Printed wiring board manufacturing method

Abstract

To provide a manufacturing method for a printed wiring board with high quality.SOLUTION: A manufacturing method for a printed wiring board includes: forming, on an insulation layer, a conductor layer with a conductor circuit; preparing a forming member having a thermosetting resin insulation layer with a first surface and a second surface on a side opposite to the first surface, and a first protective film formed on the first surface of the resin insulation layer, each side of the outer peripheral edge of the first protective film overlapping each side of the resin insulation layer when the resin insulation layer and the first protective film are projected with light perpendicular to the first surface; sticking the forming member on the conductor layer so that the conductor circuit and the second surface make contact with each other; after the sticking of the forming member, removing the first protective film from the resin insulation layer; and after the removing of the first protective film, pressing the entire surface of the first surface to flatten the first surface.SELECTED DRAWING: Figure 2E

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for manufacturing a wiring board, which includes the steps of preparing an insulating layer-forming member having a semi-cured insulating layer provided on one side of a support film, attaching the insulating layer-forming member so that the semi-cured insulating layer contacts the pad, and curing the insulating layer after the insulating layer-forming member has been attached. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-99649 Summary of the Invention

[0004] [Problem of Patent Document 1] In the technology of Patent Document 1, it is believed that pressure is applied to the support film and the semi-cured insulating layer when the insulating layer-forming member is attached. It is believed that the pressure causes a portion of the semi-cured insulating layer to protrude outward from the outer periphery of the support film. The protruding portion of the insulating layer is called bleed. It is believed that a portion of the bleed protrudes upward from the support film. If the bleed protrudes upward, it is believed that the flatness of the wiring board will be impaired. As a result, it is believed that the quality of the wiring board will be reduced. [Means for solving the problem]

[0005] A method for manufacturing a printed wiring board of the present invention includes forming a conductor layer having a conductor circuit on an insulating layer; preparing a forming member having a thermosetting resin insulating layer having a first surface and a second surface opposite the first surface and a first protective film formed on the first surface of the resin insulating layer, wherein each side of the outer edge of the first protective film overlaps each side of the resin insulating layer when the resin insulating layer and the first protective film are projected with light perpendicular to the first surface; attaching the forming member to the conductor layer so that the conductor circuit and the second surface are in contact; removing the first protective film from the resin insulating layer after the attaching; and pressing the entire first surface to flatten the first surface after the removing.

[0006] In the manufacturing method of the embodiment of the present invention, when a forming member is attached to the conductor layer, a portion of the resin insulating layer may protrude outward from the outer periphery of the first protective film and protrude above the first protective film. However, in the manufacturing method of the embodiment of the present invention, after the first protective film is removed from the resin insulating layer, the entire first surface is pressed to flatten the first surface. After flattening, there are no upwardly protruding portions on the first surface. As a result, the flatness of the printed wiring board manufactured by the manufacturing method of the present invention is prevented from being impaired. A high-quality printed wiring board is provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a printed wiring board according to an embodiment. [Figure 2A] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2B] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2C] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2D] 1A to 1C are plan views schematically showing a method for manufacturing a printed wiring board according to an embodiment. [Figure 2E] 1A to 1C are plan views schematically showing a method for manufacturing a printed wiring board according to an embodiment. [Figure 2F]FIG. 2F is a plan view schematically showing the step of FIG. 2E. [Figure 2G] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2H] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2I] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 2J] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 3A] 10A to 10C are cross-sectional views schematically showing a method for manufacturing a printed wiring board according to a modified example. [Figure 3B] 10A to 10C are cross-sectional views schematically showing a method for manufacturing a printed wiring board according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Embodiment] 1 is a cross-sectional view showing a printed wiring board 2 according to an embodiment. As shown in FIG. 1, the printed wiring board 2 has an insulating layer 4, a first conductor layer 10, a resin insulating layer 20, a second conductor layer 60, and via conductors 70.

[0009] The insulating layer 4 is made of a thermosetting resin and may contain inorganic particles such as silica. The insulating layer 4 may also contain a reinforcing material such as glass cloth.

[0010] The first conductor layer 10 is formed on the insulating layer 4. The first conductor layer 10 includes pads 12 and signal wiring 14. Although not shown in the figure, the first conductor layer 10 also includes conductor circuits other than the pads 12 and signal wiring 14. The first conductor layer 10 is made of copper. The first conductor layer 10 is formed of a seed layer 10a and an electrolytic plated film 10b on the seed layer 10a.

[0011] The resin insulating layer 20 is formed on the insulating layer 4 and the first conductor layer 10. The resin insulating layer 20 has a first surface 20F (the upper surface in the figure) and a second surface 20B (the lower surface in the figure) opposite the first surface 20F. An opening 22 is formed in the resin insulating layer 20 to expose the pad 12. The resin insulating layer 20 is made of a thermosetting resin. The thermosetting resin contains an epoxy resin, a polymer resin, and an inorganic filler.

[0012] The second conductor layer 60 is formed on the first surface 20F of the resin insulating layer 20. The second conductor layer 60 includes lands 62 and signal wiring 64. Although not shown in the figure, the second conductor layer 60 also includes conductor circuits other than the lands 62 and the signal wiring 64. The second conductor layer 60 is made of copper. The second conductor layer 60 is formed of a seed layer 60a and an electrolytic plated film 60b on the seed layer 60a.

[0013] The via conductor 70 is formed in the opening 22. The via conductor 70 connects the first conductor layer 10 and the second conductor layer 60. In Fig. 1, the via conductor 70 connects the pad 12 and the land 62. The via conductor 70 is formed of a seed layer 60a and an electrolytic plated film 60b on the seed layer 60a.

[0014] [Method for manufacturing printed wiring board 2 according to the embodiment] 2A to 2J show a method for manufacturing printed wiring board 2 according to the embodiment. 2A to 2E and 2G to 2J are cross-sectional views. 2F is a plan view.

[0015] 2A shows an insulating layer 4 and a first conductor layer 10 formed on the insulating layer 4. The first conductor layer 10 is formed by a semi-additive method.

[0016] As shown in FIG. 2B, a forming member 30 is prepared, which includes a resin insulating layer 20 and a first protective film 32 formed on the first surface 20F of the resin insulating layer 20. At this point, the resin insulating layer 20 is in a semi-cured state. The first protective film 32 completely covers the first surface 20F of the resin insulating layer 20. When the forming member 30 is viewed in a plan view, each side of the outer periphery of the first protective film 32 overlaps with each side of the outer periphery of the resin insulating layer 20. In other words, when the resin insulating layer 20 and the first protective film 32 are projected using light perpendicular to the first surface 20F of the resin insulating layer 20, each side of the outer periphery of the first protective film 32 overlaps with each side of the outer periphery of the resin insulating layer 20. An example of the first protective film 32 is a film made of polyethylene terephthalate (PET). A release agent is formed between the first protective film 32 and the resin insulating layer 20.

[0017] As shown in FIG. 2C , a forming member 30 is attached to the insulating layer 4 and the first conductor layer 10 so that the second surface 20B contacts the pads 12 and signal wiring 14 of the first conductor layer 10. At this time, heat and pressure are applied to the first protective film 32 and the semi-cured resin insulating layer 20. The first protective film 32 and the resin insulating layer 20 are pressed toward the insulating layer 4 by a pressure plate 50 placed on the first protective film 32. The pressure plate 50 is, for example, a stainless steel (SUS) plate. In this embodiment, the semi-cured resin insulating layer 20 is deformed by the attachment of the forming member 30. A portion of the resin insulating layer 20 protrudes outward from the outer periphery of the first protective film 32. The protruding portion of the resin insulating layer 20 is called a bleed 23. The bleed 23 has a protrusion 21 that protrudes above the first protective film 32. The resin insulating layer 20 is heated by a heating mechanism (not shown). The heating promotes curing of the resin insulating layer 20.

[0018] As shown in FIG. 2D, the first protective film 32 is removed from the first surface 20F of the resin insulating layer 20.

[0019] As shown in FIG. 2E, a second protective film 42, which is different from the first protective film 32, is attached to the first surface 20F of the resin insulating layer 20. The second protective film 42 is larger than the resin insulating layer 20. The second protective film 42 completely covers the first surface 20F. An example of the second protective film 42 is a film made of polyethylene terephthalate (PET). A release agent is formed between the second protective film 42 and the resin insulating layer 20.

[0020] 2F is a plan view schematically showing the second protective film 42 and the resin insulating layer 20 at the time of FIG. 2E. As shown in FIG. 2F, when the resin insulating layer 20 and the second protective film 42 are projected using light perpendicular to the first surface 20F of the resin insulating layer 20, each side of the outer periphery of the second protective film 42 is located outside each side of the outer periphery of the resin insulating layer 20. When the resin insulating layer 20 and the second protective film 42 are viewed in plan, each side of the outer periphery of the second protective film 42 is located outside each side of the outer periphery of the resin insulating layer 20.

[0021] When the second protective film 42 is attached to the first surface 20F of the resin insulating layer 20 (see FIG. 2E), heat and pressure are applied to the second protective film 42 and the resin insulating layer 20. As shown in FIG. 2E, the second protective film 42 and the resin insulating layer 20 are pressed toward the insulating layer 4 by a pressure plate 50 placed on the second protective film 42. The entire first surface 20F of the resin insulating layer 20 is pressed by the second protective film 42. The resin insulating layer 20 is deformed. As described above, each side of the outer periphery of the second protective film 42 is located outside each side of the resin insulating layer 20 (see FIG. 2F). Therefore, a portion of the resin insulating layer 20 does not protrude outward from the outer periphery of the second protective film 42. A portion of the bleed 23 does not protrude above the second protective film 42. By attaching the second protective film 42, the first surface 20F of the resin insulating layer 20 is flattened. The protruding portions 21 (FIG. 2D) of the bleeds 23 disappear. After planarization, there are no upwardly protruding portions on the first surface 20F. The resin insulating layer 20 is heated by a heating mechanism (not shown). This heating further promotes the hardening of the resin insulating layer 20.

[0022] As shown in FIG. 2G, laser light L is irradiated from above the second protective film 42. The laser light L penetrates the second protective film 42 and the resin insulating layer 20 at the same time. An opening 22 for a via conductor is formed, which reaches the pad 12 of the first conductor layer 10. The laser light L is, for example, a UV laser light or a CO2 laser light. The pad 12 is exposed through the opening 22.

[0023] As shown in FIG. 2H, the second protective film 42 is removed from the first surface 20F of the resin insulating layer 20.

[0024] As shown in FIG. 2I, a seed layer 60a is formed on the first surface 20F of the resin insulating layer 20. The seed layer 60a is formed by electroless plating. A plating resist 100 is formed on the seed layer 60a. The plating resist 100 has openings for forming the lands 62 and the signal wiring 64 (FIG. 1).

[0025] As shown in FIG. 2J, an electrolytic plated film 60b is formed on the seed layer 60a exposed from the plating resist 100. The electrolytic plated film 60b fills the opening 22. The seed layer 60a and the electrolytic plated film 60b on the first surface 20F form a land 62 and a signal wiring 64. The second conductor layer 60 is formed. The seed layer 60a and the electrolytic plated film 60b in the opening 22 form a via conductor 70. The via conductor 70 connects the pad 12 and the land 62.

[0026] Thereafter, plating resist 100 is removed. Seed layer 60a exposed from electrolytic plated film 60b is removed. Second conductor layer 60 and via conductors 70 are formed simultaneously. Heat treatment is performed to completely harden resin insulating layer 20. Printed wiring board 2 (FIG. 1) of the embodiment is obtained.

[0027] According to the manufacturing method of the embodiment, when the forming member 30 is attached to the first conductor layer 10, a portion of the resin insulating layer 20 may protrude outward from the outer periphery of the first protective film 32 and may protrude above the first protective film 32 (FIG. 2C). However, in the manufacturing method of the embodiment, after the first protective film 32 is removed from the resin insulating layer 20 (FIG. 2D), the second protective film 42 is attached to the first surface 20F of the resin insulating layer 20 (FIG. 2E). As a result, the entire first surface 20F of the resin insulating layer 20 is pressed, and the first surface 20F is flattened (FIG. 2E). The protruding portion 21 of the resin insulating layer 20 disappears. After flattening, there is no upwardly protruding portion on the first surface 20F. As a result, the flatness of the printed wiring board 2 manufactured by the manufacturing method of the embodiment is prevented from being impaired. A high-quality printed wiring board 2 is provided.

[0028] [Modification of the embodiment] In the modified example, the resulting printed wiring board 2 is the same as that of the embodiment (FIG. 1). In the first modified example, a part of the manufacturing method differs from that of the embodiment. In the modified example, the method of planarizing the first surface 20F of the resin insulating layer 20, which is performed after attaching the forming member 30 (FIG. 2C) and removing the first protective film 32 (FIG. 2D), differs from that of the embodiment.

[0029] As shown in FIG. 3A, in the modified example, instead of attaching the second protective film 42 (FIG. 2E), the entire first surface 20F of the resin insulating layer 20 is pressed by a pressure plate 150. That is, the entire first surface 20F is directly pressed by the pressure plate 150. As a result, the first surface 20F is flattened. The pressure plate 150 is, for example, a rubber plate. The pressure plate 150 may also be a stainless steel plate. Heating is performed in addition to the application of pressure by the pressure plate 150. The heating further promotes the hardening of the resin insulating layer 20.

[0030] As shown in Fig. 3B, after the first surface 20F is planarized, laser light L is irradiated from above the first surface 20F. Openings 22 for via conductors reaching the pads 12 of the first conductor layer 10 are formed. The steps subsequent to the formation of the openings 22 are the same as the steps shown in Figs. 2I and 2J of the embodiment.

[0031] According to the manufacturing method of the modified example, after the first protective film 32 is removed from the resin insulating layer 20 (FIG. 2D), the entire first surface 20F of the resin insulating layer 20 is pressed by a pressure plate 150 (FIG. 3A). The first surface 20F is flattened. The protruding portion 21 (FIG. 2D) of the resin insulating layer 20 disappears. After flattening, there are no upwardly protruding portions on the first surface 20F. This prevents the flatness of the printed wiring board 2 from being impaired. A high-quality printed wiring board 2 is provided. [Explanation of symbols]

[0032] 2: Printed wiring board 4: Insulating layer 10: First conductor layer 12: Pad 14: Signal wiring 20: Resin insulating layer 20F: 1st page 20B: 2nd side 21:Protrusion 30: Forming member 32: 1st protective film 42:Second protective film 50: Pressure plate

Claims

1. forming a conductor layer having a conductor circuit on an insulating layer; preparing a forming member having a thermosetting resin insulating layer having a first surface and a second surface opposite to the first surface, and a first protective film formed on the first surface of the resin insulating layer, wherein when the resin insulating layer and the first protective film are projected with light perpendicular to the first surface, each side of the outer periphery of the first protective film overlaps each side of the resin insulating layer; attaching the forming member onto the conductor layer so that the conductor circuit and the second surface are in contact; removing the first protective film from the resin insulating layer after the attaching; and after the removing, pressing the entire first surface to flatten the first surface.

2. 2. The method for manufacturing a printed wiring board of claim 1, wherein the planarizing step includes attaching a second protective film to the first surface, and when the resin insulating layer and the second protective film are projected by light perpendicular to the first surface, each side of the outer periphery of the second protective film is located outside each side of the resin insulating layer.

3. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the attaching step includes applying heat and pressure to the first protective film and the resin insulating layer.

4. 4. The method for manufacturing a printed wiring board according to claim 3, wherein the attaching step includes causing a portion of the resin insulating layer to protrude outward and above an outer periphery of the first protective film.

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