Printed wiring board

Abstract

To provide a high-quality printed wiring board.SOLUTION: A printed wiring board includes: an uppermost resin insulating layer; an uppermost conductor layer which is formed on the uppermost resin insulating layer and includes a plurality of electrodes and a conductor circuit to mount an electronic component; a solder resist layer which is formed on the uppermost resin insulating layer and the uppermost conductor layer and includes a plurality of first openings that reach the electrodes and a second opening that reaches the conductor circuit; a dam conductor that is formed in the second opening; and a metal dam which is formed on the solder resist layer and the dam conductor. The electrodes are formed in a mounting area where the electronic component is to be mounted. The metal dam substantially surrounds the mounting area. The conductor circuit is a ground circuit or a power supply circuit. The metal dam is connected to the conductor circuit via the dam conductor.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to printed wiring boards. [Background technology]

[0002] Patent Document 1 discloses a printed wiring board having a base substrate and a dam formed on the base substrate. The dam is formed by applying a dam ink onto the base substrate by an inkjet method and curing the dam ink. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-96558 A Summary of the Invention

[0004] [Problem of Patent Document 1] If the wettability of the top surface of the base substrate is poor, it is believed that the dam ink and the top surface of the base substrate will not adhere sufficiently. It is believed that the dam will peel off from the base substrate. It is believed that the dam will be formed only on the top surface of the base substrate. It is believed that the base substrate will warp due to the hardening and shrinkage of the dam ink. [Means for solving the problem]

[0005] The printed wiring board of the present invention comprises a top resin insulating layer, a top conductor layer formed on the top resin insulating layer and including a plurality of electrodes and a conductor circuit for mounting electronic components, a solder resist layer formed on the top resin insulating layer and the top conductor layer and having a plurality of first openings leading to the electrodes and a second opening leading to the conductor circuit, a dam conductor formed in the second opening, and a metal dam formed on the solder resist layer and the dam conductor. The plurality of electrodes are formed in a mounting area for mounting the electronic components, the metal dam substantially surrounds the mounting area, the conductor circuit is a ground circuit or a power circuit, and the metal dam is connected to the conductor circuit via the dam conductor.

[0006] In the printed wiring board according to the embodiment of the present invention, the metal dam is connected to the conductor circuit via the dam conductor. Therefore, the metal dam is unlikely to peel off from the upper surface of the solder resist layer. The metal dam does not shrink upon hardening. Alternatively, the amount of shrinkage of the metal dam is very small. The metal dam has a higher strength than the resin dam. The printed wiring board is unlikely to warp. A high-quality printed wiring board can be obtained. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view illustrating a printed wiring board according to an embodiment. [Diagram 2] Cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III of FIG. 1. [Figure 4] FIG. 11 is a cross-sectional view illustrating a printed wiring board according to another embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional view illustrating a printed wiring board according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Embodiment] FIG. 1 is a plan view showing a printed wiring board 2 of an embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. As shown in FIGS. 1 to 3, the printed wiring board 2 has a top resin insulating layer 10, a top conductor layer 20, a solder resist layer 40 having openings 50 and 60, a dam conductor 70 formed in the opening 60, and a metal dam 80. The top resin insulating layer 10 has a first surface 10a and a second surface 10b opposite to the first surface 10a. The top conductor layer 20 is formed on the first surface 10a of the resin insulating layer 10. The solder resist layer 40 is formed on the first surface 10a of the top resin insulating layer 10 and on the top conductor layer 20. The printed wiring board 2 may have a core substrate below the top resin insulating layer 10 and the top conductor layer 20.

[0009] The resin insulating layer 10 is formed using a thermosetting resin. The material of the resin insulating layer 10 may be a photocurable resin. The resin insulating layer 10 may contain inorganic particles such as silica. The resin insulating layer 10 may contain a reinforcing material such as glass cloth.

[0010] The top conductor layer 20 has a plurality of electrodes 22 for mounting electronic components and a conductor circuit 30. The top conductor layer 20 is mainly made of copper. The top conductor layer 20 is formed of a seed layer 20a and an electrolytic plating layer 20b on the seed layer 20a. The seed layer 20a is formed by electroless plating or sputtering. The electrolytic plating layer 20b is formed by electrolytic plating. The top conductor layer 20 may have signal wiring 24 in addition to the electrodes 22 and the conductor circuit 30. The electrodes 22 include signal electrodes, power electrodes, and ground electrodes. Examples of the conductor circuit 30 are a ground circuit and a power circuit. As the conductor circuit 30, the top conductor layer 20 includes a power circuit. Alternatively, as the conductor circuit 30, the top conductor layer 20 includes a ground circuit. Alternatively, as the conductor circuit 30, the top conductor layer 20 includes a ground circuit and a power circuit. The top conductor layer 20 may have conductor circuits 30 having approximately the same potential. Conductive circuits 30 having the same potential are called equipotential circuits. When the uppermost conductor layer 20 has equipotential circuits, there are a plurality of equipotential circuits. The first equipotential circuit is the first conductive circuit 31, the second equipotential circuit is the second conductive circuit 32, and the third equipotential circuit is the third conductive circuit 33. The signal wiring 24 is connected to one signal electrode. The power supply circuit is connected to at least one power supply electrode. It is preferable that one power supply circuit is connected to three or more power supply electrodes. The ground circuit is connected to at least one ground electrode. It is preferable that one ground circuit is connected to three or more ground electrodes.

[0011] The uppermost conductor layer 20 of the embodiment is depicted in a perspective view in FIG. 1. FIG. 1 shows only the signal electrodes, and the power electrodes and the ground electrodes are omitted. FIG. 1 depicts electrodes 22, signal wiring 24, and ground circuit 25. Ground circuit 25 is an example of conductor circuit 30. Ground circuit 25 has an opening 251, and signal wiring 24 is formed in the opening 251. Ground circuit 25 is a continuous pattern (solid pattern). Uppermost conductor layer 20 may have a plurality of ground circuits 25x, 25y, and 25z. These are examples of equal potential circuits. Ground circuit (first ground circuit) 25x in FIG. 1 is an example of first conductor circuit 31, ground circuit (second ground circuit) 25y is an example of second conductor circuit 32, and ground circuit (third ground circuit) 25z is an example of third conductor circuit 33. Signal wiring 24 may be formed between first conductor circuit 31 and second conductor circuit 32. If the uppermost conductor layer 20 includes a power supply circuit, the ground circuit in FIG. 1 is replaced with the power supply circuit.

[0012] Electronic components are mounted on the printed wiring board 2 via electrodes 22. The electrodes 22 are formed within a mounting area 4 for mounting the electronic components.

[0013] The solder resist layer 40 is formed on the uppermost resin insulating layer 10 and the uppermost conductor layer 20. The solder resist layer 40 has a plurality of openings 50 and a plurality of openings 60 penetrating the solder resist layer 40. The openings 50 are first openings. The openings (first openings) 50 are openings for exposing the electrodes 22, penetrating the solder resist layer 40 to reach the electrodes 22. The openings 60 are second openings. The openings (second openings) 60 are openings for exposing the conductor circuits 30, penetrating the solder resist layer 40 to reach the conductor circuits 30. The second openings 60 also serve as openings for the dam conductors 70. In the embodiment, the second openings 60 reach the ground circuits 25. In that case, the second openings 60 expose the ground circuits 25. It is preferable that the number of second openings 60 leading to one conductor circuit 30 is more than one. Each equipotential circuit is exposed by the multiple openings 60. When the top conductor layer 20 includes a ground circuit, a plurality of second openings 60 reach one ground circuit. When the top conductor layer 20 includes a power supply circuit, a plurality of second openings 60 reach one power supply circuit. When the top conductor layer 20 has a plurality of conductor circuits (same-potential circuits) having approximately the same potential, a second opening 60 is formed for each same-potential circuit. Examples of the same-potential circuit are the first conductor circuit 31 and the second conductor circuit 32. It is preferable that a plurality of second openings 60 reach each same-potential circuit. When the top conductor layer 20 includes a plurality of ground circuits, an opening 60 is formed for each ground circuit. It is preferable that the number of openings 60 reaching one ground circuit is more than one. When the top conductor layer 20 includes a plurality of power supply circuits, an opening 60 is formed for each power supply circuit. It is preferable that the number of openings 60 reaching one power supply circuit is more than one. When a same-potential circuit exists, the second opening 60 has a first opening 61 for the same-potential circuit leading to the first conductor circuit 31 and a second opening 62 for the same-potential circuit leading to the second conductor circuit 32. Furthermore, second opening 60 may have a third opening 63 for the same potential circuit leading to third conductive circuit 33. First opening 61 for the same potential circuit may be referred to as opening 61. Second opening 62 for the same potential circuit may be referred to as opening 62. Third opening 63 for the same potential circuit may be referred to as opening 63. Opening 61 exposes first conductive circuit 31. Opening 62 exposes second conductive circuit 32. Opening 63 exposes third conductive circuit 33. The number of openings 61, the number of openings 62, and the number of openings 63 are multiple. The number of openings 61 and the number of openings 62 are different.The number of openings 61 and the number of openings 63 are different. The number of openings 61 and the number of openings 62 may be the same. The number of openings 61 and the number of openings 63 may be the same. The size of the first openings 50 and the size of the second openings 60 are equal. Alternatively, the size of the second openings 60 is larger than the size of the first openings 50. The shape of the openings 61 and the shape of the openings 62 are approximately the same. The shape of the openings 61 and the shape of the openings 63 are approximately the same.

[0014] The metal dam 80 prevents the underfill from flowing out. The metal dam 80 is formed on the solder resist layer 40 and the dam conductor 70. The metal dam 80 substantially surrounds the mounting area 4. The metal dam 80 is mainly made of copper. The metal dam 80 is formed of a seed layer 80a and an electrolytic plating layer 80b on the seed layer 80a. The seed layer 80a forming the metal dam 80 is similar to the seed layer 20a forming the uppermost conductor layer 20. The electrolytic plating layer 80b forming the metal dam 80 is similar to the electrolytic plating layer 20b forming the uppermost conductor layer 20.

[0015] The dam conductor 70 is formed in the opening (second opening) 60. The metal dam 80 is connected to the conductor circuit 30 via the dam conductor 70. The dam conductor 70 connecting the metal dam 80 and the conductor circuit 30 is located directly below the metal dam 80. The conductor circuit 30 connected to the metal dam 80 is located directly below the metal dam 80. In the embodiment, the metal dam 80 is connected to the ground circuit 25 via the dam conductor 70. The metal dam 80 may be connected to the power supply circuit via the dam conductor 70. When the conductor circuit 30 has the first conductor circuit 31 and the second conductor circuit 32, the dam conductor 70 has a first dam conductor 71 formed in the opening 61 and a second dam conductor 72 formed in the opening 62. When the conductor circuit 30 further includes the third conductor circuit 33, the dam conductor 70 has a third dam conductor 73 formed in the opening 63. The metallic dam 80 is connected to the first conductive circuit 31 via the first dam conductor 71. The metallic dam 80 is connected to the second conductive circuit 32 via the second dam conductor 72. The metallic dam 80 is connected to the third conductive circuit 33 via the third dam conductor 73. In this manner, one metallic dam 80 is connected to a plurality of equal potential circuits. One metallic dam 80 is connected to each equal potential circuit via a plurality of dam conductors 70. The dam conductor 70 is mainly made of copper. The dam conductor 70 is formed of a seed layer 80a and an electrolytic plating layer 80b on the seed layer 80a. The seed layer 80a forming the metallic dam 80 and the seed layer 80a forming the dam conductor 70 are common. The electrolytic plating layer 80b forming the metallic dam 80 and the electrolytic plating layer 80b forming the dam conductor 70 are common. The dam conductor 70 is formed simultaneously with the metallic dam 80. The metal dam 80 and the dam conductor 70 are integrally formed. The metal dam 80 and all the dam conductors 70 are integrally formed. In the embodiment, the metal dam 80 is connected to the ground circuit 25 via the dam conductor 70. The metal dam 80 and the conductor circuit 30 are connected by the dam conductor 70. The metal dam 80 is strongly joined to the ground circuit via the dam conductor 70. The metal dam 80 may be joined to the power supply circuit via the dam conductor 70. In that case, the metal dam 80 is strongly joined to the power supply circuit via the dam conductor 70.Since the conductive circuit 30 is covered with the solder resist layer 40, the metal dam 80 connected to the conductive circuit 30 is unlikely to come off the printed wiring board 2.

[0016] When the metal dam 80 is formed with a plurality of sides, each side is preferably connected to a ground circuit or a power supply circuit via a dam conductor 70. Each side is preferably connected to a ground circuit or a power supply circuit via a plurality of dam conductors 70. The dam 80 in FIG. 1 is formed with four sides 81x, 81y, 81z, and 81w. Each side may be connected to one ground circuit or one power supply circuit via a dam conductor 70. Each side may be connected to an equipotential circuit via a dam conductor 70. Each side may be connected to a different equipotential circuit via a dam conductor 70. The metal dam 80 is unlikely to peel off from the upper surface of the solder resist layer 40.

[0017] In the printed wiring board 2 of the embodiment, the metal dam 80 is connected to the first ground circuit 25x via the first dam conductor 71. The metal dam 80 is connected to the second ground circuit 25y via the second dam conductor 72. The metal dam 80 is connected to the third ground circuit 25z via the third dam conductor 73. One metal dam 80 is connected to at least one conductor circuit 30 via multiple dam conductors 70. Therefore, the metal dam 80 is unlikely to peel off from the upper surface of the solder resist layer 40. The metal dam 80 does not shrink due to hardening. Alternatively, the amount of shrinkage of the metal dam 80 is smaller than that of resin. The metal dam 80 has higher strength than a resin dam. The printed wiring board 2 is unlikely to warp. A high-quality printed wiring board 2 can be obtained.

[0018] [Method of manufacturing printed wiring board 2 according to embodiment] An intermediate substrate having a top resin insulating layer 10 and a top conductor layer 20 is prepared. The top conductor layer 20 has electrodes 22 for mounting electronic components, signal wiring 24, and a ground circuit 25. The ground circuit 25 includes a first ground circuit 25x, a second ground circuit 25y, and a third ground circuit 25z. The first ground circuit 25x, the second ground circuit 25y, and the third ground circuit 25z are examples of equal potential circuits. A solder resist layer 40 is formed on the top resin insulating layer 10 and the top conductor layer 20. A plurality of openings 50, 60 are formed penetrating the solder resist layer 40. Each of the openings 50, 60 is formed by a laser. The opening (first opening) 50 exposes the electrode 22. The opening (second opening) 60 exposes the ground circuit 25. The opening 60 has a plurality of openings 61, a plurality of openings 62, and a plurality of openings 63. The opening 61 exposes the first ground circuit 25x. The opening 62 exposes the second ground circuit 25y. The opening 63 exposes the third ground circuit 25z. The size of the opening 50 and the size of the opening 60 are equal. Alternatively, the size of the opening 60 is larger than the size of the opening 50. The size of the opening 61 and the size of the opening 62 may be different. It is preferable that the size of the opening 61 is larger than the size of the opening 62. The size of each of the openings 50, 60 is measured on the upper surface of the solder resist layer 40 (the surface away from the uppermost resin insulating layer 10). The planar shape of each of the openings 50, 60 on the upper surface of the solder resist layer 40 is approximately circular. The size of each of the openings 50, 60 is represented by the diameter on the upper surface of the solder resist layer 40.

[0019] A seed layer 80a is formed on the solder resist layer 40, on the inner wall surfaces of the openings 50 and 60, on the electrode 22 exposed from the opening 50, and on the ground circuit 25 exposed from the opening 60. A plating resist is formed on the seed layer 80a. The plating resist has openings for forming a metal dam 80 and a dam conductor 70. An electrolytic plating layer 80b is formed on the seed layer 80a exposed from the plating resist. The electrolytic plating layer 80b fills the opening 60. The electrolytic plating layer 80b is formed on the solder resist layer 40. The dam conductor 70 and the metal dam 80 are formed. These are formed simultaneously. The dam conductor 70 consists of the seed layer 80a in the opening 60 and the electrolytic plating layer 80b on the seed layer 80a. The metal dam 80 is composed of a portion formed of the seed layer 80a on the solder resist layer 40 and the electrolytic plating layer 80b on the seed layer 80a (a portion on the solder resist layer), and a portion formed of the electrolytic plating layer 80b on the dam conductor 70 (a portion on the dam conductor). The metal dam 80 and the dam conductor 70 are continuous. The metal dam 80 and the dam conductor 70 are integrally formed. The dam conductor 70 connects the ground circuit 25 and the metal dam 80. A first dam conductor 71 is formed in the opening 61. A second dam conductor 72 is formed in the opening 62. A third dam conductor 73 is formed in the opening 63. The first dam conductor 71 connects the first ground circuit 25x and the metal dam 80. The second dam conductor 72 connects the second ground circuit 25y and the metal dam 80. The third dam conductor 73 connects the third ground circuit 25z and the metal dam 80. The plating resist is removed. The seed layer 80a exposed from the electrolytic plating layer 80b is removed, thereby obtaining the printed wiring board 2 of the embodiment.

[0020] [Another embodiment] FIG. 4 shows a cross-sectional view of a printed wiring board 102 according to another example of the embodiment. FIG. 4 corresponds to a cross-sectional view taken along line II-II in FIG. 1. The embodiment and the other example have different planar shapes of the opening 60. The planar shapes of the opening 50 and the opening 60 are observed on the upper surface of the solder resist layer 40. The size of the opening 50 is represented by the area of ​​the planar shape of the opening 50. The size of the opening 60 is represented by the area of ​​the planar shape of the opening 60. The planar shape of the opening 50 according to the embodiment and the planar shape of the opening 50 according to the other example of the embodiment are substantially circular. The planar shape of the opening 60 according to the embodiment is substantially circular. In contrast, the other example has an opening 60 having a substantially elliptical planar shape. Alternatively, the other example has an opening 60 having a substantially rectangular planar shape. The other example may have an opening 60 having a substantially elliptical planar shape and an opening 60 having a substantially rectangular planar shape. The other example may have an opening 60 having a substantially circular planar shape and an opening 60 having a substantially rectangular planar shape. As another example, there may be an opening 60 having a substantially elliptical planar shape and an opening 60 having a substantially circular planar shape. In another example, the size of opening 60 is larger than the size of opening 50. The size of opening 61 is larger than the size of opening 50. The size of opening 62 is larger than the size of opening 50. The planar shape of opening 61 is substantially elliptical or substantially rectangular. The planar shape of opening 62 is substantially elliptical or substantially rectangular. The shapes of opening 61 and opening 62 are approximately the same. In another example of the embodiment, the planar shape of opening 60 is substantially elliptical.

[0021] Comparing the embodiment and the alternative example, the size of the opening 60 in the alternative example is larger than the size of the opening 60 in the embodiment. Therefore, the alternative example can increase the bonding strength between the metal dam 80 and the ground circuit 25. The metal dam 80 is less likely to peel off from the upper surface of the solder resist layer 40.

[0022] [Another Example of a Method for Manufacturing Printed Wiring Board 102] Except for the method of forming the openings 60, the manufacturing method of the alternative embodiment is similar to the manufacturing method of the embodiment. In the alternative embodiment, the solder resist layer 40 is irradiated with a laser so that the openings 60 have a planar shape of an approximately ellipse or an approximately rectangular shape. The planar shape of the openings 60 in the alternative embodiment of the embodiment is approximately elliptical. The openings 60 having an approximately elliptical planar shape, the openings 60 having an approximately rectangular planar shape, and the openings 60 having an approximately circular planar shape may be mixed. It is preferable that the openings 60 having an approximately elliptical planar shape and the openings 60 having an approximately circular planar shape are mixed. Alternatively, it is preferable that the openings 60 having an approximately rectangular planar shape and the openings 60 having an approximately circular planar shape are mixed.

[0023] [Modifications of the embodiment] FIG. 5 shows a cross-sectional view of a printed wiring board 202 according to a modified example of the embodiment. FIG. 5 corresponds to a cross-sectional view taken along line III-III in FIG. 1. As shown in FIG. 5, the printed wiring board 202 according to the modified example has a metal post 100 on the electrode 22. The printed wiring board 202 according to the modified example is formed by adding a metal post 100 to the printed wiring board 2 according to the embodiment. Alternatively, the printed wiring board 202 according to the modified example is formed by adding a metal post 100 to the printed wiring board 102 according to another example of the embodiment. The metal post 100 is composed of a via conductor 75 formed in the opening 50 and a post 90 formed on the via conductor 75. The post 90 protrudes from the upper surface of the solder resist layer 40. The post 90 is formed by a portion directly above the via conductor 75 and a portion on the solder resist layer 40 around the opening 50. The via conductor 75 and the post 90 are integrally formed. The via conductor 75 and the post 90 are continuous. The via conductor 75 connects the electrode 22 and the post 90. The electronic components are mounted on a printed wiring board 202 via metal posts 100 .

[0024] The metal post 100 is mainly made of copper. The metal post 100 is formed of a seed layer 80a and an electrolytic plating layer 80b on the seed layer 80a. The seed layer 80a forming the metal dam 80 and the dam conductor 70 and the seed layer 80a forming the metal post 100 are common. The electrolytic plating layer 80b forming the metal dam 80 and the dam conductor 70 and the electrolytic plating layer 80b forming the metal post 100 are common. The metal post 100 and the metal dam 80 are formed simultaneously. The post 90 and the metal dam 80 are formed simultaneously. The via conductor 75 and the dam conductor 70 are formed simultaneously.

[0025] As shown in Fig. 5, the height of the upper surface 80T of the metal dam 80 and the height of the upper surface 100T of the metal post 100 are different. In Fig. 5, the upper surface 100T of the metal post 100 is higher than the upper surface 80T of the metal dam 80. The upper surface 80T of the metal dam 80 may be higher than the upper surface 100T of the metal post 100. The distance between the upper surface 100T of the metal post 100 and the upper surface 80T of the metal dam 80 (the difference in height between the two) is 3 µm or more and 15 µm or less. It is preferable that the difference in height between the two is 5 µm or more and 12 µm or less.

[0026] The modified printed wiring board 202 has metal posts 100 in the mounting area 4. Electronic components are mounted on the printed wiring board 202 via the metal posts 100. Even though the printed wiring board 202 has metal dams 80, the modified example makes it easy to mount electronic components on the printed wiring board 202. The metal dams 80 are unlikely to interfere with mounting. The modified example can increase the connection reliability between the electronic components and the printed wiring board 202.

[0027] [Manufacturing method of the modified printed wiring board 202] An intermediate substrate having openings 50 and 60 is formed using a method similar to the manufacturing method of the embodiment. Alternatively, an intermediate substrate having openings 50 and 60 is formed using a method similar to the manufacturing method of another embodiment. Therefore, the modified printed wiring board 202 has openings 50 and 60 similar to the embodiment. Alternatively, the modified printed wiring board 202 has openings 50 and 60 similar to the other embodiment. Therefore, the planar shape of the opening 50 of the modified printed wiring board 202 is approximately circular. The planar shape of the opening 60 of the modified printed wiring board 202 is selected from approximately circular, approximately elliptical, and approximately rectangular. A seed layer 80a is formed on the solder resist layer 40, on the inner wall surfaces of the openings 50 and 60, on the electrode 22 exposed from the opening 50, and on the ground circuit 25 exposed from the opening 60. A plating resist is formed on the seed layer 80a. The plating resist has openings for forming a metal dam 80, a dam conductor 70, and a metal post 100. An electrolytic plating layer 80b is formed on the seed layer 80a exposed from the plating resist. The electrolytic plating layer 80b fills the openings 50, 60. A metal dam 80 having similar elements to those in the embodiment is formed. A metal post 100 is formed, which is composed of the seed layer 80a and the electrolytic plating layer 80b on the seed layer 80a. The metal post 100 and the metal dam 80 are formed simultaneously.

[0028] The plating resist is removed. The seed layer 80a exposed from the electrolytic plating layer 80b is removed. A modified printed wiring board 202 is obtained.

[0029] When the electrolytic plating layer 80b is formed, the magnitude of the current for forming the metal dam 80 and the magnitude of the current for forming the post 90 are controlled. For example, the magnitude of the current is controlled by using a shielding plate. In a modified example, the thickness of the electrolytic plating layer 80b for forming the metal dam 80 and the thickness of the electrolytic plating layer 80b for forming the post 90 are controlled. The thickness of the electrolytic plating layer 80b for forming the metal dam 80 is greater than the thickness of the electrolytic plating layer 80b for forming the post 90. Alternatively, the thickness of the electrolytic plating layer 80b for forming the metal dam 80 is less than the thickness of the electrolytic plating layer 80b for forming the post 90. Therefore, the height of the upper surface 90T of the post 90 is different from the height of the upper surface 80T of the metal dam 80. The upper surface 90T of the post 90 is higher than the upper surface 80T of the metal dam 80. In another example, the upper surface 80T of the metal dam 80 is higher than the upper surface 90T of the post 90. Since the height of the metal post 100 and the height of the metal dam 80 are approximately equal, the modified printed wiring board 202 can increase the connection strength between the metal post 100 and the electronic component. Even if the printed wiring board 202 is subjected to an impact, the connection reliability between the metal post 100 and the electronic component is likely to remain stable for a long period of time. [Explanation of symbols]

[0030] 2, 102, 202: Printed wiring board 4: Mounting area 10: Top resin insulation layer 20: Top conductor layer 22: Electrode 24: Signal wiring 30: Conductor circuit 31: First conductive circuit 32: Second conductive circuit 40: Solder resist layer 50: First opening 60: Second opening 61: 1st opening for same potential circuit 62:Second opening for same potential circuit 70: Dam conductor 71: First conductor for dam 72: Second conductor for dam 75: Via conductor 80: Metal dam 90: Post 100: Metal post

Claims

1. A top resin insulating layer; an uppermost conductor layer formed on the uppermost resin insulating layer and including a plurality of electrodes and conductor circuits for mounting electronic components; a solder resist layer formed on the uppermost resin insulating layer and the uppermost conductor layer, the solder resist layer having a plurality of first openings leading to the electrodes and second openings leading to the conductor circuits; a dam conductor formed in the second opening; A printed wiring board having the solder resist layer and a metal dam formed on the dam conductor, The multiple electrodes are formed within a mounting area for mounting the electronic components, the metal dam substantially surrounds the mounting area, the conductor circuit is a ground circuit or a power supply circuit, and the metal dam is connected to the conductor circuit via the dam conductor.

2. 2. The printed wiring board according to claim 1, wherein the number of said second openings leading to said conductor circuit is more than one.

3. 2. The printed wiring board of claim 1, wherein the conductor circuit has a first conductor circuit and a second conductor circuit having approximately the same potential as the first conductor circuit, the second opening has a first opening for the same potential circuit leading to the first conductor circuit and a second opening for the same potential circuit leading to the second conductor circuit, the dam conductor has a first dam conductor formed in the first opening for the same potential circuit and a second dam conductor formed in the second opening for the same potential circuit, the metal dam is connected to the first conductor circuit via the first dam conductor, and the metal dam is connected to the second conductor circuit via the second dam conductor.

4. 4. The printed wiring board according to claim 3, wherein the number of said first openings for equipotential circuits is plural, and the number of said second openings for equipotential circuits is plural.

5. 4. The printed wiring board according to claim 3, wherein said uppermost conductor layer further includes a signal wiring formed between said first conductor circuit and said second conductor circuit.

6. 2. The printed wiring board according to claim 1, wherein the first opening and the second opening have the same size, or the second opening has a larger size than the first opening.

7. 7. The printed wiring board according to claim 6, wherein the second opening is larger than the first opening, and the second opening has a planar shape that is substantially elliptical or substantially rectangular.

8. 4. The printed wiring board according to claim 3, wherein the first opening and the second opening have the same size, or the second opening has a larger size than the first opening.

9. 9. The printed wiring board according to claim 8, wherein the second opening is larger than the first opening, and the second opening has a planar shape that is substantially elliptical or substantially rectangular.

10. 9. The printed wiring board of claim 8, wherein the size of the second opening is larger than the size of the first opening, the shape of the second opening is approximately elliptical or approximately rectangular, and the shape of the first opening for the equipotential circuit and the shape of the second opening for the equipotential circuit are approximately the same.

11. The printed wiring board of claim 1 further comprises a metal post consisting of a via conductor formed in the first opening and a post protruding from an upper surface of the solder resist layer and formed on the via conductor, and the electronic component is mounted on the printed wiring board via the metal post.

12. 12. The printed wiring board of claim 11, wherein the metal dam and the metal post are formed simultaneously.

13. 12. The printed wiring board according to claim 11, wherein the via conductor and the dam conductor are formed simultaneously.

14. 12. The printed wiring board according to claim 11, wherein the height of an upper surface of the metal dam is different from the height of an upper surface of the metal post.

15. 5. The printed wiring board according to claim 4, wherein the number of said first openings for said equipotential circuits is different from the number of said second openings for said equipotential circuits.

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