JP2018029173A - Printed circuit board and manufacturing method for printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed board capable of reducing a processing failure of a viahole in a thinned insulation layer.SOLUTION: A printed board includes: an internal insulation layer 100; external insulation layers 200 laminated on one face and the other face of the internal insulation layer 100; an external conductor pattern layer 400 formed on one face of each of the external insulation layers 200; a through-via TV for penetrating the internal insulation layer 100 and the external insulation layer 200 for connecting the external conductor pattern layers 400 for each other; and an inner conductor pattern layer 300 formed on one face and the other face of the internal insulation layer 100 respectively and at least a part of which is inserted in the through-via TV.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a printed circuit board and a printed circuit board manufacturing method.

  As electronic components become lighter, thinner and smaller, printed circuit boards (PCBs) are also required to be reduced in size, thickness and pattern. For this reason, the insulating layer which comprises a printed circuit board is also thinned.

  A via for interlayer connection of a printed circuit board is formed by processing a via hole in an insulating layer and then filling the via hole with a conductive material. Normally, the via hole is formed in the insulating layer using a laser drill.

  However, in the case of a thin insulating layer, it is difficult to adjust the depth of a laser drill (depth control), and it is increasingly difficult to process a via hole with a laser drill.

Korean Published Patent No. 10-2013-0055335

  According to the embodiment of the present invention, it is possible to provide a printed circuit board thinned to a thickness of 50 μm inside or outside.

  Further, according to the embodiment of the present invention, it is possible to provide a printed circuit board capable of reducing processing defects of via holes.

It is a figure which shows the printed circuit board which concerns on one Example of this invention. It is the figure which expanded the A section of FIG. It is a flow chart showing a manufacturing method of a printed circuit board concerning one example of the present invention. It is a figure which shows 1 process for demonstrating the manufacturing method of the printed circuit board which concerns on one Example of this invention. It is a figure which shows the next process of the process of FIG. It is a figure which shows the next process of the process of FIG. It is a figure which shows the next process of the process of FIG. It is a figure which shows the next process of the process of FIG. It is a figure which shows the next process of the process of FIG.

  The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context.

  In this application, terms such as “include” or “have” designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof, as described in the specification. It should be understood that the existence or additional possibilities of one or more other features or numbers, steps, actions, components, parts or combinations thereof are not excluded in advance.

  In addition, throughout the specification, “on” means located above or below the target portion, and does not necessarily mean located above the gravity direction.

  In addition, the term “coupled” does not mean that in the contact relationship between the components, the components are physically directly in contact with each other, and other configurations are interposed between the components. It is used as a concept encompassing even when the components are in contact with other components.

  The size and thickness of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited thereto.

  In the following, embodiments of a printed circuit board and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same or corresponding components are denoted by the same reference numerals. A duplicate description is omitted.

<Printed circuit board>
FIG. 1 is a view showing a printed circuit board according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A in FIG.

  1 and 2, a printed circuit board 1000 according to an embodiment of the present invention includes an inner insulating layer 100, an outer insulating layer 200, an outer conductor pattern layer 400, a through via TV, and an inner conductor pattern. Layer 300, and may further include an interlayer via V.

  The inner insulating layer 100 and the outer insulating layer 200 are formed of an electrically insulating material, and the outer insulating layer 200 is stacked on one surface and the other surface of the inner insulating layer 100. That is, as shown in FIG. 1, the printed circuit board 1000 according to the present embodiment has a symmetrical structure in which an outer insulating layer 200 is laminated on one surface and the other surface of the inner insulating layer 100 with the inner insulating layer 100 as a center. Can have.

  Hereinafter, when it is necessary to distinguish between the outer insulating layers 200, the outer insulating layer 200 stacked on the upper surface of the inner insulating layer 100 based on FIG. 1 is stacked on the upper insulating layer and the lower surface of the inner insulating layer 100. The formed outer insulating layer 200 is referred to as a lower insulating layer. When it is not necessary to distinguish between the outer insulating layers 200, the upper insulating layer and the lower insulating layer are all referred to as an outer insulating layer.

  Each of the inner insulating layer 100 and the outer insulating layer 200 may be formed to a thickness of 5 μm to 10 μm.

  The inner insulating layer 100 includes a soft resin. The internal insulating layer 100 can be formed of a polyimide resin. The internal insulating layer 100 can be formed using a flexible copper clad laminate (FCCL).

  The outer insulating layer 200 includes an electrically insulating resin and an inorganic filler f. The outer insulating layer 200 may include a thermosetting resin and / or a photocurable resin as an electrically insulating resin. The thermosetting resin can be an epoxy resin and is not limited thereto. As the epoxy resin, bisphenol A type epoxy resin, naphthalene deformed epoxy resin, cresol novolac epoxy resin, rubber-modified epoxy resin, or the like can be used.

  The inorganic filler f is dispersed in the electrically insulating resin of the outer insulating layer 200. The weight ratio of the inorganic filler f with respect to the total weight of the outer insulating layer 200 can be variously changed according to design requirements.

  The inorganic filler f can be at least one selected from the group consisting of alumina, silica, glass, silicon carbide, and a mixture thereof.

  The inorganic filler f can be formed in various shapes such as a spherical shape, a hemispherical shape, a polygonal shape, a cylindrical shape, or a plate shape. The shape of the inorganic filler f shown in FIGS. 1 and 2 is merely an example.

  The diameter of the inorganic filler f is several nanometers to several hundred nanometers and can be variously selected. The diameter of the inorganic filler f when the inorganic filler f is not spherical is the longest length of the lengths of a plurality of lines connecting two different points on the surface of the inorganic filler f and passing through the center of gravity of the inorganic filler f. Means.

  The external conductor pattern layer 400 is a conductor pattern layer formed on the outermost surface of the printed circuit board 1000 according to the present embodiment, and is formed on each surface of the external insulating layer 200. That is, referring to FIG. 1, the outer conductor pattern layer 400 is formed on the upper surface of the upper insulating layer 200 and the lower surface of the lower insulating layer 200, respectively. The external conductor pattern layer 400 may include a circuit pattern and external connection pads.

  The outer conductor pattern layer 400 is formed of an electrically conductive material. For example, the outer conductor pattern layer 400 may be formed of copper (Cu), but is not limited thereto, and may be formed of various electrically conductive materials such as nickel (Ni) and aluminum (Al). .

  The through via TV penetrates the internal insulating layer 100 and the external insulating layer 200 in order to connect the external conductor pattern layer 400 to each other. That is, the through via TV is formed in the through via hole TVH penetrating all of the upper insulating layer 200, the inner insulating layer 100, and the lower insulating layer 200, and the outer conductor pattern layer 400 formed on the upper surface of the upper insulating layer 200, and the lower portion The external conductor pattern layer 400 formed on the lower surface of the insulating layer 200 is electrically connected.

  The through via TV is formed of an electrically conductive material. For example, the through via TV can be formed of copper (Cu), but is not limited thereto, and can be formed of various electrically conductive materials such as nickel (Ni) and aluminum (Al).

  In order to form the through via hole TVH, an upper insulating material (200 'in FIGS. 5 to 8) and a lower insulating material (200' in FIGS. 5 to 8) which are base materials of the upper insulating layer 200 and the lower insulating layer 200 are formed. Then, the inner insulating layer 100 is etched with a strong alkaline etchant. At this time, since the internal insulating layer and the insulating material (200 ′ in FIGS. 5 to 8) include different insulating resins, the cross-sectional area of the through via hole TVH in the insulating material (200 ′ in FIGS. 5 to 8) The cross-sectional area of the through via hole TVH in the inner insulating layer 100 may be different from each other. For example, when the inner insulating layer 100 includes a polyimide resin and the insulating material (200 ′ in FIGS. 5 to 8) includes a semi-cured epoxy resin, the reactivity of the polyimide resin with respect to the strong alkaline etching solution and the strong alkaline property The reactivity of the semi-cured epoxy resin with respect to the etching solution may differ.

  In the process of forming the through via hole TVH, the strong alkaline etching solution is applied from the upper part of the upper insulating material (200 'in FIGS. 5 to 8) and the lower insulating material (200' in FIGS. 5 to 8). Supplied from the bottom. Thereby, the internal insulating layer 100 is etched symmetrically from the upper surface and the lower surface toward the thickness center of the internal insulating layer 100. Therefore, the cross-sectional area of the through via hole TVH in the internal insulating layer 100 is reduced as it goes in the direction of the thickness center of the internal insulating layer 100. As a result, the cross-sectional area of the through via TV in the internal insulating layer 100 is It decreases as it goes to the center.

  Further, the insulating material containing the epoxy resin in a semi-cured state (200 ′ in FIGS. 5 to 8) has a lower degree of curing as it goes in the direction of the thickness center of the inner insulating layer 100, and has a reactivity with a strong alkaline etching solution. To increase. As a result, the cross-sectional area of the through via hole TVH in the outer insulating layer 200 formed by completely curing the insulating material (200 ′ in FIGS. 5 to 8) increases toward the center of the thickness of the inner insulating layer 100. After all, the cross-sectional area of the through via TV in the outer insulating layer 200 increases as it goes in the direction of the thickness center of the inner insulating layer 100.

  On the other hand, the degree of cure of the insulating material (200 ′ in FIGS. 5 to 8) at the time of chemical etching can be changed according to the necessity of design. Therefore, the degree to which the cross section of the through via TV in the outer insulating layer 200 changes toward the thickness center of the inner insulating layer 100 can be variously changed according to the design needs.

  1 and 2, the boundary between the vertical cross section of the through via TV and the external insulating layer 200 and the boundary between the vertical cross section of the through via TV and the internal insulating layer 100 are shown by straight lines. However, this is merely an example, and may be curved due to the nature of the chemical etching described above.

  The inner conductor pattern layer 300 is formed on one surface and the other surface of the inner insulating layer 100, respectively, and at least a part thereof is inserted into the through via TV. Referring to FIGS. 1 and 2, at least a part of the inner conductor pattern layer 300 is inserted into the side surface of the through via TV. This is because the etching amount from the lower side of the insulating material (200 ′ in FIGS. 5 to 8) in the etching process of the insulating material (200 ′ in FIGS. 5 to 8) is the insulating material (FIGS. 5 to 8). This is because at least a part of the inner conductor pattern layer 300 is exposed from the outside of the insulating material (200 ′ in FIGS. 5 to 8).

  The inner conductor pattern layer 300 is formed of an electrically conductive material. For example, the internal conductor pattern layer 300 can be formed of copper (Cu), but is not limited thereto, and can be formed of various electrically conductive materials such as nickel (Ni) and aluminum (Al).

  The interlayer via V is formed in the outer insulating layer 200 to connect the inner conductor pattern layer 300 and the outer conductor pattern layer 400, and the cross-sectional area of the interlayer via V increases toward the thickness center of the inner insulating layer 100. To increase. That is, the interlayer via V connects any one of the inner conductor pattern layers 300 formed in the inner insulating layer 100 and any one of the outer conductor pattern layers 400 formed in the outer insulating layer 200 to each other. Connect electrically.

  Further, the interlayer via V is formed in the outer insulating layer 200, and its cross-sectional area increases as it goes in the direction of the thickness center of the inner insulating layer 100. This is because the through via TV in the outer insulating layer 200 is crossed. Since it is the same as that of an area increasing, detailed description is abbreviate | omitted.

  On the other hand, although not shown in FIG. 1, the printed circuit board 1000 according to the present embodiment forms a solder resist layer whose opening is patterned so that at least a part of the outer conductor pattern layer 400 is exposed. can do.

<Method for manufacturing printed circuit board>
FIG. 3 is a flow chart illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention, and FIGS. 4 to 9 illustrate a method for manufacturing a printed circuit board according to an embodiment of the present invention. In addition, FIG.

  Referring to FIG. 3, the printed circuit board manufacturing method according to the present embodiment includes a step of supplying an internal insulating layer formed with an internal conductor pattern layer, a step of laminating an insulating material on both surfaces of the internal insulating layer, Chemically etching the internal insulating layer and the insulating material to form through via holes and interlayer via holes.

  First, as shown in FIG. 4, an internal insulating layer 100 on which an internal conductor pattern layer 300 is formed is supplied. In order to form the inner conductor pattern layer 300 in the inner insulating layer 100, a subtractive method, an additive method, a semi-additive method, and a modified semi-additive method are used. A normal circuit pattern forming method such as a method can be used.

  When the semi-additive method or the modified semi-additive method is used, the inner conductor pattern layer 300 may include a seed layer formed on the inner insulating layer 100 and an electrolytic plating layer formed on the seed layer.

  The inner conductor pattern layer 300 includes an overetching prevention pattern for preventing overetching of the insulating material (200 ′ in FIGS. 5 to 8). In the subsequent process, the insulating material (200 ′ in FIGS. 5 to 8) is chemically etched, but since the over-etching prevention pattern is formed in the internal insulating layer 100, the insulating material (200 in FIGS. 5 to 8) is formed. ') Excessive etching can be prevented.

  Here, the step of supplying the inner insulating layer 100 on which the inner conductor pattern layer 300 is formed includes the steps of providing the inner conductor pattern layer 300 on both surfaces of the flexible insulating sheet by a roll-to-roll method. And forming and cutting the flexible insulating sheet on which the inner conductor pattern layer 300 is formed.

  The flexible insulating sheet can include polyimide. Forming a conductor pattern on the flexible sheet by the roll-to-roll method and cutting the flexible sheet are obvious to ordinary engineers, and thus detailed description thereof is omitted.

  In forming the inner conductor pattern layer 300 on both surfaces of the flexible insulating sheet by the roll-to-roll method, a flexible copper clad laminate (FCCL) can be used. A flexible copper foil laminate is made by laminating copper foil on both sides of a flexible insulating resin such as polyimide, and since it is soft, a roll-to-roll method is possible, and workability And productivity can be improved.

  Next, as shown in FIG. 5, an insulating material 200 ′ is laminated on both surfaces of the internal insulating layer 100. The insulating material 200 ′ is a member that becomes the above-described outer insulating layer of FIG. 1 (see 200 of FIG. 1) through a subsequent curing process, is formed in a film type, and is laminated on both surfaces of the inner insulating layer 100. be able to.

  The insulating material 200 ′ includes an electrically insulating resin and an inorganic filler f. The insulating material 200 ′ is an electrically insulating resin and can include a thermosetting resin and / or a photocurable resin. The thermosetting resin may be an epoxy resin, but is not limited thereto. As the epoxy resin, bisphenol A type epoxy resin, naphthalene deformed epoxy resin, cresol novolac epoxy resin, rubber-modified epoxy resin, or the like can be used.

  The inorganic filler f is dispersed in the electrically insulating resin of the insulating material 200 ′. As the inorganic filler f, at least one selected from the group consisting of alumina, silica, glass, silicon carbide, and a mixture thereof can be used.

  As the inorganic filler f, those formed in various shapes such as a spherical shape, a hemispherical shape, a polygonal shape, a cylindrical shape, or a plate shape can be used. That is, it should be understood that the shape of the inorganic filler f shown in FIGS. 4 to 9 is merely an example.

  The diameter of the inorganic filler f is several nanometers to several hundred nanometers and can be variously selected. The diameter of the inorganic filler f when the inorganic filler f is not spherical is the longest length among the lengths of a plurality of lines that connect two different points on the surface of the inorganic filler f and pass through the center of gravity of the inorganic filler f. Is used to mean

  The insulating material 200 ′ is laminated in a semi-cured state for adhesion to the inner insulating layer 100.

  The insulating material 200 ′ is maintained in a semi-cured state until a through via hole (see TVH in FIG. 7) and an interlayer via hole (see VH in FIG. 7) are formed, or completely after being laminated on the internal insulating layer 100. Can be cured. In the latter case, the insulating material 200 ′ is in a state of being laminated on the internal insulating layer 100, and energy necessary for the curing reaction is provided from the outside of the internal insulating layer 100. Thereby, the energy provided for the curing reaction of the insulating material 200 ′ decreases as it goes in the thickness center direction of the inner insulating layer 100. Therefore, even if the insulating material 200 ′ is completely cured while being laminated on the inner insulating layer 100, the degree of cure of the insulating material 200 ′ decreases as it goes in the thickness center direction of the inner insulating layer 100.

  The degree of curing of the semi-cured insulating material 200 ′ laminated on the inner insulating layer 100 may be 50% to 80%, and can be variously changed according to design needs.

  On the other hand, a metal foil MF can be formed on one surface of the insulating material 200 ′ laminated on both surfaces of the inner insulating layer 100. The metal foil MF can be processed as an etching resist pattern MF ′ by a subsequent process. The metal foil MF can be formed on the insulating material 200 ′ simultaneously with the lamination of the insulating material 200 ′ or at a different time. In the former case, it can be realized by laminating a member in which an insulating material 200 ′ is formed on one surface of a metal foil MF, such as a single-sided copper foil laminate (RCC), on the inner insulating layer 100. .

  The metal foil MF may be a copper foil, but is not limited thereto.

  Next, as shown in FIGS. 6 to 8, the internal insulating layer 100 and the insulating material 200 ′ are chemically etched to form through via holes TVH and interlayer via holes VH. The through via hole TVH penetrates all of the internal insulating layer 100 and the insulating material 200 ′, and the interlayer via hole VH penetrates the insulating material 200 ′. This will be described in more detail.

  First, as shown in FIG. 6, the metal foil MF is selectively etched to form an etching resist pattern MF ′ having an opening O formed on one surface of the insulating material 200 ′.

  The etching resist pattern MF ′ is formed by laminating a photosensitive dry film on the entire area of the metal foil MF, and selectively exposing and developing the dry film to form a resist pattern for etching the metal foil. It can be formed by selectively etching the metal foil MF with an etchant for metal foil that can be etched. Since the etching resist pattern MF ′ formed in this manner is a metallic material, it may not react to the strong alkaline etching solution used in the subsequent etching process for the inner insulating layer 100 and the insulating material 200 ′.

  Thereafter, as shown in FIG. 7, the internal insulating layer 100 and the insulating material 200 ′ are selectively etched with a strong alkaline etchant using the etching resist pattern MF ′ to form the through via hole TVH and the interlayer via hole VH.

  Since the strong alkaline etching solution flows in through the opening O of the etching resist pattern MF ′, the cross-sectional area of the through via hole TVH in the internal insulating layer 100 decreases as it goes in the thickness center direction of the internal insulating layer 100. .

  On the other hand, the semi-cured insulating material 200 ′ has a lower degree of curing as it goes in the direction of the thickness center of the internal insulating layer 100, so the interlayer via hole VH formed in the insulating material 200 ′ The cross-sectional area increases as going toward the center. Further, based on the same concept, the cross-sectional area of the through via hole TVH in the insulating material 200 ′ increases as it goes in the direction of the thickness center of the internal insulating layer 100.

  Thereafter, as shown in FIG. 8, the etching resist pattern MF ′ formed on one surface of the insulating material 200 ′ is removed. The etching resist pattern MF ′ can be removed by a physical or chemical method.

  Next, as shown in FIG. 9, the through via TV, the interlayer via V, and the external conductor pattern layer 400 are formed.

  The through via TV, the interlayer via V, and the external conductor pattern layer 400 can be formed by a normal circuit pattern forming method such as an additive method, a semi-additive method, or a modified semi-additive method. The electrolytic plating for forming the through via TV, the interlayer via V, and the outer conductor pattern layer 400 can be repeated several times.

  Meanwhile, although not described in detail, the printed circuit board manufacturing method according to the present embodiment includes a step of completely curing the insulating material 200 ′ to form the outer insulating layer 200, and the outer conductor pattern layer 400. The method may further include forming a solder resist layer having an opening on the outer conductor pattern layer 400 to cover the outer conductor pattern layer 400.

  In the above, one embodiment of the present invention has been described. However, those who have ordinary knowledge in the technical field can add components without departing from the spirit of the present invention described in the claims. The present invention can be modified and changed in various ways by changes or deletions, and it can be said that this is also included in the scope of the present invention.

f Inorganic filler MF Metal foil MF 'Etching resist pattern O Opening TV Through via TVH Through via hole V Interlayer via VH Interlayer via hole 100 Internal insulating layer 200 External insulating layer 200' Insulating material 300 Internal conductive pattern layer 400 External conductive pattern layer 1000 Printed circuit substrate

Claims (10)

An internal insulating layer;
An outer insulating layer laminated on one side and the other side of the inner insulating layer, and
An external conductor pattern layer formed on one surface of each of the external insulating layers;
In order to connect the outer conductor pattern layers to each other, a through via that penetrates the inner insulating layer and the outer insulating layer;
An inner conductor pattern layer formed on one surface and the other surface of the inner insulating layer, respectively, at least a part of which is inserted into the through via;
Including printed circuit board. The through via is
2. The printed circuit board according to claim 1, wherein a cross-sectional area of the inner insulating layer is reduced toward a thickness center direction of the inner insulating layer. The through via is
The printed circuit board according to claim 2, wherein a cross-sectional area of the outer insulating layer increases toward a thickness center direction of the inner insulating layer. In order to connect the inner conductor pattern layer and the outer conductor pattern layer, further comprising an interlayer via formed in the outer insulating layer,
4. The printed circuit board according to claim 1, wherein a cross-sectional area of the interlayer via increases in a direction toward a thickness center of the internal insulating layer. 5. The inner insulating layer includes a soft resin,
The printed circuit board according to any one of claims 1 to 4, wherein the external insulating layer includes a thermosetting resin and an inorganic filler.   6. The printed circuit board according to claim 1, wherein each of the inner insulating layer and the outer insulating layer is formed with a thickness of 5 μm to 10 μm. Supplying an inner insulating layer on which an inner conductor pattern layer is formed;
Laminating an insulating material on both surfaces of the internal insulating layer;
A through via hole that chemically etches the internal insulating layer and the insulating material to penetrate all of the internal insulating layer and the insulating material, and an interlayer via hole that exposes the internal conductor pattern layer through the insulating material And forming a step,
The inner conductor pattern layer is
A method of manufacturing a printed circuit board including an overetching prevention pattern for preventing overetching of the insulating material. In the step of chemically etching the inner insulating layer and the insulating material,
The method for manufacturing a printed circuit board according to claim 7, wherein the insulating material is in a semi-cured state. Supplying the inner insulating layer on which the inner conductor pattern layer is formed,
Forming inner conductor pattern layers on both sides of the flexible insulating sheet by a roll-to-roll method;
Cutting the flexible insulating sheet on which the inner conductor pattern layer is formed;
The manufacturing method of the printed circuit board of Claim 7 or Claim 8 containing this. The step of chemically etching the inner insulating layer and the insulating material includes:
The method for manufacturing a printed circuit board according to claim 7, further comprising a step of forming an etching resist pattern on one surface of the insulating material.

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