Wiring board

Abstract

To provide a wiring board capable of suppressing generation of a solder bridge.SOLUTION: A wiring board 1 has one or more layers of wiring 3a, 3b and one or more layers of insulation layers 4a, 4b arranged on a first surface 2a side of a base material 2. The one or more layers of the wiring 3a, 3b have at least outermost wiring 13 located farthest from the base material 2. The one or more layers of the insulation layers 4a, 4b include at least an outermost insulation layer 14 that is arranged on a surface side opposite to a surface on the base material 2 side of the outermost wiring 13 and has opening units 5a, 5b positioned on the outermost wiring 13. The wiring board 1 further includes connection units 8 that are arranged in the opening units 5a, 5b of the outermost insulation layer 14 and are electrically connected to the outermost wiring 13. The outermost insulation layer 14 has a protrusion 15 on a surface opposite to a surface on the outermost wiring 13 side and on a peripheral edge of the opening units 5a, 5b. A height of the protrusion 15 of the outermost insulation layer 14 from the first surface 2a of the base material is higher than that of the connection unit 8 from the first surface 2a of the base material, and a pitch of the connection unit 8 is 50 μm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a wiring board.

Background Art

[0002] As a method for mounting electronic components, a method of surface-mounting electronic components on a wiring board is mainstream (see, for example, Patent Document 1).

[0003] In recent years, with the miniaturization and high functionality of electronic devices, technological development of multi-layerization, high density, and high speed has been promoted also for wiring boards on which electronic components are mounted. Therefore, in a wiring board, narrow pitch reduction that narrows the interval (pitch) between connection parts is required. Note that the connection part is also referred to as a pad or a terminal part.

[0004] However, when the pitch of the connection part is narrow, there is a problem that so-called solder bridge occurs in which solder on adjacent connection parts comes into contact.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present disclosure is an invention made in view of the above problems, and a main object thereof is to provide a wiring board capable of suppressing the occurrence of solder bridge.

Means for Solving the Problems

[0007] To achieve the above object, the present disclosure provides a wiring board having a base material with a first surface and a second surface facing the first surface, and one or more wiring layers and one or more insulating layers disposed on the first surface side of the base material, wherein the one or more wiring layers include at least an outermost wiring layer located farthest from the base material, the one or more insulating layers are disposed on a surface side opposite to the surface of the outermost wiring layer on the base material side, and include at least an outermost insulating layer having an opening located on the outermost wiring layer, the wiring board further includes a connection portion disposed in the opening of the outermost insulating layer and electrically connected to the outermost wiring layer, the outermost insulating layer has a convex portion on a surface opposite to the surface on the outermost wiring layer side and at a peripheral portion of the opening, a height of the convex portion of the outermost insulating layer from the first surface of the base material is higher than a height of the connection portion from the first surface of the base material, and a pitch of the connection portion is 50 μm or less.

[0008] According to the present disclosure, since the outermost insulating layer has a convex portion on a surface opposite to the surface on the outermost wiring layer side and at a peripheral portion of the opening, and a height of the convex portion of the outermost insulating layer from the first surface of the base material is higher than a height of the connection portion from the first surface of the base material, it is possible to suppress the occurrence of solder bridges when mounting an electronic component on the wiring board of the present disclosure. Therefore, even with a narrow pitch, short circuits can be suppressed.

[0009] The present disclosure also provides a wiring board having a base material having a first surface and a second surface facing the first surface, and one or more wiring layers and one or more insulating layers disposed on the first surface side of the base material, wherein the one or more wiring layers include at least an outermost wiring layer positioned farthest from the base material, the one or more insulating layers include at least an outermost insulating layer disposed on a surface side opposite to the surface of the outermost wiring layer on the base material side and having an opening positioned on the outermost wiring layer, the wiring board includes a connection portion disposed in the opening of the outermost insulating layer and electrically connected to the outermost wiring layer, and a recess positioned on the outermost insulating layer and the surface side of the connection portion and extending over the entire circumference of the peripheral edge of the opening of the outermost insulating layer, the height of the bottom of the recess from the first surface of the base material is lower than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer and the maximum height of the connection portion from the first surface of the base material, the maximum height of the connection portion from the first surface of the base material is higher than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer, and the pitch of the connection portion is 50 μm or less.

[0010] According to the present disclosure, since the wiring board has a recess positioned on the outermost insulating layer and the surface side of the connection portion and extending over the entire circumference of the peripheral edge of the opening of the outermost insulating layer, and the height of the bottom of the recess from the first surface of the base material is lower than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer and the maximum height of the connection portion from the first surface of the base material, it is possible to suppress the occurrence of solder bridges when mounting electronic components on the wiring board of the present disclosure. Therefore, even with a narrow pitch, short circuits can be suppressed. Further, since the maximum height of the connection portion from the first surface of the base material is higher than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer, the electrical connectivity between the connection portion and the electronic component can be improved.

[0011] In the present disclosure, it is preferable that the outermost insulating layer includes a cured product of a photosensitive resin composition. This is because the outermost insulating layer having the convex portions at the peripheral portions of the openings or the concave portions at the peripheral portions of the outermost insulating layer can be easily formed by a photolithography method.

Advantages of the Invention

[0012] In the present disclosure, there is an effect that it is possible to suppress the occurrence of solder bridges.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings and the like. However, the present disclosure can be implemented in many different modes and is not to be construed as being limited to the description of the embodiments exemplified below. Also, in order to make the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is merely an example and does not limit the interpretation of the present disclosure. Further, in this specification and each drawing, elements that are the same as those described above with respect to the previously presented drawings may be denoted by the same reference numerals, and detailed descriptions may be appropriately omitted.

[0015] In this specification, when expressing the manner of arranging one member on another member, if simply denoted as "above" or "below", unless otherwise specified, it includes both the case where another member is arranged directly above or below so as to be in contact with one member, and the case where another member is arranged above or below one member with yet another member in between. Also, in this specification, when expressing the manner of arranging one member on the surface of another member, if simply denoted as "on the surface side" or "on the surface", unless otherwise specified, it includes both the case where another member is arranged directly above or below so as to be in contact with one member, and the case where another member is arranged above or below one member with yet another member in between.

[0016] Hereinafter, the wiring board of the present disclosure will be described in detail. The wiring board of the present disclosure has two embodiments. Each embodiment will be described below.

[0017] I. First Embodiment The first embodiment of the wiring board of the present disclosure is a wiring board having a base material with a first surface and a second surface facing the first surface, and one or more layers of wiring and one or more layers of insulating layers arranged on the first surface side of the base material, wherein the one or more layers of wiring have at least an outermost wiring located farthest from the base material, the one or more layers of insulating layers are arranged on the surface side opposite to the surface of the outermost wiring on the base material side, and have at least an outermost insulating layer having an opening located on the outermost wiring, the wiring board further has a connection portion arranged in the opening of the outermost insulating layer and electrically connected to the outermost wiring, the outermost insulating layer has a convex portion on the surface opposite to the surface on the outermost wiring side and at the peripheral edge of the opening, the height of the convex portion of the outermost insulating layer from the first surface of the base material is higher than the height of the connection portion from the first surface of the base material, and the pitch of the connection portion is 50 μm or less.

[0018] The wiring board of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a wiring board according to the present embodiment. As shown in FIG. 1, a wiring board 1 according to the present embodiment includes a base material 2 having a first surface 2a and a second surface 2b facing the first surface 2a, and one or more wiring layers 3a, 3b and one or more insulating layers 4a, 4b disposed on the first surface 2a side of the base material 1. The one or more wiring layers 3a, 3b include at least an outermost wiring 13(3b) located farthest from the base material 2, and the one or more insulating layers 4a, 4b include at least an outermost insulating layer 14(4b) disposed on the surface side opposite to the surface of the outermost wiring 13(3b) on the base material 2 side and having an opening 5b located on the outermost wiring 13(3b). The wiring board 1 further includes a connection portion 8 disposed in the opening 5b of the outermost insulating layer 14(4b) and electrically connected to the outermost wiring 13(3b). The outermost insulating layer 14(4b) has a convex portion 15 on the surface opposite to the surface on the outermost wiring 13(3b) side and at the peripheral edge of the opening 5b. As shown in FIG. 2, the height H1 of the convex portion 15 of the outermost insulating layer 14(4b) from the first surface 2a of the base material 2 is higher than the height H2 of the connection portion 8 from the first surface 2a of the base material 2. Also, the pitch P of the connection portion 8 is within a predetermined range. Note that FIG. 2 is an enlarged view of FIG. 1.

[0019] The wiring board according to the present embodiment only needs to have one or more wiring layers and one or more insulating layers disposed on the first surface side of the base material. Although not shown, it may have one wiring layer and one insulating layer, or as shown in FIG. 1, it may have two wiring layers 3a, 3b and two insulating layers 4a, 4b. Although not shown, it may have three or more wiring layers and three or more insulating layers.

[0020] The insulating layer has an opening for disposing a wiring or a connection portion. When the wiring board according to the present embodiment has two or more insulating layers, each of the two or more insulating layers has an opening, but the outermost insulating layer only needs to have the convex portion, and the insulating layer other than the outermost insulating layer may or may not have the convex portion. For example, in FIG. 1, the two insulating layers 4a, 4b each have an opening 5a, 5b, but the outermost insulating layer 14(4b) has the convex portion 15, while the insulating layer 4a other than the outermost insulating layer 14(4b) does not have the convex portion, but may have the convex portion.

[0021] In this embodiment, as shown in FIG. 1, the connection portion 8 may have a first connection layer 6 disposed in the opening 5b of the outermost insulating layer 14(4b) and a second connection layer 7 disposed on the first connection layer 6.

[0022] According to this embodiment, the outermost insulating layer has a convex portion on the surface opposite to the surface on the outermost wiring side and at the peripheral portion of the opening, and the height of the convex portion of the base material of the outermost insulating layer from the first surface is higher than the height of the base material of the connection portion from the first surface. When mounting an electronic component on the wiring board of this embodiment, the convex portion of the outermost insulating layer can block the solder and suppress the spread of the solder, and it is possible to suppress the occurrence of solder bridges. Therefore, even with a narrow pitch, electrical connection can be made without causing a short circuit.

[0023] Hereinafter, the wiring board of this embodiment will be described for each configuration.

[0024] 1. Insulating layer The insulating layer in this embodiment is a member that is disposed on the first surface side of the base material and has insulating properties. The wiring board of this embodiment has one or more insulating layers.

[0025] The insulating layer may be one or more, and may be one layer, or two or more layers.

[0026] One or more insulating layers are disposed on the surface side opposite to the surface on the base material side of the outermost wiring described later, and at least have an outermost insulating layer having an opening located on the outermost wiring.

[0027] The outermost insulating layer has a convex portion on the surface opposite to the surface on the outermost wiring side and at the peripheral portion of the opening.

[0028] When the wiring board of this embodiment has two or more insulating layers, it is sufficient that the outermost insulating layer has the above convex portion, and the insulating layer other than the outermost insulating layer may or may not have the above convex portion.

[0029] The height of the convex portion of the outermost insulating layer from the first surface of the base material is higher than the height of the connecting portion from the first surface of the base material. Specifically, the difference between the height of the convex portion of the outermost insulating layer from the first surface of the base material and the height of the connecting portion from the first surface of the base material is preferably 0.1 μm or more, more preferably 0.1 μm or more and 0.5 μm or less, and particularly preferably 0.2 μm or more and 0.3 μm or less. When an electronic component is mounted on the wiring board of the present embodiment, the spread of solder can be suppressed by the convex portion of the outermost insulating layer, and the occurrence of solder bridges can be suppressed due to the height difference being within the above range.

[0030] Here, the "height of the convex portion of the outermost insulating layer from the first surface of the base material" refers to the height from the first surface of the base material to the top of the convex portion of the outermost insulating layer. For example, in FIG. 2, it refers to the height H1 from the first surface 2a of the base material 2 to the top a of the convex portion 15 of the outermost insulating layer 14. Also, the "height of the connecting portion from the first surface of the base material" refers to the height from the first surface of the base material to the portion where the surface opposite to the outermost wiring side of the connecting portion and the side surface of the opening of the outermost insulating layer are in contact. For example, in FIG. 2, it refers to the height H2 from the first surface 2a of the base material 2 to the portion b where the surface opposite to the outermost wiring 13 side of the connecting portion 8 and the side surface of the opening 5b of the outermost insulating layer 14(4b) are in contact.

[0031] Also, in the outermost insulating layer, the height of the convex portion from the first surface of the base material is higher than the height of the portion other than the convex portion from the first surface of the base material. Specifically, in the outermost insulating layer, the difference between the height of the convex portion from the first surface of the base material and the height of the portion other than the convex portion from the first surface of the base material is preferably 0.2 μm or more, more preferably 0.3 μm or more and 5.0 μm or less, and particularly preferably 0.5 μm or more and 3.0 μm or less.

[0032] Here, the "height of the portion other than the convex portion of the outermost insulating layer from the first surface of the base material" refers to the height from the first surface of the base material to the portion other than the convex portion on the surface opposite to the outermost wiring side of the outermost insulating layer. For example, in FIG. 2, it refers to the height H3 from the first surface 2a of the base material 2 to the portion other than the convex portion 15 on the surface opposite to the outermost wiring 13 side of the outermost insulating layer 14.

[0033]

[0033] The height from the first surface of the base material of the convex portion of the outermost insulating layer, the height from the first surface of the base material of the connection portion, and the height from the first surface of the base material of the portion other than the convex portion of the outermost insulating layer can be measured, for example, using a stylus type film thickness measuring machine (manufactured by KLA-Tencor, P-15) under the conditions of a needle pressure of 5 mg and a scanning speed of 50 μm / second. Note that the same applies to the measurement methods of each height described later.

[0034]

[0034] The cross-sectional shape of the convex portion is not particularly limited as long as the height from the first surface of the base material of the convex portion of the outermost insulating layer is higher than the height from the first surface of the base material of the connection portion.

[0035] Moreover, the outermost insulating layer only needs to have a convex portion at the peripheral edge of the opening of the outermost insulating layer. Among them, for example, as shown in FIG. 3, it is preferable to have a convex portion 15 over the entire circumference of the peripheral edge of the opening 5 of the outermost insulating layer 14. By providing convex portions over the entire circumference of the peripheral edge of the opening of the outermost insulating layer, when mounting an electronic component on the wiring board of the present embodiment, the spread of solder can be effectively suppressed by the convex portions of the outermost insulating layer, and the occurrence of solder bridges can be further suppressed.

[0036] The material of the insulating layer is not particularly limited as long as it is an insulating material, and an insulating material generally used for the insulating layer of a wiring board can be used, and either an organic material or an inorganic material can be used.

[0037] Moreover, the material of the outermost insulating layer is not particularly limited as long as it is an insulating material capable of forming the convex portion. Among them, the material of the outermost insulating layer is preferably a photosensitive resin. That is, the outermost insulating layer preferably contains a cured product of a photosensitive resin composition. This is because the outermost insulating layer having the convex portion can be easily formed by photolithography. Specifically, when forming the outermost insulating layer, the coating film of the photosensitive resin composition can be made into a shape that bulges depending on the thickness of the outermost wiring on the outermost wiring. Therefore, an outermost insulating layer having a convex portion at the peripheral edge of the opening can be formed.

[0038] The thickness of the insulating layer can be the thickness of the insulating layer in a general wiring board.

[0039] As a method for forming the insulating layer, a general method for forming an insulating layer can be used, and it is appropriately selected according to the material of the insulating layer and the like. Further, as a method for forming an opening in the insulating layer, a general method for forming an opening can be used, and it is appropriately selected according to the material of the insulating layer and the like. Examples of the method for forming the opening include laser irradiation, etching such as plasma etching and wet etching, or mechanical processing methods such as sandblasting and ultrasonic drilling, and photolithography. Among them, the method for forming the outermost insulating layer is preferably the photolithography method. This is because the outermost insulating layer having the convex portions can be easily formed by the photolithography method.

[0040] Further, when the method for forming the outermost insulating layer is the photolithography method and a negative photosensitive resin composition is used, for example, after applying the photosensitive resin composition, it is immediately exposed, so that the coating film of the photosensitive resin composition can be cured while maintaining the raised shape, and the outermost insulating layer having convex portions at the peripheral edge of the opening can be easily formed.

[0041] Further, when the method for forming the outermost insulating layer is the photolithography method and a photosensitive resin composition is used, for example, after applying the photosensitive resin composition on a substrate, by performing reduced-pressure drying within a predetermined time to increase the drying speed, the coating film of the photosensitive resin composition is likely to have a raised shape on the outermost wiring, and the outermost insulating layer having convex portions at the peripheral edge of the opening can be easily formed. The time from the end of the application of the photosensitive resin composition to the start of the reduced-pressure drying is preferably, for example, within 60 seconds, more preferably within 50 seconds, and even more preferably within 40 seconds.

[0042] In order to increase the drying rate of the photosensitive resin composition, for example, the boiling point of the main solvent contained in the photosensitive resin composition is preferably 170°C or lower, and more preferably 150°C or lower. The main solvent refers to a solvent having a content of 50 parts by mass or more when the total amount of the solvents contained in the photosensitive resin composition is 100 parts by mass.

[0043] 2. Wiring The wiring in this embodiment is arranged on the first surface side of the base material and is a member having conductivity. The wiring board of this embodiment has one or more layers of wiring.

[0044] The wiring may be one or more layers, and may be one layer or two or more layers.

[0045] The one or more layers of wiring include at least the outermost wiring located farthest from the base material.

[0046] The material of the wiring is not particularly limited as long as it is a conductive material, and a conductive material used for general wiring can be used. Examples of the conductive material include metals such as copper, molybdenum, titanium, tungsten, tantalum, aluminum, gold, silver, nickel, palladium, alloys containing at least one selected from these metals, or conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). By using copper or aluminum with high conductivity, an increase in resistance can be suppressed. Also, by using copper with relatively low hardness, a wiring board capable of constructing a more reliable electrical connection can be provided.

[0047] The wiring may be a single layer or a multilayer in which a plurality of layers are laminated.

[0048] The thickness of the wiring can be the thickness of the wiring in a general wiring board. The thickness of the wiring can be, for example, 0.05 μm or more and 20 μm or less, may be 0.1 μm or more and 15 μm or less, or may be 0.2 μm or more and 10 μm or less. Thereby, sufficient conductivity can be obtained.

[0049] As a method for forming the wiring, a general method for forming the wiring can be used, and examples thereof include a CVD method, a sputtering method, and a plating method.

[0050] 3. Connection part The connection part in the present embodiment is a member that is disposed in the opening of the outermost insulating layer and is electrically connected to the outermost wiring.

[0051] The pitch of the connection part is 50 μm or less, and can be, for example, 10 μm or more and 50 μm or less, and preferably 15 μm or more and 45 μm or less. In the present embodiment, since the pitch of the connection part is within the above range, even if the pitch is narrow, electrical connection can be performed without causing a short circuit.

[0052] Here, the above pitch can be measured by, for example, observation with an optical microscope or observation with a scanning electron microscope (SEM).

[0053] The material of the connection part is not particularly limited as long as it is a conductive material, and can be the same as the material of the above wiring.

[0054] The connection part may be a single layer or a multilayer in which a plurality of layers are laminated.

[0055] The thickness of the connection part is not particularly limited, and is appropriately set according to the shape of the terminal part of the electronic component mounted on the wiring board of the present embodiment.

[0056] As shown in, for example, FIG. 2, the maximum height H4 of the connection portion 8 from the first surface 2a of the base material 2 of the connection portion 8 may be higher than the height H3 of the portion of the base material 2 other than the convex portion 15 of the outermost insulating layer 14 from the first surface 2a. Thereby, it becomes possible to increase the size of the terminal portion of the electronic component mounted on the wiring board of the present embodiment, improve the electrical connectivity, and increase the productivity.

[0057] In the above case, the difference H10 between the maximum height H4 of the connection portion 8 from the first surface 2a of the base material 2 and the height H3 of the portion of the base material 2 other than the convex portion 15 of the outermost insulating layer 14 from the first surface 2a is preferably 3 μm or less. For example, in the CVD method, sputtering method, plating method, etc., film growth is usually isotropic. Therefore, for example, in FIG. 2, if the difference H10 between the maximum height H4 of the connection portion 8 from the first surface 2a of the base material 2 and the height H3 of the portion of the base material 2 other than the convex portion 15 of the outermost insulating layer 14 from the first surface 2a is large, on the surface of the outermost insulating layer 14 opposite to the surface on the outermost wiring 13 side, the overlapping portion of the connection portion 8 and the outermost insulating layer 14 also becomes large. When the overlapping portion of the connection portion 8 and the outermost insulating layer 14 on the surface of the outermost insulating layer 14 opposite to the surface on the outermost wiring 13 side becomes large, the convex portion 15 of the outermost insulating layer 14 is likely to be covered by the connection portion 8, and it may be difficult to suppress the occurrence of solder bridges depending on the convex portion of the outermost insulating layer. Therefore, the difference H10 between the maximum height H4 of the connection portion 8 from the first surface 2a of the base material 2 and the height H3 of the portion of the base material 2 other than the convex portion 15 of the outermost insulating layer 14 from the first surface 2a is preferably 3 μm or less.

[0058] Here, the "maximum height from the first surface of the base material of the connection portion" refers to the maximum height among the heights from the first surface of the base material to the surface opposite to the outermost wiring side surface of the connection portion. For example, in FIG. 2, it refers to the maximum height H4 among the heights from the first surface 2a of the base material 2 to the surface opposite to the outermost wiring 13 side surface of the connection portion 8.

[0059] As the method for forming the connection portion, it can be the same as the method for forming the above wiring.

[0060] 4. Base Material The base material in this embodiment has a first surface and a second surface facing the first surface, and is a member that supports the above-mentioned insulating layer, wiring, and connection portion.

[0061] The base material is not particularly limited as long as it has insulating properties, and an insulating base material generally used for wiring boards can be used. For example, ceramic base materials such as glass base materials, glass epoxy base materials, glass composite base materials, and alumina base materials, resin base materials such as fluororesin base materials and polyimide base materials, and paper phenol base materials can be mentioned.

[0062] As will be described later, when the wiring board of this embodiment has a second wiring that electrically connects the first surface and the second surface of the base material, the base material may or may not have through holes. When the base material has through holes, the second wiring becomes through wiring arranged in the through holes.

[0063] The size of the diameter of the through hole can be appropriately selected according to the use of the wiring board and is not particularly limited. For example, it may be 10 μm or more and 200 μm or less, or may be 20 μm or more and 100 μm or less.

[0064] Examples of the method for forming the through hole include etching such as plasma etching and wet etching, laser irradiation, or mechanical processing methods such as sandblasting and ultrasonic drilling.

[0065] The thickness of the base material is not particularly limited as long as it can support the above-mentioned insulating layer, wiring, and connection portion, and can be appropriately selected according to the use of the wiring board. The thickness of the base material can be, for example, 10 μm or more and 800 μm or less, may be 100 μm or more and 600 μm or less, or may be 300 μm or more and 500 μm or less.

[0066] II. Second Embodiment A second embodiment of the wiring board of the present disclosure is a wiring board having a base material having a first surface and a second surface facing the first surface, and one or more wirings and one or more insulating layers disposed on the first surface side of the base material, wherein the one or more wirings include at least an outermost wiring located farthest from the base material, the one or more insulating layers are disposed on a surface side opposite to the surface of the outermost wiring on the base material side, and include at least an outermost insulating layer having an opening located on the outermost wiring, the wiring board has a connection portion disposed in the opening of the outermost insulating layer and electrically connected to the outermost wiring, and has a recess located over the entire circumference of the edge of the opening of the outermost insulating layer and on the surface on the connection portion side, and the height of the bottom of the recess from the first surface of the base material is lower than the maximum height of the outermost insulating layer from the first surface of the base material at the edge of the opening of the outermost insulating layer and the maximum height of the connection portion from the first surface of the base material, the maximum height of the connection portion from the first surface of the base material is higher than the maximum height of the outermost insulating layer from the first surface of the base material at the edge of the opening of the outermost insulating layer, and the pitch of the connection portion is 50 μm or less.

[0067] FIG. 4 is a schematic cross-sectional view showing an example of a wiring board according to the present embodiment. As shown in FIG. 4, the wiring board 1 of the present embodiment includes a base material 2 having a first surface 2a and a second surface 2b facing the first surface 2a, and one or more wiring layers 3a, 3b and one or more insulating layers 4a, 4b disposed on the first surface 2a side of the base material 1. The one or more wiring layers 3a, 3b include at least an outermost wiring 13(3b) located farthest from the base material 2, and the one or more insulating layers 4a, 4b are disposed on the surface side opposite to the surface of the outermost wiring 13(3b) on the base material 2 side, and include at least an outermost insulating layer 14(4b) having an opening 5b located on the outermost wiring 13(3b). The wiring board 1 further includes a connection portion 8 disposed in the opening 5b of the outermost insulating layer 14(4b) and electrically connected to the outermost wiring 13(3b). Further, as shown in FIGS. 4 and 5, the wiring board 1 further has a recess 16 on the surface of the outermost insulating layer 14(4b) and the connection portion 8 side, and over the entire circumference of the peripheral edge of the opening 5b of the outermost insulating layer 14(4b). For example, as shown in FIG. 6, the height H11 of the bottom c of the recess 16 from the first surface 2a of the base material 2 is lower than the maximum height H12 of the outermost insulating layer 14(4b) from the first surface 2a of the base material 2 at the peripheral edge of the opening 5b of the outermost insulating layer 14(4b), and the maximum height H13 of the connection portion 8 from the first surface 2a of the base material 2, and the maximum height H13 of the connection portion 8 from the first surface 2a of the base material 2 is higher than the maximum height H12 of the outermost insulating layer 14(4b) from the first surface 2a of the base material 2 at the peripheral edge of the opening 5b of the outermost insulating layer 14(4b). Further, the pitch P of the connection portion 8 is within a predetermined range. Note that FIG. 6 is an enlarged view of FIG. 4, and FIG. 5 is a top view of FIG. 6.

[0068] The wiring board of the present embodiment only needs to have one or more wiring layers and one or more insulating layers disposed on the first surface side of the base material. Although not shown, it may have one wiring layer and one insulating layer, and as shown in FIG. 4, it may have two wiring layers 3a, 3b and two insulating layers 4a, 4b, and although not shown, it may have three or more wiring layers and three or more insulating layers.

[0069] Here, generally, in a wiring board, from the viewpoints of electrical connectivity, electrical connection reliability, etc., the connection part is arranged so as to cover the opening of the outermost insulating layer. That is, it is preferable that the connection part is provided such that the height from the base material of the connection part is higher than the height from the base material of the outermost insulating layer. However, if the connection part is arranged so as to cover the opening of the outermost insulating layer and the height from the base material of the connection part is higher than the height from the base material of the outermost insulating layer, solder bridges are likely to occur at a narrow pitch.

[0070] On the other hand, according to the present embodiment, the wiring board has a recess on the outermost insulating layer and the surface on the connection part side, and also over the entire periphery of the peripheral edge of the opening of the outermost insulating layer. By making the height from the first surface of the base material at the bottom of the recess lower than the maximum height from the first surface of the base material of the outermost insulating layer at the peripheral edge of the opening of the outermost insulating layer and the maximum height from the first surface of the base material of the connection part, when mounting an electronic component on the wiring board of the present embodiment, it is easy for solder to flow into the recess, the spread of the solder can be suppressed, and the occurrence of solder bridges can be suppressed. Therefore, even at a narrow pitch, electrical connection can be performed without causing a short circuit.

[0071] Also, according to the present embodiment, since the maximum height from the first surface of the base material of the connection part is higher than the maximum height from the first surface of the base material of the outermost insulating layer at the peripheral edge of the opening of the outermost insulating layer, it becomes possible to increase the size of the terminal part of the electronic component mounted on the wiring board of the present embodiment, improve the electrical connectivity, and increase the productivity.

[0072] Hereinafter, the wiring board of the present embodiment will be described for each configuration.

[0073] 1. Insulating layer The insulating layer in the present embodiment is a member that is arranged on the first surface side of the base material and has insulating properties. The wiring board of the present embodiment has one or more insulating layers.

[0074] The insulating layer may be one or more, and may be one layer or two or more layers.

[0075] The insulating layer of one or more layers is disposed on the side opposite to the surface on the base material side of the outermost wiring described later, and has at least an outermost insulating layer having an opening located on the outermost wiring.

[0076] The material of the insulating layer is not particularly limited as long as it is an insulating material, and an insulating material generally used for the insulating layer of a wiring board can be used, and either an organic material or an inorganic material can be used.

[0077] Also, the material of the outermost insulating layer is not particularly limited as long as it is an insulating material capable of forming the above-mentioned recess. Among them, the material of the outermost insulating layer is preferably a photosensitive resin. That is, the outermost insulating layer preferably contains a cured product of a photosensitive resin composition. This is because the above-mentioned recess can be easily formed by a photolithography method.

[0078] The thickness of the insulating layer can be the thickness of the insulating layer in a general wiring board.

[0079] As a method for forming the insulating layer, a general method for forming an insulating layer can be used, and it is appropriately selected according to the material of the insulating layer and the like. Also, as a method for forming an opening in the insulating layer, a general method for forming an opening can be used, and it is appropriately selected according to the material of the insulating layer and the like. Examples of the method for forming the opening include laser irradiation, etching such as plasma etching and wet etching, or mechanical processing methods such as sandblasting and ultrasonic drilling, and photolithography. Among them, the method for forming the outermost insulating layer is preferably a photolithography method. This is because the above-mentioned recess can be easily formed by a photolithography method.

[0080] Also, when the method for forming the outermost insulating layer is a photolithography method and a photosensitive resin composition is used, for example, when exposing the coating film of the photosensitive resin composition, stepwise exposure is performed so that the exposure amount differs among the region corresponding to the opening, the region corresponding to the peripheral edge of the opening, and the other regions, whereby the concave portion can be easily formed. Specifically, when a positive photosensitive resin composition is used, the region corresponding to the opening becomes the unexposed portion, and by performing stepwise exposure so that the exposure amount of the region corresponding to the peripheral edge of the opening is smaller than the exposure amount of the other regions, the concave portion can be easily formed.

[0081] 2. Concave portion The concave portion in the present embodiment is a portion that is located on the outermost insulating layer and the surface on the connection portion side and extends over the entire circumference of the peripheral edge of the opening of the outermost insulating layer.

[0082] The height of the bottom of the concave portion from the first surface of the base material is lower than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer and the maximum height of the connection portion from the first surface of the base material.

[0083] The difference between the height of the bottom of the concave portion from the first surface of the base material and the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer is preferably, for example, 0.5 μm or more, more preferably 0.5 μm or more and 3.0 μm or less, and particularly preferably 0.5 μm or more and 2.5 μm or less. When an electronic component is mounted on the wiring board of the present embodiment with the height difference within the above range, the spread of solder can be suppressed by the concave portion, and the occurrence of solder bridges can be suppressed.

[0084] Further, the difference between the height of the bottom of the recess from the first surface of the base material and the maximum height of the connection portion from the first surface of the base material is preferably, for example, 0.2 μm or more, more preferably 0.3 μm or more and 3.0 μm or less, and particularly preferably 0.5 μm or more and 2.5 μm or less. When an electronic component is mounted on the wiring board of the present embodiment, the spread of solder can be suppressed by the recess within the above range of the height difference, and the occurrence of solder bridges can be suppressed.

[0085] Here, the "height of the bottom of the recess from the first surface of the base material" refers to the height from the first surface of the base material to the bottom of the recess. For example, in FIG. 6, it refers to the height H11 from the first surface 2a of the base material 2 to the bottom c of the recess 16. Further, the "maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer" refers to the maximum height among the heights from the first surface of the base material to the surface opposite to the outermost wiring side of the outermost insulating layer at the peripheral edge of the opening of the outermost insulating layer. For example, in FIG. 6, it refers to the maximum height H12 among the heights from the first surface 2a of the base material 2 to the surface opposite to the outermost wiring 13 (3b) side of the outermost insulating layer 14 (4b) at the peripheral edge of the opening 5b of the outermost insulating layer 14 (4b). Further, the "maximum height of the connection portion from the first surface of the base material" refers to the maximum height among the heights from the first surface of the base material to the surface opposite to the outermost wiring side of the connection portion. For example, in FIG. 6, it refers to the maximum height H13 among the heights from the first surface 2a of the base material 2 to the surface opposite to the outermost wiring 13 side of the connection portion 8.

[0086] The cross-sectional shape of the recess is not particularly limited as long as the height of the bottom of the recess from the first surface of the base material is lower than the maximum height of the outermost insulating layer from the first surface of the base material at the peripheral edge of the opening of the outermost insulating layer and the maximum height of the connection portion from the first surface of the base material.

[0087] Further, the concave portion is located on the outermost insulating layer and the surface on the connection portion side, and extends over the entire circumference of the peripheral edge of the opening of the outermost insulating layer. By providing the concave portion over the entire circumference of the peripheral edge of the opening of the outermost insulating layer, when an electronic component is mounted on the wiring board of the present embodiment, the spread of solder can be effectively suppressed by the concave portion, and the occurrence of solder bridges can be suppressed.

[0088] 3. Wiring The wiring in the present embodiment is arranged on the first surface side of the base material and is a member having conductivity. The wiring board of the present embodiment has one or more layers of wiring. The wiring can be the same as the wiring of the first embodiment described above.

[0089] 4. Connection portion The connection portion in the present embodiment is a member that is arranged in the opening of the outermost insulating layer and is electrically connected to the outermost wiring.

[0090] The maximum height of the base material of the connection part from the first surface is higher than the maximum height of the base material of the outermost insulating layer from the first surface at the peripheral part of the opening of the outermost insulating layer. The difference between the maximum height of the base material of the connection part from the first surface and the maximum height of the base material of the outermost insulating layer from the first surface at the peripheral part of the opening of the outermost insulating layer is preferably, for example, 3.0 μm or less, more preferably 0.1 μm or more and 2.5 μm or less, and particularly preferably 0.1 μm or more and 2.0 μm or less. By the height difference being within the above range, the electrical connectivity between the connection part and the electronic component can be improved. Also, in, for example, the CVD method, the sputtering method, the plating method, etc., film growth is usually isotropic. Therefore, for example, in FIG. 6, if the difference H20 between the maximum height H13 of the base material 2 of the connection part 8 from the first surface 2a and the maximum height H12 of the base material 2 of the outermost insulating layer 14(4b) from the first surface 2a at the peripheral part of the opening 5b of the outermost insulating layer 14(4b) is large, on the surface of the outermost insulating layer 14 opposite to the surface on the outermost wiring 13 side, the overlapping part of the connection part 8 and the outermost insulating layer 14 also becomes large. When the overlapping part of the connection part 8 and the outermost insulating layer 14 on the surface of the outermost insulating layer 14 opposite to the surface on the outermost wiring 13 side becomes large, the recess 16 is likely to be covered by the connection part 8, and there is a possibility that it becomes difficult to suppress the generation of solder bridges due to the recess. Therefore, the difference H20 between the maximum height H13 of the base material 2 of the connection part 8 from the first surface 2a and the maximum height H12 of the base material 2 of the outermost insulating layer 14(4b) from the first surface 2a at the peripheral part of the opening 5b of the outermost insulating layer 14(4b) is preferably 3 μm or less.

[0091] Regarding the pitch, material, thickness, formation method, etc. of the connection part, it can be the same as the connection part of the first embodiment above.

[0092] 5. Substrate The substrate in this embodiment has a first surface and a second surface facing the first surface, and is a member that supports the above-mentioned insulating layer, wiring, and connection part. Regarding the substrate, it can be the same as the substrate of the first embodiment above.

[0093] Note that the present disclosure is not limited to the above-described embodiments. The above-described embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits the same operational effects is included in the technical scope of the present disclosure.

Example

[0094] Examples and comparative examples are shown below to explain the present disclosure in more detail. [Example 1] A wiring board as shown in FIG. 1 was fabricated.

[0095] (Formation of wiring and insulating layer) First, a glass substrate (manufactured by AGC, AN100, 300 mm × 400 mm) was irradiated with ultraviolet rays and washed. Thereafter, chromium sputtering treatment and copper sputtering treatment were performed on the glass substrate, and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Toppur Tin SF) was performed in the openings of the resist pattern to form a wiring layer (first layer) having a thickness of 10 μm. Next, the dry film resist was peeled off with a 50°C aqueous sodium hydroxide solution, and the exposed chromium layer and copper layer were removed with a chromium etching solution (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and a copper etching solution (manufactured by Meltech Co., Ltd., AD-331), respectively. Thereby, wiring (first layer) was formed. Thereafter, a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000) was used to form an insulating layer (first layer) having a thickness of 3 μm and an opening pitch of 45 μm so as to cover the wiring (first layer).

[0096] Next, chromium sputtering treatment and copper sputtering treatment were performed on the above insulating layer (first layer), and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Toplina SF) was performed on the opening of the resist pattern to form a wiring layer (second layer) with a thickness of 10 μm. Next, the dry film resist was peeled off with an aqueous sodium hydroxide solution at 50°C, and the exposed chromium layer and copper layer were removed with an etching solution for chromium (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and an etching solution for copper (manufactured by Meltec Co., Ltd., AD-331), respectively. Thereby, a wiring (second layer) was formed. Thereafter, using a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000), an insulating layer (second layer) with a thickness of 3 μm and an opening pitch of 45 μm was formed so as to cover the wiring (second layer). When forming the second-layer insulating layer, the time from the end of the application of the photosensitive resist to the start of vacuum drying was set to 40 seconds. The insulating layer (second layer) had convex portions at the peripheral edges of the openings.

[0097] (Formation of connection part) Next, electroless nickel plating was performed on the opening of the insulating layer (second layer) to form a connection part. First, the surface of the wiring (second layer) exposed at the opening of the insulating layer (second layer) was degreased using an acidic cleaner (manufactured by Okuno Pharmaceutical Co., Ltd., ICP Clean S-135K). Next, soft etching was performed with an etching solution for copper (manufactured by Meltec Co., Ltd., AD-331). Next, Pd was applied to the surface of the wiring (second layer) using an activator (manufactured by Okuno Pharmaceutical Co., Ltd., ICP Accelerator), and electroless nickel plating (manufactured by Okuno Pharmaceutical Co., Ltd., ICP Nicoron GM-SE) was performed to form a nickel-plated part. Thereafter, electroless gold plating (manufactured by Okuno Pharmaceutical Co., Ltd., Flash Gold NC) was performed on the surface of the nickel-plated part to form a protective plating part with a thickness of 0.05 μm. Thereby, a wiring board having a connection part was obtained. The pitch of the connection part was 45 μm.

[0098] In the obtained wiring board, the height H1 from the first surface of the glass substrate of the convex portion of the insulating layer (second layer) was higher than the height H2 from the first surface of the glass substrate of the connection portion. Also, the height H1 from the first surface of the glass substrate of the convex portion of the insulating layer (second layer) was higher than the height H3 from the first surface of the glass substrate of the portion other than the convex portion of the insulating layer (second layer). The differences between the height H1 and the height H2, and between the height H1 and the height H3 are shown in Table 1.

[0099] [Example 2] A wiring board as shown in FIG. 4 was fabricated.

[0100] (Formation of Wiring and Insulating Layer) First, a glass substrate (manufactured by AGC, AN100, 300 mm × 400 mm) was irradiated with ultraviolet rays and washed. Thereafter, chromium sputtering treatment and copper sputtering treatment were performed on the glass substrate, and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Toplina SF) was performed in the openings of the resist pattern to form a wiring layer (first layer) with a thickness of 2 μm. Next, the dry film resist was peeled off with a 50°C aqueous sodium hydroxide solution, and the exposed chromium layer and copper layer were removed with a chromium etching solution (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and a copper etching solution (manufactured by Mertec Co., Ltd., AD-331), respectively. Thereby, the wiring (first layer) was formed. Thereafter, a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000) was used to form an insulating layer (first layer) with a thickness of 3 μm and an opening pitch of 45 μm so as to cover the wiring (first layer).

[0101] Next, chromium sputtering treatment and copper sputtering treatment were performed on the above insulating layer (the first layer), and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Topple Tiner SF) was performed on the opening of the resist pattern to form a wiring layer (the second layer) with a thickness of 2 μm. Next, the dry film resist was peeled off with an aqueous sodium hydroxide solution at 50 °C, and the exposed chromium layer and copper layer were removed with an etching solution for chromium (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and an etching solution for copper (manufactured by Mertec Co., Ltd., AD-331), respectively. Thereby, a wiring (the second layer) was formed. Thereafter, an insulating layer (the second layer) with a thickness of 3 μm and an opening pitch of 45 μm was formed so as to cover the wiring (the second layer) using a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000). When forming the second-layer insulating layer, during the exposure of the photosensitive resist, the region corresponding to the opening was an unexposed portion, and the region 5 μm outside the outer periphery of the opening was exposed at an exposure dose of 20 mJ / cm 2 and the other regions were exposed at an exposure dose of 60 mJ / cm 2 and stepwise exposure was performed.

[0102] (Formation of connection part) Next, in the same manner as in Example 1, a connection part was formed in the opening of the insulating layer (the second layer). Thereby, a wiring board having a connection part was obtained. The pitch of the connection part was 45 μm.

[0103] The obtained wiring board had recesses located over the entire circumference of the peripheral edge of the opening of the insulating layer (the second layer) on the surface of the insulating layer (the second layer) and the connection part side. In the obtained wiring board, the height H11 of the bottom of the recess from the first surface of the glass substrate was lower than the maximum height H12 of the second insulating layer from the first surface of the glass substrate at the peripheral edge of the opening of the insulating layer (second layer) and the maximum height H13 of the connection portion from the first surface of the glass substrate. Further, the maximum height H13 of the connection portion from the first surface of the glass substrate was higher than the maximum height H12 of the second insulating layer from the first surface of the glass substrate at the peripheral edge of the opening of the insulating layer (second layer). Table 1 shows the differences between the height H11 and the height H12, the differences between the height H11 and the height H13, and the differences between the height H12 and the height H13.

[0104] [Comparative Example 1] (Formation of Wiring and Insulating Layer) First, a glass substrate (manufactured by AGC, AN100, 300 mm × 400 mm) was irradiated with ultraviolet rays and cleaned. Then, chromium sputtering treatment and copper sputtering treatment were performed on the glass substrate, and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Toppur Tinas SF) was performed on the opening of the resist pattern to form a wiring layer (first layer) with a thickness of 2 μm. Next, the dry film resist was peeled off with a 50°C aqueous sodium hydroxide solution, and the exposed chromium layer and copper layer were removed with a chromium etching solution (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and a copper etching solution (manufactured by Meltec Co., Ltd., AD-331), respectively. Thereby, the wiring (first layer) was formed. Then, a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000) was used to form an insulating layer (first layer) with a thickness of 3 μm and an opening pitch of 45 μm so as to cover the wiring (first layer). When forming the first insulating layer, the time from the end of the application of the photosensitive resist to the start of vacuum drying was set to 80 seconds.

[0105] Next, chromium sputtering treatment and copper sputtering treatment were performed on the above insulation layer (first layer), and a resist pattern was formed thereon using a dry film resist (manufactured by Asahi Kasei Electronics Co., Ltd., Sunfort AQ4038). Next, copper sulfate electrolytic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Topp Rutina SF) was performed on the opening of the resist pattern to form a wiring layer (second layer) with a thickness of 10 μm. Next, the dry film resist was peeled off with an aqueous sodium hydroxide solution at 50 °C, and the exposed chromium layer and copper layer were removed with an etching solution for chromium (manufactured by Sasaki Chemical Industry Co., Ltd., Esclean S-24) and an etching solution for copper (manufactured by Meltec Co., Ltd., AD-331), respectively. Thereby, a wiring (second layer) was formed. Thereafter, an insulating layer (second layer) with a thickness of 3 μm and an opening pitch of 45 μm was formed so as to cover the wiring (second layer) using a photosensitive resist (manufactured by Toray Industries, Inc., Photoneece PW-1000). When forming the second-layer insulating layer, the time from the end of the application of the photosensitive resist to the start of vacuum drying was set to 80 seconds.

[0106] (Formation of connection part) Next, in the same manner as in Example 1, a connection part was formed in the opening of the insulating layer (second layer). Thereby, a wiring board having a connection part was obtained. The pitch of the connection part was 45 μm.

[0107] [Evaluation] Solder paste was applied to the connection part of the obtained wiring board, held at 150 °C for 2 minutes in a reflow furnace, then held at 210 °C for 10 seconds, and the presence or absence of solder bridges between the connection parts was observed with a microscope. The results are shown in Table 1.

[0108] [Table 1] [Explanation of symbols]

[0109] 1... Wiring board 2... Substrate 2a... First surface of the substrate 2b... Second surface of the substrate 3a, 3b... Wiring 4a, 4b... Insulating layer 5a, 5b... Opening 6... First connection layer 7... Second connection layer 8... Connection part 13... Outermost wiring 14... Outermost insulating layer 15... Protrusion 16... Recess P... Pitch of the connection part

Claims

1. A wiring board having a substrate having a first surface and a second surface facing the first surface, and one or more wirings and one or more insulating layers disposed on the first surface side of the substrate, wherein the one or more wirings include at least an outermost wiring located farthest from the substrate, the one or more insulating layers are disposed on a surface side opposite to the surface of the outermost wiring on the substrate side, and the outermost insulating layer has at least two openings located on the outermost wiring, the wiring board further having at least two connection portions disposed in at least two openings of the outermost insulating layer and electrically connected to the outermost wiring, the outermost insulating layer having a portion where the height from the first surface of the substrate is higher than the height from the first surface of the substrate of the connection portion within a range of 0.1 μm or more and 0.5 μm or less between adjacent connection portions, the outermost insulating layer around any of the connection portions having a portion where the height from the first surface of the substrate is lower than the height from the first surface of the substrate of the connection portion, the wiring board having a pitch of the connection portions of 50 μm or less.

2. The wiring board according to claim 1, wherein the outermost insulating layer includes a cured product of a photosensitive resin composition.

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