Printed circuit board

Abstract

To provide a printed circuit board having a highly reliable fine metal layer. [Solution] One embodiment of the present invention provides a printed circuit board comprising a first insulating layer 110 including a protrusion P, and a metal layer 130 disposed on the protrusion P of the first insulating layer, wherein the protrusion P has a shape in which the width at its lowest point is wider than the width at its highest point.

Description

Technical Field

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[0001] The present invention relates to a printed circuit board.

Background Art

[0002] Recently, in order to meet the trend of lighter weight and smaller size of mobile devices, there has been an increasing need to achieve a thinner, lighter, shorter, and smaller printed circuit board implemented thereon. On the other hand, during the process of realizing a fine circuit while the mobile device is being made thinner, lighter, shorter, and smaller, an undercut phenomenon occurs, which may cause defects in the fine circuit. In response to the technical requirements for this, research has continued to improve the reliability while realizing a circuit with a fine line width and pitch.

Summary of the Invention

Problems to be Solved by the Invention

[0003] One of the objects of the present invention is to provide a printed circuit board having a highly reliable fine metal layer.

Means for Solving the Problems

[0004] As a method for solving the above problems, a novel structure of a printed circuit board is proposed through an example. Specifically, a printed circuit board according to an embodiment of the present invention includes a first insulating layer including a protruding portion, and a metal layer disposed on the protruding portion of the first insulating layer, and the protruding portion has a shape in which the width of the lowermost part is wider than the width of the uppermost part.

[0005] In one embodiment, the protruding portion may have a shape in which the width increases from the uppermost part toward the lowermost part.

[0006] In one embodiment, the metal layer may have a shape in which the width of the lowermost part is wider than the width of the uppermost part.

[0007] In one embodiment, the metal layer may have a shape in which its width increases from the top to the bottom.

[0008] In one embodiment, the width of the lowest part of the metal layer may be narrower than the width of the lowest part of the protrusion.

[0009] In one embodiment, the width of the lowest part of the metal layer and the width of the upper part of the protrusion may be the same as each other.

[0010] In one embodiment, in the region where the metal layer and the protrusion are connected, the side surface of the metal layer and the side surface of the protrusion can be coplane in at least a portion of the region.

[0011] In one embodiment, the metal layer and the protrusion may have a shape in which the width increases from the top of the metal layer to the bottom of the protrusion.

[0012] In one embodiment, the metal layer may include a seed layer and a plating layer disposed on the seed layer.

[0013] In one embodiment, the width of the lowest part of the seed layer may be wider than the width of the lowest part of the plating layer.

[0014] In one embodiment, the seed layer may not extend beyond the region away from the protrusion from the first insulating layer.

[0015] In one embodiment, the first insulating layer includes a plurality of protrusions, and the width of the lowest part of the metal layer may be wider than the spacing between adjacent protrusions.

[0016] In one embodiment, the width of the uppermost part of the metal layer may be wider than the spacing between adjacent protrusions among the plurality of protrusions.

[0017] In one embodiment, the width of the lowermost part of the protruding portion may be wider than the interval between the adjacent protruding portions among the plurality of protruding portions.

[0018] In one embodiment, the metal layer may have the same width at the uppermost part and the lowermost part.

[0019] In one embodiment, the upper surface of the metal layer may include a curved surface.

[0020] In one embodiment, the upper surface of the metal layer may have a pointed shape.

Effect of the Invention

[0021] In the case of the printed circuit board according to an example of the present invention, a metal layer having fineness and high reliability can be realized.

Brief Description of the Drawings

[0022] [Figure 1] It is a block diagram schematically showing an example of an electronic device system. [Figure 2] It is a perspective view schematically showing an example of an electronic device. [Figure 3] It is a cross-sectional view schematically showing an example of a printed circuit board. [Figure 4] It is a plan view seen from above of a metal layer disposed on a protruding portion of a first insulating layer. [Figure 5] It is a cross-sectional view schematically showing another example of a printed circuit board. [Figure 6] It is a cross-sectional view schematically showing another example of a printed circuit board. [Figure 7] It is a cross-sectional view schematically showing another example of a printed circuit board. [Figure 8] An example of a method for manufacturing a printed circuit board is shown. [Figure 9] An example of a method for manufacturing a printed circuit board is shown. [Figure 10] An example of a method for manufacturing a printed circuit board is shown. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described below with reference to specific embodiments and accompanying drawings. However, embodiments of the present invention can be modified into several other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to give a more complete explanation of the present invention to a person of the ordinary skill. Accordingly, the shapes and sizes of elements in the drawings may be enlarged or reduced (or highlighted or simplified) for a clearer explanation, and elements indicated by the same reference numerals in the drawings are the same elements.

[0024] [Electronic equipment] Figure 1 is a block diagram illustrating an example of an electronic equipment system.

[0025] Referring to the drawing, the electronic device 1000 houses the main board 1010. The main board 1010 is physically and / or electrically connected to chip-related components 1020, network-related components 1030, and other components 1040, etc. These, in combination with other electronic components described later, form various signal lines 1090.

[0026] 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., CPUs), graphics processors (e.g., GPUs), digital signal processors, cryptographic processors, microprocessors, and microcontrollers; and logic chips such as analog-to-digital converters and ASICs (application-specific ICs). Furthermore, these chip-related components 1020 can be combined with each other. The chip-related components 1020 can also be in the form of a package containing the aforementioned chips or electronic components.

[0027] Network-related component 1030 includes, but is not limited to, any other wireless and wired protocols designated as Wi-Fi (IEEE 802.11 family, etc.), WiMAX (IEEE 802.16 family, etc.), IEEE 802.20, LTE (long term evolution), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPS, GPRS, CDMA, TDMA, DECT, Bluetooth®, 3G, 4G, 5G, and later. It may also include any other numerous wireless or wired standards or protocols. Furthermore, network-related component 1030 can be combined with chip-related component 1020.

[0028] Other components 1040 include high-frequency inductors, ferrite inductors, power inductors, ferrite beads, LTCCs (low-temperature co-firing ceramics), EMI (electromagnetic interference) filters, and MLCCs (multi-layer ceramic condensers). However, they are not limited to these, and may also include passive elements in the form of chip components used for various other applications. Furthermore, other components 1040 can be combined with chip-related components 1020 and / or network-related components 1030.

[0029] Depending on the type of electronic device 1000, it may include other electronic components that are physically and / or electrically connected to the main board 1010, or not connected. Examples of other electronic components include a camera module 1050, an antenna module 1060, a display 1070, and a battery 1080. However, it is not limited to these, and may also include audio codecs, video codecs, power amplifiers, compasses, accelerometers, gyroscopes, speakers, mass storage devices (e.g., hard disk drives), CDs (compact disks), DVDs (digital versatile disks), etc. In addition, depending on the type of electronic device 1000, it may also include other electronic components used for various purposes.

[0030] Electronic device 1000 can be a smartphone, personal digital assistant, digital video camera, digital still camera, network system, computer, monitor, tablet, laptop, netbook, television, video game, smartwatch, automobile, etc. However, it is not limited to these, and can also be any other electronic device that processes data.

[0031] Figure 2 is a schematic perspective view showing an example of an electronic device.

[0032] Referring to the drawings, the electronic device could be, for example, a smartphone 1100. Inside the smartphone 1100 is a motherboard 1110, to which various components 1120 are physically and / or electrically connected. Furthermore, other components, such as a camera module 1130 and / or a speaker 1140, are housed inside the motherboard 1110, either physically and / or electrically connected or not. Some of the components 1120 can be the chip-related components described above, and can be, for example, a component package 1121, but are not limited to this. The component package 1121 can be in the form of a printed circuit board on which electronic components, including active and / or passive components, are mounted on the surface. Alternatively, the component package 1121 can be in the form of a printed circuit board with the active and / or passive components embedded within it. On the other hand, the electronic device is not necessarily limited to a smartphone 1100, and as described above, it can be other electronic devices.

[0033] [Printed circuit board] Figure 3 is a schematic cross-sectional view showing an example of a printed circuit board, and Figure 4 is a plan view from above of a metal layer placed on a protrusion of the first insulating layer. Referring to Figures 3 and 4, the printed circuit board according to this embodiment includes first and second insulating layers 110 and 120, and a metal layer 130, where the first insulating layer 110 includes a protrusion P. The metal layer 130 is placed on the protrusion P of the first insulating layer 110, and the protrusion P has a shape in which the width W1 at the bottom is wider than the width W2 at the top. This shape of the protrusion P can be obtained by an anisotropic etching process to minimize undercuts of the metal layer 130, as will be described later. The main components of the printed circuit board will be described in detail below.

[0034] The first insulating layer 110 may include an insulating material. The insulating material may include a thermosetting resin such as epoxy resin, a thermoplastic resin such as polyimide, or a material containing such a resin along with an inorganic filler, an organic filler, and / or glass fiber (glass cloth, and / or glass fabric). The insulating material may be a photosensitive material and / or a non-photosensitive material. For example, insulating materials such as SR (Solder Resist), ABF (Ajinomoto Build-up Film), FR-4, BT (Bismaleimide Triazine), PPG (Prepreg), RCC (Resin Coated Copper), and CCL (Copper Clad Laminate) can be used, but are not limited to these, and other polymer materials may also be used.

[0035] In this embodiment, the first insulating layer 110 includes protrusions P. For example, the first insulating layer 110 may include a plurality of protrusions P formed on its upper surface. As described above, the protrusions P are realized in a shape where the width W1 at the bottom is wider than the width W2 at the top. As a more specific example, the shape may be such that the width increases from the top to the bottom. Here, the widths W1 and W2 of the protrusions P may be widths measured at any cross-section, or they may be obtained by averaging values ​​measured at multiple cross-sections spaced at regular intervals. Such a method of measuring width can also be applied to the width of other regions.

[0036] The second insulating layer 120 may be placed on the first insulating layer 110, but may be omitted if necessary. The second insulating layer 120 may include, but is not limited to, one material from the group of insulating materials such as the first insulating layer 110. The second insulating layer 120 can be placed on the first insulating layer 110 to embed the metal layer 130. A structure in which the metal layer 130 is embedded in the second insulating layer 120 means that the sides and top of the metal layer 130 are covered by the second insulating layer 120, while the bottom of the metal layer 130 is not covered by the second insulating layer 120 and is exposed to the bottom surface of the second insulating layer 120. In Figure 3, the second insulating layer 120 is shown to be placed on the first insulating layer 110, but is not limited to this, and the top-bottom relationship in the drawing is merely a direction set for convenience. Considering the inverted printed circuit board shown in Figure 3, the structure of the printed circuit board described in this example can also be applied to so-called coreless structures manufactured using a carrier board.

[0037] On the other hand, the printed circuit board according to one example may further include insulating layers and metal layers disposed on the lower surface of the first insulating layer 110 and the upper surface of the second insulating layer 120, and may further include vias that connect the metal layers. Furthermore, it is not limited to this, and may further include other insulating layers, other circuit patterns, through-vias and cavities, which are common components of a printed circuit board, and may further include components that can be used by a person with ordinary skill in the art.

[0038] The metal layer 130 is positioned on the protrusions P of the first insulating layer 110, but a portion of it may also exist in other areas besides the protrusions P. The metal layer 130, while formed on the protrusions P, can have a shape similar to that of the protrusions P. Specifically, as shown in the illustrated form, the metal layer 130 may have a shape in which the width W2 at the bottom is wider than the width W3 at the top. More specifically, the metal layer 130 may have a shape in which the width increases from the top to the bottom. Also, the width W2 at the bottom of the metal layer 130 may be narrower than the width W1 at the bottom of the protrusions P. Furthermore, the width W2 at the bottom of the metal layer 130 and the width W2 at the top of the protrusions P may be the same. However, contrary to this, the metal layer 130 may be realized in a form in which the width W2 at the bottom is even wider or narrower than the width W2 at the top of the protrusions P. More specifically, in the region where the metal layer 130 and the protrusion P are connected, the side surfaces of the metal layer 130 and the side surfaces of the protrusion P can form a coplane in at least a portion of the region. This makes it possible to achieve a shape in which the width of the metal layer 130 and the protrusion P increases from the top of the metal layer 130 to the bottom of the protrusion P.

[0039] Such forms of the metal layer 130 and the protrusion P can be obtained through an anisotropic etching process to remove the seed layer 131, in which case the remaining area that is not removed as a portion of the first insulating layer 110 is removed can become the protrusion P. In this case, on the other hand, in the embodiment of Figure 3, the upper surface of the metal layer 130 has a flat shape, but the upper surface of the metal layer 130 may be realized in a non-flat shape, as in the modified examples of Figures 5 and 6. Specifically, Figure 5 shows an example in which the upper surface of the metal layer 130 is realized in a pointed shape, and Figure 6 shows an example in which the upper surface of the metal layer 130 is realized in a curved shape. Such modified forms of the upper surface of the metal layer 130 can be obtained by adjusting the etching process described later. Furthermore, the metal layer 130 does not necessarily have to have the shape shown in Figure 3, and there may be no substantial change in width. That is, as in the modified example of Figure 7, the uppermost and lowermost widths of the metal layer 130 may be the same shape.

[0040] The metal layer 130 may include a seed layer 131 and a plating layer 132 placed on the seed layer 131, in which case the seed layer 131 may be in contact with the protrusion P. The seed layer 131 can serve as a seed for forming the plating layer 132. Considering this function, the seed layer 131 may contain copper (Cu), and may also contain aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof. In the case of the seed layer 131, it may be patterned in such a way that it is broadly formed on the first insulating layer 110 and then partially removed, as will be described later with respect to the process. In this embodiment, undercuts of the metal layer 130 are minimized in such a process, thereby obtaining the protrusion P of the first insulating layer 110 and the metal layer 130 in the form described above. In this case, the width W2 of the bottom of the seed layer 131 may be wider than the width W4 of the bottom of the plating layer 132. Furthermore, by removing a portion of the seed layer 131 and forming a metal layer 130 corresponding to the circuit pattern, the seed layer 131 can be prevented from extending beyond the protruding portion P from the first insulating layer 110.

[0041] The plating layer 132 can be placed on the seed layer 131. The plating layer 132 may include copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof. The plating layer 132 can be a general circuit pattern and can be formed with multiple patterns. The multiple patterns can send and receive electrical signals with each other, and can also send and receive electrical signals with other metal layers further placed on other layers. On the other hand, the multiple patterns can also function by electrically short-circuiting with other patterns, and can perform various functions depending on the design, such as mounting components. The plating layer 132 can be formed via electroplating or the like using the seed layer 131 as a seed. The detailed process can be one of the following: SAP (Semi Additive Process), MSAP (Modified Semi Additive Process), TT (Tenting), or subtractive process. However, it is not limited to these methods; any known method of forming a circuit pattern using electroplating with a seed layer can be used without restriction.

[0042] On the other hand, the seed layer 131 can function as a seed layer for plating the plating layer 132, and the plating layer 132 can function as a pattern or the like, so the thickness of the plating layer 132 can be formed to be greater than the thickness of the seed layer 131. In this case, the thickness of the seed layer 131 and the thickness of the plating layer 132 can represent the vertical distance between their respective upper and lower surfaces. That is, the thickness of the seed layer 131 and the thickness of the plating layer 132 can represent the thickness of the printed circuit board in the stacking direction.

[0043] The metal material of the seed layer 131 and the metal material of the plating layer 132 may be the same, but are not limited to this, and may include different metal materials. For example, the seed layer 131 and the plating layer 132 may each be metal layers containing copper (Cu), but are not necessarily limited to this. Further examples include the seed layer 131 containing materials such as aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof, while the plating layer 132 may contain copper (Cu). In other words, the seed layer 131 and the plating layer 132 may contain different metal materials.

[0044] When the protrusions P and metal layers 130 are formed using the method described above, undercuts in the metal layers 130 are minimized, allowing for miniaturization of the metal layers 130 while also achieving narrow spacing between them. As a result, the width W1 at the bottom of the protrusions P may be wider than the spacing W5 between adjacent protrusions P. Similarly, the width W2 at the bottom of the metal layers 130 may be wider than the spacing W5 between adjacent protrusions P. In a more limited example, the width W3 at the top of the metal layers 130 may be wider than the spacing W5 between adjacent protrusions P.

[0045] Referring to Figures 8 to 10, an example of a method for manufacturing a printed circuit board will be described. First, referring to Figure 8, a seed layer 131 is formed on the first insulating layer 110. The seed layer 131 can be formed by a known electroless plating method, but is not limited to this, and it is also possible to prepare a material on which the seed layer 131 is formed on the first insulating layer 110. The seed layer 131 can function as a seed for plating the plating layer 132 in the plating layer formation stage, which will be described later. Next, a mask layer 200, for example, a dry film resist (DFR), is placed on the seed layer 131. The mask layer 200 can be a known dry film material, but is not necessarily limited to a dry film resist (DFR), and can be used without restriction as long as it can function as a plating resist. After placing the mask layer 200 on the seed layer 131, a portion of the mask layer 200 can be patterned by exposure and development. Subsequently, in the step of forming the plating layer 132, which will be described later, the mask layer 200 can function as a plating resist, and the plating layer 132 can be formed on the region of the seed layer 131 where the mask layer 200 is not formed.

[0046] Next, a plating layer 132 is formed on the seed layer 131. The plating layer 132 can be formed using the seed layer 131 as a seed through an electroplating process or the like. As described above, the plating layer 132 can be formed in the area of ​​the seed layer 131 where the mask layer 200 has not been formed. After this, the mask layer 200 is removed. The mask layer 200 can be removed using known methods such as delamination.

[0047] Next, referring to Figure 9, the seed layer 131 is removed to realize the circuit pattern, thereby obtaining the metal layer 130 and the first insulating layer 110 described above. Figure 10 shows the state after the seed layer 131 process. In the case of the seed layer 131 process, an anisotropic etching process, such as a dry etching method using plasma gas, can be used. By using such a dry etching method, the seed layer 131 that is exposed without being covered by the plating layer 132 can be selectively removed, and the undercut of the metal layer 130 can be minimized, so that the spacing between metal layers 130 can be reduced while the metal layer 130 is being miniaturized. In addition, when using the dry etching method, some areas of the first insulating layer 110 that are not covered by the plating layer 132 can also be removed, and a protruding portion P can be formed that narrows in width from bottom to top. As a result, the width of the plating layer 132 can also be narrowed from bottom to top.

[0048] Of these other steps, the same configuration as in the manufacturing method of a printed circuit board described in one example or in another example can also be applied to the printed circuit board described in yet another example; therefore, redundant explanations regarding this will be omitted.

[0049] In this disclosure, "cross-sectional" can mean the cross-sectional shape when the object is cut vertically, or the cross-sectional shape when the object is viewed from the side. "Planar" can mean the shape when the object is cut horizontally, or the planar shape when the object is viewed from above or below.

[0050] In this disclosure, terms such as "upper," "top," and "upper surface" are used for convenience to mean the direction toward the surface on which electronic components can be mounted, based on the cross-section of the drawing, while terms such as "lower," "bottom," and "lower surface" are used to mean the opposite direction. However, these are merely definitions of directions for explanatory purposes, and it goes without saying that the scope of rights in the patent claims is not particularly limited by such descriptions of directions.

[0051] In this disclosure, the term "connected" includes not only direct connection but also indirect connection via an adhesive layer or the like. Furthermore, the term "electrically connected" includes both physically connected and unconnected cases. In addition, expressions such as "first," "second," etc., are used to distinguish one component from another and do not limit the order and / or importance of those components. In some cases, without departing from the scope of the rights, the first component may be named the second component, and similarly, the second component may be named the first component.

[0052] The expression "example" as used in this disclosure does not mean that each embodiment is identical to the others, but is provided to highlight and illustrate the unique and distinct features of each embodiment. However, the examples presented above do not preclude their implementation in combination with features of other examples. For example, even if a matter described in one example is not described in another example, it can be understood as a description related to the other example, unless there is a description in the other example that contradicts or inconsistes with that matter.

[0053] The terms used in this disclosure are for illustrative purposes only and are not intended to limit the disclosure. Where otherwise, singular expressions include plural expressions unless the context clearly indicates otherwise. [Explanation of symbols]

[0054] 1000 electronic equipment 1010 Mainboard 1020 Chip-related components 1030 Network-related components 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 speakers 110 First insulating layer 120 Second insulating layer 130 Metal layer 131 Seed Layer 132 Plating layer P protrusion

Claims

1. A first insulating layer including a protruding portion, The first insulating layer includes a metal layer disposed on the protruding portion, The aforementioned protrusion is a printed circuit board in which the width at the bottom is wider than the width at the top.

2. The printed circuit board according to claim 1, wherein the protruding portion has a shape in which the width increases from the top to the bottom.

3. The printed circuit board according to claim 1, wherein the metal layer has a shape in which the width of the lowest part is wider than the width of the upper part.

4. The printed circuit board according to claim 1, wherein the metal layer has a shape in which the width increases from the top to the bottom.

5. The printed circuit board according to claim 1, wherein the width of the lowest part of the metal layer is narrower than the width of the lowest part of the protrusion.

6. The printed circuit board according to claim 1, wherein the width of the lowest part of the metal layer and the width of the upper part of the protrusion are the same as each other.

7. The printed circuit board according to claim 1, wherein in the region where the metal layer and the protrusion are connected, the side surface of the metal layer and the side surface of the protrusion form a coplane in at least a portion of the region.

8. The printed circuit board according to claim 7, wherein the metal layer and the protrusions have a shape in which the width increases from the top of the metal layer to the bottom of the protrusions.

9. The printed circuit board according to claim 1, wherein the metal layer includes a seed layer and a plating layer disposed on the seed layer.

10. The printed circuit board according to claim 9, wherein the width of the lowest part of the seed layer is wider than the width of the lowest part of the plating layer.

11. The printed circuit board according to claim 9, wherein the seed layer does not extend from the first insulating layer to the region away from the protruding portion.

12. The first insulating layer includes a plurality of protrusions, The printed circuit board according to claim 1, wherein the width of the lowest part of the metal layer is wider than the distance between adjacent protrusions among the plurality of protrusions.

13. The printed circuit board according to claim 12, wherein the width of the uppermost part of the metal layer is wider than the distance between adjacent protrusions among the plurality of protrusions.

14. The printed circuit board according to claim 12, wherein the width of the lowest part of the protrusion is wider than the distance between adjacent protrusions among the plurality of protrusions.

15. The printed circuit board according to claim 1, wherein the uppermost and lowermost widths of the metal layer are the same.

16. The printed circuit board according to claim 1, wherein the upper surface of the metal layer includes a curved surface.

17. The printed circuit board according to claim 1, wherein the upper surface of the metal layer has a pointed shape.

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