TWI399147B - Circuit board manufacturing method - Google Patents

Description

Circuit board manufacturing method

The present invention relates to a method of fabricating a circuit board, and more particularly to a method of fabricating a circuit board incorporating high/low wiring density.

The market demand for consumer electronic products is large. In addition to the demand for powerful functions, consumers are also required to be light, thin, short, and small. Therefore, the lines of electronic products on the market are becoming more and more fine, and the printed circuit boards for mounting electronic components are also To the multi-layer development, from two or four layers to six, eight, or even ten or more, so that electronic components can be more densely mounted on the printed circuit board, reducing the area of the printed circuit board, making the electronics The product is smaller in size.

However, as the number of layers of printed wiring boards increases, the manufacturing steps become extremely complicated, making the manufacturing time very long. In order to make a wiring with a high wiring density, the number of layers of the printed wiring board often exceeds four layers, but when manufacturing a four-layer printed wiring board, it is time required to press the film, the copper foil and the inner wiring board together. It takes about a few hours, and if you add subsequent processing steps, it will take about five hours. If the printed circuit board to be produced is a multi-layered board of four or more layers, such as a six-layer, eight-layer, and ten-layer printed wiring board, the time required for pressing will be longer, and thus the manufacturing cost is too high.

In contrast, a printed wiring board having a low wiring density has a small number of layers and few manufacturing steps, and can be completed in a short period of time, so that the output is high and the cost is low, so that the industry is eager to manufacture in fewer steps. High wiring density printed circuit boards. It is worth noting that in a local high wiring density circuit board, the area of high wiring density only occupies a part of the entire circuit board, and the remaining area is a general layout (low wiring density) line, but due to lack of innovation in the process, Knowing the production method still takes a long time, so the manufacturing cost is not reduced, and it is not economical.

The present invention provides a method of fabricating a circuit board for fabricating a circuit board having a high local wiring density, which simplifies steps and reduces manufacturing costs.

The invention provides a method for manufacturing a circuit board, comprising the following steps. First, a line mother board is cut to separate the line mother board into a plurality of line daughter boards. Next, a line daughter board is disposed in the opening of the inner circuit board, the inner circuit board has a first circuit layer, a second circuit layer, and a core layer between the first and second circuit layers, wherein the circuit board The wiring density is greater than the wiring density of the inner circuit board. Thereafter, an insulating film and a metal foil are respectively disposed on opposite sides of the circuit board and the inner circuit board, and a thermal pressing step is performed to make the metal foil, the insulating film and the circuit board on opposite sides And the inner circuit board is integrated into one.

In an embodiment of the invention, after the step of performing the thermal compression bonding, the method further includes forming a through hole to penetrate the metal foil, the insulating film, and the inner circuit board on opposite sides.

In an embodiment of the invention, after the step of performing the thermal compression bonding, the method further includes forming a plurality of blind holes to respectively expose the first and second circuit layers on the inner layer circuit board. In an embodiment of the invention, the blind hole further exposes a pad located on at least one side of the line daughter board.

In an embodiment of the invention, after the completion of the through hole and the blind hole, the method further includes performing a plating process to electrically connect at least one of the metal foil, the circuit sub-board and the inner circuit board on opposite sides. two.

In an embodiment of the invention, after the step of performing the thermal compression bonding, the method further includes patterning the metal foils on opposite sides to form a two-patterned wiring layer.

In an embodiment of the invention, before the step of performing the thermal compression bonding, further comprising forming a release film on at least one side of the wiring sub-board to isolate the insulating film also located on at least one side of the wiring sub-board.

In an embodiment of the invention, after forming the release film, cutting at least one predetermined opening area by a laser and removing a portion of the insulating film covering a portion of the predetermined opening area and a portion of the metal foil to reveal the Type film. Thereafter, the release film is removed to reveal the line daughter board in at least one of the open areas.

In an embodiment of the invention, the line daughter board has four or more circuit layers.

In an embodiment of the invention, the number of layers of the circuit sub-board is greater than the number of layers of the inner circuit board.

In an embodiment of the invention, the circuit board is embedded in the core layer, and the opposite sides of the insulating film are wrapped around the circuit board.

In an embodiment of the invention, the thickness of the line daughter board is less than or equal to the thickness of the inner layer circuit board.

Based on the above, the circuit board of the present invention integrates the pre-finished high wiring density wiring sub-board into the inner layout board of the general layout (low wiring density), and is integrated with the two insulating film and the two patterned circuit layers. To simplify the steps and reduce manufacturing costs. Therefore, the time required for the circuit board to be pressed at one time does not take a long time, and the manufacturing cost of the conventional multilayer circuit board is drastically reduced.

The above described features and advantages of the present invention will be more apparent from the following description.

1A to 1E are respectively a flow chart showing a method of fabricating a circuit board according to an embodiment of the present invention. Referring to the wiring sub-board 100 having a high wiring density in FIG. 1A, it is formed by cutting a wiring mother board 10. After the line mother board 10 is separated into a plurality of line daughter boards 100, each of the line daughter boards 100 has a high wiring density line including four or more layers of the circuit layer 102, such as six, eight or ten layers. In this embodiment, the plurality of circuit layers 102 and the insulating layer 104 are sequentially stacked on the core substrate 106, and the lines of the circuit layer 102 are electrically connected by the blind vias V and the plated vias P to form a plurality of layers. The line daughter board 100 of the same layout is on a line mother board 10. The circuit board 100 has a plurality of pads B on opposite sides thereof, and is densely arranged on the circuit board 100 so that the circuit board 100 can be electrically connected to high-order processing electronic components (not shown), such as a central processing unit. Or display a wafer or the like.

Next, referring to the steps of FIG. 1B and FIG. 1C, the line daughter board 100 that has completed the high wiring density is disposed in the opening C of the inner wiring board 200. The opening C of the inner wiring board 200 is, for example, laser cut into a predetermined shape and size for accommodating the smaller size wiring sub-board 200. In the present embodiment, the inner layer circuit board 200 has a first circuit layer 202, a second circuit layer 204, and a core layer 206 between the first and second circuit layers 202, 204, but as can be seen from FIG. 1B, the circuit The wiring density of the sub-board 100 is greater than the wiring density of the inner wiring board 200, and the number of layers (four or more layers) of the wiring sub-board 100 is also higher than the number of layers of the inner wiring board 200 (two or more layers or more). ).

The thickness of the wiring sub-board 100 can be substantially less than or equal to the thickness of the inner wiring board 200, depending on the design requirements. When the circuit board 100 is buried in the core layer 206, an insulating film 212 and a metal foil 214 are respectively disposed on opposite sides of the circuit board 100 and the inner circuit board 200, and a thermal pressing step is performed to The two metal foils 214 on the upper and lower sides are fixed to the circuit board 100 and the inner circuit board 200 by the two insulating films 212, and are integrated.

Then, referring to the steps of FIG. 1D and FIG. 1E, after the thermal pressing step is completed, a perforating process and a plating process are further performed to respectively form a conductive material in a through hole P1 and a plurality of blind holes V1. The perforation process is, for example, a laser hole burning process or a mechanical drilling process. The through hole P1 can penetrate the two metal foil pieces 214, the two insulating film 212, and the inner layer circuit board 200 on opposite sides. The plurality of blind holes V1 respectively expose the first circuit layer 202 and the second circuit layer 204 on the inner circuit board 200, and expose the pads B on opposite sides of the circuit sub-board 100. In addition, the plating process is, for example, plating a conductive material in the through hole P1 to electrically connect the two metal foils 214 on the opposite sides to the inner circuit board 200, and plating the conductive material in the blind hole V1 to be electrically connected. Two metal foils 214 on opposite sides to the circuit board 100 and the inner circuit board 200.

In detail, there are two ways to form the through holes P and P1, (1) forming a solid conductive column, and (2) forming a hollow conductive column, and the cavity of the hollow conductive column may be filled with a filling material, wherein the filling material is filled. It may be classified into (a) a conductor material, for example, including a metal paste or a conductive polymer; (b) an insulating material such as a resin material, a ceramic material or a resin material having a ceramic material particle distribution; and (c) a heat conductive material such as A resin material having a metal particle, a metal compound particle or a ceramic material particle distribution.

The manner of forming the conductive pillar generally comprises forming a electroless plating conductor layer on the surface of the via hole by a chemical deposition method, and/or forming an electroplated conductor layer by electroplating on the conductor layer.

The manner of forming the conductive vias V and V1 generally includes: (1) forming an electroless plated conductor layer on the surface of the blind via by chemical deposition, and/or forming an electroplated conductor layer on the conductor layer to form an electroplated conductor layer. a blind hole having a hollow conductive column; (2) forming an electroless plated conductor layer directly from the surface of the blind hole by chemical deposition, and continuing deposition to form a blind hole having a solid conductive column.

The through hole formed in the blind hole V of the circuit sub-board 100 and/or the inner circuit board 200 is generally formed into a hollow conductive column in the technical field, and the hollow conductive pillar is filled with a resin material, has metal particles or A resin material in which the ceramic particles are distributed, or a metal paste such as a copper paste or a silver paste. Of course, it is also possible to directly perform the thermocompression in a hollow shape as required, and the glue containing the semi-cured film is filled in the blind hole or the through hole by a hot pressing process.

Thereafter, the two metal foils 214 on opposite sides are patterned to form a second patterned wiring layer 214a. Thus, the circuit board 220 of the present invention is substantially completed, and includes a circuit sub-board 100, an inner circuit board 200, two insulating films 212, and two patterned circuit layers 214a. The wiring sub-board 100 is buried in the inner wiring board 200, and the wiring density of the wiring sub-board 100 is larger than the wiring density of the inner wiring board 200 as an area of the wiring board 220 having a high wiring density. In addition, the second insulating film 212 is wrapped around the circuit sub-board 100 and is isolated between the two patterned circuit layers 214a and the first and second circuit layers 202, 204. In addition, the circuit board 100 and the inner circuit board 200 can be electrically connected to electronic components (not shown) through the patterned circuit layer 214a of the outer layer to transmit signals.

2A-2F are respectively a flow chart showing a method of fabricating a circuit board according to another embodiment of the present invention. Please refer to the circuit sub-board 100 having a high wiring density in FIG. 2A, which is obtained by cutting a line mother board 10. After the line mother board 10 is separated into a plurality of line daughter boards 100, each of the line daughter boards 100 has a high wiring density line including four or more layers, for example, six, eight or ten layers. For related descriptions, refer to the foregoing embodiments, and details are not described herein again.

Next, referring to the steps of FIG. 2B and FIG. 2C, the line daughter board 100 that has completed the high wiring density is disposed in the opening C of the inner wiring board 200. The wiring density of the wiring sub-board 100 is greater than the wiring density of the inner wiring board 200, and the number of layers (four or more layers) of the wiring sub-board 100 is also higher than the number of layers of the inner wiring board 200 (two or two layers) the above). Different from the above embodiment, before the thermocompression bonding step, a release film 210 may be formed on one side of the wiring sub-board 100 to isolate the insulating film 212 which is also located on one side of the wiring sub-board 100. The release film 210 can be removed from the line daughter board 100 after the subsequent completion of the punching process, the plating process, and the patterned circuit process to expose the circuit daughter board 100 in an open area, as shown in FIG. 2F. Show. For the perforation process, the plated process, and the patterned circuit process of FIG. 2D and FIG. 2E, please refer to the above embodiment, and details are not described herein again.

Referring to step 2E and FIG. 2F, the circuit board 220a has a predetermined opening area A corresponding to the position where the release film 210 is located. A portion of the outer layer line 214b may remain on the predetermined opening area A, but the portion of the outer layer line 214b may not be retained. The present invention can cut a predetermined opening area A by laser and remove a portion of the insulating film 212 covering a predetermined opening area and a portion of the metal foil 214 to expose the release film 210. Thereafter, the release film 210 is removed to expose the wiring sub-board 100 in an open area C1.

In another embodiment, although not shown in the drawings, it is conceivable that the circuit board has, for example, two predetermined opening areas corresponding to the positions of the two release films, wherein the two release films are located in the circuit. The opposite sides of the board. It is also possible to remove a portion of the insulating film on the opposite sides and a portion of the metal foil by the above description to reveal the two release film. Thereafter, the release film is removed to reveal the opposite sides of the line daughter board in the two open areas.

Thus, the circuit board 220a of the present invention is substantially completed, and includes a circuit sub-board 100, an inner circuit board 200, two insulating films 212, and two patterned circuit layers 214a. The wiring sub-board 100 is buried in the inner wiring board 200, and the wiring density of the wiring sub-board 100 is larger than the wiring density of the inner wiring board 200 as an area of the wiring board 220 having a high wiring density. In addition, the second insulating film 212 is wrapped around the circuit sub-board 100 and is isolated between the two patterned circuit layers 214a and the first and second circuit layers 202, 204. In addition, at least one side of the line daughter board 100 is correspondingly exposed in an opening area C1. The opening area C1 can accommodate one or more electronic components (not shown), and can be electrically connected to the pads B of the circuit sub-board 100 by conductive balls or conductive blocks (not shown) to transmit signals.

In summary, the circuit board of the present invention integrates a pre-finished high wiring density wiring sub-board into an inner layout circuit board of a general layout (low wiring density), and combines with two insulating film and two patterned circuit layers. Integrated to simplify steps and reduce manufacturing costs. Therefore, the circuit board only needs to press the time required for one press, does not take a long time, greatly reduces the manufacturing cost of the conventional multilayer circuit board, and is economical, and is an invention that can be utilized in the industry.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

10. . . Line motherboard

100. . . Line daughter board

102. . . Circuit layer

104. . . Insulation

106. . . Core substrate

200. . . Inner circuit board

202. . . First circuit layer

204. . . Second circuit layer

206. . . Core layer

210. . . Release film

212. . . Insulating film

214. . . Metal foil

214a. . . Patterned circuit layer

214b. . . Outer line

220, 220a. . . circuit board

A. . . Scheduled open area

B. . . Pad

C. . . Opening

C1. . . Open area

P, P1. . . Through hole

V, V1. . . Blind hole

1A to 1E are respectively a flow chart showing a method of fabricating a circuit board according to an embodiment of the present invention.

2A-2F are respectively a flow chart showing a method of fabricating a circuit board according to another embodiment of the present invention.

100. . . Line daughter board

200. . . Inner circuit board

202. . . First circuit layer

204. . . Second circuit layer

206. . . Core layer

212. . . Insulating film

214. . . Metal foil

B. . . Pad

C. . . Opening

Claims (10)

A method for manufacturing a circuit board, comprising: cutting a circuit mother board to separate the circuit mother board into a plurality of circuit sub-boards; and configuring a circuit sub-board in an opening of an inner circuit board, the inner circuit board having a first circuit layer, a second circuit layer, and a core layer between the first and second circuit layers, wherein a wiring density of the circuit sub-board is greater than a wiring density of the inner circuit board; and an insulating film is respectively disposed And a metal foil on opposite sides of the circuit sub-board and the inner circuit board, and performing a thermal pressing step to make the metal foil, the insulating film and the circuit sub-board on opposite sides and the same The inner circuit board is integrated; wherein before the hot pressing step, forming a release film on at least one side of the circuit sub-board to isolate the same side of the circuit sub-board An insulating film; after forming the release film, further comprising cutting at least one predetermined opening area by a laser and removing a portion of the insulating film covering the at least one predetermined opening area and a portion of the metal foil to The release film is exposed; and removing the release film, so as to reveal the sub-circuit board at least one opening region. The method for fabricating a circuit board according to claim 1, wherein after the step of performing the thermocompression bonding, further comprising forming a through hole to penetrate the metal foil, the insulating film, and the inner layer line on opposite sides board. The method for manufacturing a circuit board according to claim 1, wherein after the hot pressing step is completed, the method further includes forming a plurality of blind holes to respectively expose the first and second lines on the inner layer circuit board. Floor. The method for fabricating a circuit board according to claim 1, wherein the blind holes further expose a pad located on at least one side of the circuit sub-board. The method for manufacturing a circuit board according to claim 2, 3 or 4, further comprising performing a plating process to electrically connect the metal foil on the opposite sides, the circuit sub-board, and the inner layer circuit. At least two of the boards. The method for fabricating a circuit board according to claim 1, wherein after the hot pressing step is completed, the metal foil of the opposite sides is further patterned to form a two patterned circuit layer. The method for fabricating a circuit board according to claim 1, wherein the circuit sub-board has four or more wiring layers. The method for fabricating a circuit board according to claim 7, wherein the number of layers of the circuit sub-board is greater than the number of layers of the inner circuit board. The method for manufacturing a circuit board according to claim 1, wherein the circuit sub-board is buried in the core layer, and the insulating film on opposite sides is wrapped around the circuit sub-board. The method for fabricating a circuit board according to claim 1, wherein the thickness of the circuit sub-board is less than or equal to the thickness of the inner circuit board.