Printed circuit board

Abstract

The present invention provides a printed circuit board in which the protective layer protecting the pads has improved structural stability. [Solution] The printed circuit board according to the present invention has an insulating layer 101, a first pad 111 disposed on the insulating layer 101, and a protective layer 120 disposed on the insulating layer 101. The protective layer 120 includes a base portion 121 having an opening O that exposes a part of the first pad 111, a dam portion 122 disposed on the base portion 121 and narrower than the base portion 121, and a connecting portion 123 disposed between the base portion 121 and the dam portion 122. The connecting portion 123 is wider than the dam portion 122 and narrower than the base portion 121, and the base portion 121, the dam portion 122, and the connecting portion 123 are an integral structure.

Description

Technical Field

[0001] The present invention relates to a printed circuit board, and more particularly to a printed circuit board with improved structural stability of a protective layer for protecting pads.

Background Art

[0002] In recent years, in order to meet the trend of weight reduction and miniaturization of mobile devices, there has been an increasing need to achieve thinner, lighter, shorter, and smaller printed circuit boards mounted on these devices. On the other hand, as mobile devices become thinner, lighter, shorter, and smaller, an undercut phenomenon occurs during the process of realizing a fine circuit, which may cause defects in the fine circuit.

[0003] In response to the technical requirements for this, it has become an issue to continue research for improving reliability while realizing a circuit with a fine line width and pitch.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made in view of the above problems in the conventional printed circuit board, and an object of the present invention is to provide a printed circuit board in which the structural stability of a protective layer for protecting pads is improved.

Means for Solving the Problems

[0005] The printed circuit board according to the present invention made to achieve the above object has an insulating layer, a first pad disposed on the insulating layer, and a protective layer disposed on the insulating layer. The protective layer includes a base portion having an opening for exposing a part of the first pad, a dam portion disposed on the base portion and narrower in width than the base portion, and a connection portion disposed between the base portion and the dam portion. The connection portion is wider in width than the dam portion and narrower in width than the base portion, and the base portion, the dam portion, and the connection portion are of an integral structure.

[0006] The connecting portion preferably includes a curved surface. In the dam section, it is preferable that the side surface separated from the base section has a flat surface. The plane is preferably positioned perpendicular to the upper surface of the insulating layer. The lower surface of the base portion is preferably in contact with an area of ​​the first pad that is not exposed by the opening. Preferably, the insulating layer is disposed of therein, and its upper surface is covered by the base portion. Preferably, the connecting portion has a shape in which the width increases from the top to the bottom of the dam portion. The connection portion preferably includes a plurality of sides that are discontinuously connected to one another. The connecting portion preferably includes a first side and a second side arranged in order of proximity to the base portion, and each of the first and second side portions preferably has a shape in which the width increases from the top to the bottom of the dam portion. Preferably, each of the aforementioned multiple sides includes a curved surface.

[0007] Preferably, the insulating layer further includes a second pad located on the outside of the dam portion. The second pad is preferably wider than the first pad. Preferably, the base portion further includes an opening that exposes a part of the second pad. Preferably, the device further includes a third pad positioned on the first pad and a fourth pad positioned on the second pad. The side surface of the base portion is preferably in contact with the side surfaces of the third pad and the fourth pad. The thickness of the third pad and the fourth pad is preferably greater than the thickness of the base portion. The protective layer preferably contains a photosensitive substance. [Effects of the Invention]

[0008] According to the printed circuit board of the present invention, In a protective layer that protects a pad, the structural stability of the protective layer can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] This block diagram shows a schematic configuration of an electronic device system according to an embodiment of the present invention. [Figure 2] This is a schematic perspective view showing an example of an electronic device according to an embodiment of the present invention. [Figure 3] This is a schematic plan view showing an example of a printed circuit board according to an embodiment of the present invention. [Figure 4] Figure 3 is a cross-sectional view of a portion of the printed circuit board. [Figure 5] This is a magnified view of the protective layer of a printed circuit board according to an embodiment of the present invention. [Figure 6] This is a magnified view of the protective layer of a printed circuit board according to an embodiment of the present invention. [Figure 7] This is a schematic cross-sectional view showing another example of a printed circuit board according to an embodiment of the present invention. [Figure 8] This is a schematic cross-sectional view illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 9] This is a schematic cross-sectional view illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Figure 10] This is a schematic cross-sectional view illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] In the present invention as described herein, "on a cross-section" means the cross-sectional shape when the object is cut vertically, or the cross-sectional shape when the object is viewed from the side. In addition, the meaning in the plane refers to the shape when the object is horizontally cut, or the planar shape when the object is viewed from a top view or a bottom view. In the present invention of this specification, terms such as "upper side, upper part, upper surface" are used for convenience to mean the direction toward the surface on which the electronic component can be mounted based on the cross-section of the drawing, and terms such as "lower side, lower part, lower surface" are used as the opposite direction. However, this is for convenience of explanation to define the direction, and it is needless to say that the scope of rights in the claims is not particularly limited by the description regarding such a direction.

[0011] In the present invention of this specification, "connected" is a concept that includes not only being directly connected but also being indirectly connected through an adhesive layer or the like. In addition, "electrically connected" is a concept that includes both the case of being physically connected and the case of not being connected. Furthermore, expressions such as "first, second" are used to distinguish one component from another component, and do not limit the order and / or importance of the component. In some cases, within the scope not departing from the scope of rights, the first component may be named the second component, and similarly, the second component may be named the first component.

[0012] The expression "an example" used in the present invention of this specification does not mean the same embodiment, but is provided to emphasize and explain the respective unique features that are different from each other. However, the above-mentioned example does not exclude being 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, in another example, it can be understood as related to the description of another example as long as there is no description contrary to or conflicting with that matter. The terms used in the present invention of this specification are merely used to explain an example and are not intended to limit the present invention. In this context, a singular expression includes plural expressions unless the meaning is clearly different.

[0013] Next, specific examples of embodiments for implementing the printed circuit board according to the present invention will be described with reference to the drawings.

[0014] However, embodiments of the present invention can be modified into various 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 invention to those of the ordinary skill. Therefore, the shape and size of elements in drawings may be exaggerated for the sake of clearer explanation, and elements indicated by the same reference numeral in drawings are the same element.

[0015] <Electronic equipment> Figure 1 is a block diagram showing a schematic configuration of an electronic device system according to an embodiment of the present invention. Referring to Figure 1, 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, among others. These components, along with other electronic components described later, form various signal lines 1090.

[0016] 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, of course, be combined with each other. The chip-related component 1020 may be in the form of a package that includes the chip and electronic components described above.

[0017] Network-related components 1030 include, but are 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. Furthermore, it goes without saying that the network-related component 1030 may be combined with the chip-related component 1020.

[0018] 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, this is not limited to these, and may also include other passive elements in the form of chip components used for various other different applications. Furthermore, it goes without saying that other components 1040 may be combined with chip-related components 1020 and / or network-related components 1030.

[0019] Depending on the type of electronic device 1000, the electronic device 1000 may include other electronic components that are or are not physically and / or electrically connected to the main board 1010. Other examples of electronic components include the camera module 1050, antenna module 1060, display 1070, and 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. Needless to say, other electronic components used for various purposes depending on the type of electronic device may also be included.

[0020] The electronic device 1000 may be a smartphone, personal digital assistant, digital video camera, digital still camera, network system, computer, monitor, tablet, laptop, netbook, television, video game, smartwatch, or automobile. However, this is not limited to these devices; it goes without saying that any other electronic device that processes data may also be used.

[0021] Figure 2 is a schematic perspective view showing an example of an electronic device according to an embodiment of the present invention. Referring to Figure 2, the electronic device is, for example, a smartphone 1100. Inside the smartphone 1100 is a motherboard 1110, to which various components 1120 are physically and / or electrically connected. Additionally, other components, such as the camera module 1130 and / or the speaker 1140, are housed inside, either physically and / or electrically connected to the motherboard 1110 or not. Some of the components 1120 may be the chip-related components described above, for example, the component package 1121, but are not limited to these. The component package 1121 may take the form of a printed circuit board on which electronic components, including active and / or passive components, are surface-mounted. Alternatively, the component package 1121 may be in the form of a printed circuit board containing active and / or passive components. On the other hand, it goes without saying that electronic devices are not necessarily limited to smartphones 1100, but can be other electronic devices as mentioned above.

[0022] <Printed circuit board> Figure 3 is a schematic plan view showing an example of a printed circuit board according to an embodiment of the present invention, Figure 4 is a cross-sectional view of a part of the printed circuit board in Figure 3, and Figures 5 and 6 show specific forms of protective layers that may be used in a printed circuit board according to an embodiment of the present invention. Referring to Figures 3 to 5, the printed circuit board 100 according to this embodiment includes an insulating layer 101, a first pad 111, and a protective layer 120, where the protective layer 120 includes a base portion 121, a dam portion 122, and a connecting portion 123.

[0023] The protective layer 120, by having a dam portion 122, can effectively protect the printed circuit board 100 during processes such as chip underfilling, and can, for example, protect the second pad 112 in the area outside the dam portion 122 on the printed circuit board 100. Furthermore, the base portion 121, dam portion 122, and connecting portion 123 that constitute the protective layer 120 are formed as a single integrated structure rather than being manufactured in separate processes. This prevents the problem of reduced structural stability caused by stress concentration at the joints between layers, which can occur when the protective layer 120 consists of multiple layers. Such an integrated protective layer 120 can improve structural stability and thus contribute to improving the performance of the printed circuit board 100. The main components of the printed circuit board 100 will be described in detail below. In the drawing, in relation to the definitions of the first direction D1, the second direction D2, and the third direction D3, the second direction D2 is defined as the width direction of the first pad 111, the third direction D3 is defined as the thickness direction of the first pad 111, and the first direction D1 is defined as the direction perpendicular to the second and third directions (D2 and D3).

[0024] The insulating layer 101 includes an insulating material and can be implemented in a multilayer structure. Here, the insulating material of the insulating layer 101 may include a thermosetting resin such as epoxy resin, a thermoplastic resin such as polyimide, or a material such as an inorganic filler, an organic filler, and / or glass fiber (glass cloth, and / or glass fabric) along with such a resin. The insulating material may be a photosensitive material and / or a non-photosensitive material. For example, insulating materials such as SR (Solder Resist), ABF (Registered Trademark) (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; other polymer materials may also be used.

[0025] The first pad 111 is placed on the insulating layer 101 and provided as an area connected to a semiconductor chip, package, interposer, etc. When the first pad 111 is placed on the insulating layer 101, it means that the first pad 111 is placed inside or on the surface of the insulating layer 101. As shown in the figure, the top surface of the first pad 111 is exposed from the insulating layer 101, and the remaining area is embedded in the insulating layer 101. The printed circuit board 100 may further include a conductor layer 110 and a second pad 112 in addition to the first pad 111. Here, the conductor layer 110 is placed on the insulating layer 101, and its upper surface is covered by the base portion 121 of the protective layer 120. The second pad 112 is positioned outside the dam portion 122 of the protective layer 120 in the insulating layer 101 and is wider than the first pad 111. In this case, the first pad 111 is provided as a chip mounting area, and the second pad 112 is provided as a connection area with a package, interposer, etc.

[0026] The conductive layer 110, the first pad 111, and the second pad 112 may contain highly electrically conductive metals, such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), and / or alloys thereof, and can be implemented in a multilayer structure as needed. Furthermore, the insulating layer 101 may include, in addition to the conductor layer 110, the first pad 111, and the second pad 112, conductor layers, pads, conductive vias, etc., arranged at different levels.

[0027] The protective layer 120 is placed on the insulating layer 101 and protects the conductor layer 110, the first pad 111, the second pad 112, and the like. In this embodiment, the protective layer 120 includes a base portion 121, a dam portion 122, and a connecting portion 123, which are realized as an integrated structure. Here, the base portion 121 has an opening O that exposes a part of the first pad 111. The dam section 122 is positioned on the base section 121 and is narrower in width than the base section 121. As can be seen from Figure 3, the dam section 122 may be in a form that surrounds the first pad 111 in the lateral direction, but it does not need to completely surround the first pad 111, and some areas may be left open. The connecting section 123 is positioned between the base section 121 and the dam section 122.

[0028] The connecting section 123 is wider than the dam section 122 and narrower than the base section 121. In other words, the base section 121, dam section 122, and connecting section 123 have the widest width W1 of the base section 121, the narrowest width W2 of the dam section 122, and the width W3 of the connecting section 123 is somewhere in between these two values. The widths (W1, W2, W3) of the base section 121, the dam section 122, and the connecting section 123 can be measured from the cross-section of the printed circuit board 100, with the width in the second direction D2 as the reference. To improve the accuracy of the measurement, an average value obtained from multiple cross-sections can be used. The width W1 of the base section 121 is defined as the width of the lowest part of the base section 121, the width W2 of the dam section 122 is defined as the width of the highest part of the dam section 122, and the width W3 of the connecting section 123 is defined as the width at the midpoint of the third direction D3.

[0029] As described above, in this embodiment, the base portion 121, dam portion 122, and connecting portion 123 included in the protective layer 120 are formed as an integrated structure, thereby improving structural stability. Specifically, when the base portion 121 and the dam portion 122 are formed in separate processes, for example, when a protective layer is achieved by laminating solder resist multiple times, stress may concentrate at these joint areas, which can lead to problems such as crack formation and reduced structural stability. This embodiment can mitigate such problems. The protective layer 120 contains a photosensitive material and functions as a solder resist. To achieve a one-piece protective layer 120, as described later, a method can be used in which the protective layer 120 is formed as a thick film and then etched to reduce its thickness.

[0030] When the dam section 122 is realized by the method described above, a connecting section 123 having the width between the base section 121 and the dam section 122 is formed at the connection point between them. In this case, the connecting portion 123 is realized in the form of an inclined surface. More specifically, as shown in the figure, the connecting portion 123 includes a curved surface S1, and by including the curved surface, the influence of stress that may be exerted on the periphery of the dam portion 122 can be reduced. In contrast, the side surface S2 of the dam section 122 that is separated from the base section 121 has a flat surface. In this case, the plane S2 of the dam section 122 is positioned perpendicular to the upper surface of the insulating layer 101. Such a flat surface S2 in the dam section 122 is an area that remains without being removed during the etching process described later.

[0031] As shown in Figure 4, the lower surface of the base portion 121 is in contact with the area of ​​the first pad 111 that is not exposed by the opening O. The base portion 121 further includes an opening O that exposes a part of the second pad 112. Furthermore, a portion of the base portion 121 covers the upper surface of the conductor layer 110.

[0032] Refer to Figure 5 for a more detailed explanation of the shape of the connection part 123. The width of the connecting section 123 is such that it increases or decreases as you move in one direction; for example, the width increases as you move from the top to the bottom of the dam section 122. In addition to this configuration, the connecting portion 123 may also include multiple sides (S11, S12) that are discontinuously connected to one another, as shown in the modified example in Figure 6. Such a multilayer structure of the connection portion 123 can be realized by using methods such as etching the protective layer 120 multiple times. In this case, the connecting portion 123 includes a first side surface S11 and a second side surface S12 arranged in order of proximity to the base portion 121, where each of the first and second side surfaces (S11, S12) has a shape in which the width increases from the top to the bottom of the dam portion 122. Furthermore, each of the multiple sides (S11, S12) of the connection portion 123 includes a curved surface.

[0033] Figure 7 is a schematic cross-sectional view showing another example of a printed circuit board according to an embodiment of the present invention. Referring to Figure 7, another modification is described, which is a configuration further equipped with additional pads (113, 114). Specifically, the third pad 113 is placed on the first pad 111, and the fourth pad 114 is placed on the second pad 112. The additionally provided third and fourth pads (113, 114) function as top ball pads. When the third and fourth pads (113, 114) are added, the sides of the base portion 121 are in contact with the sides of the third and fourth pads (113, 114), as shown in the figure. Furthermore, the thickness of the third and fourth pads (113, 114) is greater than the thickness of the base portion 121.

[0034] Figures 8 to 10 are schematic cross-sectional views illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. Referring to Figures 8 to 10, an example of a method for manufacturing a printed circuit board will be described. The following description will focus on the method for forming the protective layer 120, but for other components, the usual knowledge for manufacturing printed circuit boards can be utilized.

[0035] First, referring to Figure 8, a protective layer 120 is formed on the insulating layer 101, specifically by applying a thick film of photosensitive material, taking into consideration the thickness required to create the dam section. The insulating layer 101 may have a conductor layer, pads, conductive vias, etc., inside or on its surface. Figure 9 shows a configuration in which the insulating layer 101 is equipped with a conductor layer 110 and pads (111, 112). The insulating layer 101 and the conductive layer provided therewith can be formed using a substrate manufacturing method known in the art. Furthermore, if third and fourth pads (113, 114) are provided on the first and second pads (111, 112), a protective layer 120 is formed to cover the third and fourth pads (113, 114) after they have been formed.

[0036] Next, as shown in Figure 9, a portion of the protective layer 120 is exposed to form an exposed region 130. Exposure area 130 corresponds to the dam section. The exposed area 130 remains and is not removed in the subsequent etching process, thus forming part of the dam section. However, depending on how the etching process is carried out, the exposure process can also proceed in reverse, for example, by exposing the remaining area excluding the area indicated by reference numeral 130.

[0037] Next, as shown in Figure 10, the remaining area of ​​the protective layer 120, excluding the exposure area 130, is etched to reduce the thickness of the protective layer 120. In the case of the etching process, the process used in the photolithography process in this art can be used, and in this case, the etching process is carried out in such a way that the remaining area excluding the exposure area 130 is reduced in thickness rather than being completely removed, leaving a portion of it intact. In this process, the connection part of the form described above can be formed. Next, an additional exposure and etching process is performed to expose the first and second pads (111, 112) to realize a protective layer 120 as described above.

[0038] Among the other steps, configurations similar to those of the printed circuit board manufacturing method according to the embodiment of the present invention, or the printing circuit board manufacturing method according to other embodiments, can also be applied to printed circuit boards according to yet other embodiments; therefore, redundant explanations regarding these will be omitted.

[0039] Furthermore, the present invention is not limited to the embodiments described above. It can be modified and implemented in various ways without departing from the technical scope of the present invention. [Explanation of Symbols]

[0040] 100 Printed Circuit Boards 101 Insulating layer 110 Conductor layer 111 First Pad 112 Second pad 113 Third Pad 114 Pad 4 120 protective layer 121 Base section 122 Dam Section 123 Connection part 130 Exposure area 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 Component Package 1130 Camera Module 1140 speaker

Claims

1. Insulating layer and, A first pad disposed in the insulating layer, The insulating layer comprises a protective layer disposed on the insulating layer, The aforementioned protective layer is A base portion having an opening that exposes a part of the first pad, A dam section is positioned on the aforementioned base section and is narrower in width than the aforementioned base section, Includes a connecting portion disposed between the base portion and the dam portion, The connecting portion is wider than the dam portion and narrower than the base portion. A printed circuit board characterized in that the base portion, the dam portion, and the connecting portion are integrally structured.

2. The printed circuit board according to claim 1, characterized in that the connection portion includes a curved surface.

3. The printed circuit board according to claim 1, characterized in that the side surface of the dam portion that is separated from the base portion has a flat surface.

4. The printed circuit board according to claim 3, characterized in that the plane is arranged perpendicular to the upper surface of the insulating layer.

5. The printed circuit board according to claim 1, characterized in that the lower surface of the base portion is in contact with an area of ​​the first pad that is not exposed by the opening.

6. The printed circuit board according to claim 1, further comprising a conductive layer disposed on the insulating layer and whose upper surface is covered by the base portion.

7. The printed circuit board according to claim 1, characterized in that the connecting portion has a shape in which the width increases from the top to the bottom of the dam portion.

8. The printed circuit board according to claim 1, characterized in that the connection portion includes a plurality of sides that are discontinuously connected to one another.

9. The connecting portion includes a first side and a second side arranged in order of proximity to the base portion, The printed circuit board according to claim 8, characterized in that each of the first and second sides has a shape in which the width increases from the top to the bottom of the dam portion.

10. The printed circuit board according to claim 8, characterized in that each of the aforementioned multiple sides includes a curved surface.

11. The printed circuit board according to claim 1, further comprising a second pad disposed on the outside of the dam portion in the insulating layer.

12. The printed circuit board according to claim 11, characterized in that the second pad is wider than the first pad.

13. The printed circuit board according to claim 11, characterized in that the base portion further includes an opening that exposes a part of the second pad.

14. A third pad is placed on the first pad, The printed circuit board according to claim 11, further comprising a fourth pad disposed on the second pad.

15. The printed circuit board according to claim 14, characterized in that the side surface of the base portion is in contact with the side surfaces of the third pad and the fourth pad.

16. The printed circuit board according to claim 15, characterized in that the thickness of the third pad and the fourth pad is greater than the thickness of the base portion.

17. The printed circuit board according to claim 1, characterized in that the protective layer contains a photosensitive material.

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