KR20170141039A - Board and manufacturing method thereof - Google Patents

Abstract

Disclosed is a substrate having a laminated structure for protecting a mounted circuit element from static electricity. In the disclosed substrate, the laminated structure includes a pad layer including a signal pad formed on the substrate and a ground pad separated from the signal pad by a distance, an insulating layer stacked on the pad layer and a conductive layer stacked on the insulating layer and forming a path where electrostatic discharge (ESD) introduced into the signal pad is discharged to the ground pad.

Description

[0001] BOARD AND MANUFACTURING METHOD THEREOF [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate and a method of manufacturing the same, and more particularly, to a substrate capable of protecting a circuit element mounted on a substrate from an excessive voltage such as ESD (Electrostatic Discharge) and a method of manufacturing the same.

ESD (Electrostatic Discharge) is a phenomenon in which a charged discharge occurs when a charged conductive object (human body, etc.) touches or sufficiently approaches another conductive object (such as an electronic apparatus). Such ESD is a cause of damage or malfunction of electronic devices. In order to protect circuits and devices from such an EDS, it is necessary to prevent an excessive voltage generated during discharging from being transferred to the circuit of the electronic device.

Conventionally, these transient voltages are prevented by using ESD protection devices. The ESD protection device protects internal circuits or devices by bypassing excessive power to the outside of the circuit to prevent the voltage exceeding a certain limit from propagating inside the circuit when excessive momentary power of ESD input from the outside is applied . The ESD protection device is placed, for example, between the signal line of the circuit and ground (ground).

At this time, the ESD protection device should not interfere with the signal to cause distortion, and should not increase insertion loss or leakage current. On the other hand, ESD protection devices should be manufactured to the specifications suitable for the application, because the specifications for voltage, current, and capacitance are different and the types of surge are different depending on the application.

  Commonly used ESD protection devices are fabricated in a variety of sizes and shapes to meet a wide range of characteristics and for various purposes. This diversity is advantageous in terms of application because it is appropriate to select appropriate ESD protection device in terms of product development, but there is a problem that the manufacturing cost of the product is greatly increased when the ESD protection device is used in a large amount depending on the characteristics of the product .

In order to solve the above problems, it is an object of the present invention to provide a substrate capable of protecting a circuit element mounted on a substrate from an overvoltage caused by ESD (Electrostatic Discharge) without using an EDS protection device and a manufacturing method thereof have.

According to an aspect of the present invention, there is provided a substrate having a laminated structure for protecting a mounted circuit element from static electricity, the laminated structure including: a signal pad formed on a substrate; A pad layer comprising a ground pad; An insulating layer stacked on the pad layer; And a conductive layer stacked on the insulating layer and forming a path through which ESD (Electrostatic Discharge) introduced into the signal pad is discharged to the ground pad.

According to another aspect of the present invention, there is provided a method of manufacturing a substrate having a stacked structure for protecting a mounted circuit element from static electricity, comprising: a plurality of signal pads arranged in a line on a substrate; and a plurality of signal pads Forming a pad layer comprising a ground pad; Applying an insulating layer to one side of the metal plate; And laminating the metal plate on the substrate so that the insulating layer covers the plurality of signal pads.

According to another aspect of the present invention, there is provided a method of manufacturing a substrate having a stacked structure for protecting a mounted circuit element from static electricity, comprising: a plurality of signal pads arranged in a line on a substrate; and a plurality of signal pads Forming a pad layer comprising a ground pad; Applying an insulating layer on the pad layer; And a step of applying a conductive layer on the insulating layer, thereby achieving the above object.

1 is a perspective view illustrating a substrate according to an embodiment of the present invention.
2A is a cross-sectional view illustrating a stacked structure of a substrate according to an embodiment of the present invention.
FIG. 2B is a flowchart sequentially illustrating a manufacturing process of a substrate according to an embodiment of the present invention.
FIG. 2C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 2A. FIG.
3A is a cross-sectional view illustrating a stacked structure of a substrate according to another embodiment of the present invention.
FIG. 3B is a flowchart sequentially illustrating a manufacturing process of a substrate according to another embodiment of the present invention.
3C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 3A.
4A is a cross-sectional view illustrating a stacked structure of a substrate according to another embodiment of the present invention.
4B is a flowchart sequentially illustrating a manufacturing process of a substrate according to another embodiment of the present invention.
4C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 4A.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The embodiments described below will be explained based on the embodiments best suited to understand the technical characteristics of the present invention, and the technical features of the present invention are not limited by the embodiments described, And that the present invention may be implemented with other embodiments.

In addition, the present invention is capable of carrying out various modifications within the technical scope of the present invention through the embodiments described below, and these modified embodiments are within the technical scope of the present invention. In order to facilitate the understanding of the embodiments described below, in the reference numerals shown in the accompanying drawings, among the components having the same function in each embodiment, the related components are denoted by the same or an extension line number.

1, a substrate 10 according to an embodiment of the present invention may have a lamination structure for protecting the mounted circuit elements 11 from static electricity. Such a lamination structure may include various signal transmission and grounding An insulating layer 200 that may be formed on the pad layer 100 and a conductive layer 300 that may be formed on the insulating layer 200.

The pad layer 100 may include a signal pad 110 formed on the substrate 10 and a ground pad 130 spaced from the signal pad 110.

The signal pad 110 may apply a signal input to the substrate 10 to at least one circuit element 11 mounted on the substrate 10. [ In this case, a signal applied to the circuit element 11 can be input through one of the plurality of signal pads 110. When the substrate 10 is a multilayer, a signal applied to at least one inner layer of the substrate 10 Can be input through the signal pad formed.

Although the pad layer 100 is described as including the signal pad 110 and the ground pad 130 in the present embodiment, the present invention is not limited thereto. The pad pad 100 may include a terminal pad (not shown) Not shown), and the like.

The voltage level of the ground pad 130 may be equal to the level of the ground voltage. The voltage level of the ground pad 130 may be transferred to the circuit element 11 which may be mounted on the substrate 10. [ The ground pad 130 may form a bypass path of an unwanted signal, such as a peak high voltage.

The signal pads 110 may be plurally arranged as shown in FIG. 1 and may be arranged in a line at regular intervals. The ground pads 130 may also be plurally arranged and may be arranged in a line parallel to the plurality of signal pads 110 at regular intervals.

The plurality of ground pads 130 may be arranged symmetrically with respect to the plurality of signal pads 110 to stably support a metal plate 300 described later.

As described above, a signal applied to the circuit element 11 may be input to the signal pad 110, and an ESD (Electrostatic Discharge) component may be included in the signal. The signal of the ESD component may be abruptly increased in voltage level instantaneously or the voltage level may be kept unreasonably high. When the signal of this ESD component is transmitted to the circuit element 11 mounted on the substrate 10, There is a fear that the circuit element 11 is broken or malfunctioned. According to this embodiment, an insulating layer 200 is laminated on the pad layer 100, and a laminated structure in which the conductive layer 300 is laminated on the insulating layer 200 is formed, The signal of the ESD component can be discharged to the ground pad 130 without being transferred to the circuit element 11 to protect the circuit element 11 from ESD and at the same time to prevent the malfunction of the circuit element 11 at the same time.

The conductive layer 300 constituting the stacked structure is stacked on the insulating layer 200 and is electrically connected to the ground pad 130 before the signal of the ESD component reaches the circuit element 11 when a voltage equal to or higher than the reference voltage is applied. As shown in FIG. 2A and 2B, a lamination structure according to an embodiment of the present invention will be described in detail.

2A is a cross-sectional view illustrating a stacked structure of a substrate according to an embodiment of the present invention.

2A, the laminated structure includes a pad layer 100 including a signal pad 110 and a ground pad 130, an insulating layer 200 covering the signal pad 110, an insulating layer 200, And a metal plate 300 covering the ground pad 130.

The pad layer 100 may include a plurality of signal pads 110 and a plurality of ground pads 130. The plurality of signal pads 110 may be disposed on both sides of the plurality of signal pads 110, ) May be symmetrically arranged. The plurality of ground pads 130 are formed at regular intervals on both sides of the plurality of signal pads 110 so as to be connected to both ends of the metal plate 300. In addition, the plurality of signal pads 110 and the plurality of ground pads 130 may be disposed in parallel with each other.

The insulating layer 200 functions as a non-conductive material when a signal having a low voltage level is applied. However, when a signal having a high voltage level is applied, the insulation resistance of the insulation layer 200 is deteriorated and an insulation breakdown phenomenon through which a relatively large current is passed may occur. The insulating layer 200 may be based on a polymer resin having an insulating property at a driving voltage condition and a high voltage durability. The polymer resin may include at least one of polyimide-based, epoxy-based, acrylic-based, and polyolefin-based resins.

Here, a signal having a high voltage level is a main factor that lowers the reliability of the electronic product due to a transient voltage. The causes of transient voltages include sudden load changes in the proximity circuit, unstable fluctuations of the power supply, interference through coupled wires, switch operation, lightning, EOS (electrical overstress), and ESD.

Accordingly, the substrate 100 according to the present embodiment can protect the circuit element 11 from ESD components as well as the elements causing the above-mentioned various transient voltages.

The insulating layer 200 may include conductive particles or organic semiconductor particles so that the insulating layer 200 is conductive at a specific voltage or more at which the breakdown phenomenon occurs. The insulating layer 200 may be made of a material in which the conductive particles are mixed at a certain ratio. The conductive particles may include at least one of metal particles, carbon particles, and ceramic particles. At this time, the metal particles may include at least one of nickel (Ni), aluminum (Al) and copper (Cu), and carbon particles may be at least one of carbon black and graphite And the ceramic particles may include at least one of zinc oxide (ZnO) and titanium dioxide (TiO2).

The insulating layer 200 may be formed on one surface of the metal plate 300.

The metal plate 300 provides a path through which the ESD introduced into the signal pad 110 can travel from the insulating layer 200 to the ground pad 130. Therefore, the metal plate 300 preferably uses a conductive material having a surface resistance (for example, 0.1 m ohm / sq. Or less) lower than the resistance (50 ohm) of a typical signal line. The conductive material may be made of gold (Au), silver (Ag), copper (Cu), or the like. In addition, the metal plate 300 may be in the form of a paste obtained by dispersing ink or flake type micron particles using nanoparticles.

In addition, the metal plate 300 may be provided in the form of a reel wound at a predetermined diameter.

The metal plate 300 may have a rectangular shape with a width enough to cover a plurality of signal pads 110 and a plurality of ground pads 130 disposed on both sides of the signal pads 110. However, the metal plate 300 is not limited to a rectangular cross-section, and any shape can be used as long as it can cover a plurality of signal pads 110 and can be connected to the ground pads 130 on both sides.

Both ends of the bottom surface of the metal plate 300 may be soldered to the plurality of ground pads 130 and the bottom center of the metal plate 300 may be soldered to the plurality of signal pads 110 through the insulating layer 200 . A first soldering part 115 electrically connected to the ground pad 130 is formed at both ends of the metal plate 300 and a second soldering part 115 connected to the signal pad 110 is formed at the center of the metal plate 300. [ A portion 135 may be formed. At this time, the metal plate 300 is electrically connected to the ground pad 130 through the first soldering part 115, but is physically connected to the signal pad 110 as being indirectly connected to the insulating layer 200 But it is not electrically connected.

The metal plate 300 may be formed to cover the plurality of signal pads 110 and the plurality of ground pads 130. When the ESD component flows into the substrate 10 through the signal pad 110, the metal plate 300 serves as a path for discharging the ESD to the ground pad 130, thereby preventing malfunction of the circuit element 11 .

Since the metal plate 300 is simply mounted like a general electronic component mounted on a substrate, a separate additional process does not occur as in the case of applying a conventional ESD protection device, and productivity and cost reduction effects can be obtained . Therefore, when the ESD protection device is to be applied in a large amount due to the characteristics of the product, the cost reduction can be maximized by replacing the ESD protection device with a laminated structure according to an embodiment of the present invention.

FIG. 2B is a flowchart sequentially illustrating a manufacturing process of a substrate according to an embodiment of the present invention.

Referring to FIG. 2B, a process for manufacturing a substrate according to an embodiment of the present invention is as follows.

A pad layer 100 including a plurality of signal pads 110 arranged in a line on a prepared substrate 10 and a plurality of ground pads 130 aligned in a line with the signal pads 110 is formed (S11).

Next, the metal plate 300 is cut to have a predetermined length from the metal reel (not shown), and then the insulating layer 200 is coated on one side (S12). In this case, the insulating layer 200 may be manufactured by applying the insulating layer 200 on one side of the fabricated metal strip.

Subsequently, the metal plate 300 is laminated on the substrate 10 so that the insulating layer 200 covers the plurality of signal pads 110 in the SMT (Surface Mount Technology) line (S13).

FIG. 2C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 2A. FIG.

Referring to FIG. 2C, the movement path of the signal of the ESD component is indicated by an arrow. A signal of the ESD component flows into the signal pad 110 and an insulation breakdown phenomenon occurs in which the insulation layer 200 is destroyed by an abnormal voltage exceeding a prescribed voltage due to a signal of the introduced ESD component. The insulating layer 200 loses its insulation property due to dielectric breakdown and current flows, so that the signal of the ESD component flows into the metal plate 300 from the insulating layer 200.

The metal plate 300 may be electrically connected to the ground pad 130 to connect the signal of the ESD component to the ground. It is possible to protect the circuit element 11 from the generation of an abnormal voltage such as ESD or the like by keeping the ground and the potential equal. As a result, when the ESD component flows into the substrate 10 through the signal pad 110, the ESD component is discharged to the ground pad 130 to prevent the circuit element 11 from malfunctioning.

FIG. 3A is a cross-sectional view illustrating a stacked structure of a substrate according to another embodiment of the present invention, and FIG. 3C is a cross-sectional view schematically illustrating a movement path of an ESD in FIG. 3A.

Hereinafter, in explaining the substrate according to another embodiment shown in FIGS. 3A and 3C, the same description as the substrate according to the embodiment shown in FIGS. 2A and 2C will be omitted, .

3A, the laminated structure includes a pad layer 100 including a signal pad 110 and a ground pad 130, an insulating layer 200 'covering the pad layer 100, an insulating layer 200' And a conductive layer 300 'covering the conductive layer 300'.

The laminated structure of the substrate 10 according to another embodiment of the present invention includes a signal pad 110 formed on the substrate 10 and a pad including a ground pad 130 spaced from the signal pad 110 The ESD that is stacked on the insulating layer 200 'and the insulating layer 200' stacked on the layer 100 and the pad layer 100 and the ESD introduced into the signal pad 110 is discharged to the ground pad 130 And a conductive layer 300 '.

The conductive layer 300 'provides a path through which the ESD introduced into the signal pad 110 can move from the insulating layer 200' to the ground pad 130 in the same manner as the metal plate 300 described above with reference to FIG. Therefore, it is preferable to use a conductive material having a surface resistance (for example, 0.1 m ohm / sq. Or less) lower than the resistance (50 ohm) of a typical signal line. The conductive material may be made of gold (Au), silver (Ag), copper (Cu), or the like. The insulating layer 200 'functions as a non-conductive material when a signal having a low voltage level is applied to the insulating layer 200', similarly to the insulating layer 200 described above with reference to FIG. However, when a signal having a high voltage level is applied, the insulation resistance of the insulation layer 200 'may be deteriorated and an insulation breakdown phenomenon through which a relatively large current flows may occur.

The insulating layer 200 'covers the signal pad 110 and the ground pad 130 with a range thickness g capable of tunneling. The distance g between the top of the signal pad 110 and the conductive layer 300 'is formed by the thickness of the insulating layer 200'. The distance g between the upper portion of the signal pad 110 and the conductive layer 300 'is formed to be narrower than the distance d between the signal pad 110 and the ground pad 130. [ The insulating layer 200 'serves to keep the distance g between the signal pad 110 and the conductive layer 300' constant. Here, the distance (g) between the signal pad 110 and the conductive layer 300 'greatly affects the voltage value at which the insulation breakdown occurs. Accordingly, the value of the protection voltage due to the ESD inflow may be changed according to the thickness of the insulating layer 200 '. The material of the insulating layer 200 'can be selected from a range of insulation resistance of 105 to 1018? Cm.

According to an embodiment of the present invention, when a high voltage such as ESD is applied to the substrate 10, the conductive layer 300 ', which is a path through which the ESD introduced into the signal pad 110 is discharged to the ground pad 130 Is formed on the insulating layer 200 'so that a separate ESD protection device may not be mounted on the substrate. It is preferable that the conductive layer 300 'is in contact with the insulating layer 200' so that a high voltage such as ESD may be connected to the conductive layer 300 'directly from the insulating layer 200' It is for this reason.

By forming the insulating layer 200 'and the conductive layer 300' sequentially on the signal pad 110, it is possible to remove the ESD protection element from the substrate 10, It is possible to simplify the process because the process of mounting the ESD protection device is not required from the viewpoint of the process and the material cost can be reduced by not mounting the ESD protection device in terms of the material cost.

FIG. 3B is a flowchart sequentially illustrating a process of manufacturing a substrate according to another embodiment of the present invention. Referring to FIG. 3B, a process of manufacturing a substrate according to an embodiment of the present invention is as follows.

A pad layer 100 including a plurality of signal pads 110 arranged in a line on a prepared substrate 10 and a plurality of ground pads 130 aligned in a line with the signal pads 110 is formed (S21).

Subsequently, the insulating layer 200 'is coated on the pad layer 100 (S22).

Subsequently, the conductive layer 300 'is coated on the insulating layer 200' (S23).

Since the method of manufacturing such a substrate is to sequentially coat the insulating layer 200 'and the conductive layer 300' directly on the substrate, the advantage that the metal plate 300 described above in FIG. have.

3C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 3A.

Referring to FIG. 3C, the movement path of the signal of the ESD component is indicated by an arrow. A signal of the ESD component flows into the signal pad 110 and an insulation breakdown phenomenon occurs in which the insulation layer 200 'is destroyed by an abnormal voltage exceeding a prescribed voltage due to the signal of the introduced ESD component. The insulating layer 200 'loses its insulating property due to the primary insulation breakdown and current flows, so that the signal of the ESD component flows into the conductive layer 300' from the insulating layer 200 '. The signal of the ESD component introduced into the conductive layer 300 'is subjected to secondary insulation breakdown in the insulating layer 200' to be grounded. The signal of the ESD component can be emitted to the ground pad 130 and flow to the ground through the double insulation breakdown phenomenon. As a result, when the ESD component flows into the substrate 10 through the signal pad 110, the ESD component is discharged to the ground pad 130 to prevent malfunction of the circuit element 11. [

4A is a cross-sectional view illustrating a stacked structure of a substrate according to an embodiment of the present invention, and FIG. 4C is a cross-sectional view schematically illustrating a movement path of an ESD in FIG. 4A.

Hereinafter, in explaining the substrate according to another embodiment shown in FIGS. 4A and 4C, the same explanation as the description of the substrate according to the embodiment shown in FIGS. 3A and 3C will be omitted, .

4A, a substrate 10 according to an embodiment of the present invention includes a signal pad 110 formed on a substrate 10 and a ground pad 130 spaced from the signal pad 110 And a conductive layer 300 'including an insulating layer 200' stacked on the signal pad 110 and stacked on the ground pad 130 and the insulating layer 200 '. At this time, the conductive layer 300 'has a path through which the ESD introduced into the signal pad 110 is discharged to the ground pad 130.

The insulating layer 200 'covers the signal pad 110 with a range thickness g capable of tunneling. The distance g between the top of the signal pad 110 and the conductive layer 300 'is formed by the thickness of the insulating layer 200'. The distance g between the upper portion of the signal pad 110 and the conductive layer 300 'is formed to be narrower than the distance d between the signal pad 110 and the ground pad 130. [

ESD reliability can be enhanced by directly laminating the conductive layer 300 'on the ground pad 130 so that the ESD introduced into the conductive layer 300' can be directly connected to the ground.

The structure in which the insulating layer 200 'and the conductive layer 300' are sequentially stacked on the substrate 10 is simple, mass production is secured, and ESD protection performance can be improved. It is possible to reduce the cost when the conventional ESD protection device is applied to a product in which a large amount of ESD protection device is mounted and the productivity of the substrate 10 can be improved since there is no need to mount a separate ESD protection device on the market. Further, the substrate 10 of the present invention can be flexibly applied according to the specification of the area requiring protection from ESD.

4B is a flowchart sequentially illustrating a manufacturing process of a substrate according to another embodiment of the present invention.

Referring to FIG. 4B, a process for manufacturing a substrate according to an embodiment of the present invention is as follows.

A pad layer 100 including a plurality of signal pads 110 arranged in a line on a prepared substrate 10 and a plurality of ground pads 130 aligned in a line with the signal pads 110 is formed (S31).

Then, a plurality of ground pads 130 are masked (S32).

Next, the insulating layer 200 'is applied on the pad layer 100 (S33), and the masking is removed (S34).

Subsequently, the conductive layer 300 'is coated on the insulating layer 200' (S35).

4C is a cross-sectional view schematically showing the movement path of the ESD in FIG. 4A.

Referring to FIG. 4C, the movement path of the signal of the ESD component is indicated by an arrow. A signal of the ESD component flows into the signal pad 110 and an insulation breakdown phenomenon occurs in which the insulation layer 200 'is destroyed by an abnormal voltage exceeding a prescribed voltage due to the signal of the introduced ESD component. The insulating layer 200 'loses its insulating property due to dielectric breakdown and current flows, so that the signal of the ESD component flows into the conductive layer 300' from the insulating layer 200 '. The conductive layer 300 'may be electrically connected to the ground pad 130 to connect the signal of the ESD component to the ground. By keeping the ground and the potential equal, it is possible to protect the device from the generation of abnormal voltages such as ESD. This can prevent malfunction of the circuit element 11 when the ESD component flows into the substrate 10 through the signal pad 110.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, 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 present invention.

10: substrate 11: circuit element
100: pad layer 110: signal pad
130: grounding pad 200: insulating layer
300: metal plate 300 ': conductor layer

Claims (16)

A substrate having a laminated structure for protecting a mounted circuit element from static electricity,
In the laminated structure,
A pad layer including a signal pad formed on a substrate and a ground pad spaced apart from the signal pad;
An insulating layer stacked on the pad layer; And
And a conductive layer stacked on the insulating layer and forming a path through which ESD (Electrostatic Discharge) introduced into the signal pad is discharged to the ground pad. The method according to claim 1,
Wherein the insulating layer is laminated so as to cover only the signal pad. 3. The method of claim 2,
Wherein the conductive layer is deposited on the ground pad. The method according to claim 1,
Wherein the insulating layer is formed by mixing conductive particles or organic semiconductor particles at a predetermined ratio so as to have conductivity at a specific voltage or higher. The method of claim 3,
Wherein the conductive layer is a metal plate. 6. The method of claim 5,
Wherein the plurality of signal pads are arranged in a line,
Wherein the plurality of ground pads are arranged in a line in parallel with the plurality of signal pads. The method according to claim 6,
Wherein the plurality of ground pads are arranged symmetrically with respect to the plurality of signal pads. 6. The method of claim 5,
Wherein the insulating layer is formed on one surface of the metal plate. The method according to claim 6,
Wherein the metal plate is electrically connected to the plurality of ground pads. The method according to claim 6,
Wherein a portion of the metal plate covers the plurality of ground pads and the insulating layer is applied only to the remaining portion of the metal plate. 11. The method of claim 10,
Wherein the metal plate is soldered to the plurality of ground pads. 12. The method of claim 11,
Wherein the insulating layer is soldered to the plurality of signal pads. 6. The method of claim 5,
Wherein the metal plate is in the form of a reel. A method of manufacturing a substrate having a laminated structure for protecting a mounted circuit element from static electricity,
Forming a pad layer including a plurality of signal pads arranged in a line on a substrate and a plurality of ground pads arranged in a line spaced apart from the signal pads;
Applying an insulating layer to one side of the metal plate; And
And laminating the metal plate on the substrate such that the insulating layer covers the plurality of signal pads. A method of manufacturing a substrate having a laminated structure for protecting a mounted circuit element from static electricity,
Forming a pad layer including a plurality of signal pads arranged in a line on a substrate and a plurality of ground pads arranged in a line spaced apart from the signal pads;
Applying an insulating layer on the pad layer; And
And applying a conductive layer on the insulating layer. 16. The method of claim 15,
Masking the plurality of ground pads after forming the pad layer; And
And removing the masking after the step of applying the insulating layer.

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