Wiring board and method for manufacturing the same

Abstract

To secure insulation reliability in a wiring board having a NSMD structure.SOLUTION: A wiring board includes: a first insulation layer; a pad that is formed on one surface of the first insulation layer; a second insulation layer that is formed on one surface of the first insulation layer and including an open part to expose the pad; and a reinforcement metal layer that is formed so as to be contacted to the first insulation layer, and is provided to a circumference of the pad so as to be separated from the pad in a plan view. The pad is arranged into the open part without being contacted to the second insulation layer, and an end part on the first insulation layer side of one part of an inner side surface of the open part of the second insulation layer is contacted to the reinforcement metal layer and the end part of the first insulation layer side of the other one part of the inner side surface of the open part of the second insulation layer is contacted to one surface of the first insulation layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a wiring board and a method for manufacturing the same.

Background Art

[0002] A wiring board has, for example, pads exposed in openings provided in an insulating layer disposed on the outermost layer. These pads serve as external connection terminals for electrically connecting to a semiconductor chip, another substrate, or the like. As structures for forming pads on a wiring board, there are a NSMD (Non-Solder Mask Defined) structure in which the opening is larger than the pad and a SMD (Solder Mask Defined) structure in which the opening is smaller than the pad.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional wiring board having a NSMD structure, due to a difference in the coefficient of thermal expansion between an insulating layer having an opening for exposing a pad and an insulating layer located below it, when a high-temperature treatment such as reflow is performed, stress may occur at the interface between the two, resulting in cracks. Also, cracks may occur at the interface between the two during spray cleaning or ultrasonic cleaning. When cracks occur, the insulation reliability of the wiring board decreases.

[0005] The present disclosure has been made in view of the above points, and an object thereof is to ensure the insulation reliability in a wiring board having a NSMD structure.

Means for Solving the Problems

[0006] According to one embodiment of the present disclosure, the device comprises a first insulating layer, a pad formed on one surface of the first insulating layer, a second insulating layer formed on one surface of the first insulating layer and having an opening that exposes the pad, and a reinforcing metal layer formed in contact with the first insulating layer and provided around the pad at a distance from the pad in a plan view, wherein the pad is disposed within the opening without contacting the second insulating layer, a portion of the inner surface of the opening of the second insulating layer on the first insulating layer side is in contact with the reinforcing metal layer, and another portion of the inner surface of the opening of the second insulating layer on the first insulating layer side is in contact with one surface of the first insulating layer. The reinforcing metal layer is formed inside a groove that opens to one side of the first insulating layer. A wiring board is provided. [Effects of the Invention]

[0007] According to the disclosed technology, it is possible to ensure insulation reliability in wiring boards having an NSMD structure. [Brief explanation of the drawing]

[0008] [Figure 1] This figure illustrates a wiring board according to the first embodiment. [Figure 2] This is a diagram (part 1) illustrating the manufacturing process of a wiring board according to the first embodiment. [Figure 3] This is a diagram (part 2) illustrating the manufacturing process of a wiring board according to the first embodiment. [Figure 4] This is a cross-sectional view illustrating a wiring board according to the first comparative example. [Figure 5] This figure illustrates a wiring board according to a modified example of the first embodiment. [Figure 6] This diagram illustrates the connection between the pads and pins. [Figure 7] This figure illustrates a wiring board according to the second embodiment. [Figure 8] This figure illustrates a wiring board according to the third embodiment. [Figure 9] This figure illustrates a wiring board relating to the second comparative example. [Figure 10] This figure illustrates a wiring board according to the fourth embodiment. [Figure 11] It is a diagram illustrating a wiring board according to the fifth embodiment. [Figure 12] It is a diagram illustrating a wiring board according to the sixth embodiment. [Figure 13] It is a diagram illustrating a wiring board according to the seventh embodiment. [Figure 14] It is a diagram illustrating a wiring board according to the eighth embodiment. [Figure 15] It is a cross-sectional view illustrating a wiring board according to the ninth embodiment.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments will be specifically described with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0010] Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0011] 〈First Embodiment〉 [Structure of Wiring Board] FIG. 1 is a diagram illustrating a wiring board according to the first embodiment, FIG. 1(a) is a partial plan view, and FIG. 1(b) is a partial cross-sectional view taken along line A-A of FIG. 1(a).

[0012] Referring to FIG. 1, the wiring board 1 according to the first embodiment has an insulating layer 10, a wiring layer 20, and a solder resist layer 30.

[0013] In this embodiment, for the sake of convenience, the side of the solder resist layer 30 of the wiring board 1 is regarded as the upper side or one side, and the side of the insulating layer 10 is regarded as the lower side or the other side. Also, the surface on the solder resist layer 30 side of each part is regarded as the upper surface or one surface, and the surface on the insulating layer 10 side is regarded as the lower surface or the other surface. However, the wiring board 1 can be used in an upside-down state or arranged at an arbitrary angle. Also, a plan view means viewing an object from the normal direction of the upper surface 10a of the insulating layer 10, and a planar shape means the shape of an object viewed from the normal direction of the upper surface 10a of the insulating layer 10.

[0014] The insulating layer 10 is, for example, an insulating layer that can be formed using a build-up process as an interlayer insulating layer for multilayer wiring. Therefore, other wiring layers or other insulating layers may be laminated as the lower layer of the insulating layer 10. In this case, via holes can be provided in the insulating layer 10 and other insulating layers as appropriate, and the wiring layers can be connected to each other through the via holes.

[0015] As the material of the insulating layer 10, for example, an insulating resin mainly composed of a non-photosensitive (thermosetting resin) epoxy resin or polyimide resin can be used. Also, the insulating layer 10 may contain a filler such as silica (SiO2). The thickness of the insulating layer 10 can be, for example, about 10 to 50 μm. The thermal expansion coefficient of the insulating layer 10 is, for example, about 15 ppm / °C to 20 ppm / °C.

[0016] The wiring layer 20 is formed in contact with the insulating layer 10. The wiring layer 20 has at least a pad 21, two reinforcing metal layers 22, two reinforcing metal layers 23, and a power supply pattern 29. The wiring layer 20 may have a wiring pattern or the like separately from the pad 21, the reinforcing metal layer 22, the reinforcing metal layer 23, and the power supply pattern 29.

[0017] The pad 21 is formed on the upper surface 10a of the insulating layer 10 and is used to electrically connect the wiring board 1 to semiconductor chips or other wiring boards. The lower surface of the pad 21 is in contact with the upper surface 10a of the insulating layer 10, and the upper and side surfaces of the pad 21 are exposed from the insulating layer 10. In other words, the pad 21 protrudes upward from the upper surface 10a of the insulating layer 10.

[0018] The planar shape of the pad 21 is, for example, a rounded rectangle. However, the planar shape of the pad 21 is not limited to a rounded rectangle, and may be a circle, an ellipse, a rectangle, etc. A rounded rectangle, as used here, is a rectangle with rounded corners. The thickness of the pad 21 can be, for example, about 8 to 25 μm. For the material of the pad 21, copper (Cu) can be used, for example.

[0019] In a plan view, the power supply pattern 29 is positioned at a distance from the pad 21. The power supply pattern 29 is formed on the upper surface 10a of the insulating layer 10, and a constant potential, such as the power supply potential or ground potential, is applied to the power supply pattern 29. The lower surface of the power supply pattern 29 is in contact with the upper surface 10a of the insulating layer 10, and the upper and side surfaces of the power supply pattern 29 are exposed from the insulating layer 10. In other words, the power supply pattern 29 protrudes upward from the upper surface 10a of the insulating layer 10.

[0020] The planar shape of the reinforcing metal layers 22 and 23 is, for example, rectangular. In a plan view, the reinforcing metal layers 22 and 23 are arranged at a distance from the pad 21 and the power supply pattern 29. In a plan view, the two reinforcing metal layers 22 are positioned along the two longest sides (two major sides) of the rectangle obtained by approximating the planar shape of the pad 21. Also in a plan view, the two reinforcing metal layers 23 are positioned along the two shortest sides (two minor sides) of the rectangle obtained by approximating the planar shape of the pad 21. The reinforcing metal layers 22 and 23 are arranged at a distance from each other and are electrically insulated from the power supply pattern 29.

[0021] In a plan view, the distance between the pad 21 and the reinforcing metal layer 22 and the distance between the pad 21 and the reinforcing metal layer 23 are approximately constant, for example, 10 μm or more. Also, in a plan view, the distance between the power supply pattern 29 and the reinforcing metal layer 22 and the distance between the power supply pattern 29 and the reinforcing metal layer 23 are for example, 10 μm or more.

[0022] The reinforcing metal layer 22 is formed inside a rectangular groove 10x that opens to the upper surface 10a of the insulating layer 10. The reinforcing metal layer 23 is formed inside a rectangular groove 10y that opens to the upper surface 10a of the insulating layer 10. The upper surfaces of the reinforcing metal layers 22 and 23 are, for example, flush with the upper surface 10a of the insulating layer 10. However, the upper surfaces of the reinforcing metal layers 22 and 23 may, for example, protrude from the upper surface 10a of the insulating layer 10, or they may be recessed from the upper surface 10a of the insulating layer 10.

[0023] The thickness of the reinforcing metal layers 22 and 23 is, for example, the same as the thickness of the pad 21 and the power pattern 29. Therefore, with respect to the upper surface 10a of the insulating layer 10, the height of the reinforcing metal layers 22 and 23 is lower than the height of the pad 21 and the power pattern 29. In other words, the upper surfaces of the reinforcing metal layers 22 and 23 are located lower than the upper surfaces of the pad 21 and the power pattern 29. Note that "same" here means that an error of the magnitude of manufacturing variation is to be tolerated.

[0024] The width W1 of the reinforcing metal layer 22 and the width W2 of the reinforcing metal layer 23 can be, for example, 10 μm or more. The width W1 of the reinforcing metal layer 22 is the dimension in the direction perpendicular to the edge of the pad 21 along which the reinforcing metal layer 22 is aligned, in this case the dimension in the short side direction of the reinforcing metal layer 22. The width W2 of the reinforcing metal layer 23 is the dimension in the direction perpendicular to the edge of the pad 21 along which the reinforcing metal layer 23 is aligned, in this case the dimension in the short side direction of the reinforcing metal layer 23. The thickness of the reinforcing metal layers 22 and 23 can be, for example, about 8 to 25 μm. As the material for the reinforcing metal layers 22 and 23, for example, copper (Cu) can be used. Note that the reinforcing metal layers 22 and 23 may be dummy wiring without electrical connections.

[0025] The solder resist layer 30 is an insulating layer provided on the upper surface 10a of the insulating layer 10. The solder resist layer 30 has an opening 30x, and the pad 21 is completely exposed within the opening 30x. The pad 21 is positioned within the opening 30x without contacting the solder resist layer 30. In other words, the wiring board 1 employs an NSMD structure as the structure for forming the pads. However, the wiring board 1 may contain a mixture of NSMD and SMD structures.

[0026] In the solder resist layer 30, the lower end of a portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23. That is, a portion of the reinforcing metal layer 22 (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Similarly, a portion of the reinforcing metal layer 23 (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. In addition, in the solder resist layer 30, the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0027] For example, when the planar shape of the opening 30x is approximated as a rectangle, in a plan view, the reinforcing metal layer 22 coincides with the center of the longest side (long side) of at least the four sides included in the rectangle, and the reinforcing metal layer 23 coincides with the center of the shortest side (short side) of at least the four sides included in the rectangle. Alternatively, when the planar shape of the opening 30x is approximated as a rectangle, in a plan view, the reinforcing metal layers 22 and 23 may be spaced apart from the four vertices included in the rectangle. For example, the longitudinal direction of the reinforcing metal layer 22 is parallel to the long side of the rectangle, and the longitudinal direction of the reinforcing metal layer 23 is parallel to the short side of the rectangle. In a plan view, the longitudinal directions of the reinforcing metal layer 22 and the reinforcing metal layer 23 are orthogonal to each other.

[0028] For example, a photosensitive epoxy resin or acrylic resin can be used as the material for the solder resist layer 30. The thickness of the solder resist layer 30 can be, for example, about 5 to 40 μm. Since openings 30x are formed in the solder resist layer 30 by exposure and development, it is preferable that the solder resist layer 30 contains no filler or has a small filler content. The filler content in the solder resist layer 30 is, for example, less than the filler content in the insulating layer 10, and the thermal expansion coefficient of the solder resist layer 30 is, for example, greater than the thermal expansion coefficient of the insulating layer 10. The thermal expansion coefficient of the solder resist layer 30 is, for example, about 25 ppm / °C to 30 ppm / °C.

[0029] A surface treatment layer may be provided on the upper surfaces of the pad 21 and reinforcing metal layers 22 and 23 that are exposed within the opening 30x. Examples of surface treatment layers include metal layers such as an Au layer, a Ni / Au layer (a metal layer in which a Ni layer and an Au layer are stacked in that order), and a Ni / Pd / Au layer (a metal layer in which a Ni layer, a Pd layer, and an Au layer are stacked in that order). In addition, an anti-oxidation treatment such as water-soluble flux (Organic Solderability Preservative: OSP) treatment may be applied to the upper surfaces of the pad 21 and reinforcing metal layers 22 and 23 that are exposed within the opening 30x. Note that the OSP treatment forms an organic film consisting of an azole compound or an imidazole compound as a surface treatment layer.

[0030] [Manufacturing method for wiring boards] Next, a method for manufacturing a wiring board according to the first embodiment will be described. Figures 2 and 3 illustrate the manufacturing process of a wiring board according to the first embodiment. In this embodiment, the process of forming a single wiring board is shown, but it is also possible to manufacture multiple parts that will become wiring boards and then separate them into individual wiring boards.

[0031] First, in the process shown in Figure 2(a), an insulating layer 10 is prepared, and a rectangular groove 10x opening to the upper surface 10a is formed in the insulating layer 10. Simultaneously with the formation of groove 10x, a rectangular groove 10y opening to the upper surface 10a is also formed (see Figure 1(a)). Grooves 10x and 10y can be formed, for example, by laser processing. The width of grooves 10x and 10y can be, for example, 10 μm or more. The depth of grooves 10x and 10y can be, for example, about 8 to 25 μm. If grooves 10x and 10y are formed by laser processing, it is preferable to perform a desmear treatment to remove resin residue from the insulating layer 10 adhering to the bottom and inner surfaces of grooves 10x and 10y. In addition to removing resin residue, the desmear treatment can also roughen the upper surface 10a of the insulating layer 10 and the bottom and inner surfaces of grooves 10x and 10y.

[0032] Next, in the process shown in Figures 2(b) to 3(b), a wiring layer 20 is formed, including a pad 21, reinforcing metal layers 22 and 23, and a power supply pattern 29, so as to be in contact with the upper surface 10a of the insulating layer 10. Specifically, first, as shown in Figure 2(b), a seed layer 201 made of copper (Cu) or the like is formed by electroless plating or sputtering. The seed layer 201 is formed to continuously cover the bottom and inner surfaces of the grooves 10x and 10y, as well as the upper surface 10a of the insulating layer 10.

[0033] Next, as shown in Figure 2(c), a resist layer 300 is formed on the seed layer 201, having openings 300x corresponding to the wiring layer 20. The resist layer 300 can be formed, for example, by laminating a photosensitive dry film resist onto the seed layer 201. The openings 300x can be formed, for example, by exposing and developing the dry film resist.

[0034] Next, as shown in Figure 3(a), for example, an electroplating method is used in which the seed layer 201 is used as a power supply layer to deposit copper (Cu) or the like on the surface of the seed layer 201 exposed within the opening 300x of the resist layer 300, thereby forming an electroplated layer 202. As a result, an electroplated layer 202 is formed on the seed layer 201.

[0035] Next, as shown in Figure 3(b), after removing the resist layer 300, the seed layer 201 in the portion not covered by the electroplating layer 202 is removed by etching, using the electroplating layer 202 as a mask. This forms a wiring layer 20 in which the electroplating layer 202 is laminated on the seed layer 201. The wiring layer 20 includes a pad 21 and a power supply pattern 29 formed on the upper surface 10a of the insulating layer 10, a reinforcing metal layer 22 formed inside the groove 10x, and a reinforcing metal layer 23 formed inside the groove 10y (see Figure 1(a)). In a plan view, the reinforcing metal layers 22 and 23 are formed between the pad 21 and the power supply pattern 29, and are separated from the pad 21 and the power supply pattern 29. Note that in Figure 3(b), the seed layer 201 and the electroplating layer 202 are shown as a single wiring layer 20 without distinction (the same applies to subsequent figures and Figure 1, etc.).

[0036] Next, in the process shown in Figure 3(c), a solder resist layer 30 is formed on the upper surface 10a of the insulating layer 10 to cover the wiring layer 20, which includes the pads 21, reinforcing metal layers 22 and 23, and power supply pattern 29. Subsequently, openings 30x are formed in the solder resist layer 30. The solder resist layer 30 can be formed, for example, by applying a liquid or paste-like insulating resin to the upper surface 10a of the insulating layer 10 so as to cover the wiring layer 20, using methods such as screen printing, roll coating, or spin coating. Alternatively, a film-like insulating resin may be laminated to the upper surface 10a of the insulating layer 10 so as to cover the wiring layer 20. As the insulating resin, for example, a photosensitive epoxy resin or acrylic resin can be used.

[0037] Then, an opening 30x is formed in the solder resist layer 30 by exposing and developing the coated or laminated insulating resin. The opening 30x is formed such that the lower end of a part of the inner surface (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23, and the lower end of another part of the inner surface (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10 (see also Figure 1(a)). As a result, a part of the reinforcing metal layer 22 (the part farther from the pad 21) is covered by the solder resist layer 30, and another part (the part closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Similarly, a part of the reinforcing metal layer 23 (the part farther from the pad 21) is covered by the solder resist layer 30, and another part (the part closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. The pad 21 is also completely exposed within the opening 30x. In other words, the pad 21 is positioned within the opening 30x without coming into contact with the solder resist layer 30.

[0038] For example, when the planar shape of the opening 30x is approximated as a rectangle, the opening 30x is formed such that, in a plan view, the reinforcing metal layer 22 coincides with the center of the longest side (long side) of at least the four sides included in the rectangle, and the reinforcing metal layer 23 coincides with the center of the shortest side (short side) of at least the four sides included in the rectangle. Alternatively, when the planar shape of the opening 30x is approximated as a rectangle, the opening 30x may be formed such that, in a plan view, the reinforcing metal layers 22 and 23 are spaced apart from the four vertices included in the rectangle.

[0039] If necessary, the aforementioned surface treatment layer may be provided on the upper surfaces of the pads 21 and reinforcing metal layers 22 and 23 that are exposed within the opening 30x. The wiring board 1 is completed through the above steps.

[0040] Here, the effects of the wiring board 1 will be explained with reference to the first comparative example. Figure 4 is a cross-sectional view illustrating a wiring board according to the first comparative example. The wiring board 1X shown in Figure 4(a) differs from the wiring board 1 (see Figure 1, etc.) in that grooves 10x and 10y are not formed in the insulating layer 10, and that it does not have reinforcing metal layers 22 and 23.

[0041] In the wiring board 1X, the lower end of the inner surface of the opening 30x in the solder resist layer 30 (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10. As mentioned above, when comparing the thermal expansion coefficients of the insulating layer 10 and the solder resist layer 30, the thermal expansion coefficient of the solder resist layer 30 is larger. In addition, the insulating layer 10 is less flexible than the solder resist layer 30 and is therefore more prone to cracking.

[0042] Therefore, when high-temperature processing such as reflow soldering is performed, stress is generated at the interface between the insulating layer 10 and the solder resist layer 30 due to the difference (mismatch) in their coefficients of thermal expansion. When the adhesion between the insulating layer 10 and the solder resist layer 30 is high, as shown in Figure 4(b), a crack 400 originating from the starting point of the interface where the stress is greatest (the part indicated by arrow C) occurs in the insulating layer 10, which is less flexible and more prone to cracking than the solder resist layer 30.

[0043] Cracks 400 that occur in the insulating layer 10 propagate to the solder resist layer 30, causing chipping 450 as shown in Figure 4(c) in the solder resist layer 30. When chipping 450 occurs, the insulation reliability between adjacent pads 21 and the connection reliability between the wiring board 1X and semiconductor chips or other substrates decreases.

[0044] In contrast, in the wiring board 1, the lower end of a portion of the inner surface of the opening 30x in the solder resist layer 30 (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23. That is, in the wiring board 1, the interface between the insulating layer 10 and the solder resist layer 30 exists only in a portion of the opening 30x, so there are fewer areas that can serve as crack initiation points, corresponding to arrow C in Figure 4(b). In the wiring board 1, the reinforcing metal layer 22 or 23, made of a highly rigid metal, is in contact with the solder resist layer 30 in the opening 30x, so the reinforcing metal layer 22 or 23 will not crack even when high-temperature processing such as reflow is performed. Therefore, it is possible to suppress the occurrence of cracks and chipping in the insulating layer 10 and the solder resist layer 30. As a result, the insulation reliability between adjacent pads 21 and the connection reliability between the wiring board 1 and semiconductor chips or other substrates can be ensured.

[0045] Furthermore, cracks corresponding to arrow C in Figure 4(b) tend to occur near the centers of the four sides included in the rectangle when the planar shape of the opening 30x is approximated as a rectangle, and are particularly likely to occur near the center of the longer side. This is thought to be because the displacement due to thermal stress is greater the greater the distance from the four vertices included in the rectangle. In contrast, in this embodiment, the reinforcing metal layer 22 is arranged so as to overlap at least the center of the longer side, and the reinforcing metal layer 23 is arranged so as to overlap at least the center of the shorter side. Therefore, even if an interface exists between the insulating layer 10 and the solder resist layer 30 in some areas, the occurrence of cracks and chipping in the insulating layer 10 and the solder resist layer 30 can be suppressed.

[0046] In the pad structure of the comparative example, the occurrence of cracks and chipping is significant when the difference between the thermal expansion coefficient of the solder resist layer 30 and the thermal expansion coefficient of the insulating layer 10 is 10 ppm / °C or more. Therefore, the pad structure of the wiring board 1 is particularly effective when the difference between the thermal expansion coefficient of the solder resist layer 30 and the thermal expansion coefficient of the insulating layer 10 is 10 ppm / °C or more.

[0047] Furthermore, when the planar shape of the opening 30x is approximated as a rectangle, the reinforcing metal layers 22 and 23 are spaced apart from the four vertices included in the rectangle in a plan view, making it possible to arrange the pads 21 at a high density, as in the embodiment described later. However, it is not necessary for the entire reinforcing metal layers 22 and 23 to be spaced apart from the four vertices included in the rectangle. For example, depending on the arrangement of the pads 21, a portion of the reinforcing metal layers 22 and 23 may overlap with one of the vertices in a plan view.

[0048] Furthermore, if the entire upper and side surfaces of the reinforcing metal layer 22 or 23 are covered with the solder resist layer 30, delamination may occur at the interface between the solder resist layer 30 and the insulating layer 10, but the reinforcing metal layer 22 or 23 can suppress the propagation of delamination.

[0049] <Variations of the first embodiment> A modified example of the first embodiment shows a wiring board with a different reinforcing metal layer structure. In the modified example of the first embodiment, descriptions of components that are the same as those described in the previously described embodiment may be omitted.

[0050] Figure 5 illustrates a modified wiring board according to the first embodiment, where Figure 5(a) is a partial plan view and Figure 5(b) is a partial cross-sectional view along line BB in Figure 5(a).

[0051] Referring to Figure 5, the wiring board 1A according to a modification of the first embodiment differs from the wiring board 1 (see Figure 1, etc.) in that the reinforcing metal layer 22 is replaced by a reinforcing metal layer 22A, and the reinforcing metal layer 23 is replaced by a reinforcing metal layer 23A. The reinforcing metal layers 22A and 23A are formed on the upper surface 10a of the insulating layer 10. That is, the insulating layer 10 does not have grooves 10x and 10y, and the reinforcing metal layers 22A and 23A protrude from the upper surface 10a of the insulating layer 10. With respect to the upper surface 10a of the insulating layer 10, the height of the reinforcing metal layers 22A and 23A is the same as, for example, the height of the pad 21 and the power pattern 29. The planar shape, width, and material of the reinforcing metal layers 22A and 23A may be the same as those of the reinforcing metal layers 22 and 23.

[0052] In the solder resist layer 30, a portion of the lower end (the end on the insulating layer 10 side) of the inner surface of the opening 30x is in contact with the upper surface of the reinforcing metal layer 22A or 23A. That is, a portion of the upper surface of the reinforcing metal layer 22A (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Similarly, a portion of the side surface of the reinforcing metal layer 22A (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Likewise, a portion of the upper surface of the reinforcing metal layer 23A (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Furthermore, a portion of the side surface of the reinforcing metal layer 23A (the portion furthest from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. In addition, in the solder resist layer 30, the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0053] The wiring board 1A can be manufactured using the same manufacturing method as the wiring board 1, except that grooves 10x and 10y are not provided in the insulating layer 10 in the process shown in Figure 2(a).

[0054] Thus, reinforcing metal layers 22A and 23A may be formed on the upper surface 10a of the insulating layer 10 without providing grooves 10x and 10y in the insulating layer 10. The structure of the wiring board 1 and the structure of the wiring board 1A can be used interchangeably as needed.

[0055] Note that solder may be used to connect the pad 21 to other boards, or the pin 500 of the CPU socket as shown in Figure 6 may be used. When the wiring board 1A is used, the pin 500 may contact only the pad 21 as shown in Figure 6(a), but it may also be misaligned and contact both the pad 21 and the reinforcing metal layer 22A as shown in Figure 6(b). In the case of Figure 6(b), the reinforcing metal layer 22A is at the same potential as the pad 21, which is equivalent to substantially narrowing the distance between adjacent pads 21, and may reduce the insulation reliability between the pads 21. Similarly, the pin 500 may contact both the pad 21 and the reinforcing metal layer 23A. In this case as well, the reinforcing metal layer 23A is at the same potential as the pad 21, which is equivalent to substantially narrowing the distance between adjacent pads 21, and may reduce the insulation reliability between the pads 21.

[0056] As shown in Figure 6(c), when using the wiring board 1, even if the position of the pin 500 shifts, the pin 500 will not come into contact with the reinforcing metal layer 22 or 23, so the reinforcing metal layer 22 or 23 will never be at the same potential as the pad 21. Therefore, the distance between adjacent pads 21 will not be substantially reduced, and the insulation reliability between the pads 21 can be ensured. Accordingly, when using pins to connect to the pads 21, it is preferable to select a wiring board 1 structure in which the height of the reinforcing metal layers 22 and 23 is lower than the height of the pad 21.

[0057] <Second Embodiment> In the second embodiment, an example of a wiring board with a different reinforcing metal layer structure is shown. In the second embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0058] Figure 7 illustrates a wiring board according to the second embodiment, where Figure 7(a) is a partial plan view and Figure 7(b) is a partial cross-sectional view along the CC line in Figure 7(a).

[0059] Referring to Figure 7, the wiring board 2 according to the second embodiment differs from the wiring board 1 (see Figure 1, etc.) in that the reinforcing metal layer 22 is replaced by a plurality of island-shaped reinforcing metal layers 222, and the reinforcing metal layer 23 is replaced by a plurality of island-shaped reinforcing metal layers 223. The planar shape of the reinforcing metal layers 222 and 223 is, for example, rectangular. In a plan view, the reinforcing metal layers 222 and 223 are arranged at a distance from the pad 21 and the power supply pattern 29. In a plan view, the plurality of reinforcing metal layers 222 are arranged along the two longest sides (two major sides) of the four sides of the rectangle obtained by approximating the planar shape of the pad 21. That is, the plurality of reinforcing metal layers 222 are arranged in two rows. Also, in a plan view, the plurality of reinforcing metal layers 223 are arranged along the two shortest sides (two minor sides) of the four sides of the rectangle obtained by approximating the planar shape of the pad 21. In other words, the multiple reinforcing metal layers 223 are arranged in two rows. The reinforcing metal layers 222 and 223 are spaced apart from each other and are electrically insulated from the power supply pattern 29.

[0060] In a plan view, the distance between the pad 21 and the reinforcing metal layer 222 and the distance between the pad 21 and the reinforcing metal layer 223 are approximately constant, for example, 10 μm or more. Also, in a plan view, the distance between the power supply pattern 29 and the reinforcing metal layer 222 and the distance between the power supply pattern 29 and the reinforcing metal layer 223 are for example, 10 μm or more.

[0061] The reinforcing metal layer 222 is formed inside a plurality of rectangular grooves 210x that open to the upper surface 10a side of the insulating layer 10. The reinforcing metal layer 223 is formed inside a plurality of rectangular grooves 210y that open to the upper surface 10a side of the insulating layer 10. The upper surfaces of the reinforcing metal layers 222 and 223 are, for example, flush with the upper surface 10a of the insulating layer 10. However, the upper surfaces of the reinforcing metal layers 222 and 223 may, for example, protrude from the upper surface 10a of the insulating layer 10, or they may be recessed from the upper surface 10a of the insulating layer 10.

[0062] The thickness, widths W1 and W2, and material of the reinforcing metal layers 222 and 223 may be the same as those of the reinforcing metal layers 22 and 23. The width W1 of the reinforcing metal layer 222 is the dimension in the direction perpendicular to the edge of the pad 21 along which the row of reinforcing metal layers 222 follows, and the width W2 of the reinforcing metal layer 223 is the dimension in the direction perpendicular to the edge of the pad 21 along which the row of reinforcing metal layers 223 follows. In Figure 7, the dimension in the direction perpendicular to the direction indicated by the width W1 of the reinforcing metal layer 222 (vertical direction of the paper) is smaller than the width W1, but this dimension can also be, for example, 10 μm or more. Similarly, in Figure 7, the dimension in the direction perpendicular to the direction indicated by the width W2 of the reinforcing metal layer 223 (horizontal direction of the paper) is smaller than the width W2, but this dimension can also be, for example, 10 μm or more.

[0063] In the solder resist layer 30, the lower end of a portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 222 or 223. That is, a portion of the reinforcing metal layer 222 (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. Similarly, a portion of the reinforcing metal layer 223 (the portion farther from the pad 21) is covered by the solder resist layer 30, while another portion (the portion closer to the pad 21) is exposed within the opening 30x of the solder resist layer 30. In addition, in the solder resist layer 30, the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0064] For example, when the planar shape of the opening 30x is approximated as a rectangle, in a plan view, the two rows formed by the multiple reinforcing metal layers 222 coincide with the center of the longest side (long side) of at least the four sides included in the rectangle, and the two rows formed by the multiple reinforcing metal layers 223 coincide with the center of the shortest side (short side) of at least the four sides included in the rectangle. Also, when the planar shape of the opening 30x is approximated as a rectangle, in a plan view, the reinforcing metal layers 222 and 223 may be separated from the four vertices included in the rectangle. For example, the longitudinal direction of the row formed by the multiple reinforcing metal layers 222 is parallel to the long side of the rectangle, and the longitudinal direction of the row formed by the multiple reinforcing metal layers 223 is parallel to the short side of the rectangle. In a plan view, the longitudinal directions of the row formed by the multiple reinforcing metal layers 222 and the longitudinal directions of the row formed by the multiple reinforcing metal layers 223 are orthogonal to each other.

[0065] The other configurations are the same as in the first embodiment.

[0066] The wiring board 2 can be manufactured using the same manufacturing method as the wiring board 1, except that grooves 210x and 210y are formed in the insulating layer 10 in the process shown in Figure 2(a), replacing grooves 10x and 10y.

[0067] Similar to the first embodiment, the second embodiment also suppresses the occurrence of cracks and chipping in the insulating layer 10 and the solder resist layer 30. As a result, the insulation reliability between adjacent pads 21 and the wiring board are improved. 2 This ensures reliable connections with semiconductor chips and other substrates to which it is connected.

[0068] <Third Embodiment> The third embodiment shows an example of a wiring board with a different arrangement of pads, etc. Note that in the third embodiment, descriptions of components identical to those described in the previously described embodiments may be omitted.

[0069] Figure 8 is a diagram illustrating a wiring board according to the third embodiment. Figure 8 is a partial plan view.

[0070] Referring to Figure 8, in the wiring board 3 according to the third embodiment, a plurality of pads 21 are arranged in two rows in the X-axis direction parallel to the upper surface 10a of the insulating layer 10. The short side of the pads 21 is parallel to the X-axis direction, and the long side of the pads 21 is parallel to the Y-axis direction which is perpendicular to the X-axis direction. The Y-axis direction is also parallel to the upper surface 10a of the insulating layer 10. One row is located on the positive Y-axis side of the other row. The plurality of pads 21 are arranged at equal pitches in the X-axis direction, and are offset by half a pitch between two adjacent rows.

[0071] The solder resist layer 30 has a plurality of openings 30x, and one pad 21 is fully exposed in each opening 30x. Also, in the solder resist layer 30, similar to the first embodiment, the lower end of a portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23, and the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0072] The reinforcing metal layer 22 on the positive side in the X-axis direction, provided on the pad 21 constituting the negative side in the Y-axis direction, and the reinforcing metal layer 22 on the negative side in the X-axis direction, provided on the pad 21 constituting the positive side in the Y-axis direction, which is positioned half a pitch further to the positive side in the X-axis direction than the pad 21, are arranged in a straight line along the Y-axis direction. Similarly, the reinforcing metal layer 22 on the negative side in the X-axis direction, provided on the pad 21 constituting the negative side in the Y-axis direction, and the reinforcing metal layer 22 on the positive side in the X-axis direction, provided on the pad 21 constituting the positive side in the Y-axis direction, which is positioned half a pitch further to the negative side in the X-axis direction than the pad 21, are arranged in a straight line along the Y-axis direction.

[0073] Furthermore, the reinforcing metal layer 23 on the positive side of the Y-axis direction, provided for multiple pads 21 constituting the negative side of the Y-axis direction, and the reinforcing metal layer 23 on the negative side of the Y-axis direction, provided for multiple pads 21 constituting the positive side of the Y-axis direction, are arranged in a straight line in the X-axis direction.

[0074] Here, the effects of the wiring board 3 will be explained with reference to a second comparative example. Figure 9 is a diagram illustrating a wiring board according to the second comparative example. The wiring board 3X shown in Figure 9 differs from the wiring board 3 (see Figure 8) in that, for each pad 21, an annular reinforcing metal layer 22X is provided instead of the reinforcing metal layers 22 and 23. In the wiring board 3X according to the second comparative example, in the solder resist layer 30, the entire lower end (the end on the insulating layer 10 side) of the inner surface of the opening 30x is in contact with the upper surface 22X, and there is no portion of the lower end (the end on the insulating layer 10 side) of the inner surface of the opening 30x that is in contact with the upper surface 10a of the insulating layer 10.

[0075] In the wiring board 3X, the portion of the reinforcing metal layer 22X provided on the pad 21 constituting the negative row in the Y-axis direction that is located on the positive side in the X-axis direction and the portion of the reinforcing metal layer 22X provided on the pad 21 constituting the positive row in the Y-axis direction that is located half a pitch to the positive side in the X-axis direction of the pad 21 and is located on the negative side in the X-axis direction are aligned in a straight line in the Y-axis direction. Similarly, the portion of the reinforcing metal layer 22X provided on the pad 21 constituting the negative row in the Y-axis direction that is located on the negative side in the X-axis direction and the portion of the reinforcing metal layer 22X provided on the pad 21 constituting the positive row in the Y-axis direction that is located half a pitch to the negative side in the X-axis direction of the pad 21 and is located on the positive side in the X-axis direction are aligned in a straight line in the Y-axis direction.

[0076] On the other hand, unlike the wiring board 3, the portion of the reinforcing metal layer 22X provided on the Y-axis positive side of the multiple pads 21 constituting the Y-axis negative row is located further to the Y-axis negative side than the portion of the reinforcing metal layer 22X provided on the Y-axis negative side of the multiple pads 21 constituting the Y-axis positive row.

[0077] Therefore, according to the wiring board 3 of the third embodiment, the pads 21 can be arranged at a higher density compared to the wiring board 3X of the second comparative example.

[0078] <Fourth Embodiment> The fourth embodiment shows an example of a wiring board with a different arrangement of pads, etc. Note that in the fourth embodiment, descriptions of components identical to those described in the previously described embodiments may be omitted.

[0079] Figure 10 is a diagram illustrating a wiring board according to the fourth embodiment. Figure 10 is a partial plan view.

[0080] Referring to Figure 10, in the wiring board 4 according to the fourth embodiment, a plurality of pads 21 are arranged in a row in the X-axis direction parallel to the upper surface 10a of the insulating layer 10. The short side of the pads 21 is parallel to the X-axis direction, and the long side of the pads 21 is parallel to the Y-axis direction which is perpendicular to the X-axis direction. The Y-axis direction is also parallel to the upper surface 10a of the insulating layer 10.

[0081] The solder resist layer 30 has a plurality of openings 30x, and one pad 21 is fully exposed in each opening 30x. Also, in the solder resist layer 30, similar to the first embodiment, the lower end of a portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23, and the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0082] In the fourth embodiment, the row formed by the multiple pads 21 is a single row. Therefore, the pitch of the pads 21 in the X-axis direction can be narrower than in the third embodiment.

[0083] <Fifth Embodiment> The fifth embodiment shows an example of a wiring board with a different arrangement of reinforcing metal layers. In the fifth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0084] Figure 11 is a diagram illustrating a wiring board according to the fifth embodiment. Figure 11 is a partial plan view.

[0085] Referring to Figure 11, in the wiring board 5 according to the fifth embodiment, a plurality of pads 21 are arranged in a row in the X-axis direction parallel to the upper surface 10a of the insulating layer 10. The short side of the pads 21 is parallel to the X-axis direction, and the long side of the pads 21 is parallel to the Y-axis direction which is perpendicular to the X-axis direction. The Y-axis direction is also parallel to the upper surface 10a of the insulating layer 10.

[0086] The solder resist layer 30 has a plurality of openings 30x, and one pad 21 is fully exposed in each opening 30x. Also, in the solder resist layer 30, similar to the first embodiment, the lower end of a portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface of the reinforcing metal layer 22 or 23, and the lower end of another portion of the inner surface of the opening 30x (the end on the insulating layer 10 side) is in contact with the upper surface 10a of the insulating layer 10.

[0087] In the wiring board 4 according to the fourth embodiment, a portion of the power supply pattern 29 exists between adjacent reinforcing metal layers 22 in the X-axis direction, whereas in the wiring board 5 according to the fifth embodiment, the power supply pattern 29 does not exist between adjacent reinforcing metal layers 22 in the X-axis direction. Therefore, according to the fifth embodiment, the pitch of the pads 21 in the X-axis direction can be narrowed compared to the fourth embodiment.

[0088] <Sixth Embodiment> The sixth embodiment shows an example of a wiring board with a different arrangement of reinforcing metal layers. In the sixth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0089] Figure 12 is a diagram illustrating a wiring board according to the sixth embodiment. Figure 12 is a partial plan view.

[0090] Referring to Figure 12, the wiring board 6 according to the sixth embodiment differs from the wiring board 5 (see Figure 11) in that the reinforcing metal layer 22 is replaced by a plurality of island-shaped reinforcing metal layers 222, and the reinforcing metal layer 23 is replaced by a plurality of island-shaped reinforcing metal layers 223.

[0091] The reinforcing metal layers 222 are arranged in rows at equal pitches in the Y-axis direction. However, between two rows of reinforcing metal layers 222 located between adjacent pads 21 in the X-axis direction, the arrangement of the reinforcing metal layers 222 is offset by half a pitch.

[0092] If there is a lower limit to the distance between adjacent conductive layers in a plane parallel to the upper surface 10a of the insulating layer 10, that is, if the shortest distance between conductive layers is determined by the design rules, then according to the sixth embodiment, the pitch of the pads 21 in the X-axis direction can be narrower than in the fifth embodiment. For example, in the sixth embodiment, the distance between two rows of adjacent reinforcing metal layers 222 in the X-axis direction can be 1 / √2 times the distance between two adjacent reinforcing metal layers 222 in the X-axis direction in the fifth embodiment.

[0093] <Seventh Embodiment> The seventh embodiment shows an example of a wiring board with a different arrangement of reinforcing metal layers. In the seventh embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0094] Figure 13 is a diagram illustrating a wiring board according to the seventh embodiment. Figure 13 is a partial plan view.

[0095] Referring to Figure 13, the wiring board 7 according to the seventh embodiment has four pads 21 located at the vertices of a square grid in plan view. In plan view, a plurality of island-shaped reinforcing metal layers 222 and 223 are provided around each pad 21.

[0096] The reinforcing metal layers 222 are arranged in rows at equal pitches along the Y-axis. However, between two rows of reinforcing metal layers 222 placed between adjacent pads 21 along the X-axis, the arrangement of the reinforcing metal layers 222 is offset by half a pitch. Similarly, the reinforcing metal layers 223 are arranged in rows at equal pitches along the X-axis. However, between two rows of reinforcing metal layers 223 placed between adjacent pads 21 along the Y-axis, the arrangement of the reinforcing metal layers 223 is offset by half a pitch.

[0097] According to the seventh embodiment, similar to the sixth embodiment, the pitch of the pads 21 in the X-axis direction can be narrowed compared to the case where a reinforcing metal layer 22 is provided instead of the reinforcing metal layer 222. For example, in the seventh embodiment, the distance between two adjacent rows of reinforcing metal layers 222 in the X-axis direction can be 1 / √2 times the distance between two adjacent reinforcing metal layers 222 in the X-axis direction. Also, the pitch of the pads 21 in the Y-axis direction can be narrowed compared to the case where a reinforcing metal layer 23 is provided instead of the reinforcing metal layer 223. For example, in the seventh embodiment, the distance between two adjacent rows of reinforcing metal layers 223 in the Y-axis direction can be 1 / √2 times the distance between two adjacent reinforcing metal layers 23 in the Y-axis direction.

[0098] <Eighth Embodiment> The eighth embodiment shows an example of a wiring board with a different arrangement of reinforcing metal layers. In the eighth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0099] Figure 14 is a diagram illustrating a wiring board according to the eighth embodiment. Figure 14 is a partial plan view.

[0100] Referring to Figure 14, the wiring board 8 according to the eighth embodiment has two pads 21 aligned in the X-axis direction. In a plan view, two rows of multiple island-shaped reinforcing metal layers 222 are provided between the two pads 21. Furthermore, a reinforcing metal layer 22 is provided on the positive X-axis side of the pad 21 positioned on the positive X-axis side, and a reinforcing metal layer 22 is also provided on the negative X-axis side of the pad 21 positioned on the negative X-axis side. In addition, a reinforcing metal layer 23 is provided on the positive and negative Y-axis sides of each pad 21.

[0101] The reinforcing metal layers 222 are arranged in rows at equal pitches in the Y-axis direction. However, between two rows of reinforcing metal layers 222 located between adjacent pads 21 in the X-axis direction, the arrangement of the reinforcing metal layers 222 is offset by half a pitch.

[0102] According to the eighth embodiment, the pitch of the pads 21 in the X-axis direction can be narrowed compared to the case where a reinforcing metal layer 22 is provided instead of a reinforcing metal layer 222. Furthermore, the occurrence of cracks can be more firmly suppressed in the portions where a reinforcing metal layer 22 or 23 is provided.

[0103] Thus, the reinforcing metal layers 222 or 223 and the reinforcing metal layers 22 or 23 may be mixed. That is, with respect to a certain pad 21, the reinforcing metal layer 222 or 223 may be provided in the direction where an adjacent pad 21 exists, and the reinforcing metal layer 22 or 23 may be provided in the other direction.

[0104] In this disclosure, the length of the minor axis of the ellipse obtained by approximating the planar shape of the reinforcing metal layer is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. This is because if the reinforcing metal layer is too small in plan view, the lower end of the inner surface of the opening that contacts the upper surface of the reinforcing metal layer may, due to alignment misalignment or the like, contact the upper surface of the insulating layer instead of the reinforcing metal layer. In other words, this is to ensure a sufficient margin against alignment misalignment and the like. Also, if the reinforcing metal layer is too small, when removing the seed layer 201 during the formation of the reinforcing metal layer (see Figure 3(b)), the seed layer 201 that should be left may also be removed, and the reinforcing metal layer that should be formed may not be formed.

[0105] Furthermore, the distance between the reinforcing metal layer and the pad or power supply pattern is preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 60 μm or more. As described above, a surface treatment layer such as an Au layer may be formed on the upper surface of the pad or reinforcing metal layer. In this case, after the formation of the surface treatment layer by electroless plating, the upper surface of the insulating layer is subjected to plasma surface etching (dry desmear treatment) or wet desmear treatment using permanganate. This is to prevent electrical short circuits caused by metal deposited on the upper surface of the insulating layer. However, if the distance between the reinforcing metal layer and the pad or power supply pattern is too small, there is a risk that the metal deposited on the upper surface of the insulating layer may not be sufficiently removed.

[0106] <Ninth Embodiment> The ninth embodiment shows an example of a multilayer wiring board including the pad structure of the wiring board 1. In the ninth embodiment, descriptions of components that are the same as those described in the previously described embodiments may be omitted.

[0107] Figure 15 is a cross-sectional view illustrating a multilayer wiring board according to the ninth embodiment.

[0108] Referring to Figure 15, the multilayer wiring substrate 9 according to the ninth embodiment has a wiring layer 110, an insulating layer 111, a wiring layer 112, an insulating layer 113, a wiring layer 114, and a solder resist layer 115 sequentially laminated on one side 100a of the core layer 100. The multilayer wiring substrate 9 also has a wiring layer 120, an insulating layer 121, a wiring layer 122, an insulating layer 123, a wiring layer 124, and a solder resist layer 125 sequentially laminated on the other side 100b of the core layer 100.

[0109] As the core layer 100, for example, a so-called glass epoxy substrate can be used, which is made by impregnating glass cloth with an insulating resin such as epoxy resin or polyimide resin. As the core layer 100, a substrate may also be used, which is made by impregnating woven or nonwoven fabrics such as glass fibers, carbon fibers, or aramid fibers with epoxy resin.

[0110] The wiring layer 110 is formed on one surface 100a of the core layer 100. The wiring layer 110 is electrically connected to the wiring layer 120 via through-wiring 105 that penetrates the core layer 100. The material of the wiring layer 110 is, for example, copper. The insulating layer 111 is formed on one surface 100a of the core layer 100 so as to cover the wiring layer 110. As the material of the insulating layer 111, for example, an insulating resin mainly composed of epoxy resin or polyimide resin can be used. The thickness of the insulating layer 111 can be, for example, about 10 to 50 μm. The insulating layer 111 may contain fillers such as silica (SiO2).

[0111] The wiring layer 112 is formed on one side of the insulating layer 111. The wiring layer 112 includes via wiring filled in via holes 111x that penetrate the insulating layer 111 and expose the upper surface of the wiring layer 110, and a wiring pattern formed on the upper surface of the insulating layer 111. The wiring pattern of the wiring layer 112 is electrically connected to the wiring layer 110 via the via wiring. The via holes 111x are, for example, inverted frustoconical recesses in which the diameter of the opening that opens to the insulating layer 113 side is larger than the diameter of the bottom surface of the opening formed by the upper surface of the wiring layer 110. The material of the wiring layer 112 is, for example, copper.

[0112] The insulating layer 113 is formed so as to cover the wiring layer 112 on the upper surface of the insulating layer 111. The material and thickness of the insulating layer 113 are, for example, the same as those of the insulating layer 111. The insulating layer 113 may contain fillers such as silica (SiO2).

[0113] The wiring layer 114 is formed on one side of the insulating layer 113. The wiring layer 114 includes via wiring filled in via holes 113x that penetrate the insulating layer 113 and expose the upper surface of the wiring layer 112, and a wiring pattern formed on the upper surface of the insulating layer 113. The wiring pattern of the wiring layer 114 is electrically connected to the wiring layer 112 via the via wiring. The via holes 113x are, for example, inverted frustoconical recesses in which the diameter of the opening that opens towards the solder resist layer 115 is larger than the diameter of the bottom of the opening formed by the upper surface of the wiring layer 112. The material of the wiring layer 114 is, for example, copper.

[0114] The solder resist layer 115 is the outermost layer on one side of the multilayer wiring substrate 9 and is an insulating layer formed on the upper surface of the insulating layer 113 so as to cover the wiring layer 114. The solder resist layer 115 can be formed from, for example, a photosensitive resin such as epoxy resin or acrylic resin. The thickness of the solder resist layer 115 can be, for example, about 5 to 40 μm.

[0115] The solder resist layer 115 has an opening 115x, and a portion of the upper surface of the wiring layer 114 is exposed at the bottom of the opening 115x. The planar shape of the opening 115x is, for example, circular. If necessary, a metal layer may be formed on the upper surface of the wiring layer 114 exposed within the opening 115x, or an anti-oxidation treatment such as OSP treatment may be applied.

[0116] External connection terminals 116 are formed on the upper surface of the wiring layer 114 exposed at the bottom of the opening 115x. The external connection terminals 116 are, for example, solder bumps. As materials for the solder bumps, for example, alloys containing Pb, alloys of Sn and Cu, alloys of Sn and Ag, alloys of Sn, Ag and Cu, etc. can be used. The external connection terminals 116 serve as terminals for electrically connecting to the semiconductor chip.

[0117] The wiring layer 120 is formed on the other surface 100b of the core layer 100. The material of the wiring layer 120 is, for example, copper. The insulating layer 121 is formed on the other surface 100b of the core layer 100 so as to cover the wiring layer 120. The material and thickness of the insulating layer 121 are, for example, the same as those of the insulating layer 111. The insulating layer 121 may contain fillers such as silica (SiO2).

[0118] The wiring layer 122 is formed on the other side of the insulating layer 121. The wiring layer 122 includes via wiring filled in via holes 121x that penetrate the insulating layer 121 and expose the lower surface of the wiring layer 120, and a wiring pattern formed on the lower surface of the insulating layer 121. The wiring pattern of the wiring layer 122 is electrically connected to the wiring layer 120 via the via wiring. The via holes 121x are, for example, frustoconical recesses in which the diameter of the opening that opens to the insulating layer 123 side is larger than the diameter of the bottom surface of the opening formed by the lower surface of the wiring layer 120. The material of the wiring layer 122 is, for example, copper.

[0119] The insulating layer 123 is formed on the underside of the insulating layer 121 so as to cover the wiring layer 122. The material and thickness of the insulating layer 123 are, for example, the same as those of the insulating layer 111. The insulating layer 123 may contain fillers such as silica (SiO2).

[0120] The wiring layer 124 is formed in contact with the insulating layer 123. The wiring layer 124 has at least a pad 127, a reinforcing metal layer 128, and a power supply pattern 129. The pad 127 and the power supply pattern 129 are formed on the lower surface of the insulating layer 123, and the reinforcing metal layer 128 is formed inside a rectangular groove 123z with a planar shape that opens to the lower surface side of the insulating layer 123. The structure of the pad 127, the reinforcing metal layer 128, and the power supply pattern 129 is the same as the structure of the pad 21, the reinforcing metal layer 22 or 23, and the power supply pattern 29 of the wiring board 1 (see Figure 1). The wiring layer 124 may have a wiring pattern or the like in addition to the pad 127, the reinforcing metal layer 128, and the power supply pattern 129.

[0121] At least some of the pads 127 are electrically connected to the wiring layer 122 via via wiring filled in via holes 123x that penetrate the insulating layer 123 and expose the underside of the wiring layer 122. The via holes 123x are, for example, frustoconical recesses whose diameter is larger than the diameter of the bottom of the opening formed by the underside of the wiring layer 122, with the opening facing the solder resist layer 125. The material of the wiring layer 124 is, for example, copper.

[0122] The solder resist layer 125 is the outermost layer on the other side of the multilayer wiring board 9 and is an insulating layer provided on the underside of the insulating layer 123. The solder resist layer 125 has an opening 125x, and the pad 127 is completely exposed within the opening 125x. The pad 127 is positioned within the opening 125x without contacting the solder resist layer 125. In the solder resist layer 125, the upper end of a portion of the inner surface of the opening 125x (the end on the insulating layer 123 side) is in contact with the underside of the reinforcing metal layer 128. That is, a portion of the reinforcing metal layer 128 (the portion farther from the pad 127) is covered by the solder resist layer 125, while another portion (the portion closer to the pad 127) is exposed within the opening 125x of the solder resist layer 125. In addition, in the solder resist layer 125, the upper end of another portion of the inner surface of the opening 125x (the end on the insulating layer 123 side) is in contact with the underside of the insulating layer 123.

[0123] The material and thickness of the solder resist layer 125 are, for example, the same as those of the solder resist layer 115. The pads 127 exposed within the opening 125x can be used as pads for electrically connecting to a mounting substrate such as a motherboard. If necessary, the aforementioned metal layer may be formed on the underside of the pads 127 exposed within the opening 125x, or an anti-oxidation treatment such as OSP treatment may be applied.

[0124] Thus, the multilayer wiring board 9 has a pad structure similar to that of the wiring board 1. Specifically, it has a wiring layer 124 including pads 127, a reinforcing metal layer 128, and a power pattern 129, and a solder resist layer 125 in which the upper end of a portion of the inner surface of the opening 125x is in contact with the lower surface of the reinforcing metal layer 128. As a result, as in the first embodiment, it is possible to suppress the occurrence of cracks and chipping in the insulating layer 123 and the solder resist layer 125. Consequently, the insulation reliability between adjacent pads 127 and the connection reliability with the mounting board such as a motherboard connected to the multilayer wiring board 9 can be ensured.

[0125] In the example shown for the multilayer wiring board 9, a pad structure similar to that of the wiring board 1 is provided on the connection side with the mounting board such as the motherboard, but this is not the only option. That is, in the multilayer wiring board 9, a pad structure similar to that of the wiring board 1 may be provided on the semiconductor chip mounting side (external connection terminal 116 side).

[0126] Furthermore, a pad structure similar to that of wiring board 1 may be mixed with an SMD type pad structure, whether it is provided on the connection side to the mounting board such as a motherboard or on the semiconductor chip mounting side. Alternatively, instead of a pad structure similar to that of wiring board 1, a pad structure similar to that of wiring boards 1A, 2, 3, 4, 5, 6, 7, or 8 may be used.

[0127] Although preferred embodiments have been described in detail above, the invention is not limited to the embodiments described above, and various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims. [Explanation of Symbols]

[0128] 1, 1A, 2, 3, 4, 5, 6, 7, 8 Wiring board 9 Multilayer wiring board 10, 111, 113, 121, 123 Insulating layer 10a Top 10x, 10y, 123z, 210x, 210y groove 20, 110, 112, 114, 120, 122, 124 wiring layer 21,127 pads 22, 22A, 23, 23A, 128, 222, 223 Reinforcement metal layer 29, 129 power patterns 30, 115, 125 solder resist layers 30x, 115x, 125x, 300x aperture 100 core layers 111x, 113x, 121x, 123x Beer Hall 116 External connection terminals 201 Seed Layer 202 Electroplating layer 300 resist layers 500 pins

Claims

1. The first insulating layer and A pad formed on one side of the first insulating layer, A second insulating layer is formed on one surface of the first insulating layer and has an opening that exposes the pad, It has a reinforcing metal layer formed in contact with the first insulating layer and, in a plan view, spaced apart from the pad and provided around the pad, The pad is placed in the opening without contacting the second insulating layer. A portion of the inner surface of the opening of the second insulating layer, the end on the first insulating layer side, is in contact with the reinforcing metal layer, and The other portion of the inner surface of the opening of the second insulating layer, on the side of the first insulating layer, is in contact with one surface of the first insulating layer. The reinforcing metal layer is formed inside a groove that opens to one side of the first insulating layer, in a wiring board.

2. The wiring board according to claim 1, wherein the height of the reinforcing metal layer is lower than the height of the pad, with reference to one surface of the first insulating layer.

3. A first insulating layer and A pad formed on one side of the first insulating layer, A second insulating layer is formed on one surface of the first insulating layer and has an opening that exposes the pad, It has a reinforcing metal layer formed in contact with the first insulating layer and, in a plan view, spaced apart from the pad and provided around the pad, The pad is placed in the opening without contacting the second insulating layer. A portion of the inner surface of the opening of the second insulating layer, the end on the first insulating layer side, is in contact with the reinforcing metal layer, and The other portion of the inner surface of the opening of the second insulating layer, on the side of the first insulating layer, is in contact with one surface of the first insulating layer. A wiring board in which, with reference to one surface of the first insulating layer, the height of the reinforcing metal layer is lower than the height of the pad.

4. When the planar shape of the opening is approximated as a rectangle, The wiring board according to any one of claims 1 to 3, wherein, in a plan view, the reinforcing metal layer coincides with the center of the longest side among at least four sides included in the rectangle.

5. When the planar shape of the opening is approximated as a rectangle, The wiring board according to any one of claims 1 to 4, wherein, in a plan view, the reinforcing metal layer is separated from the four vertices included in the rectangle.

6. The wiring board according to any one of claims 1 to 5, wherein the reinforcing metal layer protrudes from one surface of the first insulating layer.

7. The wiring board according to any one of claims 1 to 6, wherein the reinforcing metal layer is a dummy wiring without electrical connections.

8. The wiring substrate according to any one of claims 1 to 7, wherein the distance between the pad and the reinforcing metal layer is 10 μm or more.

9. Having a power supply pattern formed on one side of the first insulating layer, The wiring board according to any one of claims 1 to 7, wherein the reinforcing metal layer is electrically insulated from the power supply pattern.

10. The wiring board according to claim 9, wherein the distance between the power supply pattern and the reinforcing metal layer is 10 μm or more.

11. The wiring substrate according to any one of claims 1 to 10, wherein the length of the minor axis of the ellipse obtained by approximating the planar shape of the reinforcing metal layer is 10 μm or more.

12. The wiring board according to any one of claims 1 to 11, wherein the thickness of the reinforcing metal layer is the same as the thickness of the pad.

13. The wiring board according to any one of claims 1 to 12, wherein the thermal expansion coefficient of the second insulating layer is greater than that of the first insulating layer.

14. The wiring board according to claim 13, wherein the difference between the thermal expansion coefficient of the second insulating layer and the thermal expansion coefficient of the first insulating layer is 10 ppm / °C or more.

15. A step of forming a pad and a reinforcing metal layer so as to be in contact with one surface of the first insulating layer, A step of forming a second insulating layer on one surface of the first insulating layer, covering the pad and the reinforcing metal layer, and forming an opening in the second insulating layer, It has, In the process of forming the pad and the reinforcing metal layer, the reinforcing metal layer is formed around the pad, separated from the pad in a plan view. In the step of forming the opening, the pad is placed in the opening without contacting the second insulating layer, a portion of the inner surface of the opening on the first insulating layer side is in contact with the reinforcing metal layer, and another portion of the inner surface of the opening on the first insulating layer side is in contact with one surface of the first insulating layer. The process includes forming a groove in the first insulating layer that opens to one side of the first insulating layer, A method for manufacturing a wiring board, wherein in the step of forming the pad and the reinforcing metal layer, the reinforcing metal layer is formed inside the groove.

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