KR20190038139A - Printed circuit board - Google Patents

Abstract

Provided is a printed circuit board which can reduce a void phenomenon of a solder bump. To this end, according to an embodiment of the present invention, the printed circuit board comprises: an insulating layer; a pad arranged on the insulating layer; and a protecting layer arranged on the insulating layer and having an opening exposing at least a part of the surface of the pad. The protecting layer includes: a first part arranged on the insulating layer; and a plurality of second parts protruding from the edge of an upper surface of the pad to the center of the upper surface of the pad, and exposing a central region of the upper surface of the pad.

Description

{PRINTED CIRCUIT BOARD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly, to a printed circuit board capable of improving a solder void phenomenon.

2. Description of the Related Art In recent years, application of a flip chip for forming a solder bump on a PCB (Printed Circuit Board) and connecting a device thereon is gradually increasing. In particular, in the case of a CPU and a graphic computing device that computes a large amount of data at a high speed, a flip chip which improves the connection resistance by connecting the substrate and the device with the solder in the technology of connecting the substrate and the device using the existing wire, Is increasing rapidly.

A solder bump formed on a substrate for connecting a chip and a substrate is formed by printing solder paste on a substrate and reflowing the substrate, a method of forming a fine solder ball on a substrate And a method in which molten solder is injected into the substrate directly or by using a mask. The solder bumps formed on the substrate are melted for connection with the terminals formed on the chip or the solder bumps, so that the solder bumps are bonded to each other.

On the other hand, in the case of the Pick & Place method, which is most commonly used, a vacuum hole is formed in the jig like the substrate pattern, and the solder ball is picked up in vacuum, ). In the Ball Placing method, an opening of the same size is formed in a metal mask, and then the solder ball is squeezed using a metal or urethane squeegee so that the solder ball is mounted on the pad of the substrate through the mask opening .

1 shows a printed circuit board according to the prior art.

Fig. 1 (a) is a plan view of a printed circuit board, and Fig. 1 (b) is a cross-sectional view of a printed circuit board.

1 (a) and 1 (b), a printed circuit board 10 includes an insulating layer 11, a circuit pattern 12 disposed at a predetermined interval on the insulating layer 11, And a protection layer (13) disposed on the circuit pattern (11) and having an opening (15) exposing at least a part of the surface of the circuit pattern (12). Here, a part of the circuit pattern 12 serves as a wiring for signal transmission, and a part of the circuit pattern 12 may be a pad on which solder bumps are disposed.

The protective layer 13 is disposed on the insulating layer 11 and has an opening 14 exposing the surface of the pad on which the solder bumps are disposed. At this time, the area of the opening 14 is narrower than the area of the upper surface of the pad.

In other words, the protective layer 13 covers the edge region of the pad and exposes only the central region of the pad. Accordingly, the pad has a first width W1, and the opening 14 of the passivation layer 13 has a second width W2 that is narrower than the first width W1.

The pad thus has a first region 12A exposed by the opening 14 of the protective layer 13 and disposed with solder bumps and a second region 12A covered by the protective layer 13, (12B).

However, when the solder bump is formed on the upper surface of the pad exposed through the opening 14, voids are generated in the solder bump, which is more than 30% of the total volume do.

Accordingly, in order to improve this, the reflow facility is changed from general reflow to vacuum reflow. However, the printed circuit board according to the related art has a problem in that a new facility investment occurs due to application of the reflow facility in a vacuum system, and manufacturing time increases according to the shape of the vacuum space.

The embodiments of the present invention provide a printed circuit board capable of improving the voiding phenomenon of the solder bumps by changing the shape of the protective layer.

In addition, according to the embodiment of the present invention, there is provided a printed circuit board capable of improving a void phenomenon of a solder bump by changing a shape of a pad.

In addition, according to the embodiment of the present invention, there is provided a printed circuit board capable of improving a void phenomenon of a solder bump by changing a shape of a solder bump.

Further, the technical problems to be solved by this embodiment are not limited to the above-mentioned technical problems, and other technical problems which are not mentioned can be attained by those having ordinary knowledge in the technical field to which the embodiments proposed from the following description belong It will be understood clearly.

A printed circuit board according to an embodiment includes an insulating layer; A pad disposed on the insulating layer; And a protective layer disposed over the insulating layer and having an opening exposing at least a portion of the surface of the pad, wherein the protective layer comprises: a first portion disposed over the insulating layer; And a plurality of second portions protruding toward the center of the upper surface of the pad and exposing a central region of the upper surface of the pad.

The plurality of second portions are disposed on the upper surface of the pad at a predetermined distance from one another.

The protective layer may further include a third portion disposed to surround an edge region of the upper surface of the pad, wherein the plurality of second portions extend from the third portion toward the center of the upper surface of the pad Respectively.

The pad further includes an adhesive member disposed on the pad exposed through the opening, wherein the adhesive member exposes a central region of the upper surface of the pad.

The adhesive member may include a first portion disposed on one side of the central region and a second portion disposed on the other side opposite to the one side of the central region, They are physically separated from each other.

The upper surface area of the second portion of the protective layer is 10% to 40% of the upper surface area of the entire remaining area except the edge area of the upper surface of the pad.

According to another aspect of the present invention, there is provided a printed circuit board comprising: an insulating layer; A pad disposed on the insulating layer; And a protective layer disposed on the insulating layer and having an opening exposing at least a part of the surface of the pad, wherein the pad includes a plurality of slits formed in the edge region toward the center of the pad, The protective layer is disposed on the insulating layer and the pad by exposing at least a part of the plurality of slits, wherein each of the plurality of slits has a first region in which the protective layer is inserted and a second region in which the surface of the insulating layer is exposed And a second region.

The protective layer may include a first portion disposed on the insulating layer and a second portion disposed on an edge region of the upper surface of the pad, wherein the width of the second portion is greater than the width of each of the plurality of slits It is narrower than width.

The pad further includes an adhesive member disposed on the pad exposed through the opening, wherein the adhesive member exposes a central region of the upper surface of the pad.

The adhesive member may include a first portion disposed on one side of the central region and a second portion disposed on the other side opposite to the one side of the central region, They are physically separated from each other.

Further, at least a part of the adhesive member is inserted into the second region of the plurality of slits and directly contacts the surface of the insulating layer.

The surface area of the pad exposed through the protective layer may be greater than or equal to 60 in the total area of the surface of the insulating layer exposed through the second region of the slit and the surface of the pad exposed through the protective layer. To 90%.

According to the embodiment of the present invention, voids inside the adhesive member can be removed by allowing gas generated inside the solder to be carried out through a region between the protective layer or the pad or the solder bump when the bonding member is reflowed.

In addition, according to the embodiment of the present invention, it is possible to reduce the occurrence of voids in the adhesive member even if the reflow operation is not performed in a vacuum state, thereby reducing manufacturing cost and manufacturing time.

In addition, according to the embodiment of the present invention, the reliability of the printed circuit board can be improved by preventing the voids in the adhesive member from exceeding 30% of the entire volume complying with the International Organization for Standardization (ISO) standard.

Further, according to the embodiment of the present invention, at least a part of the adhesive member is disposed inside the slit of the pad, so that the adhesive member is also brought into contact with the insulating layer, so that the adhesive force to the component can be improved.

1 shows a printed circuit board according to the prior art.
2 is a view illustrating a printed circuit board according to a first embodiment of the present invention.
3 is a plan view showing the pad and protective layer shown in Fig.
4 is a view showing a state where an adhesive member is disposed on the printed circuit board shown in FIG.
Fig. 5 is a view showing a modification of the arrangement of the adhesive member of Fig. 4;
6 is a view illustrating a printed circuit board according to a second embodiment of the present invention.
7 is a plan view showing the pad and protective layer shown in FIG.
8 is a view showing a state where an adhesive member is disposed on the printed circuit board shown in FIG.
9 is a modification of the printed circuit board according to the embodiment of the present invention.
FIGS. 10 to 15 are views showing the manufacturing method of the printed circuit board shown in FIG. 2 in the order of process.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the description of the embodiments, it is to be understood that each layer (film), region, pattern or structure is formed "on" or "under" a substrate, each layer The terms " on " and " under " encompass both being formed "directly" or "indirectly" The thickness and size of each layer in the drawings are exaggerated, omitted, or schematically shown for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size. Hereinafter, embodiments will be described with reference to the accompanying drawings.

2 is a plan view showing the pad and the protective layer shown in FIG. 2, FIG. 4 is a cross-sectional view illustrating a state in which the printed circuit board is bonded to the printed circuit board shown in FIG. Fig. 5 is a view showing a modification of the arrangement of the adhesive members of Fig. 4; Fig.

Hereinafter, a printed circuit board according to a first embodiment of the present invention will be described with reference to FIGS. 2 to 5. FIG.

Referring first to FIG. 2, a printed circuit board 100 includes an insulating layer 110, a pad 120, and a protective layer 130.

2 (a) is a plan view of the printed circuit board 100 viewed from above, and FIG. 2 (b) is a plan view of the printed circuit board 100 of FIG. 2 And FIG. 2C is a cross-sectional view of the printed circuit board 100 of FIG. 2A taken along line BB '.

The printed circuit board 100 according to the embodiment of the present invention is a support substrate to which components are attached, and more specifically, a BGA (Ball Grid Array) type package substrate to which components are attached in a flip chip manner by an adhesive member.

The insulating layer 110 may have a flat plate structure. At this time, the insulating layer 110 may be a printed circuit board (PCB). Here, the insulating layer 110 may be implemented as a single substrate, or alternatively, a plurality of substrates may be sequentially stacked.

That is, the insulating layer 110 is a support substrate of a device in which a single pattern is formed and on which components (not shown) are mounted.

The insulating layer 110 may mean an insulating layer on which any one of the multilayer boards having a plurality of laminated structures is to be formed.

The insulating layer 110 may be a thermosetting or thermoplastic polymer substrate, a ceramic substrate, an organic-inorganic composite substrate, or a glass fiber impregnated substrate. When the insulating layer 110 comprises a polymer resin, the insulating layer 110 may include an epoxy- Alternatively, it may contain a polyimide-based resin.

That is, the insulating layer 110 may include both a printed wiring board and an insulating substrate made of an insulating material capable of forming a conductor pattern on the surface of an insulating substrate on which an electric circuit capable of changing wiring is knitted. have.

The insulating layer 110 may be rigid or flexible. For example, the insulating layer 110 may comprise glass or plastic. In detail, the insulating layer 110 may include a chemically reinforced / semi-toughened glass such as soda lime glass or aluminosilicate glass, or may include polyimide (PI), polyethylene terephthalate (PET) ), Propylene glycol (PPG) polycarbonate (PC), or the like, or may include sapphire.

In addition, the insulating layer 110 may include an optically isotropic film. For example, the insulating layer 110 may include a Cyclic Olefin Copolymer (COC), a Cyclic Olefin Polymer (COP), a polycarbonate (PC) or a light polymethylmethacrylate (PMMA) .

In addition, the insulating layer 110 may be curved while partially having a curved surface. That is, the insulating layer 110 may be partially flat and partially curved with a curved surface. In detail, the end of the insulating layer 110 may have a curved surface, or may have a curved surface with a curvature, and may be curved or bent.

In addition, the insulating layer 110 may be a flexible substrate having a flexible characteristic. In addition, the insulating layer 110 may be a curved or bended substrate. At this time, the insulating layer 110 expresses the electric wiring connecting the circuit components based on the circuit design with the wiring diagram, and the electric conductor can be reproduced on the insulating material. In addition, the insulating layer 110 can form wiring for mounting electric components and connecting them in a circuit, and mechanically fixing components other than the electrical connection function of the components.

A plurality of pads 120 are disposed on the surface of the insulating layer 110 at regular intervals. Although not shown in the drawing, a plurality of wiring patterns (not shown) electrically connected to components such as the pads 120 and other terminals are disposed on the surface of the insulating layer 110, Electrical signals can be transmitted. In other words, a plurality of circuit patterns may be disposed on the surface of the insulating layer 110, and a part of the plurality of circuit patterns may be the wiring pattern, and the other part may be the pad 120.

The pad 120 is electrically connected to a component (not shown) mounted on the pad 120. Here, the part may be an element. The device may be divided into an active device and a passive device. The active device is a device that actively uses a nonlinear portion. The passive device refers to a device that does not use nonlinear characteristics even if both linear and nonlinear characteristics exist.

The passive element may include a transistor, an IC semiconductor chip, and the passive element may include a capacitor, a resistor, and an inductor. The passive element is mounted on a substrate together with a conventional semiconductor package in order to increase a signal processing speed of a semiconductor chip which is an active element, perform a filtering function, and the like.

Accordingly, a part of the circuit pattern serves as a wiring for signal transmission, another part serves as a pad for mounting the components, and another part serves as a terminal electrically connected to the components can do.

The pad 120 may be formed of a conductive metal material.

The pad 120 is formed of at least one metal material selected from gold (Au), silver (Ag), platinum (Pt), titanium (Ti), tin (Sn), copper (Cu), and zinc . The pad 120 may include at least one metal material selected from gold (Au), silver (Ag), platinum (Pt), titanium (Ti), tin (Sn), copper (Cu) The paste may further comprise a paste.

The pad 120 may be formed by a conventional manufacturing process of a printed circuit board such as an additive process, a subtractive process, a modified semi- additive process (MSAP), or a semi- additive process (SAP) And a detailed description thereof will be omitted here.

The plurality of pads 120 may be disposed on the insulating layer 110 at predetermined intervals. The number of the pads 120 may be determined according to the number of parts to be disposed on the insulating layer 110.

Meanwhile, the upper surface of the pad 120 may have a circular shape. Preferably, the overall shape of the pad 120 has a circular column shape and may be disposed on the surface of the insulating layer 110. However, this is merely an embodiment of the present invention, and the upper surface of the pad 120 may have any one of a rectangular shape, a polygonal shape, a triangular shape, and an elliptical shape. The pad 120 may have a vertical width of 0.85 mm and a horizontal width of 0.85 mm.

A protective layer 130 covering the surface of the insulating layer 110 is disposed on the insulating layer 110. The protective layer 130 may be a solder resist (SR) and has an opening 135 for opening at least a part of the surface of the pad 120 disposed on the insulating layer 110. At this time, the opening 135 exposes the central region of the pad 120. In addition, the opening 135 at least partially exposes not only the central region of the pad 120, but also a region between the edge region of the pad 120 and the central region.

In other words, the upper surface of the pad 120 may include a first region corresponding to the central region, a second region corresponding to the edge region, and a third region between the first and second regions.

The first region of the pad 120 may be exposed by the opening 135 of the passivation layer 130. In addition, the second region of the pad 120 may be completely covered with the protective layer 130. The third region of the pad 120 may include a portion covered by the protective layer 130 and a portion exposed by the opening 135 of the protective layer 130.

The upper surface of the pad 120 may include a first portion 120A exposed by the opening 135 of the protective layer 130 and a second portion 120A covered by the protective layer 130. [ 120B.

At this time, the pad 120 may have a fourth width W4 and may be disposed on the insulating layer 110. The portion of the opening 135 of the passivation layer 130 covered with the third region of the pad 120 may have a third width W3. At this time, the third width W3 corresponds to the width of the first region corresponding to the central region of the upper surface of the pad 120. [

The protective layer 130 may be divided into a first portion disposed only in a third region of the pad 120 and a second portion disposed in both the second region and the third region. The first portion of the passivation layer 130 may have a fifth width W5. Here, the fifth width W5 may correspond to the total width of the second region and the third region of the upper surface of the pad 120. [ Also, the second portion of the passivation layer 130 may have a sixth width W6. Here, the sixth width W6 may correspond to the width of the second region of the upper surface of the pad 120. [

Hereinafter, the pad 120 and the protective layer 130 will be described in more detail. 3 (a) is a plan view of the pad 120, and FIG. 3 (b) is a plan view of the protective layer 130. FIG.

Referring to FIG. 3 (a), the pad 120 is disposed on the insulating layer 110. The pad 120 includes a first portion 120A exposed through the opening 135 of the passivation layer 130 and a second portion 120B covered by the passivation layer 130 do. The second part 120B includes a second part 121 covered by the first area 132 of the protective layer 130 to be described later and a plurality of And a second -2 portion 122 covered by the second region 133. [

At this time, the second part (122) of the pad (120) may be divided into a plurality of parts. In other words, the second-second portions 122 covered by the plurality of second regions 133 of the protection layer 130 may be formed of a plurality of spaced-apart portions. Also, the plurality of second-second portions 122 are not directly connected to each other, but may be connected to each other only through the first portion 120A.

3B, the passivation layer 130 is disposed on the insulating layer 110 and has an opening 135 for exposing at least a part of the surface of the pad 120. As shown in FIG. The passivation layer 130 may include a region 131 disposed on the surface of the insulating layer 110 and regions 132 and 133 disposed on the surface of the pad 120.

The regions 132 and 133 of the passivation layer 130 disposed on the surface of the pad 120 include a first region 132 disposed in an edge region of the pad 120, And a plurality of second regions 133 protruding from an edge region of the pad 120 toward the center of the pad 120. Preferably, the first region 132 of the passivation layer 130 may be disposed in an edge region of the pad 120. The second regions 133 of the passivation layer 130 may be spaced a predetermined distance between an edge region of the pad 120 and a central region of the pad 120. That is, conventionally, only the edge region of the pad is covered with the protective layer. Accordingly, the bonding member is disposed in a region other than the edge region of the pad 120, and there is no space where the gas can be taken out to the outside during reflow.

However, in the present invention, the protective layer 130 may include a plurality of second regions 133 protruding from the edge region of the pad 120 toward the center of the pad 120, The gas can be discharged to the outside between the regions 133, thereby minimizing the voiding phenomenon.

At this time, the total top surface area of the plurality of second areas 133 of the protective layer 130 may be determined by the top surface area of the remaining area except the edge area of the pad 120. Preferably, the total top surface area of the plurality of second areas 133 of the protective layer 130 is 10% to 40% of the top surface area of the remaining area except for the edge area of the pad 120 desirable.

In other words, the area of the protective layer 130 exposed through the opening 135 is preferably 60% to 90% of the entire upper surface area of the remaining region except the edge region of the pad 120. If the total top surface area of the second region of the protective layer 130 is less than 10%, sufficient space can not be secured for the gas to be taken out during the reflow of the adhesive member, If the total top surface area of the second area of the second area exceeds 40%, a reliability problem may occur due to an insufficient exposed space of the pad 120 on which the adhesive member is disposed.

As described above, according to the embodiment of the present invention, the protective layer 130 includes a plurality of second regions 133 protruding from the edge region of the pad 120 toward the center of the pad 120 . Accordingly, it is possible to reduce the occurrence of voids that may occur in the reflow process of the adhesive member by merely changing the shape of the protective layer 130, thereby improving the reliability of the printed circuit board.

Referring to FIG. 4, the bonding member 140 may be disposed on the surface of the pad 120 exposed through the opening 135 of the protective layer 130. 4A is a plan view of the printed circuit board on which the adhesive member is disposed, FIG. 4B is a cross-sectional view of the printed circuit board of FIG. 4A taken along line AA ' (c) is a cross-sectional view of the printed circuit board 100 of FIG. 4 (a) cut along the line BB '. Hereinafter, the adhesive member 140 may be a solder bump.

The adhesive member 140 may be formed by disposing a mask (to be described later) having an opening exposing the surface of the pad 120 on the insulating layer 110 and by squeezing the solder ball through the opening of the mask .

At this time, the adhesive member 140 is not disposed in the form of a single solder ball integrally formed on the pad 120, but is divided into at least two or more parts.

Preferably, the adhesive member 140 may be disposed on the pad 120 with a ball shape. At this time, a part of the adhesive member 140 may be disposed on the upper surface of the pad 120 exposed through the opening 135 of the protective layer 130. In addition, another part of the adhesive member 140 may be disposed on the protective layer 130. [ Preferably, the other portion of the adhesive member 140 may be disposed over the second region 133 of the passivation layer 130.

At this time, the adhesive member 140 exposes at least a part of the central region of the pad 120 and is disposed on the pad 120.

Preferably, the adhesive member 140 is divided into a plurality of portions physically separated from each other on the pad 120 so that at least a portion of the central region of the pad 120 is covered with the protective layer 130, And the adhesive member 140 as shown in FIG.

In other words, the adhesive member 140 includes a first portion 141 disposed on one surface of the pad 120 exposed through the opening 135 of the protective layer 130, and a second portion 141 And a second portion 142 disposed on the other surface of the pad 120 exposed through the opening 135. The second portion 142 may include a second portion 142, The first portion 141 and the second portion 142 are spaced apart from each other by a predetermined distance, and the central region of the upper surface of the pad 120 is exposed through the spaced space.

The first portion 141 and the second portion 142 of the adhesive member 140 may be disposed on the pad 120 with a semicircular shape. The first portion 141 of the adhesive member 140 may have a shape that is symmetrical with the second portion 142.

At this time, the adhesive member 140 may be disposed to expose at least one second region 133 of the plurality of second regions 133 of the protective layer 130. That is, the adhesive member 140 may be separated from the plurality of second regions 133 of the protective layer 130 around two opposing second regions 133. The adhesive member 140 may be disposed on one side and the other side of the two second regions 133 facing each other of the protection layer 130. Accordingly, the adhesive member 140 may be spaced apart from the two second regions 133 of the protective layer 130 by a predetermined distance, 133, the adhesive member 140 may not be disposed.

Alternatively, the adhesive member 140 may be disposed so as to cover the second region 133 of the protective layer 130. In other words, the adhesive member 140 may be disposed on the pad 120 separated from each other around a virtual horizontal line. In FIG. 4, the virtual horizontal lines are located on the two second regions 133 facing each other of the protection layer 130.

5, the virtual horizontal line may be disposed only on the surface of the protective layer 130 that does not include the second region 133, that is, on the surface of the exposed pad 120. Referring to FIG.

5, a portion of the pad 120 that is not the second region 133 of the passivation layer 130 is exposed through a space between the first and second portions of the adhesive member 140A, Only the surface can be exposed.

6 is a plan view of a printed circuit board according to a second embodiment of the present invention, and FIG. 7 is a plan view showing a pad and a protective layer shown in FIG. 6, and FIG. 8 is a cross- And Fig.

Hereinafter, a printed circuit board according to a second embodiment of the present invention will be described with reference to FIGS. 6 to 8. FIG.

6, the printed circuit board 200 includes an insulating layer 210, a pad 220, and a protective layer 230.

6 (a) is a plan view of the printed circuit board 200 viewed from above, and FIG. 6 (b) is a plan view of the printed circuit board 200 of FIG. 6 And FIG. 6C is a cross-sectional view of the printed circuit board 200 of FIG. 6A taken along line BB`.

A printed circuit board 200 according to an embodiment of the present invention is a support substrate to which components are attached, and more specifically, a BGA (Ball Grid Array) type package substrate to which components are attached by a flip chip method using an adhesive member.

The insulating layer 210 may have a flat plate structure. At this time, the insulating layer 210 may be a printed circuit board (PCB). Here, the insulating layer 210 may be formed as a single substrate, or alternatively, may be a multi-layer substrate in which a plurality of substrates are sequentially stacked. That is, the insulating layer 210 is a supporting substrate of a device in which a circuit pattern is formed and a component (not shown) is mounted.

A plurality of pads 220 are disposed on the surface of the insulating layer 210 at regular intervals. Although not shown in the drawing, a plurality of wiring patterns (not shown) electrically connected to components such as the pads 220 and other terminals are disposed on the surface of the insulating layer 210, Electrical signals can be transmitted.

The pad 220 is electrically connected to a component (not shown) mounted on the pad 220. Here, the part may be an element. The device may be divided into an active device and a passive device. The active device is a device that actively uses a nonlinear portion. The passive device refers to a device that does not use nonlinear characteristics even if both linear and nonlinear characteristics exist.

The pad 220 may be formed of a conductive metal material.

The pad 220 is formed of at least one metal material selected from gold (Au), silver (Ag), platinum (Pt), titanium (Ti), tin (Sn), copper (Cu), and zinc . The pad 120 may include at least one metal material selected from gold (Au), silver (Ag), platinum (Pt), titanium (Ti), tin (Sn), copper (Cu) The paste may further comprise a paste.

The pad 220 may be formed by a conventional manufacturing process of a printed circuit board such as an additive process, a subtractive process, a modified semi- additive process (MSAP), or a semi-additive process (SAP) And a detailed description thereof will be omitted here.

A plurality of the pads 220 may be disposed on the insulating layer 210 at predetermined intervals. The number of the pads 220 may be determined according to the number of parts to be disposed on the insulating layer 210.

Meanwhile, the upper surface of the pad 220 may have a circular shape. Preferably, the overall shape of the pad 220 is a circular column shape and may be disposed on the surface of the insulating layer 210. However, this is only an embodiment of the present invention, and the upper surface of the pad 220 may have any one of a rectangular shape, a polygonal shape, a triangular shape, and an elliptic shape. The pad 120 may have a vertical width of 0.85 mm and a horizontal width of 0.85 mm.

The pad 220 includes a plurality of slits (described later) that penetrate the top and bottom surfaces of the pad 220 and are recessed inward from the outer surface of the pad 220. The plurality of slits may be formed in an edge region of the pad 220. That is, the plurality of slits may be formed at regular intervals except for the central region of the pads 220.

In other words, the upper surface of the pad 220 includes a central region, an edge region, and a region between the central region and the edge region.

The slit may be formed to pass through an edge region and a region between the pad 220 and the pad except for the central region. In addition, the slits may be spaced apart from each other on the pad 220, and may be formed as a plurality of slits physically separated from each other.

The slit may include a first slit disposed in a left region centered on an upper surface of the pad 220, a second slit disposed in a right region of the upper surface of the pad 220 facing the first slit, A third slit disposed in an upper area of the upper surface of the pad 220 and a fourth slit disposed in a lower area of the upper surface of the pad 220 facing the third slit. The first to fourth slits are all separated from each other. The spacing between neighboring slits of the first to fourth slits may be the same.

A protective layer 230 covering the surface of the insulating layer 210 is disposed on the insulating layer 210. The protective layer 230 may be a solder resist (SR) and has an opening 235 for opening at least a part of the surface of the pad 220 disposed on the insulating layer 210. At this time, the opening 235 exposes a central region of the pad 220. The opening 235 exposes not only a central region of the pad 220 but also an area between the edge region of the pad 120 and the central region.

Accordingly, the edge regions of the pads 220 are covered by the protective layer 230, and the regions and the central region are exposed through the openings 235 of the passivation layer 230. At this time, a plurality of slits are formed in the edge region and the interspace. Accordingly, the portion of the plurality of slits with respect to the edge region is filled with the protective layer 230. In addition, a portion of the plurality of slits with respect to the interspace is exposed together with the central region of the pad 220. Therefore, the surface of the insulating layer 210 is exposed through the portion of the plurality of slits with respect to the inter-area. In other words, at least a part of the surface of the insulating layer 210 is exposed to the outside through the slit of the pad 220 and the opening 235 of the protective layer 230.

Hereinafter, the pad 220 and the protective layer 230 will be described in more detail. 7 (a) is a plan view of the pad 220, and FIG. 7 (b) is a plan view of the protective layer 230. FIG.

Referring to FIG. 7A, a pad 220 is disposed on the insulating layer 210. The pad 220 includes a first portion 220A covered by the protective layer 230 and a second portion 220B exposed through the opening 235 of the protective layer 230 do.

The pad 220 includes a plurality of slits 221 passing through upper and lower surfaces of the pad 220 and formed inward from the outer surface of the pad 220. The plurality of slits 221 may be formed on the edge region and the inter-region except the central region of the pad 220.

Each of the plurality of slits 221 includes a first portion 222 positioned in an edge region of the pad 220 and a second portion 223 located in a region between the edges. The first portion 222 of the slit 221 is buried by the protective layer 230 disposed on the insulating layer 210. The second portion 223 of the slit 221 is exposed through the opening 235 of the protective layer 230. Therefore, the surface of the insulating layer 210 located under the second portion 223 of the slit 221 is exposed to the outside.

The slits 221 may be divided into a plurality of slits. In other words, the plurality of slits 221 are physically separated from each other.

7B, the passivation layer 230 is disposed on the insulating layer 210 and has an opening 235 exposing at least a part of the surface of the pad 220. In addition, The passivation layer 230 may include a first region 231 disposed on a surface of the insulating layer 210 and a second region 232 disposed in an edge region of the pad 220.

A portion of the second region 232 of the passivation layer 230 covers the surface of the pad 220 while the remaining portion of the second region 232 of the passivation layer 230 is partially covered with the first Portions 222 of the second substrate. The lower surface of the second region 232 of the passivation layer 230 is in contact with the upper surface of the pad 220 and the lower surface of the second region 232 is in contact with the upper surface of the insulating layer 210.

In addition, the passivation layer 230 has an opening 235 exposing the central region of the pad 220 and the interspace. The opening 235 includes a first region 235A that exposes a surface of the pad 220 and a second region 235A that exposes the second portion 223 of the slit 221 formed in the pad 220. [ 2 region 235B.

The surface of the pad 220 is exposed through the first region 235A of the opening 235 of the protection layer 230 and the surface of the pad 220 is exposed through the second region 235B of the opening 235, The surface of the layer 210 is exposed.

As described above, in the present invention, a plurality of slits 221 passing through the pad 220 are formed on a part of the pad 220, and the flowability of the solder ball is improved through the plurality of slits 221 The void phenomenon can be minimized.

The second region 232 of the slit 221 of the pad 220 may be determined by the area of the upper surface of the remaining region except the edge region of the pad 220. Preferably, the area of the second area 232 is 10% to 40% of the area of the upper surface of the remaining area except the edge area of the pad 220.

In other words, the area of the pad 220 exposed through the opening 235 is 60% of the total top surface area of the remaining area excluding the edge area of the pad 220 (area including the second part of the slit) To 90%.

In other words, an area occupied by the surface of the pad 220 among the total area of the surface of the pad 220 exposed through the opening 235 and the slit 221 and the surface of the insulating layer 210 Is preferably 60 to 90%.

Referring to FIG. 8, the bonding member 240 may be disposed on the surface of the pad 220 exposed through the opening 235 of the protective layer 230 as described above. 8A is a plan view of the printed circuit board on which the adhesive member is disposed, FIG. 8B is a sectional view of the printed circuit board of FIG. 8A taken along line AA ' (c) is a cross-sectional view of the printed circuit board of Fig. 4 (a) cut along the line BB '. Hereinafter, the bonding member 240 may be a solder bump.

The adhesive member 240 may be formed by disposing a mask (to be described later) having an opening exposing the surface of the pad 220 on the insulating layer 210 and by squeezing the solder ball through the opening of the mask .

At this time, the adhesive member 240 is not disposed in the form of a single solder ball integrally formed on the pad 220, but is divided into at least two or more parts.

Preferably, the adhesive member 240 may be disposed on the pad 220 with a ball shape. At this time, a part of the adhesive member 240 may be disposed on the upper surface of the pad 120 exposed through the opening 235 of the protective layer 230. Further, another part of the adhesive member 240 may be disposed on the protective layer 230 as well.

At this time, the second region 232 of the slit 221 exposed through the opening 235 of the protection layer 230 is filled through the adhesive member 240. In other words, the adhesive member 240 includes a portion disposed on the surface of the pad 220 and a portion inserted into the second region 232 of the slit 221. At this time, the inserted portion is disposed on the surface of the insulating layer 210 along the slit inner wall of the pad 220.

Further, as described above, the adhesive member 240 includes a plurality of portions physically separated from each other on the pad 220. A plurality of portions of the adhesive member 240 are spaced apart from each other by a predetermined distance, and the central region of the upper surface of the pad 220 is exposed through the spaced spaces.

Meanwhile, a plurality of mutually separated portions of the adhesive member 240 may have a semicircular shape and may have a shape symmetrical to each other.

According to the embodiment of the present invention as described above, at least a part of the adhesive member is disposed inside the slit of the pattern, so that the adhesive member is also brought into contact with the insulating layer to improve the adhesive force with the component .

9 is a modification of the printed circuit board according to the embodiment of the present invention.

Referring to FIGS. 9A and 9B, a plurality of slits formed in the pad 220 according to the second embodiment of the present invention are formed in a straight line on the opposite edge surfaces of the pads.

On the contrary, in the printed circuit board according to the modified example, the slit formed on the pad 320 has a vane shape.

That is, the upper surface of the pad 320 may have a circular shape. Preferably, the overall shape of the pad 320 has a circular columnar shape and may be disposed on the surface of the insulating layer 210. However, this is merely an embodiment of the present invention, and the upper surface of the pad 320 may have any one of a rectangular shape, a polygonal shape, a triangular shape, and an elliptical shape. The pad 320 may have a vertical width of 0.85 mm and a horizontal width of 0.85 mm.

The pad 320 includes a plurality of slits (described later) that penetrate the top and bottom surfaces of the pad 220 and are recessed inward from the outer surface of the pad 320. The plurality of slits may be formed in an edge region of the pad 320. That is, the plurality of slits may be formed at regular intervals except for the central region of the pad 320.

In other words, the upper surface of the pad 320 includes a central region, an edge region, and a region between the central region and the edge region.

The slit may be formed to penetrate an edge region and a region between the pad 320 and the pad 320, except for the central region. In addition, the slits may be formed on the pad 320 at a predetermined interval and physically separated from each other.

The slit may include a first slit disposed on the left side of the upper surface of the pad 320, a second slit disposed on the right side of the upper surface of the pad 320 facing the first slit, A third slit disposed in an upper area of the upper surface of the pad 320 and a fourth slit disposed in a lower area of the upper surface of the pad 320 facing the third slit. The first to fourth slits are all separated from each other. The spacing between neighboring slits of the first to fourth slits may be the same.

At this time, the pad 320 includes a first portion 320A covered by the protective layer and a second portion 320B exposed through the opening of the protective layer.

The pad 320 includes a plurality of slits 321 penetrating the top and bottom surfaces of the pad 320 and formed inward from the outer surface of the pad 320. The plurality of slits 321 may be formed on the edge region and the inter-region except for the central region of the pad 320.

Each of the plurality of slits 321 includes a first portion 322 located in an edge region of the pad 320 and a second portion 323 located in a region between the adjacent portions. The first portion 322 of the slit 321 is filled with a protective layer disposed on the insulating layer 310. Further, the second portion 323 of the slit 321 is exposed through the opening of the protective layer. Therefore, the surface of the insulating layer 310 located under the second portion 323 of the slit 321 is exposed to the outside.

The slits 321 may be divided into a plurality of slits. In other words, the plurality of slits 321 are physically separated from each other. At this time, the first portion 322 and the second portion 323 of the plurality of slits 321 are formed at different inclination angles.

In other words, the first portion 322 is formed with a first inclination angle toward the central region in the one edge region of the pad. The second portion 323 extends from the first portion 322 and has a second inclination angle toward the central region of the pad. At this time, the first inclination angle and the second inclination angle are different from each other. Accordingly, the shape of the slit including the first portion 322 and the second portion 323 may have a shape of '<'.

A plurality of slits having the above shape are gathered, and the shape of the whole slit formed on the pad may have a vane shape.

9B, the first portion 322 and the second portion 323 are not separated from each other and may have a shape of '(' having one specific curvature. As described above, When the slit has a curvature, the adhesive member is applied on the surface formed by the curvature of the slit, thereby further suppressing the formation of bubbles.

 In other words, each of the plurality of slits may have a certain curvature on the inner surface of the slit.

Therefore, when the adhesive member is applied later, the pad having the slit having the above-described shape is sequentially coated in each region by the inclination angle of the pad as described above, thereby minimizing the possibility of bubble formation .

Hereinafter, a method of manufacturing a printed circuit board according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIGS. 10 to 15 are views showing the manufacturing method of the printed circuit board shown in FIG. 2 in the order of process.

Referring to FIG. 10, an insulating layer 110 is first prepared. The insulating layer 110 may be a thermosetting or thermoplastic polymer substrate, a ceramic substrate, an organic-inorganic composite substrate, or a glass fiber impregnated substrate. When the polymer layer includes a polymer resin, the insulating layer 110 may be formed of FR-4, BT (bismaleimide triazine) (Ajinomoto Build up Film), and may include a polyimide resin, but the present invention is not limited thereto.

When the insulating layer 110 is prepared, electroless plating (chemical copper plating) is performed to form a metal layer 115 on the insulating layer 110. The metal layer 115 covers the entire top surface of the insulating layer 110. The metal layer 115 may include a seed layer and a plating layer disposed on the seed layer. The electroless plating is a step for forming the seed layer. In addition, the plating layer may be formed by conducting electrolytic plating on the seed layer. Meanwhile, the seed layer may be formed by a chemical copper plating method. The chemical copper plating method may be carried out in the order of a degreasing process, a soft corrosion process, a preliminary catalyst process process, a catalyst process process, an activation process, a non-electrolytic plating process, and an oxidation prevention process process.

The copper plating is divided into Heavy Copper (2 탆 or more), Medium Copper (1 ~ 2 탆) and Light Copper (1 탆 or less) depending on the thickness, Here, a seed layer satisfying 0.5 to 1.5 占 퐉 can be formed by medium copper plating or light copper plating.

Referring to FIG. 11, at least one pad 120 is formed on the insulating layer 110 by opening at least a portion of the metal layer 115 including the seed layer and the plating layer.

At this time, the pad 120 is electrically connected to a component (not shown). Here, the part may be an element. The device can be divided into an active device and a passive device. The metal layer 115 is formed of at least one metal material selected from gold (Au), silver (Ag), platinum (Pt), titanium (Ti), tin (Sn), copper (Cu), and zinc .

The pad 120 may be formed by a conventional manufacturing process of a printed circuit board such as an additive process, a subtractive process, a modified semi- additive process (MSAP), or a semi- additive process (SAP) And a detailed description thereof will be omitted here.

The plurality of pads 120 may be disposed on the insulating layer 110 at predetermined intervals. The number of the pads 120 may be determined according to the number of parts to be disposed on the insulating layer 110. Meanwhile, the upper surface of the pad 120 may have a circular shape. Preferably, the overall shape of the pad 120 has a circular column shape and may be disposed on the surface of the insulating layer 110. However, this is merely an embodiment of the present invention, and the upper surface of the pad 120 may have any one of a rectangular shape, a polygonal shape, a triangular shape, and an elliptical shape. The pad 120 may have a vertical width of 0.85 mm and a horizontal width of 0.85 mm.

Next, referring to FIG. 12, a protective layer 130 is formed on the insulating layer 110. At this time, the protective layer 130 may be disposed to cover both the surface of the insulating layer 110 and the surface of the pad 120. The protective layer 130 may be a solder resist (SR).

Next, referring to FIG. 13, an opening 135 is formed in the passivation layer 130 to open at least a part of the surface of the pad 120 disposed on the insulating layer 110. At this time, an opening 135 is formed by opening the upper region of the central region of the pad 120 among the passivation layer 130.

13 (b), the protective layer 130 includes a first region 131 disposed on the surface of the insulating layer, a second region 131 disposed on the edge region of the pad 120, (132), and a plurality of third regions (133) disposed on the region between the pads.

In other words, the upper surface of the pad 120 may include a first region corresponding to the central region, a second region corresponding to the edge region, and a third region between the first and second regions. The first region of the pad 120 may be exposed by the opening 135 of the passivation layer 130. In addition, the second region of the pad 120 may be completely covered with the protective layer 130. The third region of the pad 120 may include a portion covered by the protective layer 130 and a portion exposed by the opening 135 of the protective layer 130.

The upper surface of the pad 120 may include a first portion 120A exposed by the opening 135 of the protective layer 130 and a second portion 120A covered by the protective layer 130. [ 120B. That is, the protective layer 130 is disposed on the insulating layer 110 and has an opening 135 exposing at least a part of the surface of the pad 120. The passivation layer 130 may include a region 131 disposed on the surface of the insulating layer 110 and regions 132 and 133 disposed on the surface of the pad 120.

The regions 132 and 133 of the passivation layer 130 disposed on the surface of the pad 120 include a first region 132 disposed in an edge region of the pad 120, And a plurality of second regions 133 protruding from an edge region of the pad 120 toward the center of the pad 120. Preferably, the first region 132 of the passivation layer 130 may be disposed in an edge region of the pad 120. The second regions 133 of the passivation layer 130 may be spaced a predetermined distance between an edge region of the pad 120 and a central region of the pad 120. That is, conventionally, only the edge region of the pad is covered with the protective layer. Accordingly, the bonding member is disposed in a region other than the edge region of the pad 120, and there is no space where the gas can be taken out to the outside during reflow.

However, in the present invention, the protective layer 130 may include a plurality of second regions 133 protruding from the edge region of the pad 120 toward the center of the pad 120, The gas can be discharged to the outside between the regions 133, thereby minimizing the voiding phenomenon.

At this time, the total top surface area of the plurality of second areas 133 of the protective layer 130 may be determined by the top surface area of the remaining area except the edge area of the pad 120. Preferably, the total top surface area of the plurality of second areas 133 of the protective layer 130 is 10% to 40% of the top surface area of the remaining area except for the edge area of the pad 120 desirable.

In other words, the area of the protective layer 130 exposed through the opening 135 is preferably 60% to 90% of the entire upper surface area of the remaining region except the edge region of the pad 120.

Next, referring to FIG. 14, a mask 150 for forming an adhesive member 140 is formed on the protective layer 130. At this time, the mask 150 includes openings 155 disposed on the respective pad regions.

At this time, the openings 155 include a plurality of physically separated openings. That is, the opening 155 is divided into a first opening region 155A exposing one region of the one pad and a second opening region 155A physically separated from the first opening region 155A, And a second opening region 155B which exposes the second opening region 155B.

Referring to FIG. 15, the mask 150 may be formed by squeezing the solder ball through the opening 155 of the mask 150.

At this time, the adhesive member 140 is not disposed in the form of a single solder ball integrally formed on the pad 120, but is divided into at least two or more parts. That is, the adhesive member 140 includes a portion formed with the first opening region 155A and a portion formed through the second opening region 155B.

Preferably, the adhesive member 140 may be disposed on the pad 120 with a ball shape. At this time, a part of the adhesive member 140 may be disposed on the upper surface of the pad 120 exposed through the opening 135 of the protective layer 130. In addition, another part of the adhesive member 140 may be disposed on the protective layer 130. [ Preferably, the other portion of the adhesive member 140 may be disposed over the second region 133 of the passivation layer 130.

At this time, the adhesive member 140 exposes at least a part of the central region of the pad 120 and is disposed on the pad 120.

Preferably, the adhesive member 140 is divided into a plurality of portions physically separated from each other on the pad 120 so that at least a portion of the central region of the pad 120 is covered with the protective layer 130, And the adhesive member 140 as shown in FIG.

In other words, the adhesive member 140 includes a first portion 141 disposed on one surface of the pad 120 exposed through the opening 135 of the protective layer 130, and a second portion 141 And a second portion 142 disposed on the other surface of the pad 120 exposed through the opening 135. The second portion 142 may include a second portion 142, The first portion 141 and the second portion 142 are spaced apart from each other by a predetermined distance, and the central region of the upper surface of the pad 120 is exposed through the spaced space.

The first portion 141 and the second portion 142 of the adhesive member 140 may be disposed on the pad 120 with a semicircular shape. The first portion 141 of the adhesive member 140 may have a shape that is symmetrical with the second portion 142.

At this time, the adhesive member 140 may be disposed to expose at least one second region 133 of the plurality of second regions 133 of the protective layer 130. That is, the adhesive member 140 may be separated from the plurality of second regions 133 of the protective layer 130 around two opposing second regions 133. The adhesive member 140 may be disposed on one side and the other side of the two second regions 133 facing each other of the protection layer 130. Accordingly, the adhesive member 140 may be spaced apart from the two second regions 133 of the protective layer 130 by a predetermined distance, 133, the adhesive member 140 may not be disposed.

Alternatively, the adhesive member 140 may be disposed so as to cover the second region 133 of the protective layer 130. In other words, the adhesive member 140 may be disposed on the pad 120 separated from each other around a virtual horizontal line. At this time, the imaginary horizontal lines may be located on the two opposing second regions 133 of the protection layer 130.

Alternatively, the imaginary horizontal line may be disposed only on a region that does not include the second region 133 of the passivation layer 130, i. E., On the surface of the exposed pad 120. [

Therefore, only the surface of the pad 120 other than the second region 133 of the protective layer 130 can be exposed through the space between the first and second portions of the adhesive member 140.

According to the embodiment of the present invention, voids inside the adhesive member can be removed by allowing gas generated inside the solder to be carried out through a region between the protective layer or the pad or the solder bump when the bonding member is reflowed.

In addition, according to the embodiment of the present invention, it is possible to reduce the occurrence of voids in the adhesive member even if the reflow operation is not performed in a vacuum state, thereby reducing manufacturing cost and manufacturing time.

In addition, according to the embodiment of the present invention, the reliability of the printed circuit board can be improved by preventing the voids in the adhesive member from exceeding 30% of the entire volume complying with the International Organization for Standardization (ISO) standard.

Further, according to the embodiment of the present invention, at least a part of the adhesive member is disposed inside the slit of the pad, so that the adhesive member is also brought into contact with the insulating layer, so that the adhesive force to the component can be improved.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons skilled in the art to which the embodiments belong. Accordingly, the contents of such combinations and modifications should be construed as being included in the scope of the embodiments.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It can be seen that the modification and application of branches are possible. For example, each component specifically shown in the embodiments can be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (12)

Insulating layer;
A pad disposed on the insulating layer; And
And a protective layer disposed over the insulating layer and having an opening exposing at least a portion of the surface of the pad,
The protective layer may be formed,
A first portion disposed on the insulating layer,
And a plurality of second portions protruding from the edge of the upper surface of the pad toward the center of the upper surface of the pad and exposing a central region of the upper surface of the pad
Printed circuit board. The method according to claim 1,
Wherein the plurality of second portions comprise:
And spaced apart from each other on the upper surface of the pad
Printed circuit board. The method according to claim 1,
The protective layer may be formed,
Further comprising a third portion disposed to surround an edge region of the upper surface of the pad,
Wherein the plurality of second portions comprise:
And protruding from the third portion toward the center of the upper surface of the pad
Printed circuit board. The method according to claim 1,
And an adhesive member disposed on the pad exposed through the opening,
Wherein the adhesive member comprises:
And exposing a central region of the upper surface of the pad
Printed circuit board. 5. The method of claim 4,
Wherein the adhesive member comprises:
A first portion disposed on one side of the central region,
And a second portion disposed on the other side opposite to one side of the central region,
Wherein the first portion and the second portion comprise a first portion,
Physically separate
Printed circuit board. The method of claim 3,
The top surface area of the second portion of the protective layer
Is 10% to 40% of the upper surface area of the entire remaining area excluding the edge area of the upper surface of the pad
Printed circuit board. Insulating layer;
A pad disposed on the insulating layer; And
And a protective layer disposed over the insulating layer and having an opening exposing at least a portion of the surface of the pad,
The pad includes:
And a plurality of slits formed in the edge region toward the center of the pad,
The protective layer may be formed,
And at least a portion of the plurality of slits is exposed and disposed on the insulating layer and the pad,
Wherein each of the plurality of slits comprises:
A first region in which the protective layer is inserted and a second region in which a surface of the insulating layer is exposed;
Printed circuit board. 8. The method of claim 7,
The protective layer may be formed,
A first portion disposed on the insulating layer,
And a second portion disposed in an edge region of an upper surface of the pad,
The width of the second portion
A width of each of the plurality of slits
Printed circuit board. 8. The method of claim 7,
And an adhesive member disposed on the pad exposed through the opening,
Wherein the adhesive member comprises:
And exposing a central region of the upper surface of the pad
Printed circuit board. 10. The method of claim 9,
Wherein the adhesive member comprises:
A first portion disposed on one side of the central region,
And a second portion disposed on the other side opposite to one side of the central region,
Wherein the first portion and the second portion comprise a first portion,
Physically separate
Printed circuit board. 10. The method of claim 9,
Wherein at least a part of the adhesive member
And a second region of the plurality of slits that is inserted into the second region and is in direct contact with the surface of the insulating layer
Printed circuit board. 10. The method of claim 9,
An area of a surface of the pad exposed through the protective layer is 60 to 90 nm in a total area of a surface of the insulating layer exposed through the second region of the slit and a surface of the pad exposed through the protective layer, % Of
Printed circuit board.

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