Electronic devices and methods for manufacturing the same

Abstract

The present invention provides an electronic device which is provided with: a wiring board which has a mounting surface; a ground electrode which defines a ground region on the mounting surface; an electronic component which is arranged within the ground region on the mounting surface; a conductive component which is arranged adjacent to the outer edge of the ground electrode; an internal insulating protective layer which is arranged within the ground region and covers the electronic component; an external insulating protective layer which is arranged outside the ground region and covers the conductive component; and an electromagnetic shielding layer which is a solidified product of an ink for the electromagnetic shielding layer formation, and which is provided so as to extend across the internal insulating protective layer and the ground electrode, while covering the internal insulating protective layer and being electrically connected to the ground electrode. The present invention also provides a method for producing this electronic device.

Description

[Technical Field]

[0001] This disclosure relates to electronic devices and methods for manufacturing the same. [Background technology]

[0002] Studies have been conducted on electronic devices (i.e., electronic equipment) that have a structure in which electronic components are mounted on a wiring board.

[0003] For example, Japanese Patent Publication No. 2020-47939 discloses the following electronic device, which is equipped with an electromagnetic shield, and is characterized by reduced manufacturing costs, thinning capabilities, and high degree of freedom in wiring circuit design. The electronic device disclosed in Patent Document 1 is At least one electronic component, A conductive member that electromagnetically shields at least one of the above electronic components, The present invention comprises a resin molded body in which at least a portion of at least one of the above-mentioned electronic components and at least a portion of a conductive member that electromagnetically shields the electronic component are embedded and fixed, The above-mentioned at least one electronic component includes a first electronic component which is an electromagnetically shielded electronic component and a second electronic component which is not electromagnetically shielded. At least a portion of the above-mentioned second electronic component is embedded in the above-mentioned resin molded body. The first electronic component described above is fixed by an insulating member provided within the space formed by the conductive member described above. At least a portion of the insulating member is embedded in the resin molded body together with at least a portion of the first electronic component and at least a portion of the conductive member. The conductive member described above comprises a first conductive member embedded in the resin molded body, a second conductive member not embedded in the resin molded body, and at least one third conductive member provided between the first conductive member and the second conductive member. The first conductive member and the second conductive member are electrically connected to each other through the third conductive member. The electronic device is characterized in that the second electronic component described above does not come into contact with the insulating member embedded in the resin molded body. [Overview of the project] [Problems that the invention aims to solve]

[0004] The inventors of this invention, An electronic substrate comprising: a wiring board having a mounting surface; a ground electrode defining a ground region on the mounting surface; an electronic component located on the mounting surface and within the ground region; and a conductive component located adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode, An internal insulating protective layer is placed within the ground region and covers the electronic components, An electromagnetic shielding layer spans the above-mentioned internal insulating protective layer and the above-mentioned ground electrode, covering the above-mentioned internal insulating protective layer and electrically connected to the above-mentioned 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 an electromagnetic shielding layer is formed by a liquid process, the ink used to form the electromagnetic shielding layer may flow out of the ground region and / or mist of the ink may scatter to the outside. As a result, it was found that short circuits (specifically, short circuits between the formed electromagnetic shielding layer and the conductive component adjacent to the outer edge of the ground electrode) may occur due to the flow of the ink and / or mist.

[0005] According to one aspect of this disclosure, an electronic device and a method for manufacturing the same are provided, in which short circuits caused by the outflow and / or mist of the ink used to form the electromagnetic shielding layer are suppressed. [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, A conductive component positioned adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode, An internal insulating protective layer is placed within the ground region and covers the electronic components, An external insulating protective layer is located outside the ground region and covers the conductive components, An electromagnetic shielding layer, which is a solidified form of an ink for forming an electromagnetic shielding layer, is provided spanning the internal insulating protective layer and the ground electrode, covering the internal insulating protective layer and electrically connected to the ground electrode. An electronic device equipped with the following features. <2> The closest proximity distance between the outer edge of the ground electrode and the edge of the conductive component is 0.1 mm to 10.0 mm. <1> The electronic devices described above. <3> The thickness T1 of the external insulating protective layer on the conductive component is 2 μm to 200 μm. <1> or <2> The electronic devices described above. <4> The thickness T1 of the external insulating protective layer on the conductive component is thinner than the thickness T2 of the internal insulating protective layer on the electronic component. <1> ~ <3> An electronic device listed in any one of the following. <5> The internal insulating protective layer contains acrylic resin and the external insulating protective layer contains acrylic resin, or The internal insulating protective layer contains epoxy resin, and the external insulating protective layer contains epoxy resin. <1> ~ <4> An electronic device listed in any one of the following. <6> A preparation step of preparing an electronic substrate including a wiring substrate having a mounting surface, a ground electrode defining a ground region on the mounting surface, an electronic component disposed in the ground region on the mounting surface, and a conductive component disposed adjacent to an outer edge of the ground electrode and electrically insulated from the ground electrode; A first step of forming an internal insulating protective layer that covers the electronic component within the ground region; A second step of forming an electromagnetic shielding layer that straddles over the internal insulating protective layer and on the ground electrode, covers the internal insulating protective layer, and is electrically connected to the ground electrode, as a cured product of an ink for forming the electromagnetic shielding layer; <000007​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ [Figure 2A] In the manufacturing method according to an embodiment of the present disclosure, it is a schematic plan view of an electronic substrate on which an internal insulating protection layer and an external insulating layer are formed in the first step. [Figure 2B] It is a cross-sectional view taken along the line X-X of FIG. 2A. [Figure 3A] In the manufacturing method according to an embodiment of the present disclosure, it is a schematic plan view of an electronic substrate (that is, an electronic device according to an embodiment of the present disclosure) on which an electromagnetic shielding layer is formed in the second step. [Figure 3B] It is a cross-sectional view taken along the line X-X of FIG. 3A.

Embodiments for Carrying Out the Invention

[0009] In the present disclosure, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In the present disclosure, the amount of each component in the composition means the total amount of the plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical ranges described in other step-by-step descriptions, or may be replaced with the values shown in the examples. In the present disclosure, the term "step" includes not only an independent step but also cases where it cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. In the present disclosure, a combination of preferred embodiments is a more preferred embodiment.

[0010] 〔Electronic Device〕 The electronic device of the present disclosure A wiring board having a mounting surface, A ground electrode that defines a ground region on the mounting surface, An electronic component disposed on the mounting surface and within the ground region, A conductive component (hereinafter also referred to as "adjacent conductive component") is positioned adjacent to the outer edge of the ground electrode and is electrically insulated from the ground electrode, An internal insulating protective layer is placed within the ground region and covers the electronic components, An external insulating protective layer is located outside the ground region and covers the conductive components, An electromagnetic shielding layer, which is a solidified form of an ink for forming an electromagnetic shielding layer, is provided spanning the internal insulating protective layer and the ground electrode, covering the internal insulating protective layer and electrically connected to the ground electrode. It is equipped with.

[0011] According to the electronic device of this disclosure, short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer are suppressed. The following will explain these effects in more detail.

[0012] As described above, the present inventors have provided an electronic substrate comprising the above-mentioned wiring board, the above-mentioned ground (GND) electrode, the electronic component disposed within the ground region, and the above-mentioned adjacent conductive component, An internal insulating protective layer is placed within the ground region and covers the above-mentioned electronic components, An electromagnetic shielding layer spans the above-mentioned internal insulating protective layer and the above-mentioned ground electrode, covering the internal 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 an electromagnetic shielding layer is formed by a liquid process, the ink used to form the electromagnetic shielding layer may flow out of the ground region and / or scatter outside the ground region. As a result, a short circuit (specifically, a short circuit between the formed electromagnetic shielding layer and an adjacent conductive component) may occur due to the flow and / or mist of the ink used to form the electromagnetic shielding layer.

[0013] To address the aforementioned problems, in the electronic device of this disclosure, adjacent conductive components (i.e., conductive components adjacent to the outer edge of the ground electrode) are covered with an external insulating protective film. This ensures insulation between the formed electromagnetic shielding layer and adjacent conductive components, even if the ink for forming the electromagnetic shielding layer flows outside the ground area and / or if mist of the ink for forming the electromagnetic shielding layer is scattered outside the ground area. As a result, short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer are suppressed.

[0014] 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. In this disclosure, the outer edge of the ground electrode refers to the edge of the ground electrode that is farther from the ground region when the electronic substrate is viewed in plan view.

[0015] <Embodiment of a manufacturing method for electronic devices> The following describes embodiments of the manufacturing method for the electronic device described herein. A method for manufacturing an electronic device according to an embodiment of this disclosure 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; electronic components placed on the mounting surface and within the ground region; and adjacent conductive components (i.e., conductive components placed adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode); A first step involves forming an internal insulating protective layer that covers the electronic components within the ground region, A second step involves forming an electromagnetic shielding layer, which spans the internal insulating protective layer and the ground electrode, covering the internal insulating protective layer and electrically connecting to the ground electrode, as a solidified product of an ink for forming an electromagnetic shielding layer. Includes, Prior to the second step, an external insulating protective layer is formed outside the ground region to cover adjacent conductive components. A method for manufacturing an electronic device according to the embodiments of this disclosure may include other steps as necessary.

[0016] In the method for manufacturing an electronic device according to the embodiment of this disclosure, an external insulating protective layer that covers adjacent conductive components is formed outside the ground region before the second step of forming an electromagnetic shielding layer using an ink for forming an electromagnetic shielding layer. Therefore, even if the aforementioned electromagnetic shielding layer forming ink flows outside the ground region and / or if mist of the electromagnetic shielding layer forming ink is scattered outside the ground region, insulation between the formed electromagnetic shielding layer and adjacent conductive components (i.e., conductive components adjacent to the outer edge of the ground electrode) is ensured. As a result, short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer are 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 (i.e., the electronic device of this embodiment) on which the electromagnetic shielding layer was formed in the second step, and Figure 3B is a cross-sectional view taken along line XX of Figure 3A.

[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, an electronic component 18 located on the mounting surface 12S and within the ground region 14A, and an adjacent conductive component 20 located adjacent to the outer edge of the ground electrode 16 and electrically insulated from the ground electrode 16. 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, an adjacent conductive component 20 is mounted outside the ground region 14A, adjacent to the outer edge of the ground electrode 16, and electrically insulated from the ground electrode 16. Examples of adjacent conductive components 20 include electronic components, electrodes, wiring, and the like.

[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), 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 an annular pattern that completely encircles the multiple electronic components 18. However, the ground electrode 16 in this disclosure is not limited to this annular pattern, but can be any pattern that can define the ground region 14A (for example, a U-shaped pattern). 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] 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.

[0025] 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. Similarly, the multiple adjacent conductive components 20 mounted outside 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 outside the ground region is not limited to multiple components, and may be just one. Examples of electronic components 18 include semiconductor chips such as integrated circuits (ICs), capacitors, transistors, and the like. Adjacent conductive components 20 include, for example, semiconductor chips such as integrated circuits, electronic components such as capacitors and transistors, wiring, electrodes, and the like.

[0026] -1st process- As shown in Figures 2A and 2B, the first step involves forming an internal insulating protective layer 22 that covers the multiple electronic components 18 mounted within the ground region 14A.

[0027] The internal insulating protective layer 22 is formed within the ground region 14A, in a region that spans over the multiple electronic components 18 and the area surrounding these multiple electronic components 18. The functions of the internal 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).

[0028] In the first step of this example, both the internal insulating protective layer 22 and the external insulating protective layer 24 are formed using the same insulating protective layer forming ink (e.g., ink) and the same process.

[0029] The external insulating protective layer 24 is located outside the ground region 14A and is an insulating protective layer that covers the adjacent conductive component 20. The functions of the external insulating protective layer include, for example, protecting adjacent conductive components and suppressing short circuits between adjacent conductive components and other conductive components (e.g., electromagnetic shielding layers). In this example, the pattern of the external insulating protective layer 24 spans across multiple adjacent conductive components 20, but the pattern of the external insulating protective layer is not limited to this example. The pattern of the external insulating protective layer in this disclosure may be multiple patterns, each covering one of the multiple adjacent conductive components 20.

[0030] In this example, the internal insulating protective layer 22 and the external insulating protective layer 24 were formed in the same process (i.e., the first process), but the timing of the formation of the external insulating protective layer in the manufacturing method according to this embodiment is not limited to this example. In the manufacturing method according to this embodiment, the formation of the external insulating protective layer may be performed before the second step (i.e., the step of forming the electromagnetic shielding layer). For example, the formation of the external insulating protective layer may be performed after the first step and before the second step (i.e., after the formation of the internal insulating protective layer), or after the preparation step and before the first step (i.e., before the formation of the internal insulating protective layer). The material for forming the internal insulating protective layer (e.g., composition, sheet material, etc.) and the material for forming the external insulating protective layer (e.g., composition, sheet material, etc.) may be the same or different. For sheet materials, for example, one can refer to the insulating sheet material described in Japanese Patent Publication No. 2019-91866.

[0031] In the first step, it is preferable to use an insulating protective layer forming ink to form an internal insulating protective layer and an external insulating protective layer, as in the example above. Thus, forming the internal insulating protective layer and the external insulating protective layer using the same composition and in the same process is advantageous in terms of reducing the number of processes (i.e., the productivity of the electronic device) compared to forming the internal insulating protective layer and the external insulating protective layer in separate processes.

[0032] The ink for forming the insulating protective layer is preferably an active energy ray curing ink. In particular, when forming an internal insulating protective layer and an external insulating protective layer using an insulating protective layer forming ink in the first step, it is preferable that the insulating protective layer forming ink is an active energy ray curable ink. When the ink for forming the insulating protective layer is an active energy ray curing type ink, it is advantageous in terms of productivity and the durability of the internal insulating protective layer and / or the external insulating protective layer.

[0033] There are no particular restrictions on the method of applying the insulating protective layer ink onto the electronic substrate. In the case of forming an internal insulating protective layer and an external insulating protective layer using an insulating protective layer forming ink, the first step is preferably a step of applying the insulating protective layer forming ink by an inkjet recording method, a dispenser method, or a spray method to form the internal insulating protective layer and the external insulating protective layer. As a method for applying the ink for forming the insulating protective layer, an inkjet recording method is particularly preferred. A preferred embodiment of the inkjet recording method as a method for applying ink for forming an insulating protective layer is the same as the preferred embodiment of the inkjet recording method as a method for applying ink for forming an electromagnetic wave shielding layer, which will be described later.

[0034] -Second process- As shown in Figures 3A and 3B, in the second step, an electromagnetic shielding layer 30 is formed using an electromagnetic shielding layer forming ink. This layer is a solidified form of the electromagnetic shielding layer forming ink that spans the internal insulating protective layer 22 and at least a portion of the ground electrode 16, covering the internal insulating protective layer 22 and electrically connecting to the ground electrode 16. The electromagnetic wave shielding layer 30 is formed by applying an ink for forming the electromagnetic wave shielding layer within the ground region 14A and allowing it to solidify. The preferred range for the ink used to form the electromagnetic shielding layer and the method for forming the electromagnetic shielding layer will be described later.

[0035] An electromagnetic shielding layer is a layer designed to reduce the effects of electromagnetic waves on electronic components by shielding them from the electromagnetic waves that are irradiated onto them. In this disclosure, the performance of such an electromagnetic shielding layer is also referred to as "electromagnetic shielding property." The electromagnetic shielding properties of an electromagnetic shielding layer are achieved by the fact that the electromagnetic shielding layer is placed on the electronic component via an internal insulating protective layer. Furthermore, the electromagnetic shielding properties of the electromagnetic shielding layer are achieved by applying a ground (GND) potential to the electromagnetic shielding layer. For this reason, the electromagnetic shielding layer must be conductive as a prerequisite for being an electromagnetic shielding layer.

[0036] In the manufacturing method described in this example, when an ink for forming an electromagnetic wave shielding layer is applied to the ground region 14A and solidified to form an electromagnetic wave shielding layer 30, an external insulating protective layer 24 already exists on the adjacent conductive component 20 outside the ground region 14A. Therefore, even if the ink for forming the electromagnetic shielding layer flows out of the ground region 14A, insulation between the formed electromagnetic shielding layer 30 and the adjacent conductive component 20 is ensured. Therefore, short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer are suppressed.

[0037] The preferred scope of the electronic devices and methods for manufacturing the same described herein will be explained below.

[0038] <Distance between ground electrode and adjacent conductive component> The closest proximity distance between the outer edge of the ground electrode (e.g., ground electrode 16) and the edge of the adjacent conductive component is preferably 0.05 mm to 20.0 mm, and more preferably 0.1 mm to 10.0 mm. When the nearest neighbor distance is 0.05 mm or more, the outer insulating protective layer is easily formed such that its edge is positioned between the outer edge of the ground electrode and the edge of the adjacent conductive component. This makes it easier to ensure insulation between the ground electrode and the adjacent conductive component, thereby further suppressing short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer. When the nearest close-up distance is 20.0 mm or less, it offers excellent space-saving advantages. Furthermore, when the nearest neighbor distance is 20.0 mm or less and an external insulating protective layer is not provided, conditions are favorable for short circuits caused by the leakage and / or mist of the ink used to form the electromagnetic shielding layer. Therefore, when the nearest neighbor distance is 20.0 mm or less, providing an external insulating protective layer is of greater significance.

[0039] <Thickness T1 of the external insulating protective layer on conductive components> The thickness T1 of the external insulating protective layer on the conductive component is preferably 1 μm to 200 μm, more preferably 2 μm to 200 μm, and even more preferably 3 μm to 150 μm. When the thickness T1 is 1 μm or more, the effect of the external insulating protective layer (i.e., suppression of short circuits caused by the flow and / or mist of the ink used to form the electromagnetic shielding layer) is more effectively exhibited. When the thickness T1 is 200 μm or less, it is advantageous in that it makes it easier to reduce the weight of electronic devices.

[0040] The thickness T1 of the external insulating protective layer on the conductive component is preferably thinner than the thickness T2 of the internal insulating protective layer on the electronic component. This further improves the stability of the formation of the electromagnetic shielding layer. In detail, when forming the electromagnetic shielding layer in this disclosure, an application member (e.g., a discharge nozzle) for applying the electromagnetic shielding layer forming ink is moved from outside the ground region onto the internal insulating protective layer within the ground region, and the electromagnetic shielding layer forming ink is applied at this position. In the above preferred embodiment, the height of the external insulating protective layer is relatively lower compared to the height of the internal insulating protective layer on the electronic component, so the external insulating protective layer does not interfere with the movement of the application member (e.g., a discharge nozzle) onto the internal insulating protective layer. Therefore, the formation stability when forming the electromagnetic shielding layer on the internal insulating protective layer is further improved.

[0041] When the difference between thickness T2 and thickness T1 is defined as the thickness difference [T2-T1], the thickness difference [T2-T1] is preferably 5 μm to 200 μm, and more preferably 10 μm to 100 μm.

[0042] In this disclosure, unless otherwise specified, "height" refers to the height of the wiring board relative to the mounting surface. The height and thickness of each component (or layer) are measured based on optical microscope images of the cross-section of the electronic device.

[0043] The height of the electronic components placed within the ground region is preferably 100 μm or more, more preferably 200 μm or more, and even more preferably 300 μm or more. The height of the electronic component is preferably 1000 μm or less, and more preferably 800 μm or less.

[0044] The height of the adjacent conductive component (i.e., a conductive component positioned adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode) is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 200 μm or more. The height of the adjacent conductive component is preferably 1000 μm or less, and more preferably 800 μm or less.

[0045] The height of the ground electrode is preferably -10 μm or more, more preferably 0 μm or more, and even more preferably 5 μm or more. The height of the ground electrode is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

[0046] <Materials of the internal and external insulating protective layers> In the electronic devices disclosed herein, The internal insulating protective layer contains acrylic resin, and the external insulating protective layer contains acrylic resin, The internal insulating protective layer contains epoxy resin and the external insulating protective layer contains epoxy resin, or It is preferable that the internal insulating protective layer contains silicone resin and the external insulating protective layer contains silicone resin. In this preferred embodiment, the internal insulating protective layer and the external insulating protective layer can be easily formed using the same insulating protective layer forming composition, which is advantageous in terms of reducing the number of steps (i.e., the productivity of the electronic device). In the electronic devices disclosed herein, The internal insulating protective layer contains acrylic resin and the external insulating protective layer contains acrylic resin, or It is more preferable that the internal insulating protective layer contains epoxy resin and the external insulating protective layer also contains epoxy resin.

[0047] For example, each of the internal insulating protective layer containing acrylic resin and the external insulating protective layer containing acrylic resin is preferably formed using an insulating protective layer forming composition containing (meth)acrylate monomer. Each of the internal insulating protective layer containing epoxy resin and the external insulating protective layer containing epoxy resin is preferably formed using an insulating protective layer forming composition containing epoxy monomer. Each of the internal insulating protective layer containing silicone resin and the external insulating protective layer containing silicone resin is preferably formed using an insulating protective layer forming composition containing a silicone monomer. Preferred embodiments of the composition for forming an insulating protective layer will be described later.

[0048] 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.

[0049] <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. 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.

[0050] (Metal particle ink) A metal particle ink is, for example, an ink composition in which metal particles are dispersed in a dispersion medium.

[0051] -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.

[0052] 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).

[0053] 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.).

[0054] 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.

[0055] 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.

[0056] In addition to metal particles, metal particle inks may also contain, for example, dispersants, resins, dispersion media, thickeners, and surface tension modifiers.

[0057] -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.

[0058] The dispersant contained in the metal particle ink may be one type or two or more types.

[0059] 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.

[0060] Examples of aliphatic amines include butylamine, n-pentylamine, isopentylamine, hexylamine, 2-ethylhexylamine, and octylamine.

[0061] Examples of amines having an alicyclic structure include cycloalkylamines such as cyclopentylamine and cyclohexylamine.

[0062] Aniline is an example of an aromatic amine.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] -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.

[0070] 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.

[0071] Examples of hydrocarbons include aliphatic hydrocarbons and aromatic hydrocarbons.

[0072] 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.

[0073] Examples of aromatic hydrocarbons include toluene and xylene.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] -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.

[0080] The resin contained in the metal particle ink may be one type or two or more types.

[0081] 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.

[0082] -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.

[0083] The thickening agent contained in the metal particle ink may be one type or two or more types.

[0084] 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.

[0085] - 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.

[0086] 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.

[0087] 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.

[0088] 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.).

[0089] 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.

[0090] The surface tension of the metal particle ink is measured using, for example, the DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0091] -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.

[0092] 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.

[0093] (Metal complex ink) Metal complex inks are, for example, ink compositions in which a metal complex is dissolved in a solvent.

[0094] -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.

[0095] 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.

[0096] 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 a 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.

[0097] Examples of metal salts include thiocyanates, sulfides, chlorides, cyanides, cyanates, carbonates, nitrates, nitrites, sulfates, phosphates, perchlorates, tetrafluoroborates, acetylacetonate complex salts, and carboxylates.

[0098] From the viewpoint of electromagnetic shielding properties and storage stability, the metal salt is preferably a carboxylate salt. The carboxylic acid forming the carboxylate salt is preferably at least one selected from the group consisting of carboxylic acids having 1 to 20 carbon atoms, more preferably a carboxylic acid having 1 to 16 carbon atoms, and even more preferably a fatty acid having 2 to 12 carbon atoms. The carboxylic acid that forms the carboxylate salt may be a straight-chain fatty acid, a branched fatty acid, or may have substituents.

[0099] Examples of straight-chain fatty acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, linoleic acid, and linolenic acid.

[0100] Examples of branched fatty acids include isobutyric acid, isovaleric acid, 2-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.

[0101] Examples of substituted carboxylic acids include hexafluoroacetylacetone acid, glycolic acid, lactic acid, 3-hydroxybutyric acid, 2-methyl-3-hydroxybutyric acid, 3-methoxybutyric acid, and acetoacetic acid.

[0102] The carboxylic acid that forms the carboxylate salt may be a polyfunctional carboxylic acid. Examples of polyfunctional carboxylic acids include oxalic acid, succinic acid, glutaric acid, malonic acid, acetonedicarboxylic acid, 3-hydroxyglutaric acid, 2-methyl-3-hydroxyglutaric acid, and 2,2,4,4-hydroxyglutaric acid, as well as citric acid.

[0103] Among these metal salts, alkyl carboxylates, oxalates, and acetoacetates having 2 to 12 carbon atoms are preferred, and alkyl carboxylates having 2 to 12 carbon atoms are more preferred.

[0104] 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, and amines.

[0105] 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.

[0106] Examples of amines used as complexing agents include ammonia, primary amines, secondary amines, tertiary amines, and polyamines.

[0107] Examples of primary amines having a linear alkyl group include methylamine, ethylamine, n-propylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, and n-octadecylamine.

[0108] Examples of primary amines having branched alkyl groups include isopropylamine, sec-butylamine, tert-butylamine, isopentylamine, 2-ethylhexylamine, and tert-octylamine.

[0109] Examples of primary amines having an alicyclic structure include cyclopentylamine, cyclohexylamine, and dicyclohexylamine.

[0110] Examples of primary amines having a hydroxyalkyl group include ethanolamine, propanolamine, and isopropanolamine.

[0111] Examples of primary amines having an aromatic ring include benzylamine, aniline, N,N-dimethylaniline, and 4-aminopyridine.

[0112] Examples of secondary amines include dimethylamine, diethylamine, dipropylamine, dibutylamine, diphenylamine, dicyclopentylamine, and methylbutylamine, diethanolamine, N-methylethanolamine, dipropanolamine, and diisopropanolamine.

[0113] Examples of tertiary amines include trimethylamine, triethylamine, tripropylamine, triethanolamine, trippropanolamine, and triisopropanolamine, triphenylamine, N,N-dimethylaniline, N,N-dimethyl-p-toluidine, and 4-dimethylaminopyridine.

[0114] Examples of polyamines include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, diethylenetriamine, triethylenetetramine, tetramethylenepentamine, hexamethylenediamine, tetraethylenepentamine, and combinations thereof.

[0115] The amine is preferably an alkylamine, more preferably an alkylamine having 2 to 12 carbon atoms, and more preferably a primary alkylamine having 2 to 8 carbon atoms.

[0116] The amine constituting the metal complex may be one type or two or more types.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] In metal complex inks, 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 complex ink is applied using an inkjet recording method.

[0123] -solvent- The metal complex ink preferably contains 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 150°C.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] Examples of aromatic hydrocarbons include benzene, toluene, xylene, and tetralin.

[0129] 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.

[0130] The alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol.

[0131] 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.

[0132] Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0133] 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.

[0134] -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.

[0135] Examples of reducing agents include metal borohydride salts, aluminum hydride salts, amines, alcohols, aldehydes, organic acids, reducing sugars, sugar alcohols, sodium sulfite, and hydrazine compounds. Examples include compounds, dextrin, hydroquinone, hydroxylamine, ethylene glycol, glutathione, and oxime compounds.

[0136] 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.

[0137] The reducing agent contained in the metal complex ink may be one type or two or more types.

[0138] 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.

[0139] -resin- Metal complex inks may contain resin. The presence of resin in a metal complex ink improves its adhesion to the substrate.

[0140] 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.

[0141] The resin contained in the metal complex ink may be one type or two or more types.

[0142] - 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.

[0143] The viscosity of the metal complex ink is not particularly limited, and may be between 0.001 Pa·s and 5000 Pa·s, with a preference of 0.001 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.

[0144] 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.).

[0145] The surface tension of the metal complex ink is not particularly limited, but should be between 20 mN / m and 45 mN / m. A surface tension of 25 mN / m to 35 mN / m is preferred. The surface tension is the value measured at 25°C using a surface tension meter.

[0146] The surface tension of metal complex inks is measured, for example, using a DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0147] (Metallic salt ink) Metal salt ink is, for example, an ink composition in which a metal salt is dissolved in a solvent.

[0148] -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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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:

[0157] 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.

[0158] -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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] The alcohol may be a primary alcohol, a secondary alcohol, or a tertiary alcohol.

[0165] 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.

[0166] Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0167] 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.

[0168] 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.

[0169] 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.).

[0170] 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.

[0171] The surface tension of metal salt inks is measured, for example, using a DY-700 (manufactured by Kyowa Interface Science Co., Ltd.).

[0172] 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.

[0173] <Method for forming an electromagnetic shielding layer> In the second step, it is preferable to apply an electromagnetic wave shielding layer-forming ink to the ground region on the electronic substrate, and then solidify the applied electromagnetic wave shielding layer-forming ink by heating (for example, firing as described later) and / or ultraviolet irradiation to form an electromagnetic wave shielding layer.

[0174] (Method of applying ink for forming an electromagnetic wave shielding layer) The method for applying the ink for forming the electromagnetic wave shielding layer is preferably an inkjet recording method, a dispenser method, or a spray method, with the inkjet recording method being particularly preferred.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] From the viewpoint of electromagnetic shielding performance, the overall thickness of the electromagnetic shielding layer is preferably 0.1 μm to 30 μm, and more preferably 0.3 μm to 15 μm.

[0184] The total thickness of the electromagnetic shielding layer is measured using a laser microscope (product name "VK-X1000", manufactured by Keyence Corporation).

[0185] The average thickness per electromagnetic shielding layer is obtained by dividing the total thickness of the electromagnetic shielding layer by the number of times the electromagnetic shielding layer is formed (i.e., the number of times the ink for forming the electromagnetic shielding layer is applied).

[0186] In the second step, it is preferable that the average thickness of each electromagnetic shielding layer be 1.5 μm or less, and more preferably 1.2 μm or less.

[0187] Reducing the average thickness of each electromagnetic shielding layer to 1.5 μm or less further improves electromagnetic shielding performance.

[0188] In the lamination process, after performing multiple steps to apply an electromagnetic shielding layer-forming ink to the electromagnetic shielding layer using an inkjet recording method, a step may be performed to further form an electromagnetic shielding layer by irradiating the electromagnetic shielding layer-forming ink applied to the electromagnetic shielding layer with ultraviolet light.

[0189] From the viewpoint of image quality, electromagnetic shielding properties, and adhesion, it is preferable in the lamination process to first perform a step of applying an ink for forming an electromagnetic shielding layer onto the electromagnetic shielding layer using an inkjet recording method, and then perform a step of further forming an electromagnetic shielding layer by irradiating the ink for forming the electromagnetic shielding layer applied to the electromagnetic shielding layer with ultraviolet light. In other words, it is preferable that ultraviolet irradiation is performed each time the step of applying the ink for forming the electromagnetic wave shielding layer is carried out.

[0190] (Firing process) The second step may include a firing step in which the ink for forming the electromagnetic shielding layer applied to the electronic substrate is fired to solidify the ink and form an electromagnetic shielding layer.

[0191] The firing temperature is preferably 250°C or lower, more preferably 50°C to 200°C, and even more preferably 60°C to 180°C. Furthermore, the baking time is preferably between 1 minute and 120 minutes, and more preferably between 1 minute and 40 minutes. When the firing temperature and firing time are within the above range, it is possible to minimize the effects of thermal deformation of the substrate.

[0192] In particular, if the ink for forming the electromagnetic shielding layer contains a metal salt or metal particles, it is preferable to irradiate the electromagnetic shielding layer with ultraviolet light before firing it.

[0193] <Ink for forming an insulating protective layer> In this disclosure, the internal insulating protective layer and the external insulating protective layer are preferably solidified products of an insulating protective layer forming ink. In other words, the internal insulating protective layer and the external insulating protective layer in this disclosure are preferably formed by applying and solidifying an insulating protective layer forming ink, respectively.

[0194] 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.

[0195] (polymerizable monomer) A polymerizable monomer is a monomer that has at least one polymerizable group in one molecule. 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.

[0196] The polymerizable monomer may be a monofunctional polymerizable monomer having one polymerizable group, or a polyfunctional polymerizable monomer having two or more polymerizable groups.

[0197] The polymerizable group in the polymerizable monomer may be either a cationic polymerizable group or a radical polymerizable group. From the viewpoint of curability, the radical polymerizable group is preferably an ethylenically unsaturated group. From the viewpoint of curability, the cationic polymerizable group is preferably a group that includes at least one of an oxirane ring and an oxetane ring.

[0198] -Radical polymerizable monomer- From the viewpoint of curability, the radical polymerizable monomer (i.e., a polymerizable monomer containing a radical polymerizable group) is preferably a monofunctional ethylenically unsaturated monomer.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] Examples of monofunctional N-vinyl compounds include N-vinyl-ε-caprolactam and N-vinylpyrrolidone.

[0206] 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.

[0207] Examples of polyfunctional ethylenically unsaturated monomers include polyfunctional (meth)acrylate compounds and polyfunctional vinyl ethers.

[0208] 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.

[0209] 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.

[0210] -Cationic polymerizable monomer- As cationic polymerizable monomers, known cationic polymerizable monomers such as compounds having an oxirane ring (also called an "epoxy ring") (also called "oxirane compounds" or "epoxy compounds"), compounds having an oxetane ring (also called "oxetane compounds"), and vinyl ether compounds can be used without particular limitation from the viewpoint of curability. As for the cationic polymerizable monomer, there are no particular restrictions as long as it is a compound that initiates a polymerization reaction and hardens upon a cationic polymerization initiator generated from a photocationic polymerization initiator described later. Various known cationic polymerizable monomers known as photocationic polymerizable monomers can be used. Examples of cationic polymerizable monomers include epoxy compounds, vinyl ether compounds, and oxetane compounds described in various publications such as Japanese Patent Publication No. 6-9714, Japanese Patent Publication No. 2001-31892, 2001-40068, 2001-55507, 2001-310938, 2001-310937, and 2001-220526. Furthermore, as cationic polymerizable monomers, for example, cationic polymerized photocurable resins are known, and recently, photo-cationically polymerized photocurable resins sensitized to visible light wavelengths of 400 nm or higher have been published, for example, in Japanese Patent Publication No. 6-43633 and Japanese Patent Publication No. 8-324137.

[0211] Examples of epoxy compounds include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides. Examples of aromatic epoxides include di or polyglycidyl ethers produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or its alkylene oxide adduct with epichlorohydrin. Examples of aromatic epoxides include di- or polyglycidyl ethers of bisphenol A or its alkylene oxide adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolac-type epoxy resins. Examples of alkylene oxides include ethylene oxide and propylene oxide.

[0212] Preferred examples of alicyclic epoxides include cyclohexene oxide or cyclopentene oxide-containing compounds obtained by epoxidizing a compound having at least one cyclohexene ring or cycloalkane ring, such as a cyclopentene ring, with a suitable oxidizing agent such as hydrogen peroxide or a peracid. Aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts. Representative examples include diglycidyl ethers of alkylene glycols such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, or 1,6-hexanediol diglycidyl ether; polyglycidyl ethers of polyhydric alcohols such as glycerin or its alkylene oxide adduct di- or triglycidyl ether; diglycidyl ethers of polyethylene glycol or its alkylene oxide adduct; and diglycidyl ethers of polyalkylene glycols, such as polypropylene glycol or its alkylene oxide adduct. Examples of alkylene oxides include ethylene oxide and propylene oxide.

[0213] The following are detailed examples of monofunctional and polyfunctional epoxy compounds. Examples of monofunctional epoxy compounds include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3-vinylcyclohexene oxide, and 4-vinylcyclohexene oxide.

[0214] Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meth-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl Examples include 3',4'-epoxy-6'-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di(3,4-epoxycyclohexylmethyl) ether, ethylenebis(3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,13-tetradecadien dioxide, limonene dioxide, 1,2,7,8-diepoxyoctane, and 1,2,5,6-diepoxycyclooctane.

[0215] Among epoxy compounds, aromatic epoxides and alicyclic epoxides are preferred from the viewpoint of having excellent curing speed, and alicyclic epoxides are particularly preferred.

[0216] The oxetane compound refers to a compound having at least one oxetane ring, and a known oxetane compound as described in each of JP-A Nos. 2001-220526, 2001-310937, and 2003-341217 can be arbitrarily selected and used. As the compound having an oxetane ring, a compound having 1 to 4 oxetane rings in its structure is preferable. By using such a compound, it becomes easy to maintain the viscosity of the ink composition within a range with good handling properties, and it is possible to obtain high adhesion of the ink composition after curing to the recording medium.

[0217] Examples of the compound having 1 to 2 oxetane rings in the molecule include compounds represented by the following formulas (1) to (3).

[0218]

Chemical formula

[0219] In formulas (1) to (3), R a1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, a furyl group or a thienyl group. When two Rs a1 are present in the molecule, they may be the same or different. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, etc., and examples of the fluoroalkyl group preferably include those in which any of the hydrogens of these alkyl groups is substituted with a fluorine atom. R [[ID=2�]] a2 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, Represents a group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, or an N-alkylcarbamoyl group having 2 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, etc. Examples of the alkenyl group include a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, etc. Examples of the group having an aromatic ring include a phenyl group, a benzyl group, a fluorobenzyl group, a methoxybenzyl group, a phenoxyethyl group, etc. Examples of the alkylcarbonyl group include an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group, etc. Examples of the alkoxycarbonyl group include an ethoxycarbonyl group, a propoxycarbonyl group, a butoxycarbonyl group, etc. Examples of the N-alkylcarbamoyl group include an ethylcarbamoyl group, a propylcarbamoyl group, a butylcarbamoyl group, a pentylcarbamoyl group, etc. R a2 may have a substituent, and examples of the substituent include an alkyl group having 1 to 6 carbon atoms and a fluorine atom.

[0220] R a3 represents a linear or branched alkylene group, a linear or branched poly(alkyleneoxy) group, a linear or branched unsaturated hydrocarbon group, a carbonyl group or an alkylene group containing a carbonyl group, an alkylene group containing a carboxy group, an alkylene group containing a carbamoyl group, or a group shown below. Examples of the alkylene group include an ethylene group, a propylene group, a butylene group, etc. Examples of the poly(alkyleneoxy) group include a poly(ethyleneoxy) group, a poly(propyleneoxy) group, etc. Examples of the unsaturated hydrocarbon group include a propenylene group, a methylpropenylene group, a butenylene group, etc.

[0221] Examples of compounds represented by formula (1) include 3-ethyl-3-hydroxymethyloxetane (OXT-101: manufactured by Toagosei Co., Ltd.), 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane (OXT-212: manufactured by Toagosei Co., Ltd.), and 3-ethyl-3-phenoxymethyloxetane (OXT-211: manufactured by Toagosei Co., Ltd.). Examples of compounds represented by formula (2) include 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene (OXT-121: manufactured by Toagosei Co., Ltd.). Examples of compounds represented by formula (3) include bis(3-ethyl-3-oxetanylmethyl) ether (OXT-221: manufactured by Toagosei Co., Ltd.).

[0222] For compounds having an oxetane ring, refer to paragraphs 0021 to 0084 of Japanese Patent Publication No. 2003-341217, Japanese Patent Publication No. 2004-91556, and paragraphs 0022 to 0058 of Japanese Patent Publication No. 2004-91556.

[0223] Examples of preferred cationic polymerizable monomers are listed below.

[0224] [ka]

[0225] [ka]

[0226] Examples of cationic polymerizable monomers include vinyl ether compounds. Examples of vinyl ether compounds include di or trivinyl ether compounds such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether; and monovinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

[0227] The following provides detailed examples of monofunctional vinyl ethers and polyfunctional vinyl ethers. 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.

[0228] Examples of polyfunctional vinyl ethers include divinyl ethers such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, and other divinyl ethers; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, and dipentaerythritol pentavinyl ether. Examples include polyfunctional vinyl ethers such as ethers, dipentaerythritol hexanyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide-added pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexanyl ether, and propylene oxide-added dipentaerythritol hexanyl ether.

[0229] Divinyl ether compounds are preferred as vinyl ether compounds from the viewpoint of curability, adhesion to the recording medium, and surface hardness of the formed image, and divinyl ether compounds are particularly preferred.

[0230] 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.

[0231] (Polymerization initiator) Ink for forming an insulating protective layer may contain a polymerization initiator for the purpose of curing polymerizable monomers. Depending on the type of polymerizable monomer, a suitable polymerization initiator can be selected from either a radical polymerization initiator or a cationic polymerization initiator. Examples of polymerization initiators include 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.

[0232] From the viewpoint of further improving conductivity, the radical polymerization initiator 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 benzylketal alkylphenones. The cationic polymerization initiator is preferably a photoacid generator. As photoacid generators, for example, compounds used in chemically amplified photoresists and photocationic polymerization are used (see Organic Electronic Materials Research Group, ed., "Organic Materials for Imaging," Bunshin Publishing (1993), pp. 187-192). Among these, aromatic onium salt compounds are preferred, with onium salt compounds such as diazonium salts, phosphonium salts, sulfonium salts, and iodonium salts being preferred, and sulfonium salts or iodonium salts being more preferred.

[0233] 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.

[0234] 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.

[0235] (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.

[0236] Examples of the polyfunctional thiol include aliphatic thiols such as hexane-1,6-dithiol, decane-1,10-dithiol, dimercaptodiethyl ether, dimercaptodiethyl sulfide; aromatic thiols such as xylylene dimercaptan, 4,4'-dimercaptodiphenyl sulfide, 1,4-benzenedithiol; poly(mercaptoacetate) of 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), dipentaerythritol hexakis(mercaptoacetate); poly(3-mercaptopropionate) of 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 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).

[0237] (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).

[0238] 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.

[0239] 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.

[0240] (Sensitizer) The ink for forming an insulating protective layer may contain at least one sensitizer.

[0241] 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.

[0242] 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.

[0243] (Surfactants) The ink for forming an insulating protective layer may contain at least one surfactant.

[0244] 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.

[0245] 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.

[0246] 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.

[0247] (Organic solvents) The ink for forming an insulating protective layer may contain at least one organic solvent.

[0248] 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.

[0249] 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.

[0250] (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.

[0251] (Physical properties) The pH of the insulating protective layer forming ink is preferably 7 to 10, and more preferably 7.5 to 9.5, from the viewpoint of improving ejection stability when imparted 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.

[0252] The viscosity of the ink for forming the insulating protective layer is preferably 0.5 mPa·s to 60 mPa·s, and 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 viscometer manufactured by Toki Sangyo Co., Ltd.

[0253] 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 tensimeter, for example, by the plate method using an automatic surface tensimeter (product name "CBVP-Z") manufactured by Kyowa Interface Science Co., Ltd.

[0254] <Method for forming an insulating protective layer> In the first step, preferably, an insulating protective layer-forming ink is applied to the electronic substrate using an inkjet recording method, a dispenser coating method, or a spray coating method, and the insulating protective layer-forming ink is cured to form an insulating protective layer.

[0255] The method for applying the insulating protective layer ink is preferably an inkjet recording method, from the viewpoint that a small amount can be dropped to form a thin ink film with a single application. Details of the inkjet recording method are as described above.

[0256] The method for curing the insulating protective layer-forming ink is not particularly limited, but one example is to irradiate the insulating protective layer-forming ink applied to the substrate with active energy rays.

[0257] Examples of the active energy ray include, for example, ultraviolet rays, visible light rays, and electron beams, and among them, ultraviolet rays (hereinafter also referred to as "UV") are preferable.

[0258] The peak wavelength of the ultraviolet ray is preferably 200 nm to 405 nm, more preferably 250 nm to 400 nm, and even more preferably 300 nm to 400 nm.

[0259] The exposure amount in the irradiation of the active energy ray is preferably 100 mJ / cm 2 ~5000 mJ / cm 2 and more preferably 300 mJ / cm 2 ~1500 mJ / cm 2 .

[0260] As the light source for ultraviolet irradiation, mercury lamps, gas lasers, and solid lasers are mainly used, and mercury lamps, metal halide lamps, and ultraviolet fluorescent lamps are widely known. In addition, UV-LED (light-emitting diode) and UV-LD (laser diode) are small-sized, have a long lifespan, high efficiency, and low cost, and are expected as light sources for ultraviolet irradiation. Among them, the light source for ultraviolet irradiation is preferably a metal halide lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, or a UV-LED. <s>

[0261] In the step of obtaining the insulating protective layer, in order to obtain the insulating protective layer with a desired thickness, it is preferable to repeat the step of applying the insulating ink and irradiating with the active energy ray two or more times.

[0262] )]]The thickness of the insulating protective layer is preferably 5 μm to 5000 μm, and more preferably 10 μm to 2000 μm.

Example

[0263] Hereinafter, examples of the present disclosure will be shown, but the present disclosure is not limited to the following examples.

[0264] 〔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, electronic components disposed on the mounting surface and within the ground region, and adjacent conductive components disposed adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode). In electronic circuit board B1, Height of electronic components within the ground region, The nearest proximity distance between the outer edge of the ground electrode and the edge of the adjacent conductive component (hereinafter also referred to as the "distance between the ground electrode and the adjacent conductive component"), and, The heights of adjacent conductive components are as shown in Table 1. The ground electrode has a height of 25 μm and a width of 900 μm. The heights are all measured from the mounting surface (solder resist layer surface) of the wiring board.

[0265] (Preparation of Ink A1 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 insulating protective layer formation ink A1.

[0266] -Composition of Ink A1 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

[0267] (Preparation of ink C1 for forming the electromagnetic shielding layer) 40 g of silver neodecanoate was added to a 200 mL three-necked flask. 30.0 g of trimethylbenzene and 30.0 g of terpineol were added, and the mixture was stirred to obtain a solution containing the silver salt. The resulting solution was filtered using a PTFE (polytetrafluoroethylene) membrane filter with a pore size of 0.45 μm to obtain electromagnetic shielding layer formation ink C1.

[0268] (Formation of internal insulating protective layer and external 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.

[0269] In the above-described inkjet recording apparatus, insulating protective layer-forming ink A1 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 was designed to cover the electronic components within the ground region of the electronic substrate B1, with the pattern edges positioned inside the inner edges of the ground electrodes (see, for example, Figure 2A). The number of repetitions of ink application and UV irradiation was adjusted so that the height T2 (in μm) of the internal insulating protective layer on the electronic components within the ground region was as shown in Table 1.

[0270] Similarly, insulating protective layer formation ink A1 was ejected from the inkjet head of the above-mentioned inkjet recording apparatus and applied to the external insulating protective layer formation area on the electronic substrate (Note: The pattern of the external insulating protective layer will be described later), and the applied insulating protective layer formation ink A1 was irradiated with UV (ultraviolet) light using a UV spot cure. By repeating the process of applying the ink and irradiating with UV light, the external insulating protective layer was formed. The pattern of the external insulating protective layer spanned multiple adjacent conductive components and covered these components (see, for example, Figure 2A). The number of repetitions of ink application and UV irradiation was adjusted so that the thickness T1 (in μm) of the external insulating composition on the adjacent conductive components was the value shown in Table 1.

[0271] The conditions for applying the insulating protective layer ink A1 during the formation of both the internal and external insulating protective layers were that the resolution was 1270 dpi (dots per inch) and the droplet size was 10 picoliters per dot.

[0272] (Formation of electromagnetic shielding layer (second step)) Prepare an inkjet recording device (product name "DMP-2850", manufactured by FUJIFILM DIMATIX), and use the ink cartridges (10 picoli) for this inkjet recording device. The container (for use with the device) was filled with ink C1 for forming an electromagnetic wave shielding layer. Next, the electronic substrate, on which the internal insulating protective layer and the external insulating protective layer were formed, was heated to 60°C. Next, the ink C1 for forming the electromagnetic shielding layer was ejected from the inkjet head of the inkjet recording device and applied to the electromagnetic shielding layer formation area on the electronic substrate, which had been heated to 60°C. Ten seconds after the last ink droplet landed on the electronic substrate, the ink C1 for forming the electromagnetic shielding layer applied to the electronic substrate was heated to 160°C for 20 minutes using a hot plate. By repeating the process of applying the electromagnetic shielding layer ink C1 and heating it with a hot plate eight times, an electromagnetic shielding layer with a thickness of 3.2 μm was formed. The electromagnetic shielding layer pattern spans both the insulating protective layer and the ground electrode, covering the insulating protective layer and electrically connecting to the ground electrode (see Figure 3A).

[0273] As described above, an internal insulating protective layer, an external insulating protective layer, and an electromagnetic wave shielding layer were formed on the electronic substrate B1 to obtain the electronic device X1.

[0274] <Rating> The following evaluations were performed on the electronic device X1. The results are shown in Table 1.

[0275] (Short-circuit) One hundred of the above-mentioned electronic devices X1 were fabricated, and in each of the 100 electronic devices X1, it was confirmed whether a short circuit occurred between the electromagnetic shielding layer and conductive components outside the ground region, due to the leakage and / or mist of the ink used to form the electromagnetic shielding layer. Based on the results of the verification, the short circuit was evaluated according to the following criteria. In the evaluation criteria below, rank "4" represents the best suppression of short circuits.

[0276] -Short circuit evaluation criteria- 4. The number of electronic devices X1 experiencing a short circuit was 0 out of 100. 3. The number of electronic devices X1 experiencing a short circuit was 1 out of 100. 2: The number of electronic devices X1 experiencing a short circuit was between 2 and 5 out of 100. 1: The number of electronic devices X1 experiencing a short circuit was 6 or more out of 100.

[0277] (Formation stability of electromagnetic shielding layer) In the fabrication of the electronic device X1 described above, the height of the inkjet head for ejecting the electromagnetic shielding layer ink C1 (height from the mounting surface of the wiring board) was set to 1 mm higher than the height of the highest insulating protective layer. Under these conditions, the electromagnetic shielding layer ink C1 was ejected onto the insulating protective layer to form 50 ink dots. Subsequently, the ink dots were cured by heating at 160°C for 60 minutes to obtain a dot image. The 50 dot images after curing, as well as their surrounding areas, were observed using an optical microscope to check for the presence of satellites (i.e., unintended dot-like images) and unintended mist-like images. Based on the confirmed results, the formation stability of the electromagnetic shielding layer was evaluated according to the following criteria. In the evaluation criteria below, the rank that best represents the stability of electromagnetic shielding layer formation is "3".

[0278] -Evaluation criteria for the formation stability of the electromagnetic shielding layer- 3: No satellites or unintended misty images were observed. 2: Smaller satellites than the main droplet (intended dot image) were observed, but no satellites of the same size or larger than the main droplet (intended dot image) were observed, and no unintended mist-like images were observed. 1: At least one of the following was observed: a satellite image of a size equal to or larger than the main droplet (intended dot image), and an unintended mist-like image.

[0279] [Examples 2-5] The same procedure as in Example 1 was followed, except that the thickness of the external insulating protective layer on the adjacent conductive component was changed as shown in Table 1. The results are shown in Table 1.

[0280] [Examples 6-10] The same procedure as in Example 1 was followed, except that the distance between the ground electrode and adjacent conductive components was changed as shown in Table 1 by modifying the design of the LTE module for obtaining the electronic substrate B1. The results are shown in Table 1.

[0281] [Example 11] The same procedure as in Example 1 was followed, except that composition A1 for forming an insulating protective layer was replaced with composition E1 for forming an insulating protective layer. The results are shown in Table 1.

[0282] (Preparation of Ink E1 for forming an insulating protective layer) As ink E1 for forming an insulating protective layer, we prepared "DM-INI-7003" (manufactured by Dycotec), an ultraviolet-curing ink containing epoxy resin for forming an insulating protective layer.

[0283] [Comparative Example 1] The procedure was the same as in Example 1, except that an external insulating protective layer was not formed on the adjacent conductive component. The results are shown in Table 1.

[0284] [Table 1]

[0285] As shown in Table 1, in Examples 1 to 11, in which an external insulating protective layer was provided on adjacent conductive components, short circuits caused by the outflow and / or mist of the ink used to form the electromagnetic shielding layer were suppressed compared to Comparative Example 1, in which no external insulating protective layer was provided.

[0286] From the results of Examples 6-10, the distance between the ground electrode and the adjacent conductive component (i.e., ground When the closest proximity distance between the outer edge of the electrode and the edge of the adjacent conductive component is 0.1 mm to 10.0 mm (Examples 7 to 10), it can be seen that short circuits caused by the outflow and / or mist of the ink used to form the electromagnetic shielding layer are more effectively suppressed.

[0287] The results from Examples 1 to 5 show that when the thickness T1 of the external insulating protective layer on adjacent conductive components is 2 μm to 200 μm (Examples 2 to 5), short circuits caused by the flow and / or mist of the ink used to form the electromagnetic shielding layer are more effectively suppressed.

[0288] Furthermore, the disclosure of Japanese Patent Application No. 2021-130925, filed on August 10, 2021, is incorporated herein by reference in its entirety. In addition, 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 noted to be 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, A conductive component is positioned adjacent to the outer edge of the ground electrode and is electrically insulated from the ground electrode, An internal insulating protective layer is disposed within the ground region and covers the electronic component, An external insulating protective layer, which is located outside the ground region and covers the conductive component, An electromagnetic shielding layer, which is a solidified form of an electromagnetic shielding layer forming ink, is provided spanning the internal insulating protective layer and the ground electrode, covering the internal insulating protective layer and electrically connected to the ground electrode. An electronic device equipped with the following features.

2. The electronic device according to claim 1, wherein the closest proximity distance between the outer edge of the ground electrode and the edge of the conductive component is 0.1 mm to 10.0 mm.

3. The electronic device according to claim 1 or claim 2, wherein the thickness T1 of the external insulating protective layer on the conductive component is 2 μm to 200 μm.

4. The electronic device according to claim 1 or 2, wherein the thickness T1 of the external insulating protective layer on the conductive component is thinner than the thickness T2 of the internal insulating protective layer on the electronic component.

5. The internal insulating protective layer contains acrylic resin and the external insulating protective layer contains acrylic resin, or The internal insulating protective layer contains epoxy resin, and the external insulating protective layer contains epoxy resin. The electronic device according to claim 1 or claim 2.

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; an electronic component disposed on the mounting surface and within the ground region; and a conductive component disposed adjacent to the outer edge of the ground electrode and electrically insulated from the ground electrode; A first step is to form an internal insulating protective layer covering the electronic component within the ground region, A second step is to form an electromagnetic wave shielding layer, which spans the internal insulating protective layer and the ground electrode, covers the internal insulating protective layer, and is electrically connected to the ground electrode, as a solidified product of an ink for forming an electromagnetic wave shielding layer, Includes, Prior to the second step, an external insulating protective layer covering the conductive component is formed outside the ground region. A method for manufacturing electronic devices.

7. The first step involves forming the internal insulating protective layer and the external insulating protective layer using an insulating protective layer forming ink. A method for manufacturing an electronic device according to claim 6.

8. The first step involves applying an insulating protective layer ink by an inkjet recording method, a dispenser method, or a spray method, and forming the internal insulating protective layer and the external insulating protective layer A method for manufacturing an electronic device according to claim 7, comprising forming a protective layer.

9. The method for manufacturing an electronic device according to claim 7 or claim 8, wherein the ink for forming the insulating protective layer is an active energy ray curable ink.

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