Electronic devices and methods for manufacturing the same

Abstract

Provided is an electronic device comprising: a wiring board that has a mounting surface; a grounding electrode that defines a grounding region on the mounting surface; an electronic component that is disposed on the mounting surface and in the grounding region; an insulating protective layer that is disposed in the grounding region and covers the electronic component; and an electromagnetic shielding layer that is provided across both the insulating protective layer and the grounding electrode, covers the insulating protective layer and is electrically connected to the grounding electrode, and is a solidified product of ink for forming an electromagnetic shielding layer, wherein a porosity S1 that is the porosity of the electromagnetic shielding layer in a section positioned on the grounding electrode is lower than a porosity S2 that is the porosity of the electromagnetic shielding layer in a section positioned on the insulating protective layer. Also provided is a manufacturing method therefor.

Description

Technical Field

[0001] The present disclosure relates to an electronic device and a method for manufacturing the same.

Background Art

[0002] Conventionally, studies have been made on an electronic device (sometimes referred to as an "electronic component" or the like) having a structure in which electronic components are mounted on a wiring board.

[0003] For example, Japanese Unexamined Patent Application Publication No. 2019-91866 discloses the following manufacturing method as a manufacturing method of an electronic component having a sufficient electromagnetic wave shielding effect, facilitating heat removal from the electronic components, and enabling thinning of the electronic component. The manufacturing method of the electronic component disclosed in Japanese Unexamined Patent Application Publication No. 2019-91866 is an electronic substrate including a wiring board having a mounting surface and a plurality of electronic components mounted on the mounting surface of the wiring board, an insulating protective layer provided on the electronic substrate and including the electronic components, an electromagnetic wave shielding layer provided on the insulating protective layer and including the electronic components, and a ground portion that contacts the electromagnetic wave shielding layer and grounds the electromagnetic wave shielding layer and is a manufacturing method of an electronic component having a first step of forming the insulating protective layer from an insulating material, and a second step of forming the electromagnetic wave shielding layer from a conductive material on the insulating protective layer and is a manufacturing method of an electronic component including

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present invention with respect to an electronic substrate including a wiring board having a mounting surface, a ground electrode that defines a ground region on the mounting surface, and an electronic component disposed within the ground region on the mounting surface An insulating protective layer is placed within the ground region and covers the electronic components, An electromagnetic wave shielding layer spans the insulating protective layer and the ground electrode, covering the insulating protective layer and electrically connected to the ground electrode, We considered using this material to manufacture electronic devices. Furthermore, the inventors considered forming the electromagnetic shielding layer by a liquid process using an ink for forming the electromagnetic shielding layer, rather than by a gas phase process (e.g., sputtering, vapor deposition, chemical vapor deposition, etc.), from the viewpoint of simplifying the manufacturing process and manufacturing equipment. However, these studies revealed that when the electromagnetic shielding layer is formed by a liquid process, the durability of the electromagnetic shielding layer may be reduced.

[0005] One object of one aspect of this disclosure is to provide an electronic device and a method for manufacturing the same, which have excellent durability of an electromagnetic shielding layer formed using an ink for forming an electromagnetic shielding layer. [Means for solving the problem]

[0006] The following are examples of specific means for solving the problem: <1> A wiring board having a mounting surface, A ground electrode that defines the ground region on the mounting surface, Electronic components located on the mounting surface and within the ground region, An insulating protective layer is placed within the ground region and covers the electronic components, An electromagnetic shielding layer, which is a solidified form of an ink for forming an electromagnetic shielding layer, is provided spanning the insulating protective layer and the ground electrode, covering the insulating protective layer and electrically connected to the ground electrode. Equipped with, The void ratio S1 of the portion of the electromagnetic shielding layer located on the ground electrode is lower than the void ratio S2 of the portion of the electromagnetic shielding layer located on the insulating protective layer. Electronic devices. <2> The ratio of porosity S2 to porosity S1 is 1.10 or greater. <1> The electronic devices described above. <3> The ratio of void ratio S2 to void ratio S1 is 1.20 or greater. <1> or <2> The electronic devices described above. <4> The ratio of void ratio S2 to void ratio S1 is less than 2.00. <1> ~ <3> An electronic device listed in any one of the following. <5> The porosity S2 is 25.0% or less. <1> ~ <4> An electronic device listed in any one of the following. <6> A preparation step for preparing an electronic substrate comprising a wiring board having a mounting surface, a ground electrode defining a ground region on the mounting surface, and an electronic component placed on the mounting surface within the ground region, A first step involves forming an insulating protective layer that covers the electronic components within the ground region, A second step of forming an electromagnetic shielding layer which spans over an insulating protective layer and a ground electrode, covers the insulating protective layer and is electrically connected to the ground electrode, wherein the void ratio S1 of the portion located on the ground electrode is lower than the void ratio S2 of the portion located on the insulating protective layer. Includes, The second step is, The first electromagnetic shielding layer is formed by applying an ink for forming the first electromagnetic shield layer to a region spanning the insulating protective layer and the ground electrode, and then sintering it. The process involves applying an ink for forming a second electromagnetic shielding layer onto the ground electrode and sintering it to form the second layer, Includes, The portion located on the ground electrode in the first layer and the second layer are formed in a stacked arrangement. The sintering temperature for forming the second layer is higher than the sintering temperature for forming the first layer, and the sintering time for forming the second layer is longer than the sintering time for forming the first layer, satisfying at least one of these conditions. A method for manufacturing electronic devices. <7> The application of the ink for forming the first electromagnetic wave shielding layer in the formation of the first layer and the application of the ink for forming the second electromagnetic wave shielding layer in the formation of the second layer are each performed by an inkjet recording method, a dispenser method, or a spray method, the method for manufacturing an electronic device according to <6>. <8> The first step is the method for manufacturing an electronic device according to <6> or <7>, wherein an insulating protective layer forming ink is applied by an inkjet recording method, a dispenser method, or a spray method to form an insulating protective layer.

Advantages of the Invention

[0007] According to one aspect of the present disclosure, there are provided an electronic device having excellent durability of an electromagnetic wave shielding layer formed using an ink for forming an electromagnetic wave shielding layer and a method for manufacturing the same.

Brief Description of the Drawings

[0008] [Figure 1A] It is a schematic plan view of an electronic substrate prepared in a preparation step in the manufacturing method according to an embodiment of the present disclosure. [Figure 1B] It is a cross-sectional view taken along the line X-X of FIG. 1A. [Figure 2A] It is a schematic plan view of an electronic substrate on which an insulating protective layer is formed in the first step in the manufacturing method according to an embodiment of the present disclosure. [Figure 2B] It is a cross-sectional view taken along the line X-X of FIG. 2A. [Figure 3A] It is a schematic plan view of an electronic substrate on which the first layer is formed in the second step of forming an electromagnetic wave shielding layer in the manufacturing method according to an embodiment of the present disclosure. [Figure 3B] It is a cross-sectional view taken along the line X-X of FIG. 3A. [Figure 4A] It is a schematic plan view of an electronic substrate on which the second layer is formed in the second step of forming an electromagnetic wave shielding layer in the manufacturing method according to an embodiment of the present disclosure. [Figure 4B] It is a cross-sectional view taken along the line X-X of FIG. 4A.

Embodiments for Carrying Out the Invention

[0009] In this disclosure, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this disclosure, the amount of each component in the composition means the total amount of any multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In the numerical ranges described in stages within this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages, or with the values ​​shown in the examples. In this disclosure, the term "process" includes not only independent processes but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. In this disclosure, a preferred combination of embodiments is a more preferred embodiment.

[0010] [Electronic Devices] The electronic devices disclosed herein are A wiring board having a mounting surface, A ground electrode that defines the ground region on the mounting surface, Electronic components located on the mounting surface and within the ground region, An insulating protective layer is placed within the ground region and covers the electronic components, An electromagnetic shielding layer, which is a solidified form of an ink for forming an electromagnetic shielding layer, is provided spanning the insulating protective layer and the ground electrode, covering the insulating protective layer and electrically connected to the ground electrode. Equipped with, The void ratio S1 of the portion of the electromagnetic shielding layer located on the ground electrode is lower than the void ratio S2 of the portion of the electromagnetic shielding layer located on the insulating protective layer. It is an electronic device.

[0011] According to the electronic device of this disclosure, the durability of the electromagnetic shielding layer formed using an ink for forming an electromagnetic shielding layer is improved. The reason for these effects is thought to be that the porosity S1 of the portion of the electromagnetic shielding layer located on the ground electrode is relatively low (i.e., the density is relatively high), which improves the durability of the aforementioned portion of the electromagnetic shielding layer (i.e., the reliability of the connection with the ground electrode). Furthermore, it is thought that the porosity S2 of the portion of the electromagnetic shielding layer located on the insulating protective layer is relatively high, which reduces damage to the electromagnetic shielding layer on the insulating protective layer due to the difference in stress between the insulating protective layer and the electromagnetic shielding layer (i.e., the durability of the electromagnetic shielding layer on the insulating protective layer is improved).

[0012] In this disclosure, conductivity means a volume resistivity of 10 8 This refers to the property of being less than Ωcm. In this disclosure, insulating properties refer to a volume resistivity of 10 10 This refers to the property of being greater than or equal to Ωcm.

[0013] <Embodiment of a manufacturing method for electronic devices> The following describes embodiments of the manufacturing method of the electronic devices of this disclosure. The methods for drawing the electronic devices of this disclosure are not limited to the following embodiments.

[0014] The manufacturing method according to this embodiment is: A preparation step for preparing an electronic substrate comprising a wiring board having a mounting surface, a ground electrode defining a ground region on the mounting surface, and an electronic component placed on the mounting surface within the ground region, A first step involves forming an insulating protective layer that covers the electronic components within the ground region, A second step of forming an electromagnetic shielding layer that spans over an insulating protective layer and a ground electrode, covers the insulating protective layer, and is electrically connected to the ground electrode, wherein the void ratio S1 of the portion located on the ground electrode is lower than the void ratio S2 of the portion located on the insulating protective layer. Includes. The second step in the manufacturing method according to this embodiment is: The first electromagnetic shielding layer is formed by applying an ink for forming the first electromagnetic shield layer to a region spanning the insulating protective layer and the ground electrode, and then sintering it. The process involves applying an ink for forming a second electromagnetic shielding layer onto the ground electrode and sintering it to form the second layer, Includes, The portion located on the ground electrode in the first layer and the second layer are formed in a stacked arrangement. The sintering temperature for forming the second layer is higher than the sintering temperature for forming the first layer, and the sintering time for forming the second layer is longer than the sintering time for forming the first layer, satisfying at least one of these conditions. The manufacturing method according to this embodiment may include other steps as needed.

[0015] In the manufacturing method according to this embodiment, an electromagnetic wave shielding layer is formed in the second step by forming a first layer in a region spanning the insulating protective layer and the ground electrode, and forming a second layer on the ground electrode. Here, the portion of the first layer located on the ground electrode and the second layer are formed in a stacked arrangement. The first and second layers may be formed in any order. The portion of the electromagnetic shielding layer located on the ground electrode is formed by the first layer and the second layer. In the portion of the electromagnetic shielding layer located on the ground electrode, the laminated structure of the first layer and the second layer may be maintained as is, or the first layer and the second layer may be fused and integrated. If the laminated structure of the first layer and the second layer is maintained as is, the interface between the first layer and the second layer may or may not be clearly defined. The portion of the electromagnetic shielding layer located on the insulating protective layer is formed by the portion located on the insulating protective layer of the first layer.

[0016] In the manufacturing method according to this embodiment, by satisfying at least one of the following conditions, the sintering temperature for forming the second layer on the ground electrode is higher than the sintering temperature for forming the first layer in the region spanning the insulating protective layer and the ground electrode, and the sintering time for forming the second layer is longer than the sintering time for forming the first layer, the resulting electromagnetic wave shielding layer can have a void ratio S1 in the portion located on the ground electrode that is lower than the void ratio S2 in the portion located on the insulating protective layer. Therefore, according to the manufacturing method of this embodiment, it is possible to manufacture an electronic device in which the deterioration of connection reliability between the electromagnetic wave shielding layer formed using the electromagnetic wave shielding layer forming ink and the ground electrode is suppressed.

[0017] Hereinafter, an example of a method for manufacturing an electronic device according to the embodiments of this disclosure will be described with reference to the drawings. However, the method for manufacturing an electronic device according to the embodiments of this disclosure is not limited to the following example. In the following explanation, substantially identical elements (e.g., parts or components) will be given the same reference numeral, and redundant explanations may be omitted.

[0018] Figure 1A is a schematic plan view of the electronic substrate prepared in the preparation process, and Figure 1B is a cross-sectional view of Figure 1A along line XX. Figure 2A is a schematic plan view of the electronic substrate on which the insulating protective layer has been formed in the first step, and Figure 2B is a cross-sectional view of Figure 2A along line XX. Figure 3A is a schematic plan view of the electronic substrate in which the first layer was formed in the second step, and Figure 3B is a cross-sectional view of Figure 3A along line XX. Figure 4B is a schematic plan view of the electronic substrate in which the second layer was formed in the second step, and Figure 4B is a cross-sectional view taken along line XX of Figure 4A.

[0019] -Preparation process- As shown in Figures 1A and 1B, in the preparation step of this example, an electronic substrate 10 is prepared, comprising a wiring board 12 having a mounting surface 12S, a ground electrode 16 defining a ground region 14A on the mounting surface 12S, and an electronic component 18 located on the mounting surface 12S and within the ground region 14A. The preparation step may simply involve preparing a pre-manufactured electronic circuit board 10, or it may be a step in manufacturing the electronic circuit board 10. As a method for manufacturing the electronic circuit board 10, for example, a known method for manufacturing an electronic circuit board in which electronic components are mounted on a printed wiring board can be appropriately referenced.

[0020] As the wiring board 12, a board on which wiring is formed, such as a printed circuit board, can be used. The wiring board 12 may include electrodes other than the ground electrode 16, a solder resist layer, and the like.

[0021] The ground electrode 16 is an electrode to which the ground (GND) potential is applied. In this example, multiple electronic components 18 are mounted within a ground region 14A defined by the ground electrode 16. In this example, conductive components may be mounted outside the ground region 14A. Examples of conductive components include electronic components, electrodes, wiring, etc.

[0022] As shown in Figure 1A, the ground electrode 16 in this example is formed as a discontinuous pattern (more specifically, a segmented line pattern; in other words, a dotted line pattern), but the ground electrode in this disclosure is not limited to this example. For example, the ground electrode in this disclosure may be formed as a continuous pattern (i.e., an unsegmented line pattern).

[0023] Furthermore, in this example, the ground electrode 16 is formed as a frame-shaped pattern that completely encircles the multiple electronic components 18. However, the ground electrode 16 in this disclosure is not limited to this frame-shaped pattern, and any pattern that can define the ground region 14A (for example, a U-shaped pattern, etc.) is acceptable. From the viewpoint of further reducing the influence of external electromagnetic waves on the multiple electronic components 18, it is preferable that the ground electrode 16 surrounds the area where the multiple electronic components are located by more than half a circumference, and more preferably surrounds it by more than three-quarters of a circumference.

[0024] The ground region 14A is the region defined by the ground electrode 16. If the pattern of the ground electrode 16 is a continuous frame-shaped pattern, the ground region 14A is the region enclosed by the ground electrode 16. If the pattern of the ground electrode 16 is a discontinuous frame-shaped pattern, the ground region 14A is a region enclosed by a virtual frame formed by connecting the discontinuous (e.g., dotted line and / or U-shaped pattern) ground electrodes 16.

[0025] Furthermore, as shown in Figure 1B, in this example, the ground electrode 16 is formed such that a portion of it in the thickness direction is embedded in the wiring substrate 12. However, the ground electrode in this disclosure is not limited to this example. For example, the ground electrode in this disclosure may be formed such that the entire thickness direction of the ground electrode is embedded. Also, the ground electrode in this disclosure may not be embedded in the wiring substrate 12, but formed on the surface of the wiring substrate 12. Furthermore, the ground electrode in this disclosure may be formed as a pattern that penetrates the wiring substrate 12.

[0026] The multiple electronic components 18 mounted within the ground region 14A may be electronic components of the same design or electronic components of different designs. Furthermore, the number of electronic components mounted within the ground region is not limited to multiple components, and may be only one. Examples of electronic components 18 include semiconductor chips such as integrated circuits (ICs), capacitors, transistors, and the like.

[0027] -1st process- As shown in Figures 2A and 2B, the first step involves forming an insulating protective layer 22 that covers the multiple electronic components 18 mounted within the ground region 14A.

[0028] The insulating protective layer 22 is formed within the ground region 14A, in a region that spans over the multiple electronic components 18 and around these multiple electronic components 18. The functions of the insulating protective layer include, for example, protecting electronic components and suppressing short circuits between electronic components and other conductive components (e.g., electromagnetic shielding layers).

[0029] In the first step, for example, an insulating protective layer 22 is formed by applying an ink for forming an insulating protective layer using an inkjet recording method, a dispenser method, or a spray method. The ink for forming the insulating protective layer is preferably an active energy ray curing ink. When the ink used to form the insulating protective layer is an active energy ray curing type ink, it is advantageous in terms of productivity and the durability of the insulating protective layer.

[0030] The first step is not limited to forming an insulating protective layer using an insulating protective layer forming ink. The insulating protective layer may be formed, for example, using a sheet material. For sheet materials, for example, one can refer to the insulating sheet material described in Japanese Patent Publication No. 2019-91866.

[0031] -Second process- As shown in Figures 3A, 3B, 4A, and 4B, in the second step, the electromagnetic wave shielding layer 32 is formed by forming the first layer 30 and the second layer 31 in that order. This yields the electronic device of this embodiment. In this example, the first layer 30 is formed first, followed by the second layer 31, but the formation order may be reversed (i.e., the second layer 31 may be formed first, followed by the first layer 30).

[0032] The electromagnetic wave shielding layer 32 is a layer that reduces the effects of electromagnetic waves on the electronic component 18 by shielding the electromagnetic waves irradiated onto the electronic component 18. In this disclosure, the performance of such electromagnetic shielding layer 32 is also referred to as "electromagnetic shielding property." The electromagnetic shielding properties of the electromagnetic shielding layer 32 are achieved by placing the electromagnetic shielding layer 32 on the electronic component 18 via an insulating protective layer 22. Furthermore, the electromagnetic shielding properties of the electromagnetic shielding layer 32 are achieved by applying a ground (GND) potential to the electromagnetic shielding layer 32. For this reason, the electromagnetic shielding layer 32 is conductive as a prerequisite for electromagnetic shielding properties.

[0033] The second step is, The first electromagnetic shielding layer is formed by applying the first electromagnetic shielding layer formation ink to a region spanning the insulating protective layer 22 and the ground electrode 16, and then sintering it (see Figures 3A and 3B). The second electromagnetic shielding layer is formed by applying an ink for forming the second electromagnetic shield layer onto the ground electrode 16 and sintering it (see Figures 4A and 4B). Includes. The portion of the first layer 30 located on the ground electrode 16 and the second layer 31 are formed in an arrangement where they are stacked on top of each other. The ink for forming the first electromagnetic shielding layer and the ink for forming the second electromagnetic shielding layer may be the same ink or different inks. The sintering of the first electromagnetic shielding layer formation ink is carried out, for example, by heating the first electromagnetic shielding layer formation ink and irradiating the first electromagnetic shielding layer formation ink with active energy rays (e.g., infrared rays, visible light, ultraviolet rays, etc.). The sintering of the second electromagnetic shielding layer formation ink is carried out in the same manner.

[0034] In the second step, at least one of the following conditions is satisfied: the sintering temperature for forming the second layer 31 is higher than the sintering temperature for forming the first layer 30, and the sintering time for forming the second layer 31 is longer than the sintering time for forming the first layer 30. As a result, in the resulting electromagnetic shielding layer 32, the porosity S1 of the portion PS1 (see Figure 4B) located on the ground electrode 16 can be made lower than the porosity S2 of the portion PS2 (see Figure 4B) located on the insulating protective layer 22.

[0035] As described above, in the electronic device obtained in the second step, the porosity S1 of the portion PS1 located on the ground electrode 16 in the electromagnetic wave shielding layer 32 is lower than the porosity S2 of the portion PS2 located on the insulating protective layer 22 in the electromagnetic wave shielding layer. This suppresses a decrease in connection reliability between the electromagnetic shielding layer 32, formed using the electromagnetic shielding layer formation ink, and the ground electrode 16.

[0036] In Figure 4B, the portion PS1 located on the ground electrode 16 in the electromagnetic wave shielding layer 32 is the portion where the porosity S1 is measured. The range of this portion PS1 in the film thickness direction is from the surface of the ground electrode 16 to the surface of the second layer 31 (i.e., the combined range of the first layer 30 and the second layer 31). The range of the portion PS1 in the direction perpendicular to the film thickness direction is only required to be within the range observable by an SEM (scanning electron microscope). The portion PS2 located on the insulating protective layer 22 in the electromagnetic wave shielding layer 32 is the portion where the porosity S2 is measured. The range of this portion PS2 in the thickness direction is from the surface of the insulating protective layer 22 to the surface of the electromagnetic wave shielding layer 32 (i.e., the range in the thickness direction of the first layer 30). Note that on the insulating protective layer 22, the first layer 30 is the same as that of the electromagnetic wave shielding layer 32. The range of the portion PS2 in the direction perpendicular to the thickness direction only needs to be within the range observable by an SEM (scanning electron microscope). The specific methods for measuring void ratios S1 and S2 will be described later.

[0037] As shown in Figure 4B, the portion PS1 located on the ground electrode 16 in the formed electromagnetic shielding layer 32 (i.e., the portion where the porosity S1 is measured) consists of the second layer 31 and the portion of the first layer 30 located on the ground electrode 16. In the electromagnetic wave shielding layer 32, the second layer 31 and the portion of the first layer 30 above the ground electrode 16 may maintain a laminated structure, or they may be integrated to form a "portion PS1 located above the ground electrode 16 in the electromagnetic wave shielding layer 32". If the laminated structure of the first layer 30 and the second layer 31 is maintained as is, the interface between the first layer 30 and the second layer 31 may or may not be clearly defined.

[0038] The preferred scope of the electronic devices and methods for manufacturing the same described herein will be explained below.

[0039] <Ratio of void ratio S2 to void ratio S1 ("S2 / S1")> In this disclosure, the ratio of porosity S2 to porosity S1 (hereinafter also referred to as the "S2 / S1 ratio" or "S2 / S1") is preferably 1.10 or higher, more preferably 1.20 or higher, and even more preferably 1.25 or higher. When the S2 / S1 ratio is 1.10 or higher, the durability of the electromagnetic shielding layer is further improved.

[0040] The S2 / S1 ratio is preferably less than 2.00, more preferably 1.90 or less, and even more preferably 1.80 or less. When the S2 / S1 ratio is less than 2.00, the durability of the electromagnetic shielding layer is further improved.

[0041] In this disclosure, porosity (i.e., porosity S1, porosity S2) means values ​​measured by the following method. Specifically, a scanning electron microscope image of a cross-section parallel to the thickness direction of the electromagnetic shielding layer is acquired. The obtained scanning electron microscope image is binarized using image editing software (Adobe Photoshop, manufactured by Adobe Systems, Inc.) into white regions where conductive material is present and black regions where voids are present. The void ratio is calculated as the ratio of the area of ​​the black region to the total area of ​​the white region and the black region. The sample is cut to obtain a cross-section, for example, using a microtome (e.g., product name RM2255, manufactured by Leica). Scanning electron microscope images are acquired using a scanning electron microscope (for example, product name S-4700, manufactured by Hitachi).

[0042] The porosity S2 is preferably 25.0% or less, more preferably 20.0% or less, even more preferably 18.0% or less, and even more preferably 15.0% or less. When the porosity S2 is 25.0% or less, the electromagnetic shielding performance of the electromagnetic shielding layer is further improved. There is no particular limit to the lower limit of the porosity S2, but from the viewpoint of suitability for manufacturing the electromagnetic wave shielding layer, it is preferably 3.0% or more, and more preferably 5.0% or more.

[0043] The porosity S1 is preferably 15.0% or less, and more preferably 12.0% or less. When the porosity S1 is 15.0% or less, the durability (i.e., connection reliability) of the electromagnetic shielding layer on the ground electrode is further improved. There is no particular limit to the lower limit of the porosity S1, but from the viewpoint of suitability for manufacturing the electromagnetic wave shielding layer, it is preferably 3.0% or more, and more preferably 5.0% or more.

[0044] Next, preferred embodiments of the ink for forming the electromagnetic wave shielding layer, the method for forming the electromagnetic wave shielding layer, the ink for forming the insulating protective layer, and the method for forming the insulating protective layer will be described.

[0045] <Ink for forming electromagnetic wave shielding layer> The electromagnetic shielding layer in this disclosure is a solidified form of the ink used to form the electromagnetic shielding layer. In other words, the electromagnetic shielding layer in this disclosure is formed by applying an ink for forming an electromagnetic shielding layer and allowing it to solidify.

[0046] In the manufacturing method according to the embodiment described above, an electromagnetic shielding layer is formed by forming a first layer using an ink for forming a first electromagnetic shielding layer, and then forming a second layer using an ink for forming a second electromagnetic shielding layer. The ink for forming the first electromagnetic shielding layer and the ink for forming the second electromagnetic shielding layer may be the same ink or different inks. Hereinafter, the first electromagnetic shielding layer forming ink and the second electromagnetic shielding layer forming ink may be referred to as the first ink and the second ink, respectively. Preferred embodiments of the electromagnetic wave shielding layer forming inks (for example, the first ink and the second ink) will be described below.

[0047] Preferably, the ink for forming the electromagnetic wave shielding layer is an ink containing metal particles (hereinafter also referred to as "metal particle ink"), an ink containing a metal complex (hereinafter also referred to as "metal complex ink"), or an ink containing a metal salt (hereinafter also referred to as "metal salt ink"), with metal salt ink or metal complex ink being more preferable.

[0048] (Metal particle ink) A metal particle ink is, for example, an ink composition in which metal particles are dispersed in a dispersion medium.

[0049] -Metal particles- Examples of metals constituting the metal particles include base metals and precious metals. Examples of base metals include nickel, titanium, cobalt, copper, chromium, manganese, iron, zirconium, tin, tungsten, molybdenum, and vanadium. Examples of precious metals include gold, silver, platinum, palladium, iridium, osmium, ruthenium, rhodium, rhenium, and alloys containing these metals. In particular, from the viewpoint of electromagnetic wave shielding properties, it is preferable that the metal constituting the metal particles includes at least one selected from the group consisting of silver, gold, platinum, nickel, palladium, and copper, and it is more preferable that it includes silver.

[0050] The average particle size of the metal particles is not particularly limited, but is preferably between 10 nm and 500 nm, and more preferably between 10 nm and 200 nm. When the average particle size is within the above range, the firing temperature of the metal particles decreases, and the suitability for the process of forming the electromagnetic shielding layer is improved. In particular, when the metal particle ink is applied using a spray method or an inkjet recording method, the ejection performance tends to improve, and the pattern formation performance and the uniformity of the film thickness of the electromagnetic shielding layer tend to improve. The average particle size referred to here means the average value of the primary particle size of the metal particles (average primary particle size).

[0051] The average particle size of metal particles is measured by laser diffraction / scattering. The average particle size of metal particles is calculated, for example, by measuring the 50% volume cumulative diameter (D50) three times and averaging the values ​​of the three measurements. This can be measured using a laser diffraction / scattering particle size distribution analyzer (product name "LA-960", manufactured by Horiba, Ltd.).

[0052] Furthermore, the metal particle ink may, if necessary, contain metal particles with an average particle size of 500 nm or larger. When metal particles with an average particle size of 500 nm or larger are included, the electromagnetic shielding layer can be bonded by the melting point depression of the nm-sized metal particles around the μm-sized metal particles.

[0053] In metal particle ink, the content of metal particles is preferably 10% to 90% by mass, and more preferably 20% to 50% by mass, relative to the total amount of metal particle ink. When the metal particle content is 10% by mass or more, the surface resistivity is further reduced. When the metal particle content is 90% by mass or less, the ejection performance is improved when the metal particle ink is applied using an inkjet recording method.

[0054] In addition to metal particles, metal particle inks may also contain, for example, dispersants, resins, dispersion media, thickeners, and surface tension modifiers.

[0055] -Dispersant- The metal particle ink may contain a dispersant that adheres to at least a portion of the surface of the metal particles. The dispersant, together with the metal particles, substantially constitutes metal colloid particles. The dispersant coats the metal particles, improving their dispersibility and preventing aggregation. The dispersant is preferably an organic compound capable of forming metal colloid particles. From the viewpoint of electromagnetic shielding properties and dispersion stability, the dispersant is preferably an amine, carboxylic acid, alcohol, or resin dispersant.

[0056] The dispersant contained in the metal particle ink may be one type or two or more types.

[0057] Examples of amines include saturated or unsaturated aliphatic amines. Among these, the amine is preferably an aliphatic amine having 4 to 8 carbon atoms. The aliphatic amine having 4 to 8 carbon atoms may be linear, branched, or have a ring structure.

[0058] Examples of aliphatic amines include butylamine, n-pentylamine, isopentylamine, hexylamine, 2-ethylhexylamine, and octylamine.

[0059] Examples of amines having an alicyclic structure include cycloalkylamines such as cyclopentylamine and cyclohexylamine.

[0060] Aniline is an example of an aromatic amine.

[0061] Amines may have functional groups other than amino groups. Examples of functional groups other than amino groups include hydroxyl groups, carboxyl groups, alkoxy groups, carbonyl groups, ester groups, and mercapto groups.

[0062] Examples of carboxylic acids include formic acid, oxalic acid, acetic acid, hexanoic acid, acrylic acid, octic acid, oleic acid, thianciic acid, ricinoleic acid, gallic acid, and salicylic acid. The carboxyl group, which is part of the carboxylic acid, may form a salt with a metal ion. The metal ion that forms the salt may be one type or two or more types.

[0063] Carboxylic acids may have functional groups other than carboxyl groups. Examples of functional groups other than carboxyl groups include amino groups, hydroxyl groups, alkoxy groups, carbonyl groups, ester groups, and mercapto groups.

[0064] Examples of alcohols include terpene alcohols, allyl alcohols, and oleyl alcohols. Alcohols readily coordinate to the surface of metal particles and can suppress the aggregation of metal particles.

[0065] Examples of resin dispersants include dispersants having a nonionic group as a hydrophilic group and being uniformly soluble in a solvent. Examples of resin dispersants include polyvinylpyrrolidone, polyethylene glycol, polyethylene glycol-polypropylene glycol copolymer, polyvinyl alcohol, polyallylamine, and polyvinyl alcohol-polyvinyl acetate copolymer. The molecular weight of the resin dispersant is preferably 1,000 to 50,000, and more preferably 1,000 to 30,000.

[0066] In the metal particle ink, the dispersant content is preferably 0.5% to 50% by mass, and more preferably 1% to 30% by mass, relative to the total amount of the metal particle ink.

[0067] -Dispersion medium- The metal particle ink preferably contains a dispersion medium. The type of dispersion medium is not particularly limited and includes, for example, hydrocarbons, alcohols, and water.

[0068] The dispersion medium contained in the metal particle ink may be one type or two or more types. The dispersion medium in the metal particle ink is preferably volatile. The boiling point of the dispersion medium is preferably 50°C to 250°C, more preferably 70°C to 220°C, and even more preferably 80°C to 200°C. A boiling point of 50°C to 250°C tends to provide both stability and calcinability for the metal particle ink.

[0069] Examples of hydrocarbons include aliphatic hydrocarbons and aromatic hydrocarbons.

[0070] Examples of aliphatic hydrocarbons include saturated or unsaturated aliphatic hydrocarbons such as tetradecane, octadecane, heptamethylnonane, tetramethylpentadecane, hexane, heptane, octane, nonane, decane, tridecane, methylpentane, normal paraffin, and isoparaffin.

[0071] Examples of aromatic hydrocarbons include toluene and xylene.

[0072] Examples of alcohols include aliphatic alcohols and alicyclic alcohols. When using an alcohol as a dispersion medium, the dispersant is preferably an amine or a carboxylic acid.

[0073] Examples of aliphatic alcohols include heptanol, octanol (e.g., 1-octanol, 2-octanol, 3-octanol, etc.), decanol (e.g., 1-decanol, etc.), lauryl alcohol, tetradecyl alcohol, cetyl alcohol, 2-ethyl-1-hexanol, octadecyl alcohol, hexadecenol, oleyl alcohol, and other aliphatic alcohols having 6 to 20 carbon atoms, which may contain ether bonds in their saturated or unsaturated chains.

[0074] Examples of alicyclic alcohols include cycloalkanols such as cyclohexanol; terpene alcohols such as terpineol (including α, β, γ isomers, or any mixture thereof) and dihydroterpineol; and dihydroterpineol, myrtenol, sobrerol, menthol, carveol, periryl alcohol, pinocarbeol, sobrerol, and verbenol.

[0075] The dispersion medium may be water. From the viewpoint of adjusting physical properties such as viscosity, surface tension, and volatility, the dispersion medium may be a mixed solvent of water and another solvent. The other solvent mixed with water is preferably an alcohol. The alcohol used in combination with water is preferably an alcohol with a boiling point of 130°C or lower that is miscible with water. Examples of alcohols include 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and propylene glycol monomethyl ether.

[0076] In the metal particle ink, the content of the dispersion medium is preferably 1% to 50% by mass relative to the total amount of the metal particle ink. If the content of the dispersion medium is 1% to 50% by mass, sufficient conductivity can be obtained as an ink for forming an electromagnetic wave shielding layer. The content of the dispersion medium is more preferably 10% to 45% by mass, and even more preferably 20% to 40% by mass.

[0077] -resin- The metal particle ink may contain a resin. Examples of resins include polyester, polyurethane, melamine resin, acrylic resin, styrene resin, polyether, and terpene resin.

[0078] The resin contained in the metal particle ink may be one type or two or more types.

[0079] The resin content in the metal particle ink is preferably 0.1% to 5% by mass relative to the total amount of the metal particle ink.

[0080] -Thickener- Metal particle inks may contain thickeners. Examples of thickeners include clay minerals such as clay, bentonite, and hectorite; cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose; and polysaccharides such as xanthan gum and guar gum.

[0081] The thickening agent contained in the metal particle ink may be one type or two or more types.

[0082] In the metal particle ink, the content of the thickener is preferably 0.1% to 5% by mass relative to the total amount of the metal particle ink.

[0083] - Surfactants - Metal particle ink may contain a surfactant. The presence of a surfactant in the metal particle ink facilitates the formation of a uniform electromagnetic shielding layer.

[0084] The surfactant may be anionic, cationic, or nonionic surfactant. Among these, a fluorine-based surfactant is preferred because it can adjust surface tension with a small amount. Furthermore, the surfactant is preferably a compound with a boiling point exceeding 250°C.

[0085] The viscosity of the metal particle ink is not particularly limited and may be between 0.01 Pa·s and 5000 Pa·s, with a preference of 0.1 Pa·s and 100 Pa·s. When the metal particle ink is applied using a spray method or an inkjet recording method, the viscosity of the metal particle ink is preferably between 1 mPa·s and 100 mPa·s, more preferably between 2 mPa·s and 50 mPa·s, and even more preferably between 3 mPa·s and 30 mPa·s.

[0086] The viscosity of metal particle ink is measured using a viscometer at 25°C. Viscosity is measured using, for example, a VISCOMETER TV-22 viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0087] The surface tension of the metal particle ink is not particularly limited, but is preferably 20 mN / m to 45 mN / m, and more preferably 25 mN / m to 40 mN / m. Surface tension is a value measured at 25°C using a surface tension meter.

[0088] The surface tension of the metal particle ink is measured using, for example, the DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0089] -Method for manufacturing metal particles- The metal particles may be commercially available or manufactured by known methods. Examples of methods for manufacturing metal particles include wet reduction, gas phase, and plasma methods. A preferred method for manufacturing metal particles is the wet reduction method, which is capable of producing metal particles with an average particle size of 200 nm or less with a narrow particle size distribution. An example of a method for manufacturing metal particles by wet reduction is a method that includes the steps of: mixing a metal salt and a reducing agent as described in Japanese Patent Publication No. 2017-37761, International Publication No. 2014-57633, etc., to obtain a complexing reaction solution; and heating the complexing reaction solution to reduce the metal ions in the complexing reaction solution to obtain a slurry of metal nanoparticles.

[0090] In the manufacture of metal particle ink, heat treatment may be performed to adjust the content of each component contained in the metal particle ink to a predetermined range. The heat treatment may be performed under reduced pressure or under normal pressure. Furthermore, when performed under normal pressure, it may be performed in air or under an inert gas atmosphere.

[0091] (Metal complex ink) Metal complex inks are, for example, ink compositions in which a metal complex is dissolved in a solvent.

[0092] -Metal complex- Examples of metals that constitute the metal complex include silver, copper, gold, aluminum, magnesium, tungsten, molybdenum, zinc, nickel, iron, platinum, tin, copper, and lead. In particular, from the viewpoint of electromagnetic wave shielding properties, it is preferable that the metal constituting the metal complex includes at least one selected from the group consisting of silver, gold, platinum, nickel, palladium, and copper, and it is more preferable that it includes silver.

[0093] The metal content in the metal complex ink is preferably 1% to 40% by mass, more preferably 5% to 30% by mass, and even more preferably 7% to 20% by mass, relative to the total amount of the metal complex ink in terms of metal elements.

[0094] Metal complexes can be obtained, for example, by reacting a metal salt with a complexing agent. A method for producing metal complexes includes, for example, adding a metal salt and a complexing agent to an organic solvent and stirring for a predetermined time. The stirring method is not particularly limited and can be appropriately selected from known methods such as stirring with a stirring bar, impeller, or mixer, or applying ultrasonic waves.

[0095] Examples of metal salts include metal oxides, thiocyanates, sulfides, chlorides, cyanides, cyanates, carbonates, acetates, nitrates, nitrites, sulfates, phosphates, perchlorates, tetrafluoroborates, acetylacetonate complexes, and carboxylates.

[0096] Examples of complexing agents include amines, ammonium carbamate compounds, ammonium carbonate compounds, ammonium bicarbonate compounds, and carboxylic acids. In particular, from the viewpoint of electromagnetic shielding properties and the stability of the metal complex, it is preferable that the complexing agent includes at least one selected from the group consisting of ammonium carbamate compounds, ammonium carbonate compounds, amines, and carboxylic acids having 8 to 20 carbon atoms.

[0097] The metal complex has a structure derived from a complexing agent, and it is preferable that the metal complex has a structure derived from at least one selected from the group consisting of ammonium carbamate compounds, ammonium carbonate compounds, amines, and carboxylic acids having 8 to 20 carbon atoms.

[0098] Examples of amines used as complexing agents include ammonia, primary amines, secondary amines, tertiary amines, and polyamines.

[0099] Examples of primary amines having a linear alkyl group include methylamine, ethylamine, 1-propylamine, n-butylamine, n-pentylamine, n-hexylamine, heptylamine, octylamine, nonylamine, n-decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, and octadecylamine.

[0100] Examples of primary amines having branched alkyl groups include isopropylamine, sec-butylamine, tert-butylamine, isopentylamine, 2-ethylhexylamine, and tert-octylamine.

[0101] Examples of primary amines having an alicyclic structure include cyclohexylamines and dicyclohexylamines.

[0102] Examples of primary amines having a hydroxyalkyl group include ethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, propanolamine, isopropanolamine, dipropanolamine, diisopropanolamine, trippropanolamine, and triisopropanolamine.

[0103] Examples of primary amines having an aromatic ring include benzylamine, N,N-dimethylbenzylamine, phenylamine, diphenylamine, triphenylamine, aniline, N,N-dimethylaniline, N,N-dimethyl-p-toluidine, 4-aminopyridine, and 4-dimethylaminopyridine.

[0104] Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diphenylamine, dicyclopentylamine, and methylbutylamine.

[0105] Examples of tertiary amines include trimethylamine, triethylamine, tripropylamine, and triphenylamine.

[0106] Examples of polyamines include ethylenediamine, 1,3-diaminopropane, diethylenetriamine, triethylenetetramine, tetramethylenepentamine, hexamethylenediamine, tetraethylenepentamine, and combinations thereof.

[0107] The amine is preferably an alkylamine, more preferably an alkylamine having 3 to 10 carbon atoms, and more preferably a primary alkylamine having 4 to 10 carbon atoms.

[0108] The amine constituting the metal complex may be one type or two or more types.

[0109] When a metal salt reacts with an amine, the ratio of the molar amount of amine to the molar amount of metal salt is preferably 1 to 15 times, and more preferably 1.5 to 6 times. When the above ratio is within the above range, the complex formation reaction is completed and a clear solution is obtained.

[0110] Examples of ammonium carbamate compounds used as complexing agents include ammonium carbamate, methylammonium methyl carbamate, ethylammonium ethyl carbamate, 1-propylammonium 1-propyl carbamate, isopropylammonium isopropyl carbamate, butylammonium butyl carbamate, isobutylammonium isobutyl carbamate, amylammonium amyl carbamate, hexylammonium hexyl carbamate, heptylammonium heptyl carbamate, octylammonium octyl carbamate, 2-ethylhexylammonium 2-ethylhexyl carbamate, nonylammonium nonyl carbamate, and decylammonium decyl carbamate.

[0111] Examples of ammonium carbonate compounds used as complexing agents include ammonium carbonate, methylammonium carbonate, ethylammonium carbonate, 1-propylammonium carbonate, isopropylammonium carbonate, butylammonium carbonate, isobutylammonium carbonate, amylammonium carbonate, hexylammonium carbonate, heptylammonium carbonate, octylammonium carbonate, 2-ethylhexylammonium carbonate, nonylammonium carbonate, and decylammonium carbonate.

[0112] Examples of ammonium bicarbonate compounds used as complexing agents include ammonium bicarbonate, methylammonium bicarbonate, ethylammonium bicarbonate, 1-propylammonium bicarbonate, isopropylammonium bicarbonate, butylammonium bicarbonate, isobutylammonium bicarbonate, amylammonium bicarbonate, hexylammonium bicarbonate, heptylammonium bicarbonate, octylammonium bicarbonate, 2-ethylhexylammonium bicarbonate, nonylammonium bicarbonate, and decylammonium bicarbonate.

[0113] When reacting a metal salt with an ammonium carbamate compound, an ammonium carbonate compound, or an ammonium bicarbonate compound, the ratio of the molar amount of the ammonium carbamate compound, ammonium carbonate compound, or ammonium bicarbonate compound to the molar amount of the metal salt is preferably 0.01 to 1, and more preferably 0.05 to 0.6.

[0114] Examples of carboxylic acids used as complexing agents include caproic acid, caprylic acid, pelargonic acid, 2-ethylhexanoic acid, capric acid, neodecanoic acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, linoleic acid, and linolenic acid. Among these, the carboxylic acid is preferably a carboxylic acid having 8 to 20 carbon atoms, and more preferably a carboxylic acid having 10 to 16 carbon atoms.

[0115] In the metal complex ink, the content of the metal complex is preferably 10% to 90% by mass, and more preferably 10% to 40% by mass, relative to the total amount of the metal complex ink. When the content of the metal complex is 10% by mass or more, the surface resistivity is further reduced. When the content of the metal complex is 90% by mass or less, the ejection performance is improved when the metal particle ink is applied using an inkjet recording method.

[0116] -solvent- Metal complex inks preferably contain a solvent. The solvent is not particularly limited as long as it can dissolve the components contained in the metal complex ink, such as the metal complex. From the viewpoint of ease of manufacture, the solvent preferably has a boiling point of 30°C to 300°C, more preferably 50°C to 200°C, and even more preferably 50°C to 180°C.

[0117] In metal complex inks, the solvent content is preferably such that the concentration of metal ions relative to the metal complex (the amount of metal present as free ions per gram of metal complex) is 0.01 mmol / g to 3.6 mmol / g, and more preferably 0.05 mmol / g to 2 mmol / g. When the concentration of metal ions is within the above range, the metal complex ink exhibits excellent fluidity and electromagnetic shielding properties.

[0118] Examples of solvents include hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, carbamates, alkenes, amides, ethers, esters, alcohols, thiols, thioethers, phosphines, and water. The solvent contained in the metal complex ink may be one type or two or more types.

[0119] The hydrocarbon is preferably a linear or branched hydrocarbon having 6 to 20 carbon atoms. Examples of hydrocarbons include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, nonadecane, and eicosane.

[0120] The cyclic hydrocarbon is preferably a cyclic hydrocarbon having 6 to 20 carbon atoms. Examples of cyclic hydrocarbons include cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, and decalin.

[0121] Examples of aromatic hydrocarbons include benzene, toluene, xylene, and tetralin.

[0122] The ether may be a linear ether, a branched ether, or a cyclic ether. Examples of ethers include diethyl ether, dipropyl ether, dibutyl ether, methyl-t-butyl ether, tetrahydrofuran, tetrahydropyran, dihydropyran, and 1,4-dioxane.

[0123] The alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol.

[0124] Examples of alcohols include ethanol, 1-propanol, 2-propanol, 1-methoxy-2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-octanol, 2-octanol, 3-octanol, tetrahydrofurfuryl alcohol, cyclopentanol, terpineol, decanol, isodecyl alcohol, lauryl alcohol, isolauryl alcohol, myristyl alcohol, isomiristyl alcohol, cetyl alcohol (cetanol), isocetyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, isooleyl alcohol, linolyl alcohol, isolinolyl alcohol, palmityl alcohol, isopalmityl alcohol, icosyl alcohol, and isoicosyl alcohol.

[0125] Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0126] Examples of esters include methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and 3-methoxybutyl acetate.

[0127] -Reducing agent- Metal complex inks may contain a reducing agent. The presence of a reducing agent in a metal complex ink promotes the reduction of the metal complex back to the metal.

[0128] Examples of reducing agents include metal borohydride salts, aluminum hydride salts, amines, alcohols, organic acids, reducing sugars, sugar alcohols, sodium sulfite, hydrazine compounds, dextrin, hydroquinone, hydroxylamine, ethylene glycol, glutathione, and oxime compounds.

[0129] The reducing agent may be an oxime compound described in Japanese Patent Publication No. 2014-516463. Examples of oxime compounds include acetone oxime, cyclohexanone oxime, 2-butanone oxime, 2,3-butanedione monooxime, dimethylgly oxime, methylacetoacetate monooxime, methylpyrubate monooxime, benzaldehyde oxime, 1-indanone oxime, 2-adamantanone oxime, 2-methylbenzamido oxime, 3-methylbenzamido oxime, 4-methylbenzamido oxime, 3-aminobenzamido oxime, 4-aminobenzamido oxime, acetophenone oxime, benzamido oxime, and pinacolone oxime.

[0130] The reducing agent contained in the metal complex ink may be one type or two or more types.

[0131] The amount of reducing agent in the metal complex ink is not particularly limited, but it is preferably 0.1% to 20% by mass, more preferably 0.3% to 10% by mass, and even more preferably 1% to 5% by mass, relative to the total amount of the metal complex ink.

[0132] -resin- Metal complex inks may contain resin. The presence of resin in a metal complex ink improves its adhesion to the substrate.

[0133] Examples of resins include polyester, polyethylene, polypropylene, polyacetal, polyolefin, polycarbonate, polyamide, fluororesin, silicone resin, ethylcellulose, hydroxyethylcellulose, rosin, acrylic resin, polyvinyl chloride, polysulfone, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl resins, polyacrylonitrile, polysulfide, polyamide-imide, polyether, polyarylate, polyetheretherketone, polyurethane, epoxy resin, vinyl ester resin, phenolic resin, melamine resin, and urea resin.

[0134] The resin contained in the metal complex ink may be one type or two or more types.

[0135] - Additives - The metal complex ink may further contain, to the extent that it does not impair the effects of the present disclosure, inorganic salts, organic salts, inorganic oxides such as silica; and additives such as surface modifiers, wetting agents, crosslinking agents, antioxidants, rust inhibitors, heat stabilizers, surfactants, plasticizers, curing agents, thickeners, and silane coupling agents. Preferably, the total content of additives in the metal complex ink is 20% by mass or less of the total amount of the metal complex ink.

[0136] The viscosity of the metal complex ink is not particularly limited and may be between 0.01 Pa·s and 5000 Pa·s, with a preference of 0.1 Pa·s and 100 Pa·s. When the metal complex ink is applied using a spray method or an inkjet recording method, the viscosity of the metal complex ink is preferably between 1 mPa·s and 100 mPa·s, more preferably between 2 mPa·s and 50 mPa·s, and even more preferably between 3 mPa·s and 30 mPa·s.

[0137] The viscosity of metal complex inks is measured using a viscometer at 25°C. Viscosity is measured using, for example, a VISCOMETER TV-22 viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0138] The surface tension of the metal complex ink is not particularly limited, but is preferably 20 mN / m to 45 mN / m, and more preferably 25 mN / m to 35 mN / m. The surface tension is measured using a surface tensimeter at 25°C.

[0139] The surface tension of metal complex inks is measured, for example, using a DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0140] (Metallic salt ink) Metal salt ink is, for example, an ink composition in which a metal salt is dissolved in a solvent.

[0141] -Metal salts- Examples of metals that make up a metal salt include silver, copper, gold, aluminum, magnesium, tungsten, molybdenum, zinc, nickel, iron, platinum, tin, copper, and lead. In particular, from the viewpoint of electromagnetic wave shielding properties, it is preferable that the metals that make up the metal salt include at least one selected from the group consisting of silver, gold, platinum, nickel, palladium, and copper, and it is more preferable that it includes silver.

[0142] The metal content in the metal salt ink is preferably 1% to 40% by mass, more preferably 5% to 30% by mass, and even more preferably 7% to 20% by mass, relative to the total amount of the metal salt ink in terms of metal elements.

[0143] In metal salt ink, the content of the metal salt is preferably 10% to 90% by mass, and more preferably 10% to 40% by mass, relative to the total amount of the metal salt ink. When the metal salt content is 10% by mass or more, the surface resistivity is further reduced. When the metal salt content is 90% by mass or less, the ejection performance is improved when the metal particle ink is applied using a spray method or an inkjet recording method.

[0144] Examples of metal salts include metal benzoates, halides, carbonates, citrates, iodates, nitrites, nitrates, acetates, phosphates, sulfates, sulfides, trifluoroacetates, and carboxylates. Two or more salts may be combined.

[0145] The metal salt is preferably a metal carboxylate salt from the viewpoint of electromagnetic shielding properties and storage stability. The carboxylic acid forming the carboxylate salt is preferably at least one selected from the group consisting of formic acid and carboxylic acids having 1 to 30 carbon atoms, more preferably a carboxylic acid having 8 to 20 carbon atoms, and even more preferably a fatty acid having 8 to 20 carbon atoms. The fatty acid may be linear, branched, or have substituents.

[0146] Examples of straight-chain fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, pentanoic acid, hexanoic acid, heptanoic acid, behenic acid, oleic acid, octanoic acid, nonanoic acid, decanoic acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, and undecanoic acid.

[0147] Examples of branched fatty acids include isobutyric acid, isovaleric acid, ethylhexanoic acid, neodecanoic acid, pivalic acid, 2-methylpentanoic acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2,2-dimethylbutanoic acid, 2,3-dimethylbutanoic acid, 3,3-dimethylbutanoic acid, and 2-ethylbutanoic acid.

[0148] Examples of substituted carboxylic acids include hexafluoroacetylacetone acid, hydroangelic acid, 3-hydroxybutyric acid, 2-methyl-3-hydroxybutyric acid, 3-methoxybutyric acid, acetonedicarboxylic acid, 3-hydroxyglutaric acid, 2-methyl-3-hydroxyglutaric acid, and 2,2,4,4-hydroxyglutaric acid.

[0149] The metal salt may be a commercially available product or may be manufactured by a known method. Silver salts can be manufactured, for example, by the following method:

[0150] First, a silver compound (e.g., silver acetate), which serves as a source of silver, and an equal amount of formic acid or a fatty acid having 1 to 30 carbon atoms relative to the molar equivalent of the silver compound are added to an organic solvent such as ethanol. The mixture is stirred for a predetermined time using an ultrasonic stirrer, and the resulting precipitate is washed with ethanol and decanted. All of these steps can be carried out at room temperature (25°C). The mixing ratio of the silver compound to the formic acid or fatty acid having 1 to 30 carbon atoms is preferably 1:2 to 2:1 in molar ratio, and more preferably 1:1.

[0151] -solvent- The metal salt ink preferably contains a solvent. The type of solvent is not particularly limited as long as it can dissolve the metal salt contained in the metal salt ink. From the viewpoint of ease of manufacture, the boiling point of the solvent is preferably 30°C to 300°C, more preferably 50°C to 300°C, and even more preferably 50°C to 250°C.

[0152] In metal salt inks, the solvent content is preferably such that the concentration of metal ions relative to the metal salt (the amount of metal present as free ions per gram of metal salt) is 0.01 mmol / g to 3.6 mmol / g, and more preferably 0.05 mmol / g to 2.6 mmol / g. When the concentration of metal ions is within the above range, the metal salt ink exhibits excellent fluidity and electromagnetic shielding properties.

[0153] Examples of solvents include hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, carbamates, alkenes, amides, ethers, esters, alcohols, thiols, thioethers, phosphines, and water. The solvent contained in the metal salt ink may be one type or two or more types.

[0154] The solvent preferably contains aromatic hydrocarbons. Examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, propylbenzene, isopropylbenzene, butylbenzene, isobutylbenzene, t-butylbenzene, trimethylbenzene, pentylbenzene, hexylbenzene, tetralin, benzyl alcohol, phenol, cresol, methyl benzoate, ethyl benzoate, propyl benzoate, and butyl benzoate. From the viewpoint of compatibility with other components, the number of aromatic rings in an aromatic hydrocarbon is preferably one or two, and more preferably one. From the viewpoint of ease of production, the boiling point of aromatic hydrocarbons is preferably 50°C to 300°C, more preferably 60°C to 250°C, and even more preferably 80°C to 200°C.

[0155] The solvent may contain aromatic hydrocarbons and hydrocarbons other than aromatic hydrocarbons. Other hydrocarbons besides aromatic hydrocarbons include linear hydrocarbons with 6 to 20 carbon atoms, branched hydrocarbons with 6 to 20 carbon atoms, and alicyclic hydrocarbons with 6 to 20 carbon atoms. Examples of hydrocarbons other than aromatic hydrocarbons include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, octadecane, nonadecane, decalin, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, decene, terpene compounds, and eicosane. Hydrocarbons other than aromatic hydrocarbons preferably contain unsaturated bonds. Examples of hydrocarbons other than aromatic hydrocarbons that contain unsaturated bonds include terpene compounds. Terpene compounds are classified according to the number of isoprene units that make up the terpene compound, for example, into hemiterpenes, monoterpenes, sesquiterpenes, diterpenes, sesterterpenes, triterpenes, sesqualterpenes, and tetraterpenes. Any of the above-mentioned terpene compounds can be used as the solvent, but monoterpenes are preferred. Examples of monoterpenes include pinene (α-pinene, β-pinene), terpineol (α-terpineol, β-terpineol, γ-terpineol), myrcene, camphene, limonene (d-limonene, l-limonene, dipentene), ocimene (α-ocimene, β-ocimene), allo-ocimene, phellandrene (α-phellandrene, β-phellandrene), terpinene (α-terpinene, γ-terpinene), terpinolene (α-terpinolene, β-terpinolene, γ-terpinolene, δ-terpinolene), 1,8-cineole, 1,4-cineole, sabinene, paramentadiene, and carene (δ-3-carene). As the monoterpene, cyclic monoterpenes are preferred, and pinene, terpineol, or carene are more preferred.

[0156] The ether may be a linear ether, a branched ether, or a cyclic ether. Examples of ethers include diethyl ether, dipropyl ether, dibutyl ether, methyl-t-butyl ether, tetrahydrofuran, tetrahydropyran, dihydropyran, and 1,4-dioxane.

[0157] The alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol.

[0158] Examples of alcohols include ethanol, 1-propanol, 2-propanol, 1-methoxy-2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-octanol, 2-octanol, 3-octanol, tetrahydrofurfuryl alcohol, cyclopentanol, terpineol, decanol, isodecyl alcohol, lauryl alcohol, isolauryl alcohol, myristyl alcohol, isomiristyl alcohol, cetyl alcohol (cetanol), isocetyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, isooleyl alcohol, linolyl alcohol, isolinolyl alcohol, palmityl alcohol, isopalmityl alcohol, icosyl alcohol, and isoicosyl alcohol.

[0159] Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0160] Examples of esters include methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, and 3-methoxybutyl acetate.

[0161] The viscosity of the metal salt ink is not particularly limited and may be between 0.01 Pa·s and 5000 Pa·s, with a preference of 0.1 Pa·s and 100 Pa·s. When the metal salt ink is applied using a spray method or an inkjet recording method, the viscosity of the metal salt ink is preferably between 1 mPa·s and 100 mPa·s, more preferably between 2 mPa·s and 50 mPa·s, and even more preferably between 3 mPa·s and 30 mPa·s.

[0162] The viscosity of metal salt ink is measured using a viscometer at 25°C. Viscosity is measured using, for example, a VISCOMETER TV-22 viscometer (manufactured by Toki Sangyo Co., Ltd.).

[0163] The surface tension of the metal salt ink is not particularly limited, but is preferably 20 mN / m to 45 mN / m, and more preferably 25 mN / m to 35 mN / m. The surface tension is measured using a surface tensimeter at 25°C.

[0164] The surface tension of metal salt inks is measured, for example, using a DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0165] The ink for forming the electromagnetic shielding layer preferably contains a metal complex or a metal salt. The metal complex is preferably a metal complex having a structure derived from at least one selected from the group consisting of ammonium carbamate compounds, ammonium carbonate compounds, amines, and carboxylic acids having 8 to 20 carbon atoms. The metal salt is preferably a metal carboxylate salt.

[0166] <Method for forming an electromagnetic wave shielding layer> The second step is, The first electromagnetic shielding layer is formed by applying an ink for forming the first electromagnetic shield layer to a region spanning the insulating protective layer and the ground electrode, and then sintering it. The process involves applying an ink for forming a second electromagnetic shielding layer onto the ground electrode and sintering it to form the second layer, It is preferable that it includes. It is preferable that at least one of the following conditions is met: the sintering temperature for forming the second layer is higher than the sintering temperature for forming the first layer, and the sintering time for forming the second layer is longer than the sintering time for forming the first layer. This makes it easier to form an electromagnetic shielding layer in which the porosity S1 of the portion located on the ground electrode is lower than the porosity S2 of the portion located on the insulating protective layer.

[0167] If the sintering temperature for forming the second layer (hereinafter also referred to as the sintering temperature of the second layer) is higher than the sintering temperature for forming the first layer (hereinafter also referred to as the sintering temperature of the first layer), the value obtained by subtracting the sintering temperature of the first layer from the sintering temperature of the second layer is preferably 3°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher.

[0168] The formation of the first layer (i.e., application of the ink for forming the first electromagnetic shielding layer and sintering) and the formation of the second layer (i.e., application of the ink for forming the second electromagnetic shielding layer and sintering) may each be performed only once or two or more times. The number of times the first layer is formed is preferably two or more, and more preferably three or more. The number of times the second layer is formed is preferably one or more, and more preferably two or more.

[0169] (Method of applying ink for forming an electromagnetic wave shielding layer) The method for applying the electromagnetic wave shielding layer ink (specifically, the first ink and the second ink) is preferably an inkjet recording method, a dispenser method, or a spray method, with the inkjet recording method being particularly preferred.

[0170] The inkjet recording method may be any of the following: a charge control method that ejects ink using electrostatic attraction; a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element; an acoustic inkjet method that converts an electrical signal into an acoustic beam, irradiates the ink with it, and ejects the ink using the radiation pressure; or a thermal inkjet (BubbleJet®) method that heats the ink to form bubbles and utilizes the resulting pressure.

[0171] As an inkjet recording method, in particular, the method described in Japanese Patent Publication No. 54-59936, in which the ink, when subjected to thermal energy, undergoes a rapid volume change, and the force resulting from this state change causes the ink to be ejected from the nozzle, can be effectively utilized.

[0172] Furthermore, regarding the inkjet recording method, the method described in paragraphs 0093 to 0105 of Japanese Patent Publication No. 2003-306623 can also be referenced.

[0173] Inkjet heads used in inkjet recording methods include a shuttle method, which uses a short serial head and records while scanning the head in the width direction of the substrate, and a line method, which uses a line head in which recording elements are arranged to cover the entire area of ​​one side of the substrate.

[0174] In the line method, the substrate can be scanned in a direction intersecting the arrangement direction of the recording elements, allowing for pattern formation across the entire surface of the substrate and eliminating the need for a transport system such as a carriage to scan the short head.

[0175] Furthermore, since the complex scanning control of the carriage movement and substrate is eliminated, and only the substrate moves, a faster recording speed can be achieved compared to the shuttle method.

[0176] The amount of insulating ink droplets ejected from the inkjet head is preferably 1 pL (picoliters) to 100 pL, more preferably 3 pL to 80 pL, and even more preferably 3 pL to 20 pL.

[0177] The temperature of the electronic substrate when applying the ink for forming the electromagnetic wave shielding layer is preferably 20°C to 120°C, and more preferably 28°C to 80°C.

[0178] (Sintering temperature) The firing temperature for sintering the electromagnetic wave shielding layer-forming inks (e.g., first ink and second ink) is preferably 250°C or lower, more preferably 50°C to 200°C, and even more preferably 60°C to 120°C. Furthermore, the baking time is preferably between 1 minute and 120 minutes, and more preferably between 1 minute and 40 minutes.

[0179] As mentioned above, the formation of the first layer and the second layer may be carried out by repeating the ink application and firing cycle multiple times. Furthermore, the ink application and firing cycle may include ultraviolet irradiation between the application and firing stages.

[0180] From the viewpoint of electromagnetic shielding performance, the thickness of the electromagnetic shielding layer is preferably 0.1 μm to 30 μm, and more preferably 0.3 μm to 15 μm.

[0181] The thickness of the electromagnetic shielding layer is measured using a laser microscope (product name "VK-X1000", manufactured by Keyence Corporation).

[0182] <Ink for forming an insulating protective layer> In this disclosure, the insulating protective layer is preferably a solidified product of an ink for forming an insulating protective layer. In other words, the insulating protective layer in this disclosure is preferably formed by applying an insulating protective layer forming ink and allowing it to solidify.

[0183] The ink for forming the insulating protective layer is preferably an active energy ray curing ink. The active energy ray curable ink for forming an insulating protective layer contains a polymerizable monomer and a polymerization initiator.

[0184] (polymerizable monomer) A polymerizable monomer is a monomer that has at least one polymerizable group in one molecule. The polymerizable group in a polymerizable monomer may be a cationic polymerizable group or a radical polymerizable group, but from the viewpoint of curability, a radical polymerizable group is preferable. Furthermore, from the viewpoint of curability, the radical polymerizable group is preferably an ethylenically unsaturated group.

[0185] In this disclosure, "monomer" refers to a compound having a molecular weight of 1000 or less. The molecular weight can be calculated from the types and number of atoms that make up the compound.

[0186] The polymerizable monomer may be a monofunctional polymerizable monomer having one polymerizable group, or a polyfunctional polymerizable monomer having two or more polymerizable groups.

[0187] The monofunctional polymerizable monomer is not particularly limited as long as it is a monomer having one polymerizable group. From the viewpoint of curability, the monofunctional polymerizable monomer is preferably a monofunctional radical polymerizable monomer, and more preferably a monofunctional ethylenically unsaturated monomer.

[0188] Examples of monofunctional ethylenically unsaturated monomers include monofunctional (meth)acrylates, monofunctional (meth)acrylamides, monofunctional aromatic vinyl compounds, monofunctional vinyl ethers, and monofunctional N-vinyl compounds.

[0189] Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, isoamyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate. 4-n-butylcyclohexyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, 2-ethylhexyldiglycol (meth)acrylate, butoxyethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 4-bromobutyl (meth)acrylate, cyanoethyl (meth)acrylate, benzyl (meth)acrylate, butoxymethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-(2-meth Xyethoxyethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, 2-phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, glycidyl (meth)acrylate Glycidyloxybutyl (meth)acrylate, glycidyloxyethyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate,Phenylglycidyl ether (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, polyethylene oxide (meth)acrylate, polyethylene oxide monoalkyl ether (meth)acrylate, dipropylene glycol (meth)acrylate, polypropylene oxide monoalkyl ether (meth)acrylate, 2-methacryloyloxyethyl succinate, 2-methacryloyloxyhexahydrophthalate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, ethoxydiethylene glycol (meth)acrylate, butoxydiethyl Examples include ethylene glycol (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, ethylene oxide (EO)-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, propylene oxide (PO)-modified nonylphenol (meth)acrylate, EO-modified 2-ethylhexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (3-ethyl-3-oxetanylmethyl) (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-carboxyethyl (meth)acrylate, and 2-(meth)acryloyloxyethyl succinate.

[0190] In particular, from the viewpoint of improving heat resistance, the monofunctional (meth)acrylate is preferably a monofunctional (meth)acrylate having an aromatic ring or an aliphatic ring, and is more preferably isobornyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, or dicyclopentanyl (meth)acrylate.

[0191] Examples of monofunctional (meth)acrylamides include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, Nn-butyl(meth)acrylamide, Nt-butyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, and (meth)acryloylmorpholin.

[0192] Examples of monofunctional aromatic vinyl compounds include styrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, methyl vinylbenzoate, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octylstyrene, 4-octylstyrene, 3-(2-ethylhexyl)styrene, 4-(2-ethylhexyl)styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-t-butoxycarbonylstyrene, and 4-t-butoxystyrene.

[0193] Examples of monofunctional vinyl ethers include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, 4-methylcyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, and phenoxypolyethylene glycol vinyl ether.

[0194] Examples of monofunctional N-vinyl compounds include N-vinyl-ε-caprolactam and N-vinylpyrrolidone.

[0195] The polyfunctional polymerizable monomer is not particularly limited as long as it is a monomer having two or more polymerizable groups. From the viewpoint of curability, the polyfunctional polymerizable monomer is preferably a polyfunctional radical polymerizable monomer, and more preferably a polyfunctional ethylenically unsaturated monomer.

[0196] Examples of polyfunctional ethylenically unsaturated monomers include polyfunctional (meth)acrylate compounds and polyfunctional vinyl ethers.

[0197] Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. Acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, heptanediol di(meth)acrylate, EO-modified neopentyl glycol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, EO-modified hexanediol di(meth)acrylate, PO-modified hexanediol di(meth)acrylate, octanediol di(meth)acrylate Acrylate, nonanediol di(meth)acrylate, decanediol di(meth)acrylate, dodecanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, tri Examples include methylolpropane EO-added tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, and tris(2-acryloyloxyethyl) isocyanurate.

[0198] Examples of polyfunctional vinyl ethers include 1,4-butanediol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, and ditrimethylolpropane. Examples include trivinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexanyl ether, EO-added trimethylolpropane trivinyl ether, PO-added trimethylolpropane trivinyl ether, EO-added ditrimethylolpropane tetravinyl ether, PO-added ditrimethylolpropane tetravinyl ether, EO-added pentaerythritol tetravinyl ether, PO-added pentaerythritol tetravinyl ether, EO-added dipentaerythritol hexanyl ether, and PO-added dipentaerythritol hexanyl ether.

[0199] In particular, from the viewpoint of curability, the polyfunctional polymerizable monomer is preferably a monomer in which the number of carbon atoms in the part other than the (meth)acryloyl group is 3 to 11. Specifically, as monomers in which the number of carbon atoms in the part other than the (meth)acryloyl group is 3 to 11, it is more preferable that the monomer is 1,6-hexanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate (EO chain n=4), or 1,10-decanediol di(meth)acrylate.

[0200] The polymerizable monomer content is preferably 10% to 98% by mass, and more preferably 50% to 98% by mass, based on the total amount of the ink for forming the insulating protective layer.

[0201] (Polymerization initiator) Polymerization initiators included in inks for forming insulating protective layers include, for example, oxime compounds, alkylphenone compounds, acylphosphine compounds, aromatic onium salt compounds, organic peroxides, thio compounds, hexaarylbisimidazole compounds, borate compounds, azinium compounds, titanocene compounds, active ester compounds, compounds having carbon-halogen bonds, and alkylamines.

[0202] In particular, from the viewpoint of further improving conductivity, the polymerization initiator contained in the insulating layer forming ink is preferably at least one selected from the group consisting of oxime compounds, alkylphenone compounds, and titanocene compounds, more preferably an alkylphenone compound, and even more preferably at least one selected from the group consisting of α-aminoalkylphenone compounds and benzyl ketal alkylphenones.

[0203] The polymerization initiator content is preferably 0.5% to 20% by mass, and more preferably 2% to 10% by mass, relative to the total amount of the insulating layer forming ink.

[0204] The insulating protective layer-forming ink may contain components other than polymerization initiators and polymerizable monomers. Examples of other components include chain transfer agents, polymerization inhibitors, sensitizers, surfactants, and additives.

[0205] (Chain transfer agent) The ink for forming an insulating protective layer may contain at least one chain transfer agent. From the viewpoint of improving the reactivity of the photopolymerization reaction, the chain transfer agent is preferably a polyfunctional thiol.

[0206] Examples of polyfunctional thiols include aliphatic thiols such as hexane-1,6-dithiol, decane-1,10-dithiol, dimercaptodiethyl ether, and dimercaptodiethyl sulfide, and aromatic thiols such as xylylene dimercaptan, 4,4′-dimercaptodiphenyl sulfide, and 1,4-benzenedithiol; Polyhydric alcohols such as ethylene glycol bis(mercaptoacetate), polyethylene glycol bis(mercaptoacetate), propylene glycol bis(mercaptoacetate), glycerin tris(mercaptoacetate), trimethylolethane tris(mercaptoacetate), trimethylolpropane tris(mercaptoacetate), pentaerythritol tetrakis(mercaptoacetate), and dipentaerythritol hexakis(mercaptoacetate) are poly(mercaptoacetate); Polyhydric alcohols such as ethylene glycol bis(3-mercaptopropionate), polyethylene glycol bis(3-mercaptopropionate), propylene glycol bis(3-mercaptopropionate), glycerin tris(3-mercaptopropionate), trimethylolethane tris(mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), and poly(3-mercaptopropionate); and Examples of poly(mercaptobutyrates) include 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and pentaerythritol tetrakis(3-mercaptobutyrate).

[0207] (Polymerization inhibitor) The ink for forming an insulating protective layer may contain at least one polymerization inhibitor. Polymerization inhibitors include p-methoxyphenol, quinones (e.g., hydroquinone, benzoquinone, methoxybenzoquinone, etc.), phenothiazines, catechols, alkylphenols (e.g., dibutylhydroxytoluene (BHT), etc.), alkylbisphenols, zinc dimethyldithiocarbamate, copper dimethyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionates, mercaptobenzimidazole, phosphites, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (TEMPOL), and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt (also known as cuperone Al).

[0208] In particular, the polymerization inhibitor is preferably at least one selected from p-methoxyphenol, catechols, quinones, alkylphenols, TEMPO, TEMPOL, and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt, and more preferably at least one selected from p-methoxyphenol, hydroquinone, benzoquinone, BHT, TEMPO, TEMPOL, and tris(N-nitroso-N-phenylhydroxylamine)aluminum salt.

[0209] If the ink for forming an insulating protective layer contains a polymerization inhibitor, the amount of polymerization inhibitor is preferably 0.01% to 2.0% by mass, more preferably 0.02% to 1.0% by mass, and particularly preferably 0.03% to 0.5% by mass, based on the total amount of the ink for forming an insulating protective layer.

[0210] (Sensitizer) The ink for forming an insulating protective layer may contain at least one sensitizer.

[0211] Examples of sensitizers include polynuclear aromatic compounds (e.g., pyrene, perylene, triphenylene, and 2-ethyl-9,10-dimethoxyanthracene), xanthene compounds (e.g., fluorescein, eosin, erythrosine, rhodamine B, and rose bengal), cyanine compounds (e.g., thiacarbocyanine and oxacarbocyanine), merocyanine compounds (e.g., merocyanine and carbomerocyanine), thiazine compounds (e.g., thionine, methylene blue, and toluidine blue), acridine compounds (e.g., acridine orange, chloroflavin, and acriflavin), anthraquinones (e.g., anthraquinone), squalium compounds (e.g., squalium), coumarin compounds (e.g., 7-diethylamino-4-methylcoumarin), thioxanthone compounds (e.g., isopropylthioxanthone), and thiochromanone compounds (e.g., thiochromanone). In particular, the sensitizer is preferably a thioxanthone compound.

[0212] When the ink for forming an insulating protective layer contains a sensitizer, the amount of sensitizer is not particularly limited, but it is preferably 1.0% to 15.0% by mass, and more preferably 1.5% to 5.0% by mass, relative to the total amount of the ink for forming an insulating protective layer.

[0213] (Surfactants) The ink for forming an insulating protective layer may contain at least one surfactant.

[0214] Examples of surfactants include those described in Japanese Patent Publication No. 62-173463 and Japanese Patent Publication No. 62-183457. Other examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycol, and polyoxyethylene-polyoxypropylene block copolymers; and cationic surfactants such as alkylamine salts and quaternary ammonium salts. The surfactant may also be a fluorine-based surfactant or a silicone-based surfactant.

[0215] When the ink for forming an insulating protective layer contains a surfactant, the surfactant content is preferably 0.5% by mass or less, and more preferably 0.1% by mass or less, based on the total amount of the ink for forming the insulating protective layer. The lower limit of the surfactant content is not particularly limited.

[0216] When the surfactant content is 0.5% by mass or less, the insulating protective layer-forming ink does not spread easily after it has been applied. Therefore, the outflow of the insulating protective layer-forming ink is suppressed, and the electromagnetic shielding performance is improved.

[0217] (Organic solvents) The ink for forming an insulating protective layer may contain at least one organic solvent.

[0218] Examples of organic solvents include (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME), dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether; (Poly)alkylene glycol dialkyl ethers such as ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, and tetraethylene glycol dimethyl ether; (Poly)alkylene glycol acetates such as diethylene glycol acetate; (Poly)alkylene glycol diacetates such as ethylene glycol diacetate and propylene glycol diacetate; (Poly)alkylene glycol monoalkyl ether acetates such as ethylene glycol monobutyl ether acetate and propylene glycol monomethyl ether acetate, and ketones such as methyl ethyl ketone and cyclohexanone; Lactones such as γ-butyrolactone; Esters such as ethyl acetate, propyl acetate, butyl acetate, 3-methoxybutyl acetate (MBA), methyl propionate, and ethyl propionate; Cyclic ethers such as tetrahydrofuran and dioxane; and Examples include amides such as dimethylformamide and dimethylacetamide.

[0219] When the ink for forming an insulating protective layer contains an organic solvent, the content of the organic solvent is preferably 70% by mass or less, and more preferably 50% by mass or less, based on the total amount of the ink for forming the insulating protective layer. The lower limit of the organic solvent content is not particularly limited.

[0220] (Additives) The ink for forming an insulating protective layer may contain additives such as co-sensitizers, ultraviolet absorbers, antioxidants, fade inhibitors, and basic compounds, as needed.

[0221] (Physical properties) The pH of the ink for forming the insulating protective layer is preferably 7 to 10, more preferably 7.5 to 9.5, from the viewpoint of improving ejection stability when applied using an inkjet recording method. The pH is measured at 25 °C using a pH meter, for example, using a pH meter (model number "HM-31") manufactured by Toa DKK Corporation.

[0222] The viscosity of the ink for forming the insulating protective layer is preferably 0.5 mPa·s to 60 mPa·s, more preferably 2 mPa·s to 40 mPa·s. The viscosity is measured at 25 °C using a viscometer, for example, using a TV-22 type viscometer manufactured by Toki Sangyo Co., Ltd.

[0223] The surface tension of the ink for forming the insulating protective layer is preferably 60 mN / m or less, more preferably 20 mN / m to 50 mN / m, and even more preferably 25 mN / m to 45 mN / m. The surface tension is measured at 25 °C using a surface tension meter, for example, using an automatic surface tension meter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd. and measured by the plate method.

[0224] <Method for forming the insulating protective layer> In the first step, preferably, an ink for forming an insulating protective layer is applied onto an electronic substrate using an inkjet recording method, a dispenser coating method, or a spray coating method, and the ink for forming the insulating protective layer is cured to form an insulating protective layer.

[0225] From the viewpoint of being able to reduce the thickness of the ink film formed by a single application by dropping a small amount, the method of applying the ink for forming the insulating protective layer is preferably the inkjet recording method. The details of the inkjet recording method are as described above.

[0226] The method for curing the ink for forming the insulating protective layer is not particularly limited, and examples include a method of irradiating the ink for forming the insulating protective layer applied on the substrate with active energy rays.

[0227] Examples of active energy rays include ultraviolet light, visible light, and electron beams, with ultraviolet light (hereinafter also referred to as "UV") being preferred.

[0228] The peak wavelength of ultraviolet light is preferably 200 nm to 405 nm, more preferably 250 nm to 400 nm, and even more preferably 300 nm to 400 nm.

[0229] The exposure dose during irradiation with active energy rays is 100 mJ / cm². 2 ~5000 mJ / cm 2 Preferably, it is 300 mJ / cm². 2 ~1500 mJ / cm 2 It is preferable that it be so.

[0230] Mercury lamps, gas lasers, and solid-state lasers are the main light sources used for ultraviolet irradiation, with mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps being widely known. UV-LEDs (light-emitting diodes) and UV-LDs (laser diodes) are also promising light sources for ultraviolet irradiation due to their small size, long lifespan, high efficiency, and low cost. Among these, metal halide lamps, high-pressure mercury lamps, medium-pressure mercury lamps, low-pressure mercury lamps, or UV-LEDs are preferred as light sources for ultraviolet irradiation.

[0231] In the process of obtaining an insulating protective layer, it is preferable to repeat the process of applying insulating ink and irradiating with active energy rays two or more times in order to obtain an insulating protective layer of the desired thickness.

[0232] The thickness of the insulating protective layer is preferably 5 μm to 5000 μm, and more preferably 10 μm to 2000 μm. [Examples]

[0233] The following are examples of the embodiments of this disclosure, but this disclosure is not limited to the following embodiments.

[0234] [Example 1] <Fabrication of electronic device X1> (Preparation of electronic circuit board B1) The shielding can and frame were removed from the Quectel LTE module to obtain the electronic circuit board B1. This electronic substrate B1 falls within the scope of electronic substrates in this disclosure (i.e., electronic substrates comprising a wiring board having a mounting surface, a ground electrode defining a ground region on the mounting surface, and electronic components arranged on the mounting surface within the ground region).

[0235] (Preparation of ink for forming an insulating protective layer) The components of the composition listed below were mixed, and the mixture was stirred for 20 minutes at 25°C and 5000 revolutions per minute using a mixer (product name "L4R", manufactured by Silverson) to obtain an ink for forming an insulating protective layer.

[0236] -Composition of ink for forming an insulating protective layer- • Omni.379: 2-(dimethylamino)-2-(4-methylbenzyl)-1-(4-morpholinophenyl)-butan-1-one (product name "Omnirad 379", manufactured by IGM Resins BV) …1.0% by mass • 4-PBZ: 4-phenylbenzophenone (product name "Omnirad 4-PBZ", manufactured by IGM) …7.5% by mass • NVC: N-vinylcaprolactam (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) …15.0% by mass • HDDA: 1,6-Hexanediol diacrylate (product name "SR238", manufactured by Sartomer Corporation) …25.5% by mass • IBOA: Isobornyl acrylate (product name "SR506", manufactured by Sartomer Corporation) …30.0% by mass • Pentaerythritol tetrakis(3-mercaptobutyrate), product name "Karenz MT-PE1" …20.0% by mass • MEHQ: p-Methoxyphenol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) …1.0% by mass

[0237] (Preparation of Ink for Forming Electromagnetic Wave Shielding Layer (Ink A)) 40 g of silver neodecanoate was added to a 200 mL three-neck flask. 30.0 g of trimethylbenzene and 30.0 g of terpineol were added thereto, followed by stirring to obtain a solution containing a silver salt. The obtained solution was filtered using a PTFE (polytetrafluoroethylene) membrane filter with a pore size of 0.45 μm to obtain Ink A as the ink for forming an electromagnetic wave shielding layer.

[0238] (Preparation of Ink for Forming Electromagnetic Wave Shielding Layer (Ink B)) - Preparation of Silver Particle Dispersion 1 - A solution a was prepared by dissolving 6.8 g of polyvinylpyrrolidone (weight average molecular weight: 3000, manufactured by Sigma-Aldrich) as a dispersant in 100 mL of water. Separately, a solution b was prepared by dissolving 50.00 g of silver nitrate in 200 mL of water. Solution a and solution b were mixed, and 78.71 g of an 85 mass% aqueous solution of N,N-diethylhydroxylamine was added dropwise to the obtained mixture at room temperature while stirring. Further, a solution prepared by dissolving 6.8 g of polyvinylpyrrolidone in 1000 mL of water was slowly added dropwise at room temperature. The obtained suspension was passed through an ultrafiltration unit (Vivaflo 50 manufactured by Sartorius Stedim, molecular weight cut-off: 100,000, number of units: 4) and purified by passing purified water until about 5 L of permeate came out from the ultrafiltration unit. The supply of purified water was stopped, and the solution was concentrated to obtain 30 g of silver particle dispersion 1. The content of the solid matter in this dispersion was 50 mass%. When the content of silver in the solid matter was measured by TG-DTA (simultaneous differential thermal and thermogravimetric measurement) (manufactured by Hitachi High-Tech Corporation, model: STA7000 series), it was 96.0 mass%. The obtained silver particle dispersion 1 was diluted 20-fold with ion-exchanged water, and the volume average particle diameter of the silver particles was determined using a particle size analyzer FPAR-1,000 (manufactured by Otsuka Electronics Co., Ltd.). The volume particle diameter of silver particle dispersion 1 was 60 nm.

[0239] - Adjustment of Ink B - To 10 g of silver particle dispersion, 2 g of 2-propanol and 0.1 g of Olphine E-1010 (manufactured by Nisshin Chemical Industry Co., Ltd.) as a surfactant were added, and water was added to achieve a silver concentration of 40% by mass to obtain ink B, which is used as an ink for forming an electromagnetic wave shielding layer.

[0240] (Formation of insulating protective layer (first step)) An inkjet recording device (product name "DMP-2850", manufactured by FUJIFILM DIMATIX) was prepared, and the ink cartridge (for 10 picoliters) of this inkjet recording device was filled with ink B1 for forming an insulating protective layer. A UV spot cure device, the OmniCure S2000 (manufactured by LumenDynamics), was placed next to the inkjet head of the inkjet recording device.

[0241] In the above-described inkjet recording apparatus, an insulating protective layer-forming ink was ejected from the inkjet head and applied to the insulating protective layer-forming region on the electronic substrate. The applied insulating protective layer-forming ink A1 was then irradiated with UV (ultraviolet) light using a UV spot cure. By repeating the process of applying the ink and irradiating with UV light, an insulating protective layer was formed. The insulating protective layer pattern covers the electronic components within the ground region of the electronic substrate B1, and the pattern edge is positioned inside the inner edge of the ground electrode (see, for example, Figure 2A). The conditions for applying the insulating protective layer ink were a resolution of 1270 dpi (dots per inch) and a droplet size of 10 picoliters per dot.

[0242] (Formation of electromagnetic shielding layer (second step)) Prepare an inkjet recording device (product name "DMP-2850", manufactured by FUJIFILM DIMATIX), and use the ink cartridge (for 10 picoliters) of this inkjet recording device. Ink A as the first ink (i.e., ink for forming the first electromagnetic wave shielding layer), Ink A as the second ink (i.e., ink for forming the second electromagnetic shielding layer), Each was filled with one of the following. Next, the electronic substrate with the insulating protective layer formed on it was heated to 60°C.

[0243] Next, ink A, as the first ink, was ejected from the inkjet head of the inkjet recording apparatus and applied to a region spanning the insulating protective layer and the ground electrode on the electronic substrate, and sintered at the sintering temperature and sintering time shown in Table 1. The above process of applying the first ink and sintering was repeated the number of times shown in Table 1 to obtain the first layer (see, for example, Figure 3A).

[0244] Next, ink A, as the second ink, was ejected from the inkjet head of the inkjet recording device and applied to the ground electrode on the electronic substrate, and sintered at the sintering temperature and sintering time shown in Table 1. To ensure that the second ink was reliably placed on the ground electrode during application, the width of the second ink pattern was made wider than the width of the ground electrode. Specifically, in a plan view, the pattern of the second ink was made to extend 0.15 mm from each end in the width direction of the ground electrode (width 0.7 mm). The process of applying the second ink and sintering was repeated the number of times shown in Table 1 to obtain the second layer (see, for example, Figure 4A).

[0245] By forming the first and second layers as described above, an electromagnetic shielding layer is obtained that spans over the insulating protective layer and the ground electrode, covers the insulating protective layer, and is electrically connected to the ground electrode.

[0246] As described above, an insulating protective layer, an insulating protective layer, and an electromagnetic wave shielding layer were formed on the electronic substrate B1 to obtain the electronic device X1.

[0247] <Measurement and Evaluation> The following measurements and evaluations were performed on the electronic device X1. The results are shown in Table 1.

[0248] (Measurement of void ratios S1 and S2) In electronic device X1, The void ratio S1 of the portion located on the ground electrode of the electromagnetic shielding layer, The porosity S2 of the portion located on the insulating protective layer of the electromagnetic wave shielding layer, Each of these was measured using the method described above. Based on the results obtained, the S2 / S1 ratio (referred to as "S2 / S1" in Table 1) was calculated. These results are shown in Table 1.

[0249] (Evaluation of electromagnetic shielding performance of electromagnetic shielding layers (low frequency and high frequency)) The electronic device X1 obtained above was made to communicate using LTE BAND13, and the near-field magnetic field was measured using a near-field magnetic field measuring device (product name "SmartScan550", manufactured by API Corporation), and the noise suppression level (unit: dB) was measured. Noise suppression levels were measured for both low frequencies (below 1 GHz) and high frequencies (1 GHz to 5 GHz). Based on the obtained noise suppression levels, the electromagnetic shielding performance of the electromagnetic shielding layer was evaluated according to the following evaluation criteria. The results are shown in Table 1. In the evaluation criteria below, the rank for the best electromagnetic shielding performance of the electromagnetic shielding layer is "4".

[0250] -Evaluation Criteria for Electromagnetic Shielding Performance of Electromagnetic Shielding Layers- 4. The noise suppression level was less than -30dB. 3: The noise suppression level was between -30dB and -20dB. 2: The noise suppression level was between -20dB and -10dB. 1: The noise suppression level was -10dB or higher.

[0251] (Evaluation of the durability of electromagnetic shielding layers (low frequency and high frequency)) The electronic device X1 obtained above was subjected to a cycle test consisting of 1000 cycles at temperatures ranging from -15°C to 90°C. The electronic device X1 after the cycle test was subjected to the same evaluation as the electromagnetic shielding performance (low frequency and high frequency) of the electromagnetic shielding layer. The results are shown in Table 1. The evaluation criteria for the durability of the electromagnetic shielding layer are the same as the evaluation criteria for the electromagnetic shielding performance of the electromagnetic shielding layer described above. In the evaluation criteria for the durability of electromagnetic shielding layers, the highest rank for durability is "4".

[0252] [Examples 2-12] The same procedure as in Example 1 was performed, except that the combination of the formation conditions for the first layer (including the type of the first ink) and the formation conditions for the second layer (including the type of the second ink) was changed as shown in Table 1. The results are shown in Table 1.

[0253] [Comparative Example 1] The same procedure as in Example 1 was followed, except that the second layer was not formed and the conditions for forming the first layer were changed as shown in Table 1. The results are shown in Table 1.

[0254] [Table 1]

[0255] As shown in Table 1, in Examples 1 to 12, where the porosity S1 of the portion of the electromagnetic shielding layer located on the ground electrode was lower than the porosity S2 of the portion of the electromagnetic shielding layer located on the insulating protective layer (i.e., the S2 / S1 ratio was greater than 1.00), the durability of the electromagnetic shielding layer was superior compared to Comparative Example 1, where the porosity S1 and porosity S2 were equal.

[0256] The results from Examples 1 and 2 show that when the S2 / S1 ratio is 1.20 or higher (Example 2), the durability of the electromagnetic shield is further improved.

[0257] The results from Examples 4 and 5 show that when the S2 / S1 ratio is less than 2.00 (Example 4), the durability of the electromagnetic shield is further improved.

[0258] The disclosure of Japanese Patent Application No. 2021-143242, filed on 2 September 2021, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually described as being incorporated by reference.

Claims

1. A wiring board having a mounting surface, A ground electrode that defines the ground region on the aforementioned mounting surface, An electronic component located on the aforementioned mounting surface and within the ground region, An insulating protective layer is disposed within the ground region and covers the electronic component, An electromagnetic shielding layer, which is a solidified form of an ink for forming an electromagnetic shielding layer, is provided spanning the insulating protective layer and the ground electrode, covering the insulating protective layer and electrically connected to the ground electrode. Equipped with, The void ratio S1 of the portion of the electromagnetic shielding layer located on the ground electrode is lower than the void ratio S2 of the portion of the electromagnetic shielding layer located on the insulating protective layer. Electronic devices.

2. The electronic device according to claim 1, wherein the ratio of the void ratio S2 to the void ratio S1 is 1.10 or more.

3. The electronic device according to claim 1, wherein the ratio of the void ratio S2 to the void ratio S1 is 1.20 or more.

4. The electronic device according to claim 1, wherein the ratio of the void ratio S2 to the void ratio S1 is less than 2.

00.

5. The electronic device according to any one of claims 1 to 4, wherein the porosity S2 is 25.0% or less.

6. A preparation step for preparing an electronic substrate comprising a wiring board having a mounting surface, a ground electrode defining a ground region on the mounting surface, and an electronic component disposed on the mounting surface within the ground region, A first step is to form an insulating protective layer covering the electronic component within the ground region, A second step of forming an electromagnetic shielding layer which spans the insulating protective layer and the ground electrode, covers the insulating protective layer and is electrically connected to the ground electrode, wherein the porosity S1 of the portion located on the ground electrode is lower than the porosity S2 of the portion located on the insulating protective layer. Includes, The second step is, The first electromagnetic shielding layer is formed by applying an ink for forming the first electromagnetic shield layer to a region spanning the insulating protective layer and the ground electrode, and then sintering it. The process involves applying an ink for forming a second electromagnetic wave shielding layer onto the ground electrode and sintering it to form a second layer. Includes, The portion of the first layer located on the ground electrode and the second layer are formed in an arrangement where they are stacked on top of each other. At least one of the following conditions is satisfied: the sintering temperature for forming the second layer is higher than the sintering temperature for forming the first layer, and the sintering time for forming the second layer is longer than the sintering time for forming the first layer. A method for manufacturing electronic devices.

7. The method for manufacturing an electronic device according to claim 6, wherein the application of the first electromagnetic shielding layer forming ink in the formation of the first layer and the application of the second electromagnetic shielding layer forming ink in the formation of the second layer are performed by an inkjet recording method, a dispenser method, or a spray method, respectively.

8. The method for manufacturing an electronic device according to claim 6 or 7, wherein the first step involves applying an insulating protective layer-forming ink by an inkjet recording method, a dispenser method, or a spray method to form the insulating protective layer.

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