations of one or more of the associated listed items. Exemplary embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Please refer to fig. 1. Fig. 1 is a flow chart of a method 100 for manufacturing a printed circuit board according to an embodiment of the invention. The printed circuit board manufacturing method 100 is an example and is not intended to limit the invention beyond what is specifically recited in the claims. Additional operations may be provided before, during, and after the printed circuit board manufacturing method 100, and some of the operations described may be replaced, eliminated, or rearranged to achieve additional implementations of the method. The printed circuit board manufacturing method 100 is described below in conjunction with fig. 2A through 2G. Fig. 2A to 2G are schematic cross-sectional views illustrating steps of a method for manufacturing a circuit board 200 according to an embodiment of the invention.

In step 110, referring to fig. 2A, the printed circuit board manufacturing method 100 provides a circuit board substrate 210 in the circuit board 200, and an opening 215 is formed on the circuit board substrate 210. In some embodiments, the method of forming the opening 215 may be performed by drilling (drilling), for example, the opening 215 may be formed by drilling through the layers of the circuit board substrate 210 at a time by mechanical drilling, i.e., drilling through the copper foil layer along with a resin layer (e.g., phenolic resin or epoxy resin), or by laser drilling (laser drilling). In some embodiments, the circuit board substrate 210 may be a Copper foil substrate (CCL) including glass fiber (FR 4).

In step 120, referring also to FIG. 2B, the printed circuit board manufacturing method 100 plates a first plating layer 225 on the circuit board substrate 210. The first electroplated layer 225 covers the surface of the circuit board substrate 210, wherein the thickness of the first electroplated layer 225 may be determined by the actual requirement of the designer. In some embodiments, the material of first plating layer 225 may include copper (Cu), aluminum (Al), nickel (Ni), gold (Cu), or a combination thereof. In some embodiments, first electroplated layer 225 may be a metal foil formed from a conductive metal, such as copper foil.

In step 130, referring also to fig. 2C, the printed circuit board manufacturing method 100 presses a copper block 230 into the opening 215 of the circuit board 200, wherein the size of the copper block 230 is limited. Specifically, after the opening 215 is formed between the circuit board substrates 210 and the first plating layer 225 is plated, in the present embodiment, a copper block matching the size of the opening 215 is selected to reduce the problem that a gap may be generated between the copper block 230 and the circuit board substrate 210 after the copper block 230 is pressed. In some embodiments, the copper block 230 protrudes from the first plating layer 225 above the circuit board substrate 210. In this embodiment, the copper block 230 is electrically connected to the first plating layer 225. In some embodiments, the copper block 230 may be made of red copper (C1100) with a thermal conductivity of 391W/mk and a thermal conductivity of 97%, which may have better thermal conductivity.

In step 140, reference is also made to fig. 2D. In this embodiment, although the pressed-in copper block 230 matches the size of the opening 215, there may still be a slight gap, so the printed circuit board manufacturing method 100 performs planarization of the surface of the circuit board substrate 210 to form a planarized circuit board surface 235. In some embodiments, the surface of the circuit board substrate 210 may be planarized by an automatic pressing and grinding machine, such as an eight-axis grinder, a ceramic brush grinder, or the like, to grind the copper block 230, thereby forming a planarized circuit board surface 235 with a flat top surface. In some embodiments, the planarization process may use sand blast (sand blast) and cut the portion of protruding copper slug 230 by mechanical polishing (mechanical polishing) to form planarized circuit board surface 235. In some embodiments, the first plating layer 225 is a copper plating layer, so that when the surface of the circuit board substrate 210 is planarized in step 140, the ductility of copper in the first plating layer 225 can be utilized to help level the surface of the circuit board substrate 210 and to help eliminate the gap between the copper block 230 and the circuit board substrate 210, thereby forming the planarized circuit board surface 235.

In step 150, referring also to fig. 2E, the printed circuit board manufacturing method 100 electroplates a second electroplated layer 240 on the planarized circuit board surface 235, wherein the thickness of the second electroplated layer 240 may depend on the actual requirements of the designer. In some embodiments, the second plating layer 240 is formed by a plating process, such as copper plating, to form a copper cap layer (copper cap) on the planarized circuit board surface 235. In other words, the second plating layer 240 covers the first plating layer 225 and the copper block 230. In some embodiments, the surface between the copper block 230 and the circuit board substrate 210 is electrically connected to the first plating layer 225, and the other surface of the copper block 230 is covered by the second plating layer 240. In some embodiments, the material of the second plating layer 240 may include copper (Cu), aluminum (Al), nickel (Ni), gold (Cu), or a combination thereof. In some embodiments, second electroplated layer 240 may be a metal foil formed from a conductive metal, such as a copper foil. In some embodiments, first electroplated layer 225 and second electroplated layer 240 may be electroplated layers formed from the same conductive metal, e.g., first electroplated layer 225 is a copper electroplated layer, and second electroplated layer 240 is also a copper electroplated layer.

In step 160, referring to fig. 2F, the pcb manufacturing method 100 forms a photosensitive film, referring to the position of the patterned photosensitive film 245 in fig. 2F, without performing the patterning process, and forms on the second plating layer 240. The photosensitive material contained in the photosensitive film is a material which reacts to light and undergoes intramolecular or intermolecular change after light energy is absorbed, so that the difference in the dissolution rate of the developing solution between the exposed area and the unexposed area is generated. In some embodiments, a photosensitive material including a photoresist (photoresist) may be used for the photosensitive film, such as a photosensitive resin film, a negative photosensitive film, and the like.

In step 170, referring to fig. 2F, the printed circuit board manufacturing method 100 performs a patterning process to form a patterned photosensitive film 245 to expose a plurality of grooves 220 of the circuit board substrate 210, wherein the grooves 220 further include a plurality of gaps 220a between the periphery of the copper blocks 230 and the circuit board substrate 210. In some embodiments, the patterned photosensitive film 245 can be formed by an image transfer process, which may include steps of coating, soft baking, mask alignment, exposure, post-exposure baking, developing, cleaning, and drying.

In step 180, referring to fig. 2G, the pcb manufacturing method 100 plates a third plating layer 250 to fill the grooves 220 on the surface of the pcb. Specifically, the grooves 220 including the gaps 220a between the copper blocks 230 and the circuit board base 210 exposed in fig. 2F are filled with the third plating layer 250, so that the copper blocks 230 are planarized. That is, the third plating layer 250 and the patterned photosensitive film 245 cover the copper block 230. In some embodiments, the third plating layer 250 is plated by pattern plating (patterning) to fill the grooves 220 including the gaps 220 a. In some embodiments, the top surface of the third plating layer 250 and the top surface of the patterned photosensitive film 245 form a plane. In some embodiments, the third plating layer 250 may be a metal sheet formed of a conductive metal, such as a copper foil. In some embodiments, the first, second, and third plating layers 225, 240, 250 are plating layers formed from the same conductive metal, e.g., the first, second, and third plating layers 225, 240, 250 are all copper plating layers.

In some embodiments, the third plating layer 250 may be formed using a semi-additive process.

In some embodiments, the present invention may be followed by subsequent processing after step 180. For example, the outer positive layer may be formed by a DES (leveling, etching, or striping) process, which includes three major parts of developing (leveling), etching (leveling), and stripping (striping) to obtain a desired pattern, and the stripping may be further used to dissolve and rinse a dry film on the pattern.

Although the present invention describes the disclosed printed circuit board fabrication method as a series of steps, it should be understood that the order of the steps shown should not be construed in a limiting sense. Moreover, not all illustrated steps may be required to implement a particular aspect or embodiment of the invention. Furthermore, one or more steps of the present invention may be performed in one or more separate steps and/or stages.

In summary, the printed circuit board manufacturing method of the present invention can achieve a good heat dissipation effect through the steps of electroplating, pressing in the copper block, planarizing the manufacturing process, forming the photosensitive film and patterning the photosensitive film, and the like, and can eliminate the gap between the circuit board and the copper block, so that the problem that the solder paste and the thermal conductive paste flow to the back of the circuit board in the manufacturing process of the circuit board can be improved, and the efficiency of the electronic product can be further improved.

While the invention has been described in conjunction with the above embodiments, it is not intended to limit the scope of the invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the spirit and scope of the invention, which is defined in the appended claims.

Claims

1. A method of manufacturing a printed circuit board, comprising:

providing a circuit board base material, and processing an opening on the circuit board base material;

electroplating a first electroplated layer on the circuit board base material;

pressing a copper block into the opening;

flattening the surface of the circuit board substrate to form a flattened circuit board surface;

electroplating a second plating layer on the surface of the planarized circuit board; and

forming a photosensitive film on the second plating layer;

the manufacturing method further comprises:

patterning the photosensitive film to form a plurality of grooves, wherein the grooves comprise a plurality of gaps between the periphery of the copper block and the circuit board substrate;

the first electroplated layer covers the surface of the circuit board substrate including the opening, and the second electroplated layer covers the first electroplated layer and the copper block;

electroplating the third electroplated layer to fill in the grooves of the circuit board substrate.

2. The method of claim 1, wherein the first, second, and third electroplated layers are electroplated copper layers.

3. The manufacturing method according to claim 1, further comprising:

after pressing the copper block, the first plating layer and the copper block are electrically connected.

4. A printed circuit board, comprising:

a circuit board substrate having an opening;

a first plating layer formed on the circuit board base material;

a copper block disposed in the opening;

a second plating layer formed on the first plating layer; and

a patterned photosensitive film formed on the second plating layer;

the circuit board substrate also comprises a plurality of grooves, and the patterned photosensitive film forms the grooves, wherein the grooves comprise a plurality of gaps between the periphery of the copper block and the circuit board substrate;

a third electroplated layer filled in the grooves of the circuit board base material;

the first electroplated layer covers the surface of the circuit board substrate including the opening, and the second electroplated layer covers the first electroplated layer and the copper block.

5. The printed circuit board of claim 4, wherein the first, second, and third plated layers are copper plated layers.

6. The printed circuit board of claim 4, wherein the first plated layer electrically connects the copper block.