Manufacturing method of printed wiring board

Abstract

To provide a manufacturing method for manufacturing a printed wiring board having excellent dam shape accuracy and capable of reducing steps and costs.SOLUTION: A manufacturing method of a printed wiring board includes the steps of: forming an outermost resin insulating layer; forming a pad for mounting an electronic component on the outermost resin insulating layer; forming a resin layer for forming a solder resist layer on the outermost resin insulating layer and the pad; preparing a film having a first surface and a second surface opposite to the first surface; forming a through hole having a tapered shape from the first surface toward the second surface in the film; pressing the film against the resin layer to fill the through hole with a part of the resin layer; curing the resin layer; forming a dam with the solder resist layer; and removing the film.SELECTED DRAWING: Figure 1

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 printed wiring board using a press plate with a mold. A resin layer is heated and fluidized, and then deformed into the shape of a dam by the press plate with a mold. The press plate with a mold is then removed to expose the resin layer and form the dam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-294333 Summary of the Invention

[0004] [Problem of Patent Document 1] In the printed wiring board manufacturing method of Patent Document 1, the cross-sectional shape of the dam is thought to be rectangular or trapezoidal, considering the removal of the mold after exposing the resin layer. Therefore, it is thought that the underfill material will leak out if the dam height is low. In addition, it is thought that the process and cost will increase because the mold needs to be created every time the dam layout is changed. [Means for solving the problem]

[0005] The method for manufacturing a printed wiring board of the present invention includes forming an outermost resin insulating layer, forming pads on the outermost resin insulating layer for mounting electronic components, forming a resin layer on the outermost resin insulating layer and the pads for forming a solder resist layer, preparing a film having a first surface and a second surface opposite to the first surface, forming a tapered through hole in the film from the first surface to the second surface, pressing the film against the resin layer and filling the through hole with a portion of the resin layer, hardening the resin layer, forming a dam with the solder resist layer, and removing the film.

[0006] In the manufacturing method of the present invention, through holes are formed in the film and the film is pressed against the resin layer to form the dam. This stabilizes the accuracy of the dam shape. The through holes can be formed by laser processing or router processing. This reduces the number of steps and costs compared to creating a mold for each dam layout. The through-holes in the film have an inverted trapezoidal cross-section. Therefore, the cross-section of the formed dam is also an inverted trapezoid. The underfill material flowing toward the dam sinks into the bottom of the dam, which has an inverted trapezoidal cross-section. The underfill material does not climb up along the surface of the dam, or at least it is difficult for it to climb up. Therefore, the underfill material is unlikely to flow over the top of the dam. In the manufacturing method of the embodiment, it is possible to achieve both stable dam shape accuracy and prevention of underfill material outflow, and it is also possible to reduce the number of steps and costs. [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 2] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 3] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 4] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 5] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 6] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 7] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 8] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. [Figure 9] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a printed wiring board according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Printed wiring board according to an embodiment> 1 is a cross-sectional view of a semiconductor device 200 according to an embodiment. The semiconductor device 200 is formed by a printed wiring board 10 according to an embodiment and an electronic component 90 mounted on the printed wiring board 10.

[0009] 1, printed wiring board 10 has core substrate 30 and buildup layers 80A, 80B formed on the front and back sides of core substrate 30. Buildup layers 80A, 80B are formed of resin insulating layers 150U, 150L, ​​conductor layers 158U, 158L, and via conductors 160U, 160D that penetrate resin insulating layers 150U, 150L and connect adjacent conductor layers. Resin insulating layer 150U is the outermost resin insulating layer.

[0010] Printed wiring board 10 has solder resist layers (70U, 70D) on buildup layers (80A, 80B). Solder resist layer 70U has first openings (71U). Conductive layer (158U) exposed by first openings (71U) functions as pads (158p) for mounting electronic components (90). Solder bumps (76U) for mounting electronic components (90) are formed on pads (158p).

[0011] As shown in FIG. 1 , the printed wiring board 10 has a dam 102 on the first solder resist layer 70U to prevent the underfill material 100 from flowing. The dam 102 surrounds the electronic component 90. An example of the planar shape of the dam 102 is a ring. The dam 102 is formed of solder resist. The dam 102 and the solder resist layer 70U are formed of substantially the same material. The dam 102 is integral with the solder resist layer 70U. The top 102a of the dam 102 is flat. The dam 102 has a uniform height H over substantially the entire periphery. The cross-sectional shape of the dam 102 is an inverted trapezoid. The semiconductor device 200 of this embodiment has the underfill material 100 between the electronic component 90 and the solder resist layer 70U. The cross-sectional shape of the dam 102 is an inverted isosceles trapezoid. The inverted trapezoid cross-sectional shape makes it difficult for the underfill material 100 to leak out.

[0012] <Method for manufacturing a printed wiring board according to an embodiment> 2 to 9 show a method for manufacturing a printed wiring board 10 formed by the method for manufacturing a printed wiring board according to the embodiment.

[0013] The first intermediate substrate 1 shown in FIG. 2 is manufactured. The first intermediate substrate 1 has a core substrate 30, an upper buildup layer 80A, and a lower buildup layer 80B. The core substrate 30 and the buildup layers 80A and 80B are manufactured by a well-known method. The upper buildup layer 80A has a resin insulating layer 150U and a conductor layer 158U on the resin insulating layer 150U.

[0014] As shown in FIG. 3, a resin layer 170U for forming a solder resist layer 70U is formed on the resin insulating layer 150U and the conductor layer 158U.

[0015] As shown in Fig. 4, a PET layer 91 is prepared, which has a first surface 91a and a second surface 91b opposite to the first surface 91a. The PET layer 91 is a film. The PET layer 91 is thermoplastic. The PET layer 91 has a thickness H.

[0016] As shown in FIG. 5 , a tapered through-hole 95 is formed in the PET layer 91 from the first surface 91a to the second surface 91b. The through-hole 95 is formed using a laser or a router. This reduces the process and costs compared to creating a mold for each dam 102 layout. The cross-sectional shape of the through-hole 95 is an inverted trapezoid. The cross-sectional shape of the through-hole 95 is an inverted isosceles trapezoid. An example of the planar shape of the through-hole 95 is a ring. As shown in FIG. 6 , a PET layer 91 having a through-hole 95 is formed on a resin layer 170U. Alternatively, a PET layer 91 without a through-hole 95 is formed on the resin layer 170U, and then the tapered through-hole 95 is formed in the PET layer 91. The PET layer 91 is pressed against the resin layer 170U, filling the through-hole 95 with a portion of the resin layer 170U. The filled portion of the resin layer 170U becomes the dam material 101. The through-hole 95 of the PET layer 91 has an inverted trapezoidal cross-sectional shape. Therefore, the dam material 101 that is pressed in also has an inverted trapezoidal cross-sectional shape. Thereafter, the resin layer 170U including the dam material 101 is irradiated with light L and cured.

[0017] As shown in FIG. 7, the resin layer 170U is photocured to form the solder resist layer 70U. The dam material 101 is photocured to form the dam 102. Thereafter, openings 71U exposing the conductor layer 158U are formed in the solder resist layer 70U by a known method. The conductor layer 158U exposed by the openings 71U functions as pads 158p for mounting the electronic components 90. A plurality of openings 94 are formed in the PET layer 91 by a known method. The positions of each opening 94 correspond to the positions of the solder bumps 76U. The openings 94 communicate with the openings 71U. Solder bumps 76U are formed on the pads 158p. The solder bumps 76U are exposed from each opening 94.

[0018] As shown in Figure 8, the PET layer 91 is removed from the solder resist layer 70U by heating. The PET layer 91 is peeled off from the solder resist layer 70U. The dam 102 is exposed. The dam 102 has an inverted trapezoidal cross section and is formed on the solder resist layer 70U to prevent the underfill material 100 from flowing. This stabilizes the accuracy of the dam shape.

[0019] In this embodiment, the cross-sectional shape of the dam 102 is an inverted trapezoid. Therefore, the underfill material 100 flowing toward the dam 102 sinks under the dam 102, which has an inverted trapezoidal cross-sectional shape. The underfill material 100 does not climb up along the surface of the dam 102, or it is difficult for the underfill material 100 to climb up. Therefore, the underfill material 100 is unlikely to flow over the top 102a of the dam 102.

[0020] As shown in Fig. 9, an electronic component 90 is mounted on the solder bump 76U. As shown in Fig. 1, an underfill material 100 is filled between the electronic component 90 and the solder resist layer 70U. A printed wiring board 10 (see Fig. 1) according to the embodiment is obtained. In the manufacturing method according to the embodiment, stability in the shape accuracy of the dam 102 and prevention of the outflow of the underfill material 100 are both achieved, and the number of steps and costs are reduced. [Explanation of symbols]

[0021] 1: First intermediate board 10: Printed wiring board 30: Core board 70D: Solder resist layer 70U: Solder resist layer 71U: Opening 76U: Solder bump 90: Electronic Components 91:PET layer 94 :Aperture 95:Through hole 100: Underfill material 101: Dam materials 102: Dam 102a: Top 150U: Resin insulation layer 158L: Conductor layer 158U: Conductor layer 158p: Pad 160D: Via conductor 160U: Via conductor 170U: Resin layer 200: Semiconductor device H: Dam height L: light

Claims

1. forming an outermost resin insulating layer; forming pads on the outermost resin insulating layer for mounting electronic components; forming a resin layer for forming a solder resist layer on the outermost resin insulating layer and the pads; providing a film having a first side and a second side opposite the first side; forming a tapered through hole in the film from the first surface toward the second surface; pressing the film against the resin layer to fill the through-hole with a portion of the resin layer; curing the resin layer; forming a dam with the solder resist layer; removing the film; A method for manufacturing a printed wiring board, comprising:

2. The method for manufacturing a printed wiring board according to claim 1, curing the resin layer is performed by photocuring; Removing the film comprises: This is done after curing the resin layer.

3. 2. The method for manufacturing a printed wiring board according to claim 1, The method further includes forming a film on the resin layer.

4. The method for manufacturing a printed wiring board according to claim 1, forming the film This is done after forming the through holes.

5. The method for manufacturing a printed wiring board according to claim 1, The through holes are formed using a laser or a router.

6. The method for manufacturing a printed wiring board according to claim 1, forming the film This is done before forming the through holes.

7. The method for manufacturing a printed wiring board according to claim 1, Removal of the film is accomplished by heating.

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