JP2015231005A - Wiring board and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that effectively inhibits damage from occurring in a core substrate of a wiring board.SOLUTION: A wiring board includes: a core substrate formed by an inorganic material; and a resin layer which is disposed on the core substrate, the resin layer in which at least one wiring layer is formed. The wiring board includes a groove part defined by the core substrate and the resin layer in at least a part of an outer periphery of the resin layer.

Description

  The present invention relates to a wiring board and a manufacturing method thereof.

  As a wiring board, a build-up wiring board used as an IC package board or an interposer is known. The build-up wiring board has a multilayer structure, and a resin layer as an insulating layer and a wiring layer are alternately laminated on one side or both sides of the core board. For example, in the technique described in Patent Document 1, by covering a part of the side surface of the core substrate (glass substrate) with resin, the core substrate is damaged due to the difference in thermal expansion between the core substrate and the resin layer. That is restrained.

JP 2014-22465 A Japanese Patent Laid-Open No. 05-67878 JP 2009-88173 A

  However, in the technique described in Patent Document 1, since only a part of the side surface of the core substrate is covered with the resin, it is difficult to suppress damage to a portion where the resin does not exist. Moreover, if it is attempted to cover not only a part of the side surface of the core substrate but also the resin layer, the dimensional accuracy of the substrate at the time of manufacture may be reduced, and the wiring may be displaced. Therefore, there is a need for a technique that can more effectively suppress damage to the core substrate.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms.

(1) According to one aspect of the present invention, a wiring board is provided. The wiring substrate includes a core substrate made of an inorganic material; and a resin layer disposed on the core substrate and having at least one wiring layer formed therein. The wiring board has a groove defined by the core substrate and the resin layer at least at a part of the outer periphery of the resin layer. In the case of such a wiring board, a groove defined by the core substrate and the resin layer is formed on the outer periphery of the resin layer, so that it is possible to suppress stress from being applied near the outer periphery of the core substrate. it can. Therefore, damage to the core substrate can be effectively suppressed with a simple configuration.

(2) In the wiring board of the above aspect, the depth of the groove portion from the side surface of the core substrate is 0.5% or more and 5% or less with respect to the length of the core substrate along the depth direction of the groove portion. But you can. With the wiring board having such a configuration, it is possible to ensure the depth of the groove portion that can suppress the occurrence of damage to the core substrate while leaving a sufficiently routable area.

(3) In the wiring board of the above aspect, the inorganic material may be one of glass, ceramic, and glass ceramic. When the core substrate is formed of such a material, the difference in thermal expansion between the core substrate and the resin layer increases, so that stress is applied to the vicinity of the outer periphery of the core substrate. Can be suppressed.

(4) In the wiring board of the above aspect, the outer periphery of the resin layer may be disposed on the outer peripheral side of a projection region in which the core substrate is projected in the thickness direction. With such a form of wiring board, it is possible to suppress external force and impact from the thickness direction from being directly applied to the core board, and thus more effectively suppress damage to the core board. Can do.

(5) According to the other form of this invention, the manufacturing method of a wiring board is provided. The manufacturing method includes (A) a step of forming a metal layer on a core substrate made of an inorganic material at a position corresponding to the outer periphery of the wiring substrate; and (B) on the core substrate and the metal layer. A step of disposing a resin layer in which at least one wiring layer is formed; (C) a step of cutting the wiring substrate by cutting the metal layer, the core substrate, and the resin layer; and (D). Forming a groove defined by the core substrate and the resin layer on at least a part of the outer periphery of the resin layer by removing the metal layer remaining on the cut wiring board by etching; Is provided. According to the method for manufacturing a wiring board in such a form, the groove can be formed efficiently.

(6) In the method for manufacturing a wiring board according to the above aspect, the metal layer is formed with a predetermined width along the outer shape of the wiring board, and the width of the metal layer is twice the depth of the groove. The value may be determined based on a value obtained by adding a thickness of a blade used for cutting the core substrate and the resin layer. If it is the manufacturing method of the wiring board of such a form, a groove part can be formed with sufficient precision.

  The present invention is not limited to the above-described form as a wiring board, and can be realized in various forms. For example, it is realizable with forms, such as an electronic device provided with the wiring board.

It is sectional drawing which shows the structure of a wiring board typically. It is process drawing which shows the manufacturing method of a wiring board. It is a figure which shows the manufacture state of the wiring board in each process of FIG. It is a figure which shows arrangement | positioning of an end surface metal layer. It is a figure which shows the 1st modification of a wiring board. It is a figure which shows the 2nd modification of a wiring board.

A. Embodiment:
FIG. 1 is a cross-sectional view schematically showing a configuration of a wiring board 1 as an embodiment of the present invention. FIG. 1 shows XYZ axes that are orthogonal to each other. The XYZ axes in the other figures correspond to the XYZ axes in FIG. The wiring board 1 is a board used as an IC package board or an interposer, for example. The wiring substrate 1 includes a core substrate 5 and a resin layer 10 disposed on the core substrate 5. In the present embodiment, the core substrate 5 and the resin layer 10 have the same projected area and projected shape with respect to the thickness direction (Z direction) of the core substrate 5.

  The core substrate 5 is preferably made of a material having electrical insulation and a thermal expansion coefficient larger than that of silicon and smaller than that of the resin layer 10. As such a material, for example, an inorganic material such as glass, ceramic, or glass ceramic can be used. In the present embodiment, a glass substrate is used as the core substrate 5. This is because the glass substrate has excellent surface smoothness and is highly available in a thin and large size.

  At least one wiring layer is formed inside the resin layer 10. In the present embodiment, one first wiring layer 12 is formed inside the resin layer 10. A second wiring layer 14 is formed on the resin layer 10. A solder resist 22 and bumps (solder bumps) 24 are formed on the second wiring layer 14.

  In the present embodiment, the resin layer 10, the second wiring layer 14, the solder resist 22 and the bumps 24 are formed on both surfaces of the core substrate 5. A through via electrode 8 is formed in the core substrate 5. The through via electrode 8 electrically connects the first wiring layer 12 in the resin layer 10 formed on one surface side of the core substrate 5 and the first wiring layer 12 in the resin layer 10 formed on the other surface side. Connect. The resin layer 10, the second wiring layer 14, the solder resist 22 and the bumps 24 may be formed only on one side of the core substrate 5.

  The wiring substrate 1 includes a groove 40 defined by the core substrate 5 and the resin layer 10 on at least a part of the outer periphery of the resin layer 10. In the present embodiment, the groove 40 is formed on the entire circumference of the resin layer 10. In the present embodiment, the groove 40 is formed on the upper surface and the lower surface of the core substrate 5. The depth d of the groove 40 from the side surface 6 of the core substrate 5 is 0.5% or more and 5% or less with respect to the length L of the core substrate 5 along the depth direction X of the groove 40. preferable. The reason will be described later. Hereinafter, “length L” is also referred to as “external dimension L”.

B. Production method:
FIG. 2 is a process diagram showing a method for manufacturing the wiring board 1. Moreover, FIG. 3 is a figure which shows the manufacture state of the wiring board 1 in each process of this manufacturing method.

  In the manufacturing method of this embodiment, first, the core substrate 5 is prepared (step S10). In this embodiment, a glass substrate made of borosilicate glass having 150 mm square, a thickness of 0.1 mm, and a surface roughness Ra of 0.2 nm was prepared. In the following, the wiring substrate 1 being manufactured is simply referred to as “substrate”.

When the core substrate 5 is prepared, an end face metal layer (metal layer) 41 is subsequently formed on the core substrate 5 (step S20).
FIG. 4 is a diagram showing the arrangement of the end face metal layers 41 when the core substrate 5 is viewed from above (when viewed from the + Z direction in FIG. 1). The end face metal layer 41 is formed with a predetermined width along the outer shape of the wiring substrate 1 (core substrate 5). Further, the end face metal layer 41 is formed so as to straddle a cutting line (dicing line) DL when the substrate is cut into individual pieces in a process described later. The material of the end face metal layer 41 is not particularly limited, but is preferably a material that can be quickly removed in an etching process after individual piece cutting described later. In this embodiment, after forming a Ti / Cu seed layer on a substrate by sputtering, a copper layer having a thickness of 20 μm is formed by a semi-additive method, whereby an end face having a width w (FIG. 4) of 1.03 mm. A metal layer 41 was formed on the core substrate 5.

  When the end face metal layer 41 is formed, the first resin layer 10a is subsequently laminated by applying resin lamination to the substrate (step S30). The first resin layer 10 a covers the core substrate 5 and the end face metal layer 41. As the material of the first resin layer 10a, for example, any of cycloolefin resin, epoxy resin, polyimide resin, phenol resin, urethane resin, silicone resin, polycarbonate resin, acrylic resin, polyacetal resin, and polypropylene resin is used. be able to. In the present embodiment, in step S30, the first resin layer 10a having a thickness of 40 μm is formed by laminating a cycloolefin resin sheet on the core substrate 5 by hot pressing under conditions of a pressure of 0.7 MPa and 110 ° C. . In this step S40, it is preferable to perform a silane coupling process on the core substrate 5 in order to improve the adhesion between the core substrate 5 and the first resin layer 10a before the lamination process.

  After the first resin layer 10a is stacked on the core substrate 5, the through via electrode 8 penetrating the core substrate 5 and the first resin layer 10a and the first wiring layer 12 are formed (step S40). The through via electrode 8 and the first wiring 12 form a through via hole in the substrate by a carbon dioxide laser, and then form a copper wiring on the wall surface of the through via hole and the first resin layer 10a by a semi-additive method. By doing so, they can be formed simultaneously. The through via hole is not limited to the carbon dioxide laser, but can be formed by a known method such as a UV-YAG laser, an excimer laser, sandblasting, or photoetching.

  Subsequently, a known build-up process for forming the second resin layer 10b and the second wiring layer 14 is performed on the first resin layer 10a and the first wiring layer 12 (step S50). Although the build-up method is not particularly limited, in the present embodiment, the second resin layer 10b and the second wiring layer 14 are formed by performing a build-up process by a semi-additive method. The material and laminating method of the second resin layer 10b are the same as those of the first resin layer 10a. In the present embodiment, two build-up layers (first resin layer 10a and second resin layer 10b) are formed above and below the core substrate 5 by this build-up process. The first resin layer 10a and the second resin layer 10b thus formed correspond to the resin layer 10 shown in FIG.

  After the build-up process is performed, the solder resist 22 and the bumps 24 are formed by a well-known method (step S60). After the solder resist 22 and the bumps 24 are formed, the substrate is cut by a dicer, and the substrate is singulated into a predetermined size (20 mm square in this embodiment) (step S70). In the present embodiment, the substrate was cut into individual pieces by cutting the dicing line DL shown in FIG. 4 using a dicing blade having a blade thickness of 0.03 mm. As a result, the end face metal layer 41 is exposed from the side surface of the wiring board 1 after the separation. The width of the end face metal layer 41 after singulation is half of the value obtained by subtracting the blade thickness (0.03 mm) from the width w (1.03 mm) of the end face metal layer 41 when the end face metal layer 41 is formed. (0.5 mm).

  After the wiring substrate 1 is separated into pieces, the end face metal layer 41 is removed (step S80). Specifically, the side surface metal layer 41 remaining in the wiring substrate 1 is removed by etching each side surface of the wiring substrate 1. In this embodiment, the end face metal layer 41 was removed by etching for 2 hours using a ferric chloride solution having a concentration of 39 weight percent. By doing so, as shown in FIG. 1, a groove 40 having a depth d of 0.5 mm and a height of 20 μm is formed. The manufacturing of the wiring board 1 is completed by the series of processes described above.

  According to the method for manufacturing the wiring substrate 1 described above, the groove 40 can be efficiently formed because the groove 40 is formed only by etching the end face metal layer 41. Further, since the width w of the end face metal layer 41 is determined based on a value obtained by adding the thickness of the dicing blade to a value twice the depth d of the groove 40, the groove 40 can be formed with high accuracy. .

C. Evaluation results:
Next, the results of an evaluation test performed on the wiring board 1 manufactured according to the above-described method will be described. Table 1 shown below shows evaluation results of samples of six types of wiring boards 1 in which the depth d of the groove 40 is variously changed. The outer dimension L of each sample is 20 mm, and the height h of the groove 40 is 20 μm. In addition, about these samples, formation of the soldering resist 22 and the bump 24 was abbreviate | omitted. This is because the solder resist 22 and the bump 24 do not affect the result of this evaluation test.

  In this evaluation test, each sample was subjected to a thermal shock test (environmental test standard MIL-STD-883D) for 1000 cycles of temperature rise and fall from a low temperature of −65 ° C. to a high temperature of + 150 ° C. Then, whether or not the side surface 6 of the core substrate 5 was damaged was visually confirmed using a magnifying glass, and those that were not damaged were determined to be acceptable. The evaluation results (A, B, C, and D) shown in Table 1 show that 25 pieces of wiring boards having the same form (wiring boards having the same shape of the groove 40) are produced for one sample, The percentage of wiring boards that have passed is shown. If 95% or more of the produced 25 wiring boards are acceptable (that is, if the acceptance rate is 95% or more), the evaluation result is “A” for the sample. Moreover, if the pass rate was 80% or more and less than 95%, the evaluation result was “B” for the sample. Moreover, if the pass rate was 50% or more and less than 80%, the evaluation result was “C”. Moreover, if the pass rate was less than 50%, the evaluation result was set to “D”.

  According to the evaluation results shown in Table 1, the samples 1 to 3 in which the depth d of the groove 40 is 0.5 to 2 mm have a high pass rate, and the evaluation results are all “A” and good. . In addition, the samples 4 and 5 in which the depth d of the groove part 40 is 0.1 to 0.2 mm also had a lower pass rate than the samples 1 to 3, but the evaluation result was “B” and was good. . On the other hand, the depth 6 of the groove 40 is 0 mm, that is, the sample 6 in which the groove 40 is not formed has an evaluation result of “D”, and the resin layer 10 is peeled off from the side surface of the core substrate 5. Many were observed.

  As described above, according to the evaluation results shown in Table 1, the depth d of the groove 40 is 0.1% or more and 10% or less (0.1 to 2 mm) with respect to the outer dimension L, preferably 0. It has been confirmed that damage to the core substrate 5 can be effectively suppressed when the thickness is 0.5% or more and 10% or less (0.5 to 2 mm). This is because the resin layer 10 is not in contact with the vicinity of the side surface 6 of the core substrate 5 when the groove portion 40 is formed, so that the core substrate is caused by the difference in thermal expansion between the resin layer 10 and the core substrate 5. This is because stress is suppressed from being applied to the vicinity of the side surface 6 of 5.

  The depth d of the groove portion 40 is more preferably 5% or less with respect to the outer dimension L. If the depth d of the groove portion 40 is 5% or less with respect to the outer dimension L, the groove portion 40 capable of suppressing damage to the core substrate 5 while leaving a sufficient wiring area on the core substrate 5. This is because the depth d can be secured.

  According to the present embodiment described above, stress is applied to the vicinity of the outer periphery of the core substrate 5 only by forming the groove 40 defined by the core substrate 5 and the resin layer 10 on the outer periphery of the resin layer 10. Since it can suppress, it can suppress effectively that the core board | substrate 5 is damaged with a simple structure.

  Further, with the configuration of the wiring board 1 of the present embodiment, the core substrate 5 can be structured so as not to be exposed to the outer peripheral side than the resin layer 10, so that an external force or It is possible to suppress the impact from being directly applied to the core substrate 5. Therefore, damage to the core substrate 5 can be more effectively suppressed.

  Furthermore, in this embodiment, a material (inorganic material) having a large thermal expansion difference from the resin layer 10 such as glass, ceramic, glass ceramic, or the like is used as the material of the core substrate 5. The application of stress can be more effectively suppressed by the groove 40.

D. Variation:
FIG. 5 is a diagram showing a first modification of the wiring board. The wiring board 1a in the first modification is different from the embodiment shown in FIG. 1 in the shape of the groove. In the first modification, the groove portion 40 a straddles a plurality of resin layers (the first resin layer 10 a and the second resin layer 10 b) constituting the resin layer 10. Specifically, the groove 40a includes (1) a first portion 43 defined by the core substrate 5 and the first resin layer 10a in contact with the core substrate 5, and (2) a first portion in the first resin layer 10a. 2nd part 44 extended toward 2 resin layer 10b, (3) 3rd part defined by 1st resin layer 10a and 2nd resin layer 10b provided in contact with 1st resin layer 10a 45.

  In this way, if the groove 40a is formed so as to straddle a plurality of resin layers, in addition to the same effects as those of the above embodiment, the resin layer 10 can be given flexibility. Even when the substrate 1 is warped, the connection reliability in the bumps 24 can be maintained. Such a groove 40a is formed, for example, by forming a metal layer corresponding to the shape of the groove 40a in the resin layer 10 in the processing from step S20 to step S50 shown in FIG. It can be formed by etching from the side surface.

  FIG. 6 is a diagram illustrating a second modification of the wiring board. In the wiring board 1 b in the second modification, the size of the core substrate 5 in the XY plane is smaller than the size of the resin layer 10. Specifically, the outer periphery C of the resin layer 10 is arranged on the outer peripheral side with respect to the projection area PA in which the core substrate 5 is projected in the thickness direction Z.

  Thus, if the outer periphery C of the resin layer 10 is arranged on the outer peripheral side of the projection area PA of the core substrate 5, the core substrate 5 is not exposed from the resin layer 10. The core substrate 5 can be more effectively protected from stress and impact from the direction. The wiring board 1b having such a shape is formed, for example, at the time of etching for forming an end electrode penetrating the core substrate 5 along the cutting line and forming the groove 40b, as in the case of forming the through via electrode 8. The end electrode can also be formed by removing at the same time.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features of the embodiments, examples, and modifications corresponding to the technical features in each form described in the summary section of the invention are to solve part or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be appropriately performed. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Wiring board 5 ... Core board 6 ... Side surface 8 ... Through-via electrode 10 ... Resin layer 10a ... 1st resin layer 10b ... 2nd resin layer 12 ... 1st wiring layer 14 ... 2nd wiring layer 22 ... Solder resist 24 ... Bump 40, 40a, 40b ... Groove 41 ... End face metal layer 43 ... First part 44 ... Second part 45 ... Third part PA ... Projection area DL ... Dicing line

Claims (6)

A core substrate made of an inorganic material;
A resin layer disposed on the core substrate and having at least one wiring layer formed therein;
A wiring board comprising:
A wiring board having a groove defined by the core substrate and the resin layer in at least a part of an outer periphery of the resin layer. The wiring board according to claim 1,
The depth of the groove portion from the side surface of the core substrate is 0.5% or more and 5% or less with respect to the length of the core substrate along the depth direction of the groove portion. The wiring board according to claim 1 or 2,
The wiring board according to claim 1, wherein the inorganic material is one of glass, ceramic, and glass ceramic. A wiring board according to any one of claims 1 to 3, wherein
The wiring board, wherein an outer periphery of the resin layer is disposed on an outer peripheral side with respect to a projection region obtained by projecting the core substrate in a thickness direction. A method for manufacturing a wiring board, comprising:
(A) forming a metal layer on the core substrate made of an inorganic material at a position corresponding to the outer periphery of the wiring substrate;
(B) placing a resin layer having at least one wiring layer formed on the core substrate and the metal layer;
(C) cutting the metal substrate, the core substrate, and the resin layer to cut out the wiring substrate;
(D) A groove defined by the core substrate and the resin layer is formed in at least a part of the outer periphery of the resin layer by removing the metal layer remaining on the cut-out wiring board by etching. Process,
A method of manufacturing a wiring board comprising: It is a manufacturing method of the wiring board according to claim 5,
The metal layer is formed to have a predetermined width along the outer shape of the wiring board, and the width of the metal layer is set to a value twice the depth of the groove to cut the core substrate and the resin layer. A method of manufacturing a wiring board, characterized in that the wiring board is determined based on a value obtained by adding a thickness of a blade to be used.

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