Wiring board

Abstract

To provide a wiring board that includes an upper connector and an electrode pad part capable of securing adhesion even for the electrode pad part in a small area.SOLUTION: A wiring board comprises a lower connector 108 that is connected to a wiring layer 106 within the board, and an upper connector 102 that is connected to the lower connector 108. The lower connector 108 has a veer part 109 that is embedded in an isolation layer 105, and an electrode pad part 104 that is formed above the isolation layer 105. The upper connector 102 is connected onto upper and lateral surfaces of the electrode pad part 104.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] With the passage of time and the accompanying increase in integration density and multifunctionalization of semiconductor elements, the number of terminals (electrodes) tends to increase. Along with this, as a method of mounting a semiconductor element, which is an electronic component, on a wiring board, which is also an electronic component, a method called BGA (Ball Grid Array) has been adopted, in which a plurality of electrodes (pins) are arranged in a grid pattern on the mounting surface (surface) of the semiconductor element and soldered to the wiring board, instead of solder joining using a lead frame. As a result, the connection parts between electronic components tend to have a large number of pins.

[0003] In recent years, further high integration of semiconductor elements has progressed. Therefore, there is a need to further increase the number of terminals (the number of electrodes to be arranged) by making the cross-section of the electrodes smaller and the interval between the electrodes narrower (narrow pitch).

[0004] In response to such a need for narrow pitch, for example, Patent Document 1 discloses a configuration in which, in order to accurately and favorably connect the electrodes of an electronic component and conductor bumps, the conductor bumps are made of a plated conductor, and a solder layer is deposited on a portion protruding from the solder-resistant resin layer of the conductor bumps.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the configuration described in Patent Document 1, the diameter of the portion protruding from the solder-resistant resin layer of the conductor bump connected to the electronic component connection pad is made larger than the diameter of the opening of the solder-resistant resin layer, thereby increasing the area of the upper end surface of the conductor bump. Therefore, no consideration has been given to coping with the reduction in the diameter of the conductor bump itself.

[0007] An object of the present invention is to provide a wiring board having an electrode pad portion and an upper connection body that can ensure good adhesion even to a small-area electrode pad portion.

Means for Solving the Problems

[0008] In order to solve the above problems, one of the representative wiring boards of the present invention is a wiring board including a lower connection body connected to a wiring layer in a substrate and an upper connection body connected to the lower connection body. The lower connection body has a via portion embedded inside an insulating layer and an electrode pad portion formed above the insulating layer, and the upper connection body is a wiring board connected to the upper surface and side surface of the electrode pad portion.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a substrate having an electrode pad portion and an upper connection body that can ensure good adhesion even to a small-area electrode pad portion. Problems, configurations, and effects other than those described above will be clarified by the description in the following embodiments for implementation.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 9

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, with reference to the drawings, an example of an embodiment of the substrate of the present invention will be described. This disclosure is an example of an embodiment of the present invention, and this disclosure does not limit the structure of the substrate of the present invention in any way. Needless to say, those common in the shape, material, etc. of the members described in one embodiment are also applicable to other embodiments.

[0012] In this disclosure, in order to indicate directions, the directions indicated by the X-axis, Y-axis, and Z-axis shown on the drawing may be used. Also, in this disclosure, "cross-section" means a cross-section in the XZ plane unless otherwise specified, and "planar shape" means a shape in the XY plane.

[0013] Also, in this disclosure, "upper surface" means the upper side of the surface orthogonal to the stacking direction. Conversely, "bottom surface" means the lower side of the surface orthogonal to the stacking direction. "Side surface" means the outer peripheral surface sandwiched between the upper surface and the bottom surface. "Connect" means to connect so that an electric current flows between two objects, and the two objects may be in direct contact, or there may be an intervening substance such as a seed layer between the two objects.

[0014] FIG. 9 is a cross-sectional view of a wiring board according to a conventional example. A configuration for taking out an electrical connection from the internal wiring layer 106 formed in the base layer 107 to the outside is shown. In FIG. 9, the base layer 107, the insulating layer 105, and the solder resist layer 103 are laminated in order in the Z-axis direction. Then, a solder bump 101 is formed as an external electrical connection point using a lower connector 108 composed of a via portion 109 and an electrode pad portion 104, and an upper connector 102 overlapping this.

[0015] In the conventional example, as shown in FIG. 9, the center lines in the Z-axis direction of the upper connector and the lower connector are formed overlapping each other, and the upper connector and the lower connector are connected only on the upper surface of the electrode pad portion of the upper connector. However, when the center lines of the upper connector and the lower connector are formed overlapping each other, as the diameter of the lower connector becomes smaller, the connection area of the upper connector and the lower connector also decreases. For this reason, the connection strength between the upper connector and the lower connector also decreases, and it becomes difficult to ensure adhesion.

[0016] [Embodiment 1] FIG. 1 is a plan view, a cross-sectional view, and an enlarged view of a substrate according to Embodiment 1. FIG. 1(a) is a plan view when the substrate 100 in Embodiment 1 is viewed from the side where the solder bump 101 is formed. FIG. 1(b) is a cross-sectional view taken along the line X-X' in FIG. 1(a). FIG. 1(c) is an enlarged view obtained by enlarging the plan view of the portion where the upper connector and the lower connector are connected.

[0017] As shown in FIG. 1(b), in the substrate 100, mainly the base layer 107, the insulating layer 105, and the solder resist layer 103 are laminated in order in the Z direction. And a wiring layer 106 is disposed on the surface of the base layer 107 that contacts the insulating layer 105. Furthermore, a lower connector 108 is disposed so as to penetrate the insulating layer 105 from a part of the wiring layer 106. And an upper connector 102 connected to the lower connector 108 is formed, and a solder bump 101 is formed on the top of the upper connector 102.

[0018] The lower connecting body 108 includes a substantially columnar via portion 109 connected to the wiring layer 106 and embedded inside the insulating layer 105, and an electrode pad portion 104 formed above the insulating layer 105. The shape of the via portion 109 is not particularly limited, but the diameter of the via portion 109 in the XY plane is formed smaller than the diameter of the electrode pad portion 104.

[0019] The upper connecting body 102 includes a substantially columnar post portion connected to the lower connecting body 108 and a solder mounting pad portion located above the post portion. The substantially columnar shape includes a tapered shape having an inclination in the Z direction as shown in the cross-sectional shape of FIG. 1(b). Regarding the upper connecting body 102 as well, similar to the lower connecting body 108, the diameter of the post portion is formed smaller than the diameter of the solder mounting portion. Note that the maximum diameter of the post portion is less than 100 μm, for example. Note that the upper connecting body 102 may also be referred to as a metal post.

[0020] The cross-section of the solder mounting portion of the upper connecting body 102 is not particularly limited, but considering the subsequent solder formation process, it is desirable that it is flat or has a recess formed at the center of the upper surface of the cross-section. If the upper surface of the cross-section is flat or has a recess shape, even when a process at a high temperature such as bonding is performed, the solder can maintain its shape and performance without spilling significantly from the solder mounting portion.

[0021] In Embodiment 1, the center lines of the upper connecting body 102 and the lower connecting body 108 in the Z-axis direction are formed offset without overlapping. That is, when forming the upper connecting body, the opening provided in the solder resist layer 103 is offset from directly above the electrode pad portion 104 of the lower connecting body 108 and formed at a position where the electrode pad portion 104 and the insulating layer 105 are simultaneously exposed.

[0022] The electrode pad portion 104 and the upper connection body 102 are connected on the upper surface and the side surface of the electrode pad portion 104. The contact area on the upper surface is represented by S1. The contact area on the side surface is represented by S3 = L×H1, where L is the length of the arc portion between A and B where the upper surface of the electrode pad portion 104 is exposed at the opening of the solder resist layer 103, and H1 is the height of the side surface where the electrode pad portion 104 protrudes from the insulating layer 105. Further, the upper connection body 102 contacts the insulating layer 105 with a contact area S2 at the bottom surface.

[0023] <Function and Effect> By adopting the configuration of Embodiment 1 in this way, since the upper connection body 102 contacts not only the upper surface but also the side surface of the electrode pad portion 104, it is possible to form the upper connection body 102 with a widened contact area and high adhesion strength with the lower connection body 108.

[0024] Also, since the upper connection body 102 and the insulating layer 105 generally have good adhesion, no current flows in the contact area S2 where the upper connection body 102 and the insulating layer 105 are in contact. On the other hand, it is preferable to ensure a certain contact area S2 in relation to this adhesion.

[0025] Furthermore, the effect when the upper connection body 102 contacts the side surface of the electrode pad portion 104 is that, in addition to the increase in the contact area, the effect of being less likely to peel off against stress and strain from multiple directions is added because the upper connection body and the electrode pad portion 104 are in contact on surfaces in different directions. Generally, in the case of a contact surface that is in contact in one direction, the strength against stress and strain, etc. varies depending on the direction in which the stress and strain occur. For this reason, there are variations in the adhesion strength for each direction. However, when having contact surfaces in multiple directions as in the present disclosure, these variations are alleviated, and it becomes possible to ensure stronger and better adhesion against factors that inhibit contact such as stress and strain from multiple directions.

[0026] Specifically, when the adhesion density μ per unit area with respect to the upper connection body 102 is made the same as that of the electrode pad portion 104 and the insulating layer, the adhesion increases by the amount of the adhesion strength μ×S3 that contacts on the side surface of the electrode pad portion 104.

[0027] <Design> A more detailed description will be given with reference to FIG. 1(c). The center O2 of the upper connecting body 102 is shifted by d from the center O1 of the electrode pad portion 104. In the XY plane where they are connected to each other, let the shape of the electrode pad portion 104 be a circle with a radius R, and the upper connecting body 102 be a circle with a radius r.

[0028] Then, S1, S2, and S3 are respectively, S1 = R2θ1 + r2(π - θ2) - Rdsinθ1 S2 = πr2 - S1 S3 = L×H1 = 2Rθ1×H1 represented by Note that θ1 and θ2 are related by Rsinθ1 = rsinθ2 and Rcosθ1 - rcosθ2 = d, and can be calculated as a function of d.

[0029] Therefore, assuming that the adhesion per unit area of the upper connecting body 102 to the upper surface and side surface of the electrode pad portion 104 is μ1, and the adhesion to the insulating layer 105 is μ2, the adhesion strength F when the upper connecting body 102 is shifted by d is, F = μ1(S1 + S3) + μ2S2 Since it is represented by, the adhesion strength F0 when the center line in the Z-axis direction is the same for the conventional upper connecting body 102 and the electrode pad portion 104 F0 = μ1×πr2 By designing H1, d, etc. so that F > F0 compared to, it is possible to ensure good adhesion.

[0030] The magnitude of the current flowing between the electrode pad portion 104 and the upper connecting body 102 basically depends on the magnitudes of S1 and S3 projected onto a plane perpendicular to the direction of the current. Since the contact surface S2 with the insulating layer, which is an insulator, does not contribute to the magnitude of the current, if S2 is made too large, a situation where the desired current cannot be obtained will occur. Therefore, when designing the present invention, it is preferable to optimize the adhesion strength based on F > F0 based on the contact area as disclosed above, and to design while balancing both so that the magnitude of the current also becomes an optimal value. The size of the H1 obtained in this way can be, for example, about 10 to 20 μm.

[0031] <Material> In Embodiment 1, as the material of the insulating layer 105, for example, a non-photosensitive (thermosetting resin) epoxy-based insulating resin, a polyimide-based insulating resin, or the like can be used. Also, for example, a photosensitive epoxy-based insulating resin, an acrylic-based insulating resin, or the like may be used. The insulating layer 105 may have a reinforcing material such as glass cloth. Further, the insulating layer 105 may contain a filler such as silica (SiO2). The thickness of the insulating layer 105 can be, for example, about 10 to 50 μm.

[0032] As the material of the solder resist layer 103, for example, a photosensitive epoxy-based insulating resin, an acrylic-based insulating resin, or the like can be used. The thickness of the solder resist layer 103 can be, for example, about 5 to 40 μm.

[0033] Here, the materials of the electrode pad portion 104, the wiring layer 106, and the upper connector 102 are not particularly limited as long as they are conductive materials made of metal, but copper and copper alloys that can be formed by electroless / electrolytic plating and are inexpensive and have high electrical conductivity are preferably used.

[0034] The material of the solder bump 101 is a substance having conductivity and a material having a melting point lower than that of the wiring layer 106 or the upper connector 102. For example, it may be composed of a metal or alloy containing at least tin.

[0035] Also, surface treatment may be performed between the solder bumps 101. As the surface treatment, those having an antioxidant function such as an organic thin film and tin plating, or a metal film having both a function of improving solder wetting such as Sn and also preventing diffusion such as nickel-gold and nickel-palladium-gold may be performed.

[0036] [Embodiment 2] Embodiment 2 is different from Embodiment 1 in that the outer shape of the planar shape in the plan view of the electrode pad portion 104 has a convex portion. Figure 2 is a plan view, a cross-sectional view, and an enlarged view of the substrate according to Embodiment 2. Figure 2(a) is a plan view of Embodiment 2, and Figure 2(b) is a cross-sectional view taken along line X-X' in Figure 2(a). In the following description, the same or equivalent components as those in the above-described Embodiment 1 are denoted by the same reference numerals, and the description thereof is simplified or omitted. The outer shape of the planar shape in the plan view of the electrode pad portion 104 has a convex portion 201. An opening of the solder resist layer 103 is formed so that at least a part of the convex portion 201 is exposed, and the upper connection body 102 is filled in the opening.

[0037] The dimensions of the convex portion 201 are not particularly defined. However, considering separation from adjacent electrodes, formability, etc., the width W1 in Figure 2(c) can be about 5 to 20 μm, and similarly, the protruding amount D1 can be about 5 to 20 μm.

[0038] <Function and Effect> By accommodating at least a part of the convex portion 201 of the electrode pad portion 104 in the opening of the solder resist layer 103, it becomes possible to further increase the area of the contacting side surface, and it becomes possible to form the upper connection body 102 with higher adhesion strength.

[0039] In addition, since the number of directions of the side surfaces of the electrode pad portion 104 that connect to the upper connection body 102 increases compared to Embodiment 1, due to the anchor effect, the effect of being less likely to peel off against multi-directional stress and strain is further improved.

[0040] <Modification Example> A modification example of Embodiment 2 is different from Embodiment 2 in that the shape of the electrode pad portion 104 has a concave portion 202 when viewed in a plan view. Figure 3 is a plan view, a cross-sectional view, and an enlarged view of the substrate according to the modification example of Embodiment 2. FIG. 3(a) is a plan view of a modified example of Embodiment 2, and FIG. 3(b) is a cross-sectional view taken along line X-X′ in FIG. 3(a). In the following description, the same or equivalent components as those in the above-described Embodiment 1 and Embodiment 2 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0041] Although the dimensions of the concave portion 202 are not particularly defined, considering separation from adjacent electrodes and formability, etc., the width W2 in FIG. 3(c) can be about 5 to 20 μm, and similarly the depth D2 can be about 5 to 10 μm.

[0042] <Other Modification Examples> The outer shape of the planar shape of the electrode pad portion 104 in Embodiment 2 is not limited to the above-described convex portion 201 and concave portion 202, and may be any shape obtained by appropriately combining them. FIG. 4 is a plan view of a substrate according to another modification example of Embodiment 2. The same or equivalent components as those in the above-described Embodiment 1 and Embodiment 2 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0043] [Embodiment 3] Embodiment 3 is different from Embodiment 2 in that a convex portion 201 is formed over the entire circumference of the outer shape of the planar shape of the electrode pad portion 104. FIG. 5 is a plan view and a cross-sectional view of a substrate according to Embodiment 3. FIG. 5(a) is a plan view of Embodiment 3, and FIG. 5(b) is a cross-sectional view taken along line X-X′ in FIG. 5(a). In the following description, the same or equivalent components as those in the above-described Embodiment 1 and Embodiment 2 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0044] In Embodiment 3, the convex portions do not necessarily have to be formed at equal intervals over the entire circumference. They may be formed more densely in the vicinity where the upper connecting body 102 and the lower connecting body 108 are connected.

[0045] Also, the shape is not limited to the convex portion 201, and the shape described in Embodiment 2 or those combined thereof may be formed over the entire circumference.

[0046] In Embodiment 3, the convex portion 201 or the size of the electrode pad portion 104 may be arranged so as not to conduct with the adjacent electrode pad portion 104. For example, it is desirable to arrange the distance between the electrode pad portions 104 to be greater than the diameter of the opening of the solder resist layer 103 where the upper surface of the electrode pad portion 104 is exposed. Even if the positional accuracy of the opening of the solder resist layer 103 is low as long as the distance is greater than the opening of the solder resist layer 103, it is possible to prevent a short circuit with the adjacent electrode pad portion 104. The interval of the arrangement of such electrode pad portions 104 is also applicable to other embodiments.

[0047] <Function and Effect> Since the convex portion 201 is formed over the entire circumference of the outer shape of the planar shape of the electrode pad portion 104, even when the alignment accuracy of the opening of the solder resist layer 103 is low, at least a part of the convex portions 201 provided on the entire circumference can be accommodated within the opening of the solder resist layer 103.

[0048] In addition, when forming the electrode pad portion 104 on the insulating layer 105, even when the accuracy of forming the convex portion 201 in accordance with a predetermined position of the outer shape is low, at least a part of the convex portions 201 provided on the entire circumference can be accommodated within the opening of the solder resist layer 103.

[0049] [Embodiment 4] Embodiment 4 is different from Embodiment 1 in that a depression 301 of the electrode pad portion 104 is provided between the side surface of the electrode pad portion 104 and the upper surface of the insulating layer 105. FIG. 6 is a cross-sectional view and an enlarged view of a substrate according to Embodiment 4. FIG. 6(a) is a cross-sectional view of Embodiment 4, and FIG. 6(b) is an enlarged view of the vicinity of the depression 301. In the following description, the same or equivalent components as those in the above-described Embodiments 1 to 3 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0050] When there is a depression 301 in the opening of the solder resist layer 103, a part of the upper connector 102 is filled in the depression 301.

[0051] Although the size of the depression 301 is not particularly defined, it may be any size as long as the adhesion with the upper connector 102 to be filled is improved. For example, it is desirable that both the height H2 and the depth D3 of the depression 301 in FIG. 6(b) be 1 μm or more.

[0052] <Function and Effect> By filling a part of the upper connector 102 in the depression 301, it becomes possible to further improve the adhesion due to the anchor effect.

[0053] [Manufacturing Method of Wiring Substrate] Next, the manufacturing method of the substrate of the present invention will be described. FIGS. 7 to 8 are cross-sectional views and plan views of the substrate in each step of manufacturing the substrate according to Embodiment 2. In the following description, the same or equivalent components as those in the above-described First Embodiments 1 to 4 are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0054] The manufacturing method is not limited to this example, and the manufacturing method can be freely selected as long as the same shape can be obtained. Also, although only one electrode is illustrated, processing may be performed simultaneously on one or more electrodes. It is also applicable to the manufacturing methods of other embodiments.

[0055] FIG. 7(a) shows a state in which after forming the wiring layer 106 of the substrate, an insulating layer 105 and an opening are formed thereon. A known method may be adopted for the manufacturing method up to this point.

[0056] A seed layer 401 for electrolytic plating in the next step is formed on the insulating layer 105 by electroless plating or sputtering.

[0057] As shown in FIG. 7(b), thereafter, a plating resist 402 is attached and only the portion where the wiring layer 106 including the electrode pad portion 104 is formed is opened by photolithography to expose the electrode portion.

[0058] Here, by forming a resist pattern opening for the electrode pad portion 104 including the convex portion 201, it becomes possible to form the electrode pad portion 104 having the convex portion 201.

[0059] Next, an electrolytic copper plating is performed to form a lower connection body 108 including the electrode pad portion 104 in a portion without the plating resist 402.

[0060] As shown in FIG. 7(c), after the electrolytic copper plating process is completed, the plating resist 402 is peeled off, and the seed layer on the insulating layer 105 is removed by an etching process.

[0061] As shown in FIG. 7(d), next, a solder resist layer 103 is formed. Either a liquid or a film-shaped solder resist may be used. The solder resist layer 103 is patterned so as to be provided with an opening so as to expose a part of the outer peripheral portion of the electrode pad portion 104 including the convex portion 201.

[0062] As shown in FIG. 7(e), next, a seed layer 403 for the next electrolytic plating process is formed on the solder resist layer 103 by electroless plating or sputtering.

[0063] Thereafter, as shown in FIG. 8(a), only the portion where the plating resist 404 is attached and the upper connection body 102 is formed is opened in the solder resist layer 103 by photolithography to expose the electrode pad portion 104 and the insulating layer 105. In addition, regarding the portions where plating is to be performed in the next process in the regions other than the posts to be connected at this time, they may be opened simultaneously.

[0064] Next, as shown in FIG. 8(b), an electrolytic copper plating is performed to form the upper connection body 102 in a portion without the plating resist 404. At this time, by firmly adhering the upper surface and side surfaces of the convex portion 201 and the circular outer peripheral portion which are the outer peripheral portions of the electrode pad portion 104, and also the surface of the insulating layer 105 and the upper connection body 102, it becomes possible to form the upper connection body 102 having excellent adhesion strength.

[0065] At this time, by adjusting the additives and plating conditions of the electrolytic copper plating solution, it becomes possible to flatten or add unevenness to the upper part of the upper connecting body 102.

[0066] Next, as shown in FIG. 8(c), the solder paste 405 is filled into the resist opening by a printing method. At this time, any paste type can be used as long as it is filled, but in order to achieve more efficient filling, it is desirable to use solder particles with a particle size of 1 / 5 or less of the opening diameter.

[0067] In addition to this, various means for forming solder can be used. For example, a solder layer can be formed by plating, or solder balls can be poured into the opening to form a solder layer.

[0068] Next, as shown in FIG. 8(d), the solder is heated and melted to join the upper connecting body 102 and the solder, and the round solder bumps 101 are formed.

[0069] Next, as shown in FIG. 8(e), the plating resist 404 is peeled off, and the seed layer 403 on the solder resist layer 103 is removed by an etching process. At this time, by taking a large etching selectivity ratio between the seed layer 403 and the solder, it becomes possible to form the upper connecting body 102 and the solder bumps 101 with good shapes.

[0070] By manufacturing in this way, it becomes possible to form a semiconductor substrate that can cope with a narrow pitch and has improved adhesion of the upper connecting body 102.

[0071] (Modification example) Next, a modification example in which a recess 301 is provided will be described.

[0072] The same process as described above is carried out until the plating resist 402 for the electrode pad portion 104 in FIG. 7(c) is peeled off. When the seed layer 401 is etched away, an etching solution is used such that undercutting occurs at the lower part of the electrode pad portion 104 and in the seed layer, thereby intentionally forming a depression 301 at the lower part of the electrode pad portion 104. After etching, the solder resist layer 103 and subsequent layers are formed by the same process as described above to form a semiconductor substrate. Note that as a process for providing the depression 301, it may be fabricated by a method such as forming the plating resist 402 at the time of plating in a skirt-dragging shape, in addition to etching that causes undercutting.

[0073] By providing the depression 301, a part of the upper connection body 102 is filled in the depression 301 portion, making it possible to form a semiconductor substrate with stronger adhesion and improved adhesion.

[0074] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention.

Explanation of Reference Numerals

[0075] 100 ··· Substrate 101 ··· Solder bump 102 ··· Upper connection body 103 ··· Solder resist layer 104 ··· Electrode pad portion 105 ··· Insulating layer 106 ··· Wiring layer 107 ··· Base layer 108 ··· Lower connection body 109 ··· Via portion 201 ··· Protrusion 202 ··· Recess 301 ··· Depression 401, 403 ··· Seed layer 402, 404 ··· Plating resist 405 ··· Solder paste

Claims

1. In a wiring board including a lower connector connected to a wiring layer within a substrate and an upper connector connected to the lower connector, the lower connector has a via portion embedded inside an insulating layer and an electrode pad portion integrally formed above the insulating layer, and the upper connector is a wiring board connected to the upper surface and side surface of the electrode pad portion.

2. The wiring board according to claim 1, wherein the upper connector is in contact with the insulating layer at its bottom surface.

3. The wiring board according to claim 1, wherein the electrode pad portion is provided with a convex portion on the outer shape of its planar shape, and the upper connector is connected to at least a part of the side surface of the convex portion.

4. The wiring board according to claim 1, wherein the electrode pad portion is provided with a concave portion on the outer shape of its planar shape, and the upper connector is connected to at least a part of the side surface of the concave portion.

5. The wiring board according to claim 3, wherein the convex portion is provided on the entire periphery of the outer shape of the planar shape of the electrode pad portion.

6. The wiring board according to claim 4, wherein the concave portion is provided on the entire periphery of the outer shape of the planar shape of the electrode pad portion.

7. A depression of the electrode pad portion is provided between the side surface of the electrode pad portion and the upper surface of the insulating layer, and the wiring board according to claim 2, wherein the upper connector is connected to the electrode pad portion in the depression.

8. The method for manufacturing a wiring board according to claim 2, wherein at least the height of the side surface of the electrode pad portion and the connection position between the upper connector and the lower connector are determined so that a predetermined adhesion strength is obtained from the contact area of the upper surface and the side surface of the electrode pad portion where the electrode pad portion and the upper connector are in contact, the contact area between the upper connector and the insulating layer, and the adhesion density per unit area at the contact location.

9. The method for manufacturing a wiring board according to claim 8, wherein at least the height of the side surface of the electrode pad portion and the connection position between the upper connector and the lower connector are determined so that a current of a predetermined magnitude flows between the upper connector and the lower connector.

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