TWI837050B - Manufacturing method of circuit board - Google Patents

Abstract

The present invention provides a manufacturing method of a circuit board, which includes: providing a multi-layer board that includes an insulating layer, a first copper layer formed on one side of the insulating layer, and a second copper layer formed on another side of the insulating layer; forming an oxide layer on the first copper layer; using a carbon dioxide laser to form a blind hole in the multi-layer board recessed from the oxide layer to a portion of the second copper layer that has a copper bud and a carbide covered by the copper bud; using an UV laser to form a trim slot recessed on the portion of the second copper layer for removing the copper bud and the carbide and enabling a bottom of the trim slot to have an average roughness (Ra) that is less than 3μm.

Description

Method for manufacturing circuit board

The present invention relates to a manufacturing method, and in particular to a manufacturing method for a circuit board.

The flatness of the bottom wall of the blind hole formed by the existing blind hole forming method of the circuit board has gradually been unable to meet the increasing circuit board design requirements year by year. Therefore, the inventor believed that the above-mentioned defects could be improved, so he devoted himself to research and applied scientific principles, and finally proposed an invention that is reasonably designed and effectively improves the above-mentioned defects.

An embodiment of the present invention provides a method for manufacturing a circuit board, which can effectively improve the defects that may occur in the blind hole forming method of the existing circuit board.

The present invention discloses a method for manufacturing a circuit board, which includes: a pre-step: providing a multi-layer plate, which includes an insulating layer, a first copper layer formed on one side of the insulating layer, and a second copper layer formed on the other side of the insulating layer; wherein the thickness of the first copper layer is less than 15 microns; a blackening step: forming a blackening layer on the first copper layer; a blind hole forming step: using carbon dioxide laser to form a concave hole from the blackening layer until the second copper layer is exposed; A blind hole is formed; wherein a rough surface of the second copper layer is exposed in the blind hole and has at least one copper tooth and a carbide or resin coated in at least one of the copper teeth; and a flattening step; a trimming groove is formed in the rough surface of the second copper layer by ultraviolet laser irradiation to remove at least one of the copper teeth and the carbide or resin coated in at least one of the copper teeth, and the bottom of the trimming groove has a center line average roughness of less than 3 microns.

In summary, the circuit board manufacturing method disclosed in the embodiment of the present invention can form the trimming groove with the ultraviolet laser through the planarization step, thereby improving the blindness formed by the carbon dioxide laser. Defects derived from holes effectively form holes with high flatness on the multi-layered plate to meet more stringent design requirements.

To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, such description and drawings are only used to illustrate the present invention and do not limit the protection scope of the present invention.

The following is a specific embodiment to illustrate the implementation of the "circuit board manufacturing method" disclosed in the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depictions based on actual dimensions, as is stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of the present invention.

It should be understood that although terms such as “first”, “second” and “third” may be used herein to describe various elements or signals, these elements or signals should not be limited by these terms. These terms are primarily used to distinguish one component from another component or one signal from another signal. In addition, the term "or" used in this article shall include any one or combination of multiple associated listed items, depending on the actual situation.

Please refer to FIG. 1 to FIG. 10 , which is an embodiment of the present invention. As shown in Figure 1, this embodiment discloses a circuit board manufacturing method S100, which sequentially includes a pre-step S110, a blackening step S120, a blind hole forming step S130, a planarization step S140, and a black removal step. forming step S150, a glue removal step S160, and a forming step S170. The specific implementation of the above steps S110 to S170 will be described below.

However, it should be noted that the execution sequence or implementation manner of the above-mentioned steps S110 to S170 can be adjusted according to design requirements (such as: the blackening step S150, the glue removal step S160, and the forming step S170 (at least one of them is omitted or replaced by other steps), so the content of this embodiment is not limited.

The pre-step S110: As shown in FIG. 1 to FIG. 4 , a multi-layer plate 1 is provided, which is a structure after being pressed according to design requirements. The multi-layer plate 1 shown in FIG. 2 and FIG. 3 includes three insulating layers 13, two first copper layers 11 formed on the two outermost insulating layers 13, and a second copper layer 12 is provided between any two adjacent insulating layers 13; however, for the convenience of explanation, only a local area of the multi-layer plate 1 is used for explanation below, so as to facilitate a clear understanding of the circuit board manufacturing method S100 of this embodiment.

From another perspective, as shown in FIG4 , the multi-layer plate 1 provided in the pre-step S110 in this embodiment includes an insulating layer 13, a first copper layer 11 formed on one side of the insulating layer 13 (e.g., the upper side in FIG4 ), and a second copper layer 12 formed on the other side of the insulating layer 13. The thickness of the first copper layer 11 is preferably less than 15 micrometers (μm).

The blackening step S120: As shown in FIG5 , a blackening layer 14 is formed on (the outer surface 111 of) the first copper layer 11. In this embodiment, the blackening layer 14 may be a copper oxide layer and preferably covers the entire outer surface 111 of the first copper layer 11, so as to facilitate the implementation of subsequent steps.

The blind hole forming step S130: As shown in FIG6 , a blind hole 15 is formed by processing the blackened layer 14 with carbon dioxide laser until the second copper layer 12 is exposed. A rough surface 121 of the second copper layer 12 is exposed in the blind hole 15 and has at least one copper thread C and impurities P (such as carbide or resin) coated in at least one copper thread C.

In the blind hole forming step S130 of this embodiment, the wavelength of the laser beam used by the carbon dioxide laser is preferably 10.6 microns, and the rough surface 121 of the second copper layer 12 has, for example, a medium. A centerline average roughness (Ra) of 3 microns to 5 microns. That is to say, the blind hole 15 formed by the carbon dioxide laser often has residue R (such as residual glue and carbide) attached to the hole wall 151 , so that the rough surface 121 is formed with the Center line average roughness, but the present invention is not limited to the above.

More specifically, in the blind hole forming step S130, the blind hole 15 formed by the carbon dioxide laser has a first hole diameter D1 formed on the first copper layer 11 and is located away from the A second aperture D2 smaller than the first aperture D1 is formed on the first copper layer 11 . In this embodiment, the second hole diameter D2 is approximately 75% to 85% of the first hole diameter D1, so that the hole wall 151 of the blind hole 15 is obliquely connected to the rough surface 121.

To put it another way, the problem to be solved by this embodiment comes from the blind hole 15 formed by the carbon dioxide laser, so the circuit board manufacturing method S100 (or the circuit board manufacturing method S100 disclosed in this embodiment) The blind hole forming step S130) explicitly excludes forming the blind hole 15 in other ways than the carbon dioxide laser.

The planarization step S140; as shown in FIG6 and FIG7, a trimming groove 16 is processed on the rough surface 121 of the second copper layer 12 by ultraviolet laser irradiation to remove at least one of the copper teeth C and the impurities P (such as the carbide or the resin) coated in at least one of the copper teeth C, and the groove bottom 162 of the trimming groove 16 has a centerline average roughness (Ra) of less than 3 microns.

In the planarization step S140 of the present embodiment, the wavelength of the laser beam used in the ultraviolet laser is 355 nanometers (nm), and the depth T16 of the trimming groove 16 formed by the ultraviolet laser is preferably between 3 micrometers and 5 micrometers. In other words, the blind hole 15 can be further formed with the ultraviolet laser to have the interconnected trimming grooves 16, which preferably correspond to the centerline average roughness of the rough surface 121, so as to provide better planarity through the trimming grooves 16 without any copper teeth.

In more detail, in the planarization step S140, the inner diameter D16 of the trimming groove 16 formed by the ultraviolet laser is substantially equal to the second hole diameter D2, so that the inner side wall 161 of the trimming groove 16 and the hole wall 151 of the blind hole 15 can be sandwiched by a configuration angle σ between 100 degrees and 170 degrees, thereby being able to meet more different design requirements by changing the configuration of the hole.

The de-blackening step S150: as shown in FIG. 7 and FIG. 8 , the blackening layer 14 on the first copper layer 11 is removed so that the entire outer surface 111 of the first copper layer 11 is exposed to the outside, so as to facilitate the implementation of subsequent steps.

The degumming step S160: As shown in FIG8 and FIG9, the hole wall 151 of the blind hole 15 is wet degummed with a potassium permanganate (KMnO4) solution to remove the residue R (such as the residue and the carbide) attached to the hole wall 151. It should be noted that in the degumming step S160 of this embodiment, it is preferred to further use plasma to perform dry degumming on the hole wall 151 of the blind hole 15 to remove the residue R (such as the residue and the carbide) attached to the hole wall 151, but the present invention is not limited thereto.

The forming step S170: As shown in FIG9 and FIG10, a conductor 2 is formed by electroplating in the trimming groove 16 and the blind hole 15, so that the conductor 2 connects the first copper layer 11 and the second copper layer 12. In this embodiment, the material of the conductor 2 is copper metal, and the top surface of the conductor 2 is coplanar with the outer surface 111 of the first copper layer 11, and the bottom surface of the conductor 2 forms a gap G between 3 microns and 5 microns with the adjacent surface of the second copper layer 12, but it is not limited thereto.

Furthermore, the multi-layer plate 1 improves the bonding strength between the conductor 2 and the multi-layer plate 1 through the configuration angle σ formed by the blind hole 15 and the trimming groove 16. The conductor 2 is equivalent to having one end 22 embedded in the trimming groove 16 to achieve bonding reinforcement through structural matching. Furthermore, the material of the end 22 of the conductor 2 is equivalent to the inner side wall 161 and the groove bottom 162 of the trimming groove 16, so that they can be integrally connected to each other and achieve bonding reinforcement through chemical bonding.

The above is the manufacturing method S100 of the circuit board disclosed in this embodiment, which can manufacture a circuit board 100 as shown in FIG10 by implementing the above steps S110-S170. Since the structure of the circuit board 100 disclosed in this embodiment is also different from the existing circuit board, the specific structure of the circuit board 100 in this embodiment is described below, and the technical features of the circuit board 100 can also refer to the technical content contained in the manufacturing method S100 of the circuit board.

As shown in FIG. 10 , the circuit board 100 includes a multi-layered plate 1 and a conductor 2 embedded in the multi-layered plate 1 . The number of conductors 2 is described as one in this embodiment. However, the circuit board 100 can also be provided with multiple conductors 2 at any position of the multi-layered plate 1 according to the design requirements. The conductor 2. Furthermore, for convenience of explanation, only a partial area of the multi-layered plate 1 will be described below to facilitate a clear understanding of the structure of the circuit board 100 of this embodiment.

The multi-layer plate 1 has an insulating layer 13, a first copper layer 11 formed on one side (e.g., the outer side) of the insulating layer 13, and a second copper layer 12 formed on the other side (e.g., the inner side) of the insulating layer 13. The thickness of the first copper layer 11 is less than that of the second copper layer 12 and is also less than 15 microns.

Furthermore, the multi-layered plate 1 is formed with a blind hole 15 and a trimming groove 16 connected to the blind hole 15 . The blind hole 15 is recessed from the first copper layer 11 until the second copper layer 12 is exposed, and the blind hole 15 is formed with a first hole diameter D1 in the first copper layer 11 , and a second aperture D2 smaller than the first aperture D1 is formed at a location away from the first copper layer 11 .

Furthermore, the trimming groove 16 is formed by recessing the portion of the second copper layer 12 exposed in the blind hole 15, and the groove bottom 162 of the trimming groove 16 has a centerline average roughness of less than 3 microns. The depth of the trimming groove 16 is preferably between 3 microns and 5 microns, so that no copper teeth are formed in the trimming groove 16.

From another perspective, the inner diameter D16 of the trimming groove 16 is equal to the second hole diameter D2, and the inner side wall 161 of the trimming groove 16 and the hole wall 151 of the blind hole 15 are sandwiched at a configuration angle σ between 100 degrees and 170 degrees, thereby forming a hole configuration different from the existing hole configuration.

The conductor 2 fills the trimming groove 16 and the blind hole 15 , and the conductor 2 connects the first copper layer 11 and the second copper layer 12 . That is to say, the conductor 2 has a truncated cone portion 21 located in the blind hole 15 and an end portion 22 integrally extending from the truncated cone portion 21 and located in the trimming groove 16 . In this embodiment, the conductor 2 is made of copper metal, and the top surface of the conductor 2 is coplanar with the outer surface 111 of the first copper layer 11 , and the bottom surface of the conductor 2 is coplanar with the outer surface 111 of the first copper layer 11 . A step G between 3 microns and 5 microns is formed on the adjacent surface of the second copper layer 12 .

It should be noted that in this embodiment, the circuit board 100 is described as having the blind hole 15 , the trimming groove 16 , and the conductor 2 formed on one surface of the circuit board 100 . However, the present invention Not limited to this. For example, in other embodiments not shown in the present invention, the number of the blind holes 15 , the trimming grooves 16 , and the conductors 2 can be multiple according to design requirements, and they can be distributed among all locations. Two boards of the circuit board 100 are described.

Furthermore, although the multi-layer plate 1 formed with the trimming groove 16 and the blind hole 15 is described in this embodiment as being formed with the conductor 2 filled therein, the invention is not limited thereto. For example, in other embodiments not shown in the invention, the multi-layer plate 1 formed with the trimming groove 16 and the blind hole 15 can also be used alone (e.g., sold) or used in combination with other components.

[Technical Effects of the Embodiments of the Invention]

In summary, the manufacturing method of the circuit board disclosed in the embodiment of the present invention can form the trimming groove by the ultraviolet laser in the flattening step, thereby improving the defects derived from the blind hole formed by the carbon dioxide laser, and further effectively forming holes with high flatness on the multi-layer plate to meet more stringent design requirements.

From another perspective, the circuit board and the multi-layer plate disclosed in the embodiment of the present invention further form the trimming groove connected to the blind hole in the second copper layer, so that the multi-layer plate can form holes with high flatness through a configuration different from the existing holes to meet more stringent design requirements.

The above disclosed contents are only preferred feasible embodiments of the present invention and are not intended to limit the patent scope of the present invention. Therefore, all equivalent technical changes made using the contents of the specification and drawings of the present invention are included in the patent scope of the present invention.

100: Circuit board 1: Multi-layer plate 11: First copper layer 111: Outer surface 12: Second copper layer 121: Rough surface 13: Insulation layer 14: Blackening layer 15: Blind hole 151: Hole wall 16: Trimming groove 161: Inner wall 162: Groove bottom 2: Conductor 21: Tapered part 22: End C: Copper teeth P: Impurities R: Residues D1: First aperture D2: Second aperture D16: Inner diameter T16: Depth σ: Configuration angle G: Discontinuity S100: Method for manufacturing circuit board S110: Preliminary step S120: Blackening step S130: Blind hole forming step S140: Flattening step S150: De-blackening step S160: Glue removal step S170: Forming step

FIG. 1 is a schematic diagram of the steps of a method for manufacturing a circuit board disclosed in an embodiment of the present invention.

FIG. 2 is a perspective view of the pre-steps in FIG. 1 .

FIG. 3 is a schematic cross-sectional view along section line III-III of FIG. 2 .

FIG. 4 is an enlarged schematic diagram of region IV of FIG. 3 .

Figure 5 is a schematic diagram of the blackening step in Figure 1.

FIG. 6 is a schematic diagram of the blind hole forming step of FIG. 1 .

FIG. 7 is a schematic diagram of the planarization step in FIG. 1 .

Figure 8 is a schematic diagram of the blackening step of Figure 1.

Figure 9 is a schematic diagram of the glue removal step in Figure 1.

Figure 10 is a schematic diagram of the forming steps of Figure 1.

S100: Circuit board manufacturing method

S110: Preliminary steps

S120: Blackening step

S130: Blind hole forming step

S140: Flattening step

S150: De-blackening step

S160: Glue removal step

S170: Forming step

Claims (10)

A method for manufacturing a circuit board, comprising: A pre-step: providing a multi-layer plate, which includes an insulating layer, a first copper layer formed on one side of the insulating layer, and a second copper layer formed on the other side of the insulating layer; wherein the thickness of the first copper layer is less than 15 micrometers (μm); A blackening step: forming a blackening layer on the first copper layer; A blind hole forming step: forming a blind hole by machining a recess from the blackening layer by carbon dioxide laser until the second copper layer is exposed; wherein a rough surface of the second copper layer is exposed in the blind hole and has at least one copper tooth and a carbide or resin coated in at least one of the copper teeth; and A flattening step: using ultraviolet laser to machine a trimming groove on the rough surface of the second copper layer to remove at least one of the copper teeth and the carbide or the resin coated in at least one of the copper teeth, and making the bottom of the trimming groove have a centerline average roughness (Ra) of less than 3 microns. The manufacturing method of a circuit board according to claim 1, wherein in the blind hole forming step, the rough surface of the second copper layer has a centerline average roughness of between 3 microns and 5 microns. Spend. The manufacturing method of a circuit board according to claim 1, wherein in the planarization step, the depth of the trimming groove formed by the ultraviolet laser is between 3 microns and 5 microns, and the trimming None of the copper teeth are formed in the groove. A method for manufacturing a circuit board as described in claim 1, wherein, in the blind hole forming step, the wavelength of the laser beam used in the carbon dioxide laser is 10.6 microns; and in the planarization step, the wavelength of the laser beam used in the ultraviolet laser is 355 nanometers (nm). A method for manufacturing a circuit board as described in claim 1, wherein, in the blind hole forming step, the blind hole formed by the carbon dioxide laser has a first aperture diameter formed in the first copper layer, and a second aperture diameter smaller than the first aperture diameter is formed in a portion away from the first copper layer; and in the planarizing step, the trimming groove formed by the ultraviolet laser has an inner diameter equal to the second aperture diameter. The manufacturing method of a circuit board according to claim 5, wherein in the planarization step, the inner side wall of the trimming groove formed by the ultraviolet laser is sandwiched with the hole wall of the blind hole. There is a configuration angle between 100 degrees and 170 degrees. The method for manufacturing a circuit board as described in claim 1, wherein, after the planarization step, the method for manufacturing a circuit board further implements a de-blackening step to remove the blackening layer located on the first copper layer. The manufacturing method of a circuit board according to claim 7, wherein in the blind hole forming step, the blind hole formed by the carbon dioxide laser has residual glue and carbide attached to its hole wall; After the deblackening step, the manufacturing method of the circuit board further implements a glue removal step: using potassium permanganate (KMnO ₄ ) solution to wet glue removal from the hole wall of the blind hole. , to remove the residual glue and carbide attached to the hole wall. The method for manufacturing a circuit board as described in claim 8, wherein, in the degumming step, plasma is further used to perform dry degumming on the hole wall of the blind hole to remove the residual glue and the carbide attached to the hole wall. The manufacturing method of a circuit board according to claim 8, wherein, after the glue removal step, the manufacturing method of the circuit board further implements a forming step: electroplating in the trimming groove and the blind hole to form a A conductor, so that the conductor connects the first copper layer and the second copper layer.

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