Printed circuit board

Abstract

To provide a printed circuit board that can improve the quality of a board by suppressing the formation of voids and seams even when fill plating is performed on a through hole with a high aspect ratio, such as a through hole formed in a glass core, and can minimize time and costs by minimizing the sputtering step even when a seed is formed in a through hole with a high aspect ratio, such as a through hole formed in a glass core.SOLUTION: The present invention relates to a printed circuit board including: an insulating layer; a through hole penetrating between an upper surface and a lower surface of the insulating layer and having an inclined wall surface; a metal ball disposed within the through hole and in contact with the inclined wall surface; and a metal via filling the through hole and surrounding the metal ball.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to printed circuit boards. [Background technology]

[0002] Packaging technology is continuously developing, and in particular, there are ongoing attempts to move away from organic materials in traditional substrate manufacturing methods and use silicon or glass. It is well known that glass has better warping properties and flatness than existing organic materials, which is advantageous for reducing trace lines and spaces. However, currently, when manufacturing a substrate using a glass core, there is a problem that it is difficult to form a through via in a thick glass core. For example, a seed layer is required to perform plating in a via hole, but the glass surface is smooth and the via hole has a high aspect ratio, so that the seed formation may be difficult. In addition, when the seed is formed by a sputtering process or the like, it takes a lot of time and cost to form a seed of a desired thickness. Summary of the Invention [Problem to be solved by the invention]

[0003] One of the various objects of the present invention is to provide a printed circuit board capable of improving the quality of the board by suppressing the formation of voids and seams even when fill plating is performed on a through hole having a high aspect ratio, such as a through hole formed in a glass core.

[0004] Another of the various objects of the present invention is to provide a printed circuit board that can minimize the sputtering process and minimize time and costs even when forming a seed in a through hole with a high aspect ratio, such as a through hole formed in a glass core. [Means for solving the problem]

[0005] One of several solutions proposed through the present invention is to form a through hole with an inclined wall in an insulating layer such as a glass core, insert and seat a metal ball inside the through hole, and then form a seed layer in the through hole by a sputtering process or the like, and also form a metal via surrounding the metal ball by performing fill plating or the like.

[0006] For example, an example printed circuit board may include an insulating layer, a through hole penetrating between an upper surface and a lower surface of the insulating layer and having a sloping wall surface, a metal ball disposed within the through hole and contacting the sloping wall surface, and a metal via filling the through hole and surrounding the metal ball.

[0007] For example, a printed circuit board according to one example may include an insulating layer having a through hole, a metal ball disposed in the through hole, a first seed metal layer disposed on an upper surface of the insulating layer and extending from an upper region of the through hole onto a wall surface of the through hole to cover a portion of the metal ball, a second seed metal layer disposed on a lower surface of the insulating layer and extending from a lower region of the through hole onto the wall surface of the through hole to cover another portion of the metal ball, a first metal layer disposed on the first seed metal layer and filling a portion of the through hole in the upper region of the through hole, and a second metal layer disposed on the second seed metal layer and filling the other portion of the through hole in the lower region of the through hole. Effect of the Invention

[0008] One of the various effects of the present invention is that it provides a printed circuit board that can improve the quality of the board by suppressing the formation of voids and seams, even when fill plating is applied to through holes with high aspect ratios, such as through holes formed in a glass core.

[0009] Another of the various effects of the present invention is that it is possible to provide a printed circuit board that can minimize the sputtering process and thereby minimize time and costs, even when a seed is formed in a through hole with a high aspect ratio, such as a through hole formed in a glass core. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram illustrating a schematic example of an electronic device system. [Diagram 2] FIG. 1 is a perspective view illustrating an example of an electronic device. [Diagram 3] FIG. 1 is a cross-sectional view illustrating an example of a printed circuit board. [Figure 4a] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Figure 4b] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Figure 4c] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Figure 4d] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Figure 4e] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Figure 4f] 4A to 4C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 3. [Diagram 5] FIG. 11 is a cross-sectional view illustrating another example of a printed circuit board. [Figure 6a] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 6b] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 6c] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 6d] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 6e] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 6f] 6A to 6C are cross-sectional views illustrating steps in a manufacturing process of the printed circuit board of FIG. 5. [Figure 7a] 1A to 1C are cross-sectional views illustrating various examples of metal balls. [Figure 7b] 1A to 1C are cross-sectional views illustrating various examples of metal balls. [Figure 7c] 1A to 1C are cross-sectional views illustrating various examples of metal balls. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below with reference to the accompanying drawings. The shapes and sizes of elements in the drawings may be enlarged or reduced (or highlighted or simplified) for clearer explanation, and elements denoted by the same reference numerals in the drawings are the same elements.

[0012] electronic equipment FIG. 1 is a block diagram illustrating an example of an electronic device system.

[0013] Referring to the drawing, an electronic device 1000 accommodates a main board 1010. Chip-related components 1020, network-related components 1030, and other components 1040 are physically and / or electrically connected to the main board 1010. These are also connected to other electronic components described below to form various signal lines 1090.

[0014] The chip-related components 1020 include, but are not limited to, memory chips such as volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), and flash memory; application processor chips such as central processors (e.g., CPU), graphic processors (e.g., GPU), digital signal processors, encryption processors, microprocessors, and microcontrollers; and logic chips such as analog-to-digital converters and ASICs (application-specific ICs). Needless to say, the chip-related components 1020 may include other types of chip-related electronic components. Needless to say, these chip-related components 1020 may be combined with each other. The chip-related components 1020 may be in the form of a package including the above-mentioned chips and electronic components.

[0015] The network-related components 1030 include, but are not limited to, any other wireless and wired protocols specified, such as Wi-Fi (e.g., IEEE 802.11 family), WiMAX (e.g., IEEE 802.16 family), IEEE 802.20, LTE (long term evolution), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPS, GPRS, CDMA, TDMA, DECT, Bluetooth, 3G, 4G, 5G, and beyond, and may include any of numerous other wireless or wired standards and protocols. It is also understood that the network-related components 1030 may be combined with the chip-related components 1020.

[0016] The other components 1040 include high frequency inductors, ferrite inductors, power inductors, ferrite beads, LTCC (Low Temperature Co-Firing Ceramics), EMI (Electro Magnetic Interference) filters, MLCC (Multi-Layer Ceramic Capacitors), etc. However, the other components 1040 are not limited to these, and may include passive elements in the form of chip components used for various other applications. It goes without saying that the other components 1040 can be combined with the chip-related components 1020 and / or the network-related components 1030.

[0017] Depending on the type of electronic device 1000, the electronic device 1000 may include other electronic components that may or may not be physically and / or electrically connected to the main board 1010. Examples of the other electronic components include, but are not limited to, a camera module 1050, an antenna module 1060, a display 1070, and a battery 1080. The other electronic components may include, but are not limited to, an audio codec, a video codec, a power amplifier, a compass, an accelerometer, a gyroscope, a speaker, a mass storage device (e.g., a hard disk drive), a compact disk (CD), a digital versatile disk (DVD), etc. It goes without saying that other electronic components used for various purposes may be included depending on the type of electronic device 1000.

[0018] The electronic device 1000 may be a smart phone, a personal digital assistant, a digital video camera, a digital still camera, a network system, a computer, a monitor, a tablet, a laptop, a netbook, a television, a video game, a smart watch, an automotive, etc. However, the electronic device 1000 is not limited thereto, and may be any other electronic device that processes data.

[0019] FIG. 2 is a perspective view that illustrates an example of an electronic device.

[0020] Referring to the drawings, the electronic device may be, for example, a smartphone 1100. A motherboard 1110 is housed inside the smartphone 1100, and various components 1120 are physically and / or electrically connected to the motherboard 1110. In addition, other components that may or may not be physically and / or electrically connected to the motherboard 1110, such as a camera module 1130 and / or a speaker 1140, are housed inside the smartphone 1100. Some of the components 1120 may be the above-mentioned chip-related components, for example, a component package 1121, but are not limited thereto. The component package 1121 may be in the form of a printed circuit board on which electronic components including active components and / or passive components are mounted on the surface. Alternatively, the component package 1121 may be in the form of a printed circuit board in which active components and / or passive components are embedded. Meanwhile, it goes without saying that the electronic device is not necessarily limited to the smartphone 1100, and may be other electronic devices as described above.

[0021] Printed Circuit Board FIG. 3 is a cross-sectional view that illustrates an example of a printed circuit board.

[0022] Referring to the drawing, the printed circuit board 100A according to an example may include an insulating layer 110, a through hole H1 penetrating between an upper surface and a lower surface of the insulating layer 110 and having an inclined wall surface, a metal ball 150 disposed in the through hole H1, a metal via 140 filling the through hole H1 and surrounding the metal ball 150, a first metal wiring 120 disposed on the upper surface of the insulating layer 110 and connected to an upper end of the metal via 140, and a second metal wiring 130 disposed on the lower surface of the insulating layer 110 and connected to a lower end of the metal via 140. The through hole H1 may have a tapered shape such that the width of the upper end is wider than the width of the lower end in a cross section. The metal ball 150 may be seated in the through hole H1 by the inclined wall surface of the through hole H1. The through hole H1 may have an upper region R1 and a lower region R2 separated based on the metal ball 150. Since the through hole H1 can have a tapered shape, the metal ball 150 can be disposed at an appropriate position, and the areas of the upper region R1 and the lower region R2 on the cross section can be different.

[0023] Meanwhile, the metal via 140 may include a first seed metal layer m1 disposed on an inclined wall surface in the upper region R1 and covering a part of the metal ball 150, a second seed metal layer m2 disposed on an inclined wall surface in the lower region R2 and covering another part of the metal ball 150, a first metal layer M1 disposed on the first seed metal layer m1 in the upper region R1 and filling a part of the through hole H1, and a second metal layer M2 disposed on the second seed metal layer m2 in the lower region R2 and filling the other part of the through hole H1. The first metal wiring 120 may include a first seed metal layer m1 disposed on the upper surface of the insulating layer 110 and a first metal layer M1 disposed on the first seed metal layer m1, and the second metal wiring 130 may include a second seed metal layer m2 disposed on the lower surface of the insulating layer 110 and a second metal layer M2 disposed on the second seed metal layer m2. The metal balls 150 may preferably include copper balls, and in this respect, the first and second seed metal layers m1, m2 and the first and second metal layers M1, M2 may also preferably include copper (Cu), respectively.

[0024] Meanwhile, the insulating layer 110 may include a glass layer. The glass layer may include glass, which is an amorphous solid. Glass may include, for example, pure silicon dioxide (about 100% SiO2), soda-lime glass, borosilicate glass, alumino-silicate glass, etc. However, alternative glass materials, such as fluoroglass, phosphate glass, chalcogenide glass, etc., may also be used as materials, without being limited thereto. Other additives may also be included to form glass with specific physical properties. Such additives may include calcium carbonate (e.g., lime) and sodium carbonate (e.g., soda), as well as magnesium, calcium, manganese, aluminum, lead, boron, iron, chromium, potassium, sulfur, and antimony, and carbonates and / or oxides of such elements and other elements. The glass layer may be a layer distinct from organic insulating materials including glass fibers (glass fiber, glass cloth, glass fabric), such as copper clad laminate (CCL), prepreg (PPG), etc. For example, it may be plate glass.

[0025] In this way, in the case of forming a metal via 140 with a high aspect ratio in an insulating layer 110 having a considerable thickness such as a glass layer, the printed circuit board 100A according to the embodiment includes a through hole H1 in which a metal ball 150 is inserted in advance, and then the metal ball 150 is seated using the inclined wall surface of the through hole H1, and then plating is performed. For example, after inserting the metal ball 150, the first and second seed metal layers m1 and m2 can be formed on both sides using sputtering, etc., so that the seed formation is easier and the sputtering process can be minimized. In addition, this allows the metal ball 150 to be fixed so that it does not fall. In addition, after inserting the metal ball 150, the first and second metal layers M1 and M2 can be formed on both sides using fill plating, so that the generation of voids and seams in the through hole H1 can be effectively suppressed. Therefore, the quality of the board can be improved.

[0026] Meanwhile, the printed circuit board 100A according to an embodiment may be applied as any layer of a multi-layer circuit board. For example, it may be applied as a core layer of a multi-layer circuit board, in which case a build-up process may be performed on one or both sides of the printed circuit board 100A. Such a multi-layer circuit board may be used as a film-chip board (FCB), a ball grid array (BGA), an interposer board, a package board, etc. However, it is not limited thereto, and may be applied to various other types of boards.

[0027] The components of the printed circuit board 100A according to an example are described in more detail below with reference to the drawings.

[0028] The insulating layer 110 may include an insulating material, which may include, but is not limited to, glass, as well as various other materials such as ceramic, silicon, organic insulating materials, etc. Preferably, it may include glass, and thus the insulating layer 110 may be, but is not limited to, a sheet of glass.

[0029] The first and second metal wirings 120 and 130 may each include a metal material. The metal material may include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof. For example, the first and second seed metal layers m1 and m2 and the first and second metal layers M1 and M2 of the first and second metal wirings 120 and 130 may each include the above-mentioned metal material, preferably, but not limited to, copper (Cu). The first and second metal wirings 120 and 130 may each perform various functions according to the design. For example, they may include a signal pattern, a power pattern, a ground pattern, etc. These patterns may each have various forms, such as a line, a plane, and a pad. The first and second metal wirings 120 and 130 may each include an electroless plating layer (or chemical copper) and an electrolytic plating layer (or electrolytic copper). A sputtering layer may be included instead of the electroless plating layer (or chemical copper), and both the electroless plating layer (or chemical copper) and the sputtering layer may be included as necessary.

[0030] The metal via 140 may include a metal material. The metal material may include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof. For example, the first and second seed metal layers m1 and m2 and the first and second metal layers M1 and M2 of the metal via 140 may each include the above-mentioned metal material, and may preferably include copper (Cu), but are not limited thereto. The metal via 140 may perform various functions according to the design. For example, it may include a ground via, a power via, a signal via, and the like. The metal via 140 may include an electroless plating layer (or chemical copper) and an electrolytic plating layer (or electrolytic copper). A sputtering layer may be formed instead of the electroless plating layer, and both the electroless plating layer (or chemical copper) and the sputtering layer may be included as necessary.

[0031] The metal ball 150 may include a metal material. The metal material may include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof. For example, the metal ball 150 may include a copper ball, but is not limited thereto. The metal ball 150 may further include a nickel (Ni) layer and / or a solder layer formed on the surface of the copper ball, as described below.

[0032] 4a to 4f are cross-sectional views illustrating steps of a process for manufacturing the printed circuit board of FIG.

[0033] Referring to the drawings, in FIG. 4a, an insulating layer 110 is prepared. The insulating layer 110 may be a glass layer such as a glass sheet as described above. Next, in FIG. 4b, a through hole H1 is formed in the insulating layer 110. The through hole H1 may be formed to have a tapered shape by etching after disposing a mask on the upper surface of the insulating layer 110, for example, a glass layer, but is not limited thereto, and may be formed by other chemical methods or mechanical methods, for example. A plurality of through holes H1 may be formed, and each through hole H1 may be the same or different. Next, in FIG. 4c, a metal ball 150 is inserted into the through hole H1. The metal ball 150 may be seated in contact with the inclined wall surface of the tapered through hole H1. Next, in FIG. 4d, a first seed metal layer m1 is formed on the upper surface of the insulating layer 110 and the upper region R1 of the through hole H1. The first seed metal layer m1 may be formed by sputtering, but is not limited thereto. Next, in FIG. 4e, a second seed metal layer m2 is formed on the lower surface of the insulating layer 110 and the lower region R2 of the through hole H1. The second seed metal layer m2 may be formed by sputtering, but is not limited thereto. Next, in FIG. 4f, a first and second metal layer M1, M2 is formed on the upper and lower surfaces of the insulating layer 110 and the upper and lower regions R1, R2 of the through hole H1. The first and second metal layers M1, M2 may be formed by, but are not limited to, fill plating based on the first and second seed metal layers m1, m2 after patterning a dry film resist to form an opening for plating. Thereafter, unnecessary portions of the first and second seed metal layers m1, m2 are removed by seed etching, etc., to form the first and second metal wirings 120, 130 and the metal via 140. Through a series of processes, the printed circuit board 100A according to the above-mentioned example can be formed, and other contents are substantially the same as those described above, so that repeated explanations will be omitted.

[0034] FIG. 5 is a cross-sectional view that illustrates a schematic diagram of another example of a printed circuit board.

[0035] Referring to the drawings, the printed circuit board 100B according to another example may have a through hole H2 in a cross section tapered on both sides such that the widths at the upper and lower ends are wider than any widths in the interior between the upper and lower ends in the printed circuit board 100A according to the above example. For example, the through hole H2 may have an hourglass shape. The metal ball 150 may be inserted and seated at the upper side of the through hole H2, but is not limited thereto, and may be inserted and seated at the lower side. Other contents are substantially the same as those described above, and therefore, repeated description will be omitted.

[0036] 6a to 6f are cross-sectional views illustrating steps of a manufacturing method for the printed circuit board of FIG.

[0037] 4a to 4f, except that the shape of the through hole H2 is changed, the printed circuit board 100B according to the other example described above can be formed in substantially the same process as that of the above-mentioned FIG. 4a to FIG. 4f. For example, the through hole H2 can be formed to have a tapered shape on both sides by forming a first hole having a tapered shape by a first etching after disposing a first mask on the upper surface of the insulating layer 110, for example, a glass layer, and then forming a second hole having a tapered shape by a second etching after disposing a second mask on the lower surface of the glass layer. However, the through hole H2 is not limited thereto, and can be formed by, for example, other chemical methods or mechanical methods.

[0038] 7a to 7c are cross-sectional views that diagrammatically show various examples of metal balls.

[0039] Referring to the drawings, as shown in FIG. 7a, the metal ball 150A may have a shape in which a nickel (Ni) plating layer 152 is formed on the surface of a substantially spherical copper ball 151. Or, as shown in FIG. 7b, the metal ball 150B may have a shape in which a nickel (Ni) plating layer 152 is formed on the surface of a substantially spherical copper ball 151, and a solder plating layer 153 is further formed on the surface of the nickel (Ni) plating layer 152 to a thickness greater than that of the nickel (Ni) plating layer 152. Or, as shown in FIG. 7c, the metal ball 150C may have only the copper ball 151. In this way, the metal balls 150A, 150B, and 150C may have various shapes, and these may be applied as the metal balls 150 to the printed circuit board 100A according to the above-mentioned example or the printed circuit board 100B according to another example.

[0040] In the present invention, the term "cover" can include not only the case of covering entirely, but also the case of covering at least a part, and can include not only the case of covering directly, but also the case of covering indirectly. The term "fill" can include not only the case of filling completely, but also the case of filling approximately, for example, the case where some gaps or voids are present. The term "surround" can include not only the case of surrounding completely, but also the case of surrounding approximately.

[0041] In the present invention, the meaning of "on a cross section" can mean the cross-sectional shape when an object is cut vertically or the cross-sectional shape when the object is viewed from the side, and the meaning of "on a plane" can mean the planar shape when an object is cut horizontally or the planar shape when the object is viewed from the top or bottom.

[0042] In the present invention, the thickness, width, length, depth, etc. can be measured with a scanning microscope or optical microscope based on a cross section obtained by polishing or cutting the printed circuit board. The cut section can be a vertical section or a horizontal section, and each value can be measured based on the required cut section. If the value is not constant, the value can be determined by averaging the values ​​measured at any five points. The width of the upper end and / or lower end of the through hole can be measured on a cross section obtained by cutting the central axis of the through hole in the thickness direction of the board. The depth of the through hole can be measured as the distance from the upper end to the lower end of each object on a cross section obtained by cutting the central axis of each object in the thickness direction of the board.

[0043] In the present invention, for convenience, the terms lower, bottom, and bottom surface are used to mean the bottom with respect to the cross section of the drawing, and the terms upper, top, and top surface are used to mean the opposite direction. In addition, the terms side and side surface are used to mean the direction perpendicular to the top and bottom surfaces. Meanwhile, the thickness direction is used to mean the bottom and / or top with respect to the cross section of the drawing, just like the terms lower, bottom, bottom surface, upper, top, and top surface. However, this is a definition of the direction for convenience of explanation, and it goes without saying that the scope of the claims is not particularly limited by the description of the direction, and the concepts of top / bottom can be changed at any time.

[0044] In the present invention, the term "connected" refers to a concept that includes not only direct connection but also indirect connection via an adhesive layer or the like. Furthermore, the term "electrically connected" refers to a concept that includes both cases where the components are physically connected and cases where the components are not connected. Furthermore, the terms "first" and "second" are used to distinguish one component from another component, and do not limit the order and / or importance of the components. In some cases, the first component may be named the second component, and similarly the second component may be named the first component, without departing from the scope of the right.

[0045] The term "one example" used in the present invention does not mean the same embodiment, but is provided to emphasize and describe the unique features that are different from each other. However, the above-mentioned one example does not exclude that it is realized in combination with the features of another example. For example, even if the matter described in a specific example is not described in another example, it can be understood as a description of the other example, unless there is a description that is opposite or contradictory to the matter in the other example.

[0046] The terms used in the present invention are merely used to describe an example and are not intended to limit the present invention. In this case, the singular expression includes the plural expression unless the context clearly indicates otherwise. [Explanation of symbols]

[0047] 1000 electronic equipment 1010 Mainboard 1020 Chip related parts 1030 Network related parts 1040 Other parts 1050 Camera 1060 Antenna 1070 display 1080 Battery 1090 Signal Line 1100 Smartphone 1110 Motherboard 1120 parts 1121 Parts Package 1130 Camera Module 1140 Speaker 100A, 100B Printed Circuit Board 110 Insulating layer (glass layer) 120, 130 metal wiring 140 Metal Vias 150, 150A, 150B, 150C Metal ball 151 Copper Ball 152 Nickel layer 153 Solder layer m1, m2 Seed metal layers M1, M2 Metal layers H1, H2 Through holes R1, R2 Regions

Claims

1. An insulating layer; a through hole penetrating between an upper surface and a lower surface of the insulating layer and having an inclined wall surface; a metal ball disposed in the through hole and in contact with the inclined wall surface; a metal via filling the through hole and surrounding the metal ball.

2. The through hole is divided into an upper region and a lower region based on the metal ball, The printed circuit board according to claim 1 , wherein the upper region and the lower region have different areas on a cross section.

3. 3. The printed circuit board of claim 2, wherein the metal via includes a first seed metal layer disposed on the inclined wall surface in the upper region and covering a portion of the metal ball, a second seed metal layer disposed on the inclined wall surface in the lower region and covering another portion of the metal ball, a first metal layer disposed on the first seed metal layer in the upper region and filling a portion of the through hole, and a second metal layer disposed on the second seed metal layer in the lower region and filling the other portion of the through hole.

4. The printed circuit board of claim 3 , further comprising a first metal wiring and a second metal wiring disposed on the upper and lower surfaces of the insulating layer, respectively, and connected to each other through the metal via.

5. the first metal wiring includes the first seed metal layer disposed on the upper surface of the insulating layer, and the first metal layer disposed on the first seed metal layer; The printed circuit board of claim 4 , wherein the second metal wiring includes the second seed metal layer disposed on the lower surface of the insulating layer, and the second metal layer disposed on the second seed metal layer.

6. the first seed metal layer and the second seed metal layer each include copper; The printed circuit board of claim 5 , wherein the first metal layer and the second metal layer each comprise copper.

7. The printed circuit board according to claim 1 , wherein the through hole has a tapered shape such that a width at an upper end is wider than a width at a lower end in cross section.

8. 2. The printed circuit board of claim 1, wherein the through hole has a tapered shape on both sides such that the width at each of the upper and lower ends in cross section is wider than any width in an interior portion between the upper and lower ends.

9. The printed circuit board of claim 1 , wherein the insulating layer comprises a glass layer.

10. The printed circuit board of claim 1 , wherein the metal balls comprise copper balls.

11. The printed circuit board of claim 10 , wherein the metal ball further comprises a nickel layer covering a surface of the copper ball.

12. The printed circuit board of claim 11 , wherein the metal ball further comprises a solder layer covering a surface of the nickel layer.

13. an insulating layer having a through hole; A metal ball disposed in the through hole; a first seed metal layer disposed on the upper surface of the insulating layer, extending from an upper region of the through hole onto a wall surface of the through hole and covering a portion of the metal ball; a second seed metal layer disposed on the lower surface of the insulating layer, extending from a lower region of the through hole onto a wall surface of the through hole to cover another portion of the metal ball; a first metal layer disposed on the first seed metal layer and filling a portion of the through hole in an upper region of the through hole; a second metal layer disposed on the second seed metal layer and filling another portion of the through hole in a lower region of the through hole.

14. The wall surface of the through hole has a shape in which at least a part is inclined, The printed circuit board according to claim 13 , wherein the metal ball contacts an inclined portion of a wall surface of the through hole.

15. the insulating layer includes a glass layer; The metal balls include copper balls, the first seed metal layer and the second seed metal layer each include copper; 14. The printed circuit board of claim 13, wherein the first metal layer and the second metal layer each comprise copper.

Images