KR102544563B1 - Printed circuit board and manufacturing method thereof - Google Patents

Abstract

A printed circuit board is disclosed. In the printed circuit board according to one aspect of the present invention, an inner insulating layer, an outer insulating layer laminated on one surface and the other surface of the inner insulating layer, an outer conductor pattern layer formed on each surface of the outer insulating layer, and an outer conductor pattern layer are formed on each other. A through via penetrating the inner insulating layer and the outer insulating layer to connect the through via, and an inner conductor pattern layer formed on one surface and the other surface of the inner insulating layer and having at least a portion inserted into the through via.

Description

Printed circuit board and manufacturing method of printed circuit board {PRINTED CIRCUIT BOARD AND MANUFACTURING METHOD THEREOF}

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

As electronic components become lighter, thinner and smaller, printed circuit boards (PCBs) are also miniaturized, thinned, and finely patterned. Therefore, the insulating layer constituting the printed circuit board is also being thinned.

Vias for interlayer connection of printed circuit boards are formed by processing via holes in an insulating layer and then forming a conductive material in the via holes. In general, the via hole is formed in the insulating layer through laser drilling.

However, in the case of a thinned insulating layer, it is difficult to control the depth of a laser drill, so it is increasingly difficult to process a via hole with a laser drill.

Korean Patent Publication No. 10-2013-0055335 (published on May 28, 2013)

According to an embodiment of the present invention, a printed circuit board thinned to a thickness of about 50 μm may be provided.

In addition, according to an embodiment of the present invention, a printed circuit board capable of reducing via hole machining defects may be provided.

1 is a view showing a printed circuit board according to an embodiment of the present invention.
Figure 2 is an enlarged view of part A of Figure 1;
3 is a flowchart illustrating a method of manufacturing a printed circuit board according to an embodiment of the present invention.
4 to 9 are views sequentially showing manufacturing processes to explain a manufacturing method of a printed circuit board according to an embodiment of the present invention.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded. And, throughout the specification, "on" means to be located above or below the target part, and does not necessarily mean to be located on the upper side with respect to the direction of gravity.

In addition, coupling does not mean only the case of direct physical contact between each component in the contact relationship between each component, but another configuration intervenes between each component so that the component is in the other configuration. It should be used as a concept that encompasses even the case of contact with each other.

Since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to the shown bar.

Hereinafter, an embodiment of a printed circuit board and a manufacturing method of the printed circuit board according to the present invention will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding components have the same reference numerals. , and redundant description thereof will be omitted.

printed circuit board

1 is a diagram showing a printed circuit board according to an embodiment of the present invention. FIG. 2 is an enlarged view of part A of FIG. 1 .

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 conductive pattern layer 400, a through-via (TV) ) and an internal conductor pattern layer 300, and may further include an interlayer via (V).

The inner insulating layer 100 and the outer insulating layer 200 are electrically insulating materials, and the outer insulating layer 200 is laminated on one surface and the other surface of the inner insulating layer 100 . That is, as shown in FIG. 1 , in the printed circuit board 1000 according to the present embodiment, the outer insulating layer 200 is laminated on one side and the other side of the inner insulating layer 100, respectively, with the inner insulating layer 100 as the center. may be a symmetrical structure.

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 with reference to FIG. 1 is used as an upper insulating layer, and the inner insulating layer 100 The outer insulating layer 200 laminated on the lower surface will be referred to as a lower insulating layer. When distinction between the external insulating layers 200 is unnecessary, both the upper insulating layer and the lower insulating layer will be collectively referred to as the external 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 flexible resin. The inner insulating layer 100 may be formed of polyimide resin. The inner insulating layer 100 may be formed using Flexible Copper Claude Laminate (FCCL).

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

The inorganic filler (f) is dispersed in the electrical insulating resin of the external insulating layer 200 . The weight ratio of the inorganic filler (f) to the total weight of the external insulating layer 200 may be variously changed according to design needs.

The inorganic filler (f) may be at least one selected from the group consisting of alumina, silica, glass, and silicon carbide, and mixtures thereof.

The inorganic filler (f) may be formed in various shapes such as a sphere, a hemispherical shape, a polygonal shape, a cylinder shape, or a plate shape. Accordingly, it should be understood that the shape of the inorganic filler f shown in FIGS. 1 and 2 is illustrative.

The diameter of the inorganic filler (f) can be variously selected from several nm to hundreds of nm in size. In the case where the inorganic filler (f) is not spherical, the diameter of the inorganic filler (f) is the length of each of a plurality of line segments connecting two different points on the surface of the inorganic filler (f) and passing through the center of gravity of the inorganic filler (f). It is used to mean the longest length among them.

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 one surface of each of the external insulating layers 200 . That is, referring to FIG. 1 , the external 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 circuit patterns and external connection pads.

The external conductor pattern layer 400 is formed of an electrically conductive material. For example, the external 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 inner insulating layer 100 and the outer insulating layer 200 to connect the outer conductive 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 is formed on the upper surface of the upper insulating layer 200. The external conductor pattern layer 400 and the external conductor pattern layer 400 formed on the lower surface of the lower insulating layer 200 are electrically connected.

The through via (TV) is formed of an electrically conductive material. For example, the through via (TV) 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).

An upper insulating material (200' in Figs. 5 to 8) and a lower insulating material (200' in Figs. ) and the internal insulating layer 100 are etched with a strong alkaline etchant. At this time, since the inner insulating layer and the insulating material (200' in Figs. 5 to 8) include insulating resins of different materials, the cross-sectional area of the through-via hole (TVH) in the insulating material (200' in Figs. 5 to 8) Cross-sectional areas of through-via holes (TVH) in the inner insulating layer 100 may be different from each other. For example, the internal insulating layer 100 may include a polyimide resin and the insulating material (200′ in FIGS. 5 to 8) may include a semi-cured epoxy resin. The reactivity of the mead resin and the reactivity of the semi-cured epoxy resin to the strong alkaline etchant may be different.

Further, in the above-described process of forming the through-via hole (TVH), the strong alkaline etchant is supplied from the upper part of the upper insulating material (200' in FIGS. 5 to 8) and the lower part of the lower insulating material (200' in Figs. 5 to 8). Due to this, the internal insulating layer 100 is symmetrically etched in the direction of the center of the thickness of the internal insulating layer 100 from the upper and lower surfaces. Therefore, the cross-sectional area of the through-via hole (TVH) in the inner insulating layer 100 decreases in the direction of the center of the thickness of the inner insulating layer 100, and eventually the through-via (TV) in the inner insulating layer 100 The cross-sectional area decreases toward the center of the thickness of the inner insulating layer 100 .

In addition, the curing degree of the insulating material containing the epoxy resin in a semi-cured state (200′ in FIGS. 5 to 8) decreases toward the center of the thickness of the inner insulating layer 100, so that the reactivity to the strong alkaline etchant increases. . For this reason, 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. As a result, the cross-sectional area of the through via (TV) in the outer insulating layer 200 increases toward the center of the thickness of the inner insulating layer 100.

Meanwhile, the curing degree of the insulating material (200' in FIGS. 5 to 8) upon chemical etching may be changed according to design needs. Accordingly, the degree to which the cross section of the through-via (TV) in the outer insulating layer 200 changes along the direction of the center of the thickness of the inner insulating layer 100 may be variously changed according to design needs.

1 and 2 show that the boundary between the longitudinal section of the through-via (TV) and the outer insulating layer 200 and the boundary between the longitudinal section of the through-via (TV) and the inner insulating layer 100 are straight lines, but this is an example. It can also be a curve depending on 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 portion thereof is inserted into the through via (TV). Referring to FIGS. 1 and 2 , at least a portion of the inner conductor pattern layer 300 is inserted into the side of the through via (TV). This is because in the etching process of the insulating material (200' in FIGS. 5 to 8), the etching amount on the lower side of the insulating material (200' in FIGS. 5 to 8) is greater than the etching amount on the upper side of the insulating material (200' in FIGS. 5 to 8). This is because at least a part of the internal conductor pattern layer 300 is exposed to the outside.

The inner conductor pattern layer 300 is formed of an electrically conductive material. For example, the internal conductor pattern layer 300 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 interlayer vias (V) are 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 vias V is that of the inner insulating layer 100. It increases in the direction of the center of the thickness. That is, the interlayer via V electrically connects one of the inner conductor pattern layers 300 formed on the inner insulating layer 100 and one of the outer conductor pattern layers 400 formed on the outer insulating layer 200 to each other. do. In addition, interlayer vias (V) are formed in the outer insulating layer 200, and their cross-sectional area increases in the direction of the center of the thickness of the inner insulating layer 100, which is through the outer insulating layer 200 described above. Since it is the same principle as the increase in the cross-sectional area of the via (TV), the description is omitted.

Meanwhile, although not shown in FIG. 1 , in the printed circuit board 1000 according to the present embodiment, a solder resist layer patterned with openings may be formed to expose at least a portion of the external conductor pattern layer 400 .

Manufacturing method of printed circuit board

3 is a flowchart illustrating a method of manufacturing a printed circuit board according to an embodiment of the present invention. 4 to 9 are diagrams sequentially showing manufacturing processes to explain a manufacturing method of a printed circuit board according to an embodiment of the present invention.

Referring to FIG. 3 , the method of manufacturing a printed circuit board according to the present embodiment includes supplying an inner insulating layer having an inner conductor pattern layer formed thereon, laminating an insulating material on both sides of the inner insulating layer, and forming the inner insulating layer and the insulating material. and chemically etching to form through-via holes and interlayer via-holes.

First, as shown in FIG. 4 , the internal insulating layer 100 on which the internal conductor pattern layer 300 is formed is supplied. Forming the internal conductor pattern layer 300 on the internal insulating layer 100 may use a conventional circuit pattern forming method such as a subtractive method, an additive method, a semi-additive method, or a modified semi-additive method. In the case of using the semi-additive method or the modified semi-additive method, the inner conductor pattern layer 300 may include a seed layer formed on the inner insulating layer 100 and an electroplating layer formed on the seed layer.

The inner conductor pattern layer 300 includes an over-etching prevention pattern to prevent over-etching of the insulating material (200' in FIGS. 5 to 8). Through subsequent processes, the insulating material (200' in FIGS. 5 to 8) is chemically etched. Since the over-etching prevention pattern is formed on the inner insulating layer 100, excessive etching of the insulating material (200' in FIGS. 5 to 8) can be prevented

Here, the step of supplying the internal insulating layer 100 on which the internal conductor pattern layer 300 is formed is the step of forming the internal conductor pattern layer 300 on both sides of the flexible insulating sheet in a roll-to-roll manner and A step of cutting the flexible insulating sheet on which the conductor pattern layer 300 is formed may be included.

The flexible insulating sheet may include polyimide. Forming a conductor pattern on a flexible sheet in a roll-to-roll manner and cutting the flexible sheet are obvious to those skilled in the art, so detailed descriptions thereof will be omitted.

In forming the internal conductor pattern layer 300 on both sides of the flexible insulating sheet in a roll-to-roll manner, a flexible copper clad laminate (FCCL) may be used. The flexible copper clad laminate is a laminate of copper foil on both sides of an insulating resin having flexibility such as polyimide, and due to the ductility, a roll-to-roll method is possible, and processability and productivity can be improved.

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

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

The inorganic filler (f) is dispersed in the electrically insulating resin of the insulating material 200'. The inorganic filler (f) may be at least one selected from the group consisting of alumina, silica, glass, and silicon carbide, and mixtures thereof.

The inorganic filler (f) may be formed in various shapes such as a sphere, a hemispherical shape, a polygonal shape, a cylinder shape, or a plate shape. Accordingly, it should be understood that the shape of the inorganic filler f shown in FIGS. 4 to 9 is illustrative.

The diameter of the inorganic filler (f) can be variously selected from several nm to hundreds of nm in size. In the case where the inorganic filler (f) is not spherical, the diameter of the inorganic filler (f) is the length of each of a plurality of line segments connecting two different points on the surface of the inorganic filler (f) and passing through the center of gravity of the inorganic filler (f). It is used to mean the longest length among them.

The insulating material 200' is laminated in a semi-cured state for adhesion with the inner insulating layer 100, and is in a semi-cured state until an r through via hole (TVH in FIG. 7) and an interlayer via hole (VH in FIG. 7) are formed. maintain. The curing degree of the insulating material 200' to be laminated on the inner insulating layer 100 may be 50% to 80%, but may be variously changed according to design needs.

Meanwhile, a metal foil MF may be formed on one side of the insulating material 200 ′ stacked on both sides of the inner insulating layer 100 . The metal foil MF may be processed into an etching resist pattern MF' in a subsequent process. The metal foil MF may be formed on the insulating material 200' at the same time or at the same time as the stacking of the insulating material 200'. In the former case, it can be implemented by laminating a member having an insulating material 200' formed on one side of the metal foil MF on the inner insulating layer 100, such as a single-sided copper clad laminate (Resin Coated Copper, RCC). 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 a through via hole (TVH) and an interlayer via hole (VH). The through via hole (TVH) passes through both the inner insulating layer 100 and the insulating material 200', and the interlayer via hole (VH) penetrates through the insulating material 200'. This will be explained in more detail.

First, as shown in FIG. 6 , an etching resist pattern MF' having an opening O formed on one surface of an insulating material 200' is formed by selectively etching the metal foil MF. In the etching resist pattern MF', a photosensitive dry film is laminated over the entire area of the metal foil MF, and the dry film is selectively exposed and developed to form a resist pattern for etching the metal foil, and then the metal foil MF can be etched. It can be formed by selectively etching the metal foil (MF) with an etchant for metal foil. Since the etching resist pattern MF' thus formed is made of a metallic material, it may not react to a strong alkaline etchant used in a 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 through via holes (TVH) and interlayer via holes (VH). form Since the strong alkaline etchant flows in through the opening O of the etching resist pattern MF', the cross-sectional area of the through-via hole TVH in the inner insulating layer 100 is in the direction of the center of the thickness of the inner insulating layer 100 decreases more and more

Meanwhile, since the degree of curing of the insulating material 200' in a semi-cured state decreases toward the center of the thickness of the inner insulating layer 100, the interlayer via hole VH formed in the insulating material 200' is the thickness of the inner insulating layer 100. The cross-sectional area increases in the direction of the thickness center. In the same way, the cross-sectional area of the through-via hole (TVH) in the insulating material 200' increases toward the center of the thickness of the internal insulating layer 100.

Then, 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' may be removed by a physical or chemical method.

Next, as shown in FIG. 9 , a through via (TV), an interlayer via (V), and an external conductor pattern layer 400 are formed. The through-vias (TV), the inter-layer vias (V), and the external conductor pattern layer 400 may be formed by a conventional circuit pattern formation method such as an additive method, a semi-additive method, or a modified semi-additive method. Electrolytic plating to form the through vias (TV), the interlayer vias (V), and the external conductor pattern layer 400 may be repeated several times.

On the other hand, although not described in detail, the manufacturing method of the printed circuit board according to the present embodiment includes forming the outer insulating layer 200 by completely curing the insulating material 200', and also forming the outer conductor pattern layer 400. A step of forming a solder resist layer having openings to cover the outer conductor pattern layer 400 may be further included.

In the above, one embodiment of the present invention has been described, but those skilled in the art can add, change, or delete components within the scope not departing from the spirit of the present invention described in the claims. It will be possible to modify and change the present invention in various ways, which will also be said to be included within 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: interlevel via
VH: Interlayer via hole
100: inner insulating layer
200: external insulating layer
200': Insulation
300: inner conductor pattern layer
400: external conductor pattern layer
1000: printed circuit board

Claims (10)

inner insulating layer;
an outer insulating layer laminated on one surface and the other surface of the inner insulating layer;
an external conductor pattern layer formed on one surface of each of the external insulating layers;
a through-via passing through the inner insulating layer and the outer insulating layer to connect the outer conductive pattern layers to each other; and
An internal conductor pattern layer formed on one surface and the other surface of the internal insulating layer, at least a portion of which is inserted into the through-via;
The through via is
The cross-sectional area of the inner insulating layer decreases substantially in the direction of the center of the thickness of the inner insulating layer,
The cross-sectional area of the outer insulating layer increases substantially in the direction of the center of the thickness of the inner insulating layer,
The inner insulating layer includes a flexible resin,
The outer insulating layer includes a thermosetting resin and an inorganic filler, the printed circuit board.
delete delete According to claim 1,
Further comprising an interlayer via formed in the outer insulating layer to connect the inner conductor pattern layer and the outer conductor pattern layer,
Wherein the cross-sectional area of the interlayer via increases in the direction of the center of the thickness of the inner insulating layer.
delete According to claim 1,
Each of the inner insulating layer and the outer insulating layer is formed to a thickness of 5 μm to 10 μm, the printed circuit board.
supplying an internal insulating layer on which an internal conductor pattern layer is formed;
laminating an insulating material on both sides of the inner insulating layer; and
chemically etching the inner insulating layer and the insulating material to form a through via hole penetrating both the inner insulating layer and the insulating material and an interlayer via hole penetrating the insulating material to expose the inner conductor pattern layer;
including,
The inner conductor pattern layer is
A method of manufacturing a printed circuit board comprising an over-etching prevention pattern for preventing over-etching of the insulating material.
According to claim 7,
In the step of chemically etching the inner insulating layer and the insulating material,
The insulating material is a method of manufacturing a printed circuit board in a semi-cured state.
According to claim 7,
The step of supplying the inner insulating layer on which the inner conductor pattern layer is formed is
Forming internal conductor pattern layers on both sides of the flexible insulating sheet in a roll-to-roll manner; and
Cutting the flexible insulating sheet on which the inner conductor pattern layer is formed
Method for manufacturing a printed circuit board comprising a.
According to claim 7,
Chemically etching the inner insulating layer and the insulating material
A method of manufacturing a printed circuit board comprising the step of forming an etching resist pattern on one surface of the insulating material.

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