TWI407845B - Printed circuit board and method for manufacturing the same - Google Patents

Abstract

The present invention provides a printed circuit board. The printed circuit board includes a first insulation layer, a first circuit pattern, and a number of first heat sinks. The first circuit pattern is formed on a surface of the first insulation layer and includes a first signal line and a first ground line. The first signal line is configured for transmitting electrical signals. The first ground line is configured for dispersing heat produced by the first signal line. The first heat sinks are arranged in sequence and are in contact with a surface of the first ground line. The present invention also provides a method for manufacturing the printed circuit board.

Description

Circuit board and manufacturing method thereof

The present invention relates to the field of circuit board manufacturing, and in particular to a circuit board capable of rapidly dissipating heat and a manufacturing method thereof.

With the advancement of science and technology, printed circuit boards have been widely used due to their high assembly density. For application of the circuit board, please refer to the literature Takahashi, A. Ooki, N. Nagai, A. Akahoshi, H. Mukoh, A. Wajima, M. Res. Lab, High density multilayer printed circuit board for HITAC M-880, IEEE Trans On Components, Packaging, and Manufacturing Technologv, 1992, 15(4): 418-425.

During the use of the circuit board, the signal line in the circuit board causes the temperature of the entire circuit board to rise due to the current flowing. The signal line in the board will increase the resistance of the resistor due to the temperature rise, which affects the normal performance of the board. As the temperature of the circuit board rises, the metal alloy structure of the solder joint between the electronic component packaged on the circuit board and the circuit board changes, so that the metal alloy of the solder joint becomes brittle and the mechanical strength is lowered. The temperature rise of the board will also affect the electronic components of the package on the board, such as the life of the capacitor. The life is short. Therefore, during the use of the board, the board needs to be dissipated.

In the prior art, the heat dissipation of the circuit board is usually set in the outer layer of the circuit board, and the ground wire usually has a large copper surface to achieve the heat dissipation effect. However, as the area occupied by the structure of the board product is reduced, the ground line for setting a larger copper surface is limited.

In view of this, it is necessary to provide a circuit board having a good heat dissipation effect and a method of fabricating the same.

A circuit board and a method of fabricating the same will be described below by way of embodiments.

A circuit board includes a first insulating layer, a first line pattern, and a plurality of first heat sink fins. The first line pattern is formed on a surface of the first insulating layer and includes a first signal line and a first ground line. The first signal line is used to conduct an electrical signal, and the first ground line is used to dissipate heat generated by the first signal line. The plurality of first heat dissipation fins are sequentially arranged, and are directly formed on the surface of the first ground line.

A circuit board manufacturing method includes the steps of: providing a copper clad laminate, the copper clad laminate comprising a first insulating layer and a first copper foil layer; forming a first copper foil layer to form a first circuit pattern, the first circuit pattern comprising the first a signal line and a first ground line, wherein the first signal line is used for transmitting the electrical signal, and the first ground line is used for dissipating heat generated by the first signal line; and the plurality of lines are directly formed on the surface of the first ground line The first heat sink fin.

Compared with the prior art, the circuit board provided by the technical solution is set on the ground line. The heat sink fins can significantly increase the heat dissipation area of the ground wire. The heat dissipation fins are directly formed on the ground line, and the formed heat dissipation fins are integrated with the corresponding ground lines, and no additional connection components are needed, thereby reducing the volume of the circuit board and improving the heat dissipation efficiency. The circuit board manufacturing method provided by the technical solution can directly form a heat dissipation fin on the ground line when the circuit board is manufactured, thereby increasing the heat dissipation area of the ground line.

10‧‧‧CCL

12‧‧‧First copper foil layer

13‧‧‧Second copper foil layer

20‧‧‧through hole

30‧‧‧First photoresist layer

40‧‧‧Second photoresist layer

100, 200‧‧‧ circuit board

110, 210‧‧‧ first insulation

111, 211‧‧‧ first surface

112, 212‧‧‧ second surface

120, 220‧‧‧ first line graphics

121, 221‧‧‧ first signal line

122, 222‧‧‧ first ground

123‧‧‧ edge joint

140, 240‧‧‧ first heat sink fins

201‧‧‧Heat conduction hole

202‧‧‧heat conduction layer

230‧‧‧second line graphics

231‧‧‧Second ground

250‧‧‧Second heat sink fins

1 is a schematic plan view of a circuit board provided by a first embodiment of the present technical solution.

Figure 2 is a cross-sectional view taken along line II-II of Figure 1.

3 is a top plan view of a circuit board provided by a second embodiment of the present technical solution.

4 is a bottom plan view of a circuit board provided by a second embodiment of the present technical solution.

Figure 5 is a cross-sectional view taken along line V-V of Figure 1;

6 is a schematic cross-sectional view of a copper clad laminate provided by a third embodiment of the present technical solution.

FIG. 7 is a schematic view showing a through hole formed in a copper clad laminate provided by a third embodiment of the present technical solution.

FIG. 8 is a schematic view showing a heat conduction layer formed in a through hole provided in a third embodiment of the present technical solution.

FIG. 9 is a schematic diagram of the first circuit pattern and the second line pattern formed by the third embodiment of the present technical solution.

FIG. 10 is a schematic view showing the formation of a first photoresist layer and a second photoresist layer according to a third embodiment of the present technical solution.

FIG. 11 is a schematic view showing the first photoresist layer and the second photoresist layer provided by the third embodiment of the present invention after exposure and development.

FIG. 12 is a schematic diagram of the first heat dissipation fin and the second heat dissipation fin provided by the third embodiment of the present technical solution.

The circuit board and the circuit board manufacturing method provided by the technical solution are further described below in conjunction with the multiple figures and the multiple embodiments.

Referring to FIG. 1 and FIG. 2 , the first embodiment of the present invention provides a circuit board 100 . The circuit board 100 includes a first insulating layer 110 , a first circuit pattern 120 , and a plurality of first heat dissipation fins 140 arranged in sequence.

The first insulating layer 110 is used to carry the first line pattern 120. The first insulating layer 110 may be made of a material such as polyimide or polyester. The first insulating layer 110 has a first surface 111 and a second surface 112 opposite to each other.

The first line pattern 120 is formed on the first surface 111. The first line pattern 120 includes a plurality of first signal lines 121, a plurality of first ground lines 122, and a plurality of side joints 123. The material of the first line pattern 120 may be copper, aluminum or silver. In this embodiment, the first line pattern 120 is made of copper. The first signal line 121 is used to transmit signals to implement the functions of the circuit board 100. The first ground line 122 is used to shield electromagnetic interference between the first signal lines 121 and dissipate heat. In this embodiment, the first line pattern 120 has a plurality of first signal lines 121 and a first ground line 122. The first ground line 122 extends in the same direction as the first signal line 121 but does not communicate with the first signal line 121. The size of the area occupied by the first ground line 122 can be The area of the circuit board 100 is determined, and the surface of the first insulating layer 110 except the area of the first signal line 121 may form the first ground line 122. The shape of the first ground line 122 is also determined according to the shape of the circuit board 100 and the shape of the first signal line 121. The first ground line 122 can also be formed in a plurality, which can be formed on one side of the first signal line 121 according to the needs of the circuit board 100, and can also be formed between the plurality of first signal lines 121.

The edge connector 123 forms an edge of the first surface 111, and each of the side connectors 123 is connected to a first signal line 121 for interconnecting the first signal line 121 and the external components to achieve electrical communication.

The plurality of first heat dissipation fins 140 are sequentially arranged on the first ground line 122. The first heat dissipation fin 140 is made of the same material as the first ground wire 122. In this embodiment, the first heat dissipation fins 140 are also made of copper. The plurality of first heat dissipation fins 140 are distributed over the entire surface of the first ground line 122. In this embodiment, each of the first heat dissipation fins 140 has an elongated strip shape, and the plurality of first heat dissipation fins 140 are disposed in parallel with each other. The height of the first heat dissipation fins 140, that is, the first heat dissipation fins 140 protrude from the surface of the first ground line 122 by 30 to 50 micrometers. The distance between the adjacent first heat dissipation fins 140 can be set according to the heat generated by the circuit board in practical applications. The extending direction of the plurality of first heat dissipating fins 140 may be parallel to the extending direction of the first ground line 122, or may be perpendicular to the extending direction of the first ground line 122, or may be set to other angles.

The circuit board 100 further includes a cover layer formed on the first insulating layer 110. The cover layer covers the first signal line 121 to protect the first signal line 121. The first ground line 122 is not covered by the cover layer. Ground line 122 is exposed to the outside. Cover layer It is made of a polyimide film which is common in the art. The circuit board 100 provided in this embodiment may also be a multi-layer circuit board. The second surface 112 of the first insulating layer 110 is formed with a circuit substrate including one layer or a plurality of conductive line structures.

To facilitate heat dissipation, a copper foil may be pressed onto the second surface 112 of the first insulating layer 110 as a heat dissipation layer, and the heat dissipation layer is also used to dissipate heat generated by the first signal line.

The heat generated by the first signal line 121 of the circuit board 100 is transmitted to the first ground line 122 during use, and the first heat dissipation fin 140 on the first ground line 122 is made of a material having good heat conduction performance and has a larger The surface area, the first heat dissipation fins 140 conduct heat to the outside, thereby lowering the temperature of the circuit board 100.

The circuit board 100 provided in this embodiment is provided with a plurality of first heat dissipation fins 140 on the first ground line 122, thereby expanding the area of heat exchange between the circuit board 100 and the outside, and increasing the heat dissipation efficiency of the circuit board 100.

Referring to FIG. 3 to FIG. 5 together, the second embodiment of the present invention provides a circuit board 200. The circuit board 200 includes a first insulating layer 210, a first line pattern 220, a second line pattern 230, and a plurality of sequentially arranged. A heat dissipation fin 240 and a plurality of second heat dissipation fins 250 arranged in sequence.

The first insulating layer 210 is configured to carry the first line pattern 220 and the second line pattern 230. The first insulating layer 210 has a first surface 211 and a second surface 212 opposite to each other.

The first line pattern 220 is formed on the first surface 211 of the first insulating layer 210. The first line pattern 220 includes a plurality of first signal lines 221 and a plurality of first ground lines 222. In this embodiment, the plurality of first signal lines 221 and the plurality of first ground lines 222 are spaced apart from each other. Of course, the manner in which the first signal line 221 and the first ground line 222 are distributed is not limited to the form provided in this embodiment. The plurality of first ground lines 222 are disposed around the plurality of first signal lines 221, or the plurality of first ground lines 222 are disposed on opposite sides of the plurality of first signal lines 221.

The second line pattern 230 is formed on the second surface 212 of the first insulating layer 210. In this embodiment, the second line pattern 230 includes only the second ground line 231, and the second ground line 231 is a copper layer covering the second surface 212. A plurality of heat conduction holes 201 penetrating through the first insulation layer 210 are formed from the first ground line 222 to the second ground line 231. The inner wall of the plurality of heat conduction holes 201 has a heat conduction layer 202 for conducting heat from the first ground line 222 to Second ground line 231. In this embodiment, a plurality of heat conduction holes 201 are respectively disposed in each of the first ground wires 222, so that the heat of the first ground wires 222 can be quickly transmitted to the second ground wires 231.

The second line pattern 230 can also include a second signal line. The first ground line 222 and the second ground line 231 may correspond to each other in the region where the heat conduction hole 201 is formed.

The plurality of first heat dissipation fins 240 arranged in sequence are formed on the first ground line 222 and form a unitary structure with the corresponding first ground line 222. The first heat dissipation fin 240 is configured to conduct heat generated by the first signal line 221 to the outside. In this embodiment, the first heat dissipation fins 240 extend along the length direction of the first ground line 222, and the number of the first heat dissipation fins 240 disposed on each of the first ground lines 222 may be based on the actual first ground line 222. The width is set.

The second heat dissipating fins 250 arranged in sequence are formed on the surface of the second ground line 231 and form an integral structure with the second ground line 231. In this embodiment, the plurality of second heat dissipation fins 250 are disposed on the second ground line 231 in parallel with each other. The second heat sink fin 250 protrudes from the second ground line 231 by a height of 30 to 50 microns. The number and shape of the second heat dissipation fins 250 can be set according to the requirements of the actual circuit board. The heat generated by the first signal line 221 is conducted to the second ground line 231 by the first ground line 222 and the heat conduction hole 201, and the second ground line 231 and the second heat dissipation fin 250 formed on the second ground line 231 dissipate heat. To the outside world, since the second heat dissipation fins 250 have a large heat dissipation area, the heat dissipation rate is increased.

When the second heat dissipation fins 250 can meet the heat dissipation requirements, or the first ground wire 222 has a small width and is not suitable for forming the first heat dissipation fins 240, the first heat dissipation fins 240 may not be disposed on the first ground wire 222.

The circuit board 200 can also be a multi-layer circuit board including a plurality of line patterns and a plurality of insulating layers spaced apart from each other between the first line pattern 220 and the second line pattern 230. In this way, the heat generated inside the circuit board is transferred to the first heat dissipation fin 240 and the second heat dissipation fin 250 through the heat conduction hole 201 to dissipate heat, so that the heat generated by the circuit board is quickly dissipated.

The circuit board provided by the technical solution provides heat dissipation fins on the ground line, which can significantly increase the heat dissipation area of the ground line. The heat dissipation fins are directly formed on the ground line, and the formed heat dissipation fins are integrated with the corresponding ground lines, and no additional connection components are needed, thereby reducing the volume of the circuit board and improving the heat dissipation efficiency.

The circuit board 200 provided in the second embodiment of the present invention is taken as an example to describe a method for fabricating a circuit board. The method for manufacturing the circuit board includes the following steps: Referring to FIG. 6, the first step is to provide a copper clad board. 10.

In this embodiment, the copper clad laminate 10 is a double-sided copper clad laminate, that is, the first copper foil layer 12, the second copper foil layer 13, and the first between the first copper foil layer 12 and the second copper foil layer 13. Insulation layer 110. The copper clad laminate 10 is a cut copper clad laminate 10 having a shape corresponding to the shape of the fabricated circuit board. When used to fabricate a circuit board having a single-sided wiring pattern, the copper clad laminate 10 is a single-sided copper clad laminate, that is, it includes a first copper foil layer 12 and a first insulating layer 110.

Referring to FIG. 7 and FIG. 8 together, in the second step, a heat conduction hole 201 is formed in the copper clad laminate 10.

First, a through hole 20 is formed in the copper clad laminate 10. The through holes 20 formed in the copper clad laminate 10 can be formed by mechanical drilling or laser drilling. The plurality of through holes 20 are formed in a manner corresponding to the subsequent formation of the first ground line and the second ground line, and the plurality of through holes 20 penetrate the first copper foil layer 12, the first insulating layer 110, and the second copper foil layer 13.

Then, a heat conducting layer 202 is formed on the inner wall of the through hole 20. The heat conducting layer 202 should have good thermal conductivity. The heat conductive layer 202 may be made of a metal having good thermal conductivity such as copper, aluminum or silver. In the present embodiment, the heat conducting layer 202 is obtained by forming a copper layer on the inner wall of the through hole 20 by electroplating, thereby obtaining the heat conducting hole 201 connecting the first copper foil layer 12 and the second copper foil layer 13.

When the copper clad laminate 10 is a single-sided copper clad laminate, the step of forming a heat conductive hole is not necessary.

Referring to FIG. 8 and FIG. 9 together, in the third step, the first copper foil layer 12 is formed into a first circuit pattern 220. The first circuit pattern 220 includes a first signal line 221 and a first ground line 222. The copper foil layer 13 is formed to obtain a second wiring pattern 230. The second wiring pattern 230 includes a second ground line 231, and the heat conduction hole 201 communicates with the first ground line 222 and the second ground line 231.

The first copper foil layer 12 is formed into a first wiring pattern 220 by an image transfer and etching process. The first line pattern 220 includes a plurality of first signal lines 221 and a plurality of first ground lines 222 such that the plurality of heat conduction holes 201 respectively correspond to the plurality of first ground lines 222, and each of the first ground lines 222 has a heat conduction hole 201.

In this embodiment, the second line pattern 230 does not have a second signal line, the second line pattern 230 includes only the second ground line 231, and the entire second copper foil layer 13 constitutes the second ground line 231. The first ground line 222 communicates with the second ground line 231 via the heat conduction hole 201.

When the second line pattern 230 has the second signal line, in the area having the heat conduction hole 201, the first ground line 222 and the second ground line correspond to each other, so that the first ground line 222 passes through the heat conduction hole 201 and the second ground line. Connected.

After the step, the cover layer covering the first signal line 221 may be formed to protect the first signal line 221. When the second line pattern 230 includes the second signal line, a cover layer may be formed on the surface of the second signal line.

Please refer to FIG. 10 to FIG. 12 together. The fourth step is performed by electroplating on the first ground line 222. The first heat dissipation fins 240 are formed on the surface, and the second heat dissipation fins 250 are formed on the surface of the second ground line 231.

First, a first photoresist layer 30 complementary to the shape of the first heat dissipation fin 240 to be formed is formed on the first line pattern 220 by an image transfer process, and is formed on the second ground line 231. The second heat dissipation fins 250 are complementary in shape to the second photoresist layer 40. Specifically, a first photoresist layer 30 is formed on the surface of the first line pattern 220, and a second photoresist layer 40 covering the entire second ground line 231 is formed on the surface of the second line pattern 230. The first photoresist layer 30 and the second photoresist layer 40 may be formed by printing a liquid photosensitive material, or may be formed by pressing a dry film. The thickness of the first photoresist layer 30 corresponds to the height of the first heat dissipation fins 240 to be formed, and the thickness of the second photoresist layer 40 corresponds to the height of the second heat dissipation fins 250. The first photoresist layer 30 and the second photoresist layer 40 are exposed and developed, respectively, and the first photoresist layer 30 corresponding to the first heat dissipation fin 240 to be formed is removed. The surface of the portion of the first ground line 222 is exposed, and the second photoresist layer 40 corresponding to the second heat sink fin 250 to be formed is removed such that the surface of the portion of the second ground line 231 is exposed.

Then, the surface of the first ground line 222 is exposed from the first photoresist layer 30 to be plated to obtain the first heat dissipation fin 240 to expose a portion of the second ground line from the second photoresist layer 40. The surface of 231 is plated to obtain second heat sink fins 250. In this embodiment, the first heat dissipation fins 240 and the second heat dissipation fins 250 are formed by electroplating copper.

In this embodiment, the first photoresist layer 30 and the second photoresist are formed. The thickness of the layer 40 is 30 to 50 micrometers, and the height of the first heat dissipation fin 240 and the second heat dissipation fin 250 is also 30 to 50 micrometers.

Finally, the remaining first photoresist layer 30 and second photoresist layer 40 are removed to obtain a circuit board.

When manufacturing a circuit board having only the first line pattern, it is only necessary to form heat dissipation fins on the surface of the first ground line.

The circuit board manufacturing method provided by the technical solution can directly form a heat dissipation fin on the ground line when the circuit board is manufactured, thereby increasing the heat dissipation area of the ground wire.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

100‧‧‧ boards

110‧‧‧First insulation

111‧‧‧ first surface

112‧‧‧ second surface

121‧‧‧First signal line

122‧‧‧First ground

140‧‧‧First heat sink fin

Claims (9)

A circuit board comprising: a first insulating layer, the first insulating layer having opposite first and second surfaces; a first line pattern formed on the first surface of the first insulating layer, the first line The graphic includes a first signal line for transmitting a telecommunication signal, the first ground line for transmitting heat generated by the first signal line, and a plurality of first heat dissipating fins arranged in sequence The plurality of first heat dissipation fins are directly formed on the first ground surface; and the second circuit pattern formed on the second surface of the first insulation layer, the second line pattern includes a second ground line, The surface of the second ground line is directly formed with a plurality of second heat dissipating fins arranged in sequence. The circuit board of claim 1, wherein the plurality of first heat dissipation fins and the first circuit pattern are made of the same material. The circuit board of claim 2, wherein the material of the plurality of first heat dissipation fins and the first circuit pattern is copper. The circuit board of claim 1, wherein the circuit board is formed with a heat conduction hole penetrating through the first ground line, the first insulation layer and the second ground line, and the heat conduction hole is used in the first Heat is transferred between the ground wire and the second ground wire. A circuit board comprising: a first insulating layer, the first insulating layer having opposite first and second surfaces; a first line pattern formed on the first surface of the first insulating layer, the first line pattern includes a first signal line and a first ground line, and the first signal line is used to transmit an electrical signal, the first ground The wire is used for dissipating the heat generated by the first signal line; and the plurality of first heat dissipation fins are sequentially arranged, the plurality of first heat dissipation fins are directly formed on the first ground surface: and are pressed into the first insulation a heat dissipation layer of the second surface of the layer, the material of the heat dissipation layer being the same as the material of the first circuit pattern. A circuit board manufacturing method comprising the steps of: providing a copper clad laminate, the copper clad laminate comprising a first insulating layer and a first copper foil layer and a second copper foil layer; forming a first copper foil layer to form a first line pattern, The first line pattern includes a first signal line for transmitting an electrical signal, and the first ground line is for distributing heat generated by the first signal line, and the second copper foil layer is Forming a second line pattern, the second line pattern includes a second ground line; forming a plurality of first heat dissipating fins sequentially arranged by electroplating on a surface of the first ground line, and directly forming a plurality of heat dissipation fins on the surface of the second ground line The second heat sink fins are arranged in sequence. The method for fabricating a circuit board according to claim 6, wherein the forming the plurality of first heat dissipating fins arranged in sequence comprises the steps of: forming a photoresist layer on a surface of the first ground; patterning The photoresist layer to expose the photoresist layer to at least a portion of the first ground; the copper clad plate is placed in the plating bath to expose at least a portion of the first ground The wire surface is plated to form the plurality of first heat sink fins; the remaining photoresist layer is removed. The method for fabricating a circuit board according to claim 6, wherein the forming the first circuit pattern further comprises forming a heat conduction through the first copper foil layer, the first insulating layer and the first copper foil layer in the copper clad laminate. a step of the hole connecting the first ground line and the second ground line. The method for fabricating a circuit board according to claim 8, wherein the forming of the heat conduction hole comprises the steps of: forming a plurality of through the first copper foil layer, the first insulating layer and the second copper foil layer in the copper clad laminate a through hole; a heat conducting layer is formed on the inner wall of the through hole by electroplating.