Printed wiring board

Abstract

To provide a printed wiring board that can be reduced in costs.SOLUTION: A printed wiring board 10 includes: an outermost resin insulation layer 1; an outermost conductor layer 2 that is formed on the outermost resin insulation layer 1; a solder resist layer 3 that is formed on the outermost resin insulation layer 1 and the outermost conductor layer 2, and that has an opening 5 to expose the outermost conductor layer 2; a bump formed on the outermost conductor layer 2 that is exposed by the opening 5; an electronic component that is mounted on the bump; an underfill material that fills a portion between the electronic component and the solder resist layer 3; and a dam 7 that is formed on the solder resist layer 3 to prevent the flow of the underfill material. The solder resist layer 3 is formed of inorganic particles and a first material, and the dam 7 is formed of the first material containing an epoxy resin, a hardener, and an additive such as an antifoaming agent.SELECTED DRAWING: Figure 1A

Description

[Technical field]

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

[0002] Patent Document 1 discloses a printed wiring board. In Patent Document 1, a first solder resist layer and a second solder resist layer made of a photosensitive resin such as an ultraviolet curable resin are formed. A dam is formed by removing the uncured portion of the second solder resist layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-159163 A Summary of the Invention

[0004] <Issues in Patent Document 1> In Patent Document 1, the dam is formed by the second solder resist layer. The second solder resist layer other than the dam is an unnecessary material. It is considered that it is difficult to reduce costs with the technology of Patent Document 1. [Means for solving the problem]

[0005] The printed wiring board of the present invention comprises an outermost resin insulating layer, an outermost conductor layer formed on the outermost resin insulating layer, a solder resist layer formed on the outermost resin insulating layer and the outermost conductor layer and having an opening for exposing the outermost conductor layer, a bump formed on the outermost conductor layer exposed by the opening, an electronic component mounted on the bump, an underfill material filled between the electronic component and the solder resist layer, and a dam formed on the solder resist layer for preventing the underfill material from flowing. The solder resist layer is formed of inorganic particles and a first material, and the dam is formed of the first material.

[0006] In a printed wiring board according to an embodiment of the present invention, a solder resist layer is formed from inorganic particles and a first material. A dam is formed on the solder resist layer. The dam is formed from the first material. The dam does not contain inorganic particles. Therefore, the production cost is low. According to the embodiment, a printed wiring board having a dam can be manufactured at low cost. [Brief description of the drawings]

[0007] [Figure 1A] FIG. 1 is a cross-sectional view illustrating a printed wiring board according to an embodiment. [Figure 1B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 1C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 1D] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 1E] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 1F] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Printed Wiring Board of the Embodiment> Fig. 1A is a cross-sectional view of a printed wiring board 10 according to an embodiment. As shown in Fig. 1A, the printed wiring board 10 has a resin insulating layer (outermost resin insulating layer) 1, a conductor layer 2 (outermost conductor layer) formed on the resin insulating layer 1, and a first solder resist layer (solder resist layer) 3 formed on the resin insulating layer 1 and the conductor layer 2.

[0009] The first solder resist layer 3 has an opening 5. The opening 5 exposes the conductor layer 2. The exposed conductor layer 2 is a pad 4. A bump (not shown) is formed on the pad 4 exposed by the opening 5. An electronic component (not shown) is mounted on the bump. An underfill material (not shown) is filled between the electronic component and the first solder resist layer 3. A dam 7 is formed on the first solder resist layer 3. The dam 7 prevents the underfill material from flowing out. The dam 7 surrounds the electronic component. The dam 7 is formed in a ring shape.

[0010] The first solder resist layer 3 is made of inorganic particles and a first material. The first material contains an epoxy resin and additives such as a hardener and a defoamer. The dam 7 is made of a first material. The dam 7 does not contain inorganic particles.

[0011] In the printed wiring board 10 of the embodiment, the first solder resist layer 3 is formed from inorganic particles and a first material. The dam 7 is formed on the first solder resist layer 3. The dam 7 is formed from the first material. The dam 7 does not contain inorganic particles. Therefore, the production cost is low. According to the embodiment, the printed wiring board having the dam 7 can be manufactured at low cost.

[0012] <Method of manufacturing a printed wiring board according to an embodiment> 1B to 1F show a method for manufacturing a printed wiring board 10 according to an embodiment.

[0013] As shown in FIG. 1B, an intermediate substrate having a resin insulating layer 1 and a conductor layer 2 on the resin insulating layer 1 is prepared.

[0014] As shown in FIG. 1C, a first solder resist layer 3 is formed on the resin insulating layer 1 and the conductor layer 2. The first solder resist layer 3 is formed of inorganic particles and a first material. The first material contains an epoxy resin, a hardener, and additives such as an antifoaming agent. The first solder resist layer 3 is formed by applying a first mixture containing the first material and inorganic particles. Alternatively, the first solder resist layer 3 is formed of a first film containing the first material and inorganic particles.

[0015] Then, a first mask (not shown) is placed on the first solder resist layer 3. The first mask covers the first solder resist layer 3 on each pad 4. The pads 4 are the conductor layer 2 on which the bumps are formed. The first mask does not cover the first solder resist layer 3 except on each pad 4. As shown in FIG. 1D, light L is irradiated onto the first solder resist layer 3 through the first mask. The light L is, for example, ultraviolet light. The first solder resist layer 3 on each pad 4 does not harden. The first solder resist layer 3 except on each pad 4 hardens.

[0016] As shown in FIG. 1E, a second solder resist layer 6 is formed on the first solder resist layer 3. The second solder resist layer 6 is formed of a first material. The second solder resist layer 6 does not contain inorganic particles. The second solder resist layer 6 is formed by applying a second mixture containing the first material. Alternatively, the second solder resist layer 6 is formed by a second film containing the first material. The first solder resist layer 3 is not developed.

[0017] Then, a second mask (not shown) is placed on the second solder resist layer 6. As shown in Fig. 1F, light L is irradiated onto the second solder resist layer 6 through the second mask. The light L is, for example, ultraviolet light. The second solder resist layer 6 is cured.

[0018] As shown in FIG. 1A, the uncured portion of the second solder resist layer 6 is removed by a single development process. The cured second solder resist layer 6 forms a dam 7. The uncured portion of the first solder resist layer 3 is removed. An opening 5 is formed in the first solder resist layer 3. The conductor layer 2 exposed by the opening 5 becomes the pad 4. The dam 7 and the opening 5 are formed in a single process. [Explanation of symbols]

[0019] 1: Resin insulation layer 2: Conductive layer 3: First solder resist layer 4: Pad 5:Aperture 6: Second solder resist layer 7: Dam 10: Printed wiring board L: light

Claims

1. An outermost resin insulating layer; an outermost conductor layer formed on the outermost resin insulating layer; a solder resist layer formed on the outermost resin insulating layer and the outermost conductor layer, the solder resist layer having an opening for exposing the outermost conductor layer; a bump formed on the outermost conductor layer exposed by the opening; an electronic component mounted on the bump; an underfill material filled between the electronic component and the solder resist layer; a dam formed on the solder resist layer to prevent the underfill material from flowing, The solder resist layer is formed of inorganic particles and a first material, and the dam is formed of the first material.

2. 2. The printed wiring board of claim 1, wherein said dam is free of said inorganic particles.

3. 2. The printed wiring board of claim 1, wherein the dam surrounds the electronic component.

4. 2. The printed wiring board according to claim 1, wherein the dam is formed in an annular shape.

5. 2. The printed wiring board of claim 1, wherein the first material includes an epoxy resin and a hardener.

6. 2. The printed wiring board of claim 1, wherein the solder resist layer is formed by applying a first mixture containing the first material and the inorganic particles, and the dam is formed by applying a second mixture containing the first material.

7. 2. The printed wiring board according to claim 1, wherein the solder resist layer is formed of a first film containing the first material and the inorganic particles, and the dam is formed of a second film containing the first material.

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