Printed wiring board

Abstract

To provide a printed wiring board having high productivity.SOLUTION: A printed wiring board has: an uppermost resin insulation layer; an uppermost conductor layer formed on the uppermost resin insulation layer; a solder resist layer formed on the uppermost resin insulation layer and the uppermost conductor layer; and a dam formed on the solder resist layer. The printed wiring board has a mounting area for mounting an electronic component. The dam is formed of a metal wire, and surrounds the mounting area.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an adhesive dam frame material that is made up of a resin frame and an adhesive layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-79881 Summary of the Invention

[0004] [Problem of Patent Document 1] In Patent Document 1, the adhesive dam frame material surrounds the bare chip. Therefore, according to the technology of Patent Document 1, if the size or shape of the bare chip changes, it is thought that the size and shape of the resin frame must be changed. In this case, it is thought that the time required to manufacture the resin frame will be long. It is thought that a lot of waste will be generated when the resin frame is manufactured. It is thought that the production cost of the adhesive dam frame material will be high. [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, a solder resist layer formed on the top resin insulating layer and the top conductor layer, and a dam formed on the solder resist layer. The printed wiring board has a mounting area for mounting electronic components. The dam is formed of metal wire and surrounds the mounting area.

[0006] A printed wiring board according to an embodiment of the present invention has a dam surrounding a mounting area, and the dam is formed of a metal wire. Even if the size or shape of the mounting area changes, the embodiment can form the dam by adjusting the length of the metal wire. When the dam is formed, waste material is unlikely to be generated. The embodiment can improve the productivity of the dam. The embodiment can reduce the production cost of the printed wiring board. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view schematically showing a printed wiring board according to an embodiment. [Figure 2] Cross-sectional view taken along line II-II in Figure 1. [Figure 3] Cross-sectional view of the line III-III in Figure 1. [Figure 4] 1A to 1C are plan views schematically showing a method for manufacturing a printed wiring board according to an embodiment. [Figure 5] 1A to 1C are plan views schematically showing a method for manufacturing a printed wiring board according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment] FIG. 1 is a plan view schematically 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 FIG. 1, the upper surface of the printed wiring board 2 has a mounting area A1 for mounting electronic components. As shown in FIGS. 1 to 3, the printed wiring board 2 has an uppermost resin insulating layer 4, an uppermost conductor layer 10, a solder resist layer 20, and a dam 50. The dam 50 surrounds the periphery of the mounting area A1. The dam 50 is formed of a metal wire 30.

[0009] The uppermost resin insulating layer 4 is formed using a thermosetting resin. The material of the uppermost resin insulating layer 4 may be a photocurable resin. The uppermost resin insulating layer 4 may contain inorganic particles such as silica. The uppermost resin insulating layer 4 may also contain a reinforcing material such as glass cloth.

[0010] The top conductor layer 10 is formed on the top resin insulating layer 4. The top conductor layer 10 has a plurality of conductors 12 and a plurality of conductor circuits 14. The conductors 12 are members for fixing the metal wires 30 of the dam 50. The conductor circuits 14 are, for example, signal wiring. The conductor circuits 14 may include pads for mounting electrical components. The conductor layer 10 is mainly made of copper.

[0011] The solder resist layer 20 is formed on the uppermost conductor layer 10 and the uppermost resin insulating layer 4. The solder resist layer 20 is formed using a photocurable resin. The solder resist layer 20 has openings (first openings) 22 that expose the conductors 12 individually.

[0012] The dam 50 is formed on the solder resist layer 20. The dam 50 surrounds the mounting area A1. The dam 50 prevents the underfill from flowing out. The dam 50 is formed of a plurality of metal wires 30. In an embodiment, a resin film 40 may be formed on the metal wires 30. The resin film 40 covers the metal wires 30. The metal wires 30 are completely covered by the resin layer 40. Each metal wire 30 is a wire made of metal. An example of the metal is copper. In this embodiment, the number of metal wires 30 is four. In this embodiment, each of the four metal wires 30 forms one side of a roughly square. Connecting the four metal wires 30 forms a roughly square. The mounting area A1 is located within the area obtained by connecting the metal wires 30. In FIG. 1, the mounting area A1 is located within the roughly square obtained by connecting the four metal wires 30. The number of metal wires 30 may be any number other than four, as long as there is more than one. The end 32 of each metal wire 30 is fixed to the conductor 12 exposed from the opening 22 by solder 34. Each metal line 30 is aligned along the top surface of the solder resist layer 20. A gap C exists between the metal line 30 and the solder resist layer 20.

[0013] The resin film 40 is formed on the metal wire 30. The resin film 40 covers the metal wire 30. The resin film 40 closes the gap C. The resin film 40 contacts the upper surface of the solder resist layer 20. The gap C is filled with the resin film 40. The gap C disappears. The resin film 40 bonds the metal wire 30 and the solder resist layer 20. The metal wire 30 is fixed onto the upper surface of the solder resist layer 20 by the resin film 40. The resin film 40 fills the opening 22. The resin film 40 is formed using a thermosetting resin. The resin film 40 is formed by applying resin from above the metal wire 30.

[0014] [Method for manufacturing printed wiring board 2 according to the embodiment] 4 and 5 show a method for manufacturing a printed wiring board 2 according to an embodiment. FIGS. 4 and 5 are plan views. FIG. 4 shows an intermediate substrate having an uppermost resin insulating layer 4, an uppermost conductor layer 10, and a solder resist layer 20. The upper surface of the solder resist layer 20 has a mounting area A1. The solder resist layer 20 has four openings (first openings) 22. The openings 22 expose the four conductors 12, respectively.

[0015] As shown in FIG. 5, four metal wires 30 are placed on the solder resist layer 20. The end 32 of each metal wire 30 is fixed to the conductor 12 exposed from the opening 22 with solder 34. Solder paste is formed on the conductor 12. The end 32 of the metal wire 30 is placed on the solder paste so that the end 32 of the metal wire 30 contacts the solder paste. By reflow, the end 32 is fixed to the conductor 12 with the solder 34. The four metal wires 30 form the four sides of a rectangle surrounding the mounting area A1. A gap C exists between the metal wires 30 and the solder resist layer 20.

[0016] Resin is applied onto the metal wires 30. The resin is applied, for example, with a dispenser. The resin covers the metal wires 30. The resin fills the gaps C. The resin fills the openings 22. The resin is hardened. A resin film 40 is formed. A dam 50 is formed surrounding the mounting area A1. The printed wiring board 2 of the embodiment is obtained.

[0017] In the printed wiring board 2 of the embodiment, the dam 50 is formed using the metal wire 30. Even if the size or shape of the mounting area A1 changes, the dam 50 is formed by adjusting the length of the metal wire 30. Waste of material is unlikely to occur when forming the dam 50. The productivity of the dam 50 is improved. The production cost of the printed wiring board 2 is reduced.

[0018] The dam 50 of the embodiment has the resin film 40 that fills the gap C. The underfill does not easily flow out through the gap C.

[0019] [Modification example 1] In the first modification, the end 32 of the metal wire 30 is fixed by wire bonding to the conductor 12 exposed from the opening 22. In the first modification, the solder 34 is omitted.

[0020] [Modification example 2] In the second modified example, the resin film 40 is omitted. In the second modified example, the dam 50 is formed only by the plurality of metal wires 30. [Explanation of symbols]

[0021] 2: Printed wiring board 4: Resin insulation layer 10: Conductor layer 12: conductor 20: Solder resist layer 22:Aperture 30: Metal wire 32: Edge 34: Solder 40: Resin film 50: Dam A1: Mounting area C: Gap

Claims

1. a top resin insulating layer; an uppermost conductor layer formed on the uppermost resin insulating layer; a solder resist layer formed on the uppermost resin insulating layer and the uppermost conductor layer; a dam formed on the solder resist layer, the printed wiring board has a mounting area for mounting electronic components; The dam is formed of metal wire and surrounds the mounting area.

2. 2. The printed wiring board according to claim 1, wherein the dam is formed by a plurality of the metal wires.

3. 2. The printed wiring board according to claim 1, wherein the dam further comprises a resin film formed on the metal wire.

4. 4. The printed wiring board according to claim 3, wherein a gap exists between the metal wire and the solder resist layer, and the resin film is formed on the metal wire so as to close the gap.

5. 2. The printed wiring board of claim 1, wherein the uppermost conductor layer has a conductor for fixing the metal wire, the solder resist layer has an opening exposing the conductor, and the end of the metal wire is fixed by solder to the conductor exposed from the opening.

6. 2. The printed wiring board of claim 1, wherein the uppermost conductor layer has a conductor for fixing the metal wire, the solder resist layer has an opening exposing the conductor, and the end of the metal wire is fixed to the conductor exposed from the opening by wire bonding.

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