Wire substrate and method for manufacturing the same

Abstract

To provide a technique of suppressing reduction in magnetism of a magnetic resin body.SOLUTION: The wire substrate of the present disclosure includes: a core substrate with an opening and a first through-hole; a magnetic resin body filled in the opening, the magnetic resin body having a second through-hole; a first through-hole conductor in the first through-hole; and a second through-hole conductor in the second through-hole. The second through-hole conductor includes a conductive paste filled in the second through-hole.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wiring board in which a magnetic resin body is disposed on a core substrate, and a manufacturing method thereof. [Background technology]

[0002] Conventionally, as this type of wiring board, for example, one having a through conductor that penetrates a magnetic resin body is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-178004 A (paragraph

[0014] and Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0004] The objective is to provide a technology that can suppress the deterioration of the magnetism of a magnetic resin body compared to conventional wiring boards. [Means for solving the problem]

[0005] The wiring board of the present disclosure is a wiring board comprising a core substrate having an opening and a first through hole formed therein, a magnetic resin body filled in the opening and having a second through hole, a first through-hole conductor formed in the first through hole, and a second through-hole conductor formed in the second through hole, wherein the second through-hole conductor includes a conductive paste filled in the second through hole. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view of a wiring board according to a first embodiment. [Figure 2] Figure 2 is an enlarged cross-sectional view of the core substrate. [Figure 3] 3A to 3C are cross-sectional views showing a method for manufacturing a wiring board. [Figure 4] 4A to 4C are cross-sectional views showing a method for manufacturing a wiring board. [Figure 5] 5A to 5C are cross-sectional views showing a method for manufacturing a wiring board. [Figure 6] 6A and 6B are cross-sectional views showing a method for manufacturing a wiring board. [Figure 7] FIG. 7 is a cross-sectional view showing a method for manufacturing a wiring board. [Figure 8] FIG. 8 is a cross-sectional view showing a method for manufacturing a wiring board. [Figure 9] FIG. 9 is a cross-sectional view showing a method for manufacturing a wiring board. [Figure 10] FIG. 10 is a cross-sectional view of a wiring board according to a second embodiment. [Figure 11] 11A and 11B are cross-sectional views showing a method for manufacturing a wiring board. [Figure 12] 12A and 12B are cross-sectional views showing a method for manufacturing a wiring board. [Figure 13] FIG. 13 is a cross-sectional view of a wiring board according to a third embodiment. [Figure 14] 14A to 14D are cross-sectional views showing a method for manufacturing a wiring board. DETAILED DESCRIPTION OF THE INVENTION

[0007] [First embodiment] Hereinafter, a wiring board 10 according to a first embodiment will be described with reference to Figures 1 to 9. As shown in Figure 1, wiring board 10 has a core substrate 11 and first and second buildup layers 12A and 12B laminated on both the front and back surfaces of the core substrate 11.

[0008] The first and second buildup layers 12A and 12B are formed by alternately stacking insulating layers 15 and conductive layers 20, with via conductors 21 formed in the insulating layers 15. Furthermore, a solder resist layer 17 having a plurality of openings 17H corresponding to the plurality of pads 18 included in the conductive layers 20 is stacked on the first and second buildup layers 12A and 12B. A plurality of solder bumps 19 are provided on the plurality of pads 18.

[0009] The core substrate 11 includes, for example, a core insulating layer 11K and core conductive layers 13 laminated on both the front and back surfaces of the core insulating layer 11K. The core insulating layer 11K has a structure in which a plurality of prepregs are laminated, and the core conductive layer 13 has a structure in which a plated layer is laminated on copper foil 11D laminated on the core insulating layer 11K.

[0010] The core substrate 11 is formed with through-hole conductors 32 that penetrate the core insulating layer 11K and connect the front and back core conductive layers 13 together. More specifically, a cylindrical through-hole 32H is formed in the core insulating layer 11K, and the inner surface of this through-hole 32H is coated with the through-hole conductor 32. The inside of the through-hole conductor 32 is filled with a resin 32J.

[0011] A main body hole 11H is provided in the core substrate 11. The main body hole 11H has, for example, a circular cross section and is filled with a magnetic resin body 40. The magnetic resin is formed by mixing magnetic particles such as iron oxide, nickel, cobalt, or tin into a resin such as epoxy resin or phenolic resin.

[0012] A plurality of through holes 31H are formed in the magnetic resin body 40, and penetrating conductors 31 filled with conductive paste are arranged inside the through holes. The penetrating conductors 31 connect the core conductive layers 13 on the front and back of the core substrate 11. In this embodiment, a plurality of through holes 31H are formed in one magnetic resin body 40. The conductive paste is, for example, a resin paste containing particles of copper, silver, or the like, and is in direct contact with the inner surfaces of the through holes 31H.

[0013] In this embodiment, an inductor including a plurality of through conductors 31 is formed on the core substrate 11. The through conductors 31 are disposed in a magnetic resin body 40 having magnetism, thereby improving the performance of the inductor.

[0014] Next, the core conductive layer 13, through-hole conductors 32, and penetrating conductors 31 will be described in detail with reference to Fig. 2. The core conductive layer 13 is composed of seven layers: from the core insulating layer 11K side, copper foil 11D, first electroless plated layer 51A, first electroless plated layer 51B, second electroless plated layer 52A, second electroless plated layer 52B, third electroless plated layer 53A, and third electroless plated layer 53B. The through-hole conductors 32 are continuous with the second electroless plated layer 52A and second electroless plated layer 52B of the core conductive layer 13.

[0015] In the core conductive layer 13, the first electroless plated layer 51A and the first electrolytic plated layer 51B are shield plated to prevent the magnetic resin body 40 from coming into contact with a desmear solution (e.g., potassium permanganate). The third electroless plated layer 53A and the third electrolytic plated layer 53B are cover plated to cover the resin 32J in the through-hole conductor 32.

[0016] The magnetic resin body 40 penetrates the core insulating layer 11K and the copper foils 11D on both the front and back sides thereof, and the front and back surfaces of the magnetic resin body 40 are located on the same plane as the copper foils 11D. The core conductive layer 13 on the magnetic resin body 40 is six layers that does not have the copper foils 11D, and is thinner than the core conductive layer 13 on the core insulating layer 11K.

[0017] The through conductor 31 penetrates four layers of the core conductive layer 13: the first electroless plated layer 51A, the first electrolytic plated layer 51B, the second electroless plated layer 52A, and the second electrolytic plated layer 52B, and is covered by the third electroless plated layer 53A and the third electrolytic plated layer 53B.

[0018] The wiring board 10 of the present disclosure is manufactured as follows. (1) A copper-clad laminate 11S is prepared, in which copper foil 11D is laminated on both sides of a core insulating layer 11K. As shown in Fig. 3A, a plurality of main holes 11H are formed in the copper-clad laminate 11S by, for example, drilling, and the copper-clad laminate 11S is then deburred and polished.

[0019] (2) As shown in Fig. 3B, magnetic resin paste is filled into main body hole 11H by vacuum printing to form magnetic resin body 40. Note that both front and back end surfaces of magnetic resin body 40 are polished to be flush with copper-clad laminate 11S.

[0020] (3) Next, an electroless plating process and an electrolytic plating process are performed, and a first electroless plating layer 51A and a first electrolytic plating layer 51B, which serve as shield plating, are formed on both the front and back surfaces of the copper-clad laminate 11S including the magnetic resin body 40 (see Figure 3C).

[0021] (4) As shown in Fig. 4A, through-holes 32H are formed in the copper-clad laminate 11S on which the first electrolytic plated layer 51B is laminated, for example, by drilling, and the copper-clad laminate 11S is subjected to a desmearing process. In this desmearing process, smears are removed using a solution (for example, potassium permanganate).

[0022] (5) Next, an electroless plating process and an electrolytic plating process are performed to form second electroless plated layers 52A and second electrolytic plated layers 52B on first electrolytic plated layer 51B, and also form through-hole conductors 32 (see FIG. 4B).

[0023] In this embodiment, the solution used in the electroless plating process is, for example, a plating solution containing copper sulfate, formaldehyde, and ethyleneaminetetraacetic acid (EDTA) as a complexing agent, and the solution used in the electrolytic plating process is, for example, a plating solution containing copper sulfate as a main component, but is not limited to this.

[0024] (6) As shown in FIG. 4C, resin 32J is filled into through-hole conductor 32, and both end faces of resin 32J are polished so as to be flush with second electrolytic plated layer 52B.

[0025] (7) Next, through-holes 31H are formed in the magnetic resin body 40 by cutting such as drilling (see FIG. 5A), and smears are then removed by washing with medium-pressure water or high-pressure water.

[0026] (8) As shown in FIG. 5B, the through-holes 31H are filled with a conductive paste by, for example, silk printing, to form the through conductors 31.

[0027] (9) Next, an electroless plating process and an electrolytic plating process are performed, whereby third electroless plated layers 53A and third electrolytic plated layers 53B are formed on second electrolytic plated layer 52B, on the end faces of resin 32J, and on the end faces of through conductors 31, as shown in FIG.

[0028] (10) Next, as shown in FIG. 6A, an etching resist 60 having a predetermined pattern is formed on the third electrolytic plating layer 53B.

[0029] (11) The copper foil 11D, the first to third electroless plated layers 51A to 53A, and the first to third electrolytic plated layers 51B to 53B exposed from the etching resist 60 are removed by etching, and then the etching resist 60 is removed. As a result, as shown in FIG. 6B, core conductive layers 13 are formed on both the front and back surfaces, and the core substrate 11 is obtained.

[0030] (12) Next, insulating layers 15 and conductive layers 20 are alternately stacked by the SAP (Semi-Additive Process) method to form first and second buildup layers 12A and 12B on both the front and back surfaces of the core substrate 11 (see FIG. 7). Via conductors 21 are also formed together with each conductive layer 20.

[0031] (13) As shown in Fig. 8, a solder resist layer 17 is laminated on a second conductive layer 20. Next, as shown in Fig. 9, openings 17H are formed in predetermined locations of the solder resist layer 17 by, for example, laser processing or photolithography. Then, pads 18 are formed in portions of the second conductive layer 20 that are exposed from the solder resist layer 17 by the openings 17H.

[0032] (15) Solder bumps 19 are formed on the pads 18 of the first and second buildup layers 12A and 12B (see FIG. 1). With this, the wiring board 10 is completed.

[0033] Next, the effects of the wiring board 10 will be described. Here, when the through conductors 31 are formed by plating, it is conceivable that components of the magnetic resin body 40 will be eluted when the inner surfaces of the through holes 31H of the magnetic resin body 40 are immersed in a plating solution or a plating pretreatment solution, and the magnetic properties of the magnetic resin body 40 will be reduced. In contrast, according to the wiring board 10 of this embodiment, the through conductors 31 are formed by filling the through holes 31H with a conductive paste. This prevents the inner surfaces of the through holes 31H from being immersed in a plating solution or a plating pretreatment solution, and prevents the magnetic resin body 40 from eluting from the inner surfaces of the through holes 31H. This makes it possible to suppress a reduction in the magnetic properties of the magnetic resin body 40.

[0034] In particular, when an inductor is formed by the penetrating conductors 31, if components of the magnetic resin body 40 leach out from the inner surfaces of the through holes 31H, the magnetism of the magnetic resin between the penetrating conductors 31 will decrease, and it is thought that this will result in a decrease in the performance of the inductor. In contrast, in this embodiment, leach-out from the inner surfaces of the through holes 31H is prevented, thereby preventing a decrease in the performance of the inductor, and therefore the effect of forming the penetrating conductors 31 from a conductive paste can be more effectively enjoyed.

[0035] Although the conductive paste has a higher conductive resistance than plating of a metal such as copper, the penetrating conductor 31 fills the entire through-hole 31H, and the cross-sectional area of the penetrating conductor 31 is larger than when plating is formed on the inner surface of the through-hole 31H, preventing a significant decrease in the conductivity of the penetrating conductor 31. Furthermore, the conductivity of the conductive paste can be controlled by adjusting the components of the conductive paste.

[0036] In addition, in this embodiment, multiple through conductors 31 are formed together in one magnetic resin body 40, making the magnetic resin body 40 formation process easier than in a configuration in which one magnetic resin body 40 is provided for each through conductor 31.

[0037] [Second embodiment] A wiring board 10W of the second embodiment will be described below with reference to Figures 10 to 12. The wiring board 10W of this embodiment differs from the wiring board 10 of the first embodiment in the configuration of the through conductors 31W. As shown in Figure 10, in this embodiment, a through hole 31H penetrates the core insulating layer 11K of the core substrate 11 and the insulating layers 15 on both the front and back sides of the core insulating layer 11K. The through conductors 31 also penetrate these three layers, connecting the first conductive layers 20 from the core substrate 11 together.

[0038] Wiring board 10W of this embodiment is manufactured as follows: Note that parts common to the manufacturing method of wiring board 10 of the first embodiment are omitted.

[0039] (1) As shown in FIG. 11A, first insulating layers 15 are laminated on the front and back of core substrate 11 in a state where through-holes 31H are not formed in magnetic resin body 40.

[0040] (2) Next, through-holes 31H are formed through the magnetic resin body 40 together with the front and back insulating layers 15, and smears are removed by medium-pressure water washing or high-pressure water washing. Then, conductive paste is filled into the through-holes 31H to form the penetrating conductors 31 (see FIG. 11B).

[0041] (3) As shown in FIG. 12A, a via hole 21H is formed in the insulating layer 15.

[0042] (4) An electroless plating process and an electrolytic plating process are performed to form the conductive layer 20. At this time, a partial pattern of the conductive layer 20 is formed so as to cover the end faces of the through conductors 31, and the through conductors 31 connect the conductive layers 20 together.

[0043] (5) After that, the same steps as in the first embodiment are carried out to complete the wiring board 10W.

[0044] [Third embodiment] A wiring board 10X of the third embodiment will be described below with reference to Figures 13 and 14. In the wiring board 10 of the first embodiment, the through conductor 31 penetrates four layers of the core conductive layer 13, namely, first electroless plated layer 51A, first electrolytic plated layer 51B, second electroless plated layer 52A, and second electrolytic plated layer 52B, whereas in this embodiment, the through conductor 31X penetrates two layers, namely, first electroless plated layer 51A and first electrolytic plated layer 51B. Below, the parts of the manufacturing method for the wiring board 10X of this embodiment that differ from the manufacturing method for the wiring board 10 of the first embodiment will be described.

[0045] (1) As shown in FIG. 14A, through-holes 32H are formed in copper-clad laminate 11S, which has been laminated up to first electrolytic plated layer 51B.

[0046] (2) As shown in FIG. 14B, through-holes 31H are formed in the magnetic resin body 40.

[0047] (3) Next, conductive paste is filled only in the through-holes 31H by inkjet printing to form the penetrating conductors 31X (see FIG. 14C).

[0048] (4) An electroless plating step and an electrolytic plating step are performed to form second electroless plated layer 52A and second electrolytic plated layer 52B on first electrolytic plated layer 51B, and to form through-hole conductor 32. Then, resin 32J is filled in through-hole conductor 32 (see FIG. 14D).

[0049] (4) After that, the same steps as in the first embodiment are carried out to complete the wiring board 10X.

[0050] [Other embodiments] In the above embodiment, multiple through conductors 31 are provided in one magnetic resin body 40, but the configuration may also be such that there are multiple magnetic resin bodies 40 and one through conductor 31 is provided in each magnetic resin body 40.

[0051] The through-hole conductors 32 formed in the core insulating layer 11K may also be made of conductive paste.

[0052] Although the present specification and drawings disclose specific examples of the technology included in the scope of the claims, the technology described in the claims is not limited to these specific examples, but also includes various modifications and variations of the specific examples, and also includes parts of the specific examples taken out alone. [Explanation of symbols]

[0053] 10, 10W, 10X wiring board 11 Core board 13 Core conductive layer 15 Insulating layer 31, 31W, 31X through conductor 32 through-hole conductor 32J resin 40 Magnetic resin body

Claims

1. a core substrate in which an opening and a first through hole are formed; a magnetic resin body filled in the opening and having a second through hole; a first through-hole conductor formed in the first through hole; a second through-hole conductor formed in the second through hole, The second through-hole conductor includes a conductive paste filled in the second through hole.

2. 2. The wiring board according to claim 1, The magnetic resin body and the conductive paste are in contact with each other.

3. 2. The wiring board according to claim 1, The first through-hole conductor includes a metal film formed on an inner surface of the first through hole.

4. 2. The wiring board according to claim 1, The first through-hole conductor includes a conductive paste filled in the first through hole.

5. 2. The wiring board according to claim 1, The core substrate has a core insulating layer and core conductive layers laminated on the front and back sides of the core insulating layer, The second through-hole conductor connects the core conductive layers on the front and back sides.

6. 2. The wiring board according to claim 1, An insulating layer and a conductive layer are laminated on the front and back of the core substrate, The second through-hole conductors penetrate the insulating layers on the front and back sides of the core substrate and connect the conductive layers on the front and back sides of the core substrate to each other.

7. 2. The wiring board according to claim 1, A plurality of the second through-hole conductors are provided in one magnetic resin body.

Images