Glass wiring board manufacturing method

Abstract

The present invention eliminates a phenomenon in which, when cutting a glass plate on which a resin film is formed, the glass plate is split into layers in the interior thereof. A glass wiring board manufacturing method includes: a through-hole part forming step for forming a through-hole parts in the thickness direction of a glass substrate; a conductive material embedding step for embedding a conductive material in the through-hole parts; a formation step for forming, on both surfaces of the glass substrate, a plurality of resin layer parts of a single type; a groove part forming step for, among the plurality of resin layer parts of a single type that are on both surfaces of the glass substrate, forming groove parts having a prescribed width and prescribed depth in some resin layer parts while leaving alone the closest contact parts that are in close contact with and cover the glass substrate; and a cutting step for using a cutting grindstone of a rotary blade to cut the glass substrate in the thickness direction while the closest contact parts on both surfaces of the glass substrate are in close contact with the glass substrate.

Description

Method for manufacturing a glass wiring board

[0006]

[0001] The present invention relates to a glass wiring board, a method for manufacturing a glass wiring board, and a glass wiring board manufacturing apparatus, and more particularly to a glass wiring board that avoids cracks occurring in the glass wiring board, a method for manufacturing the same, and further a glass wiring board manufacturing apparatus corresponding to the manufacturing.

[0002] Various semiconductor elements such as various memories, CPUs, GPUs, etc. mounted on a circuit board have terminals for electrical connection. The pitch of the connection terminals and the pitch of the connection portion of the circuit board electrically connected to the semiconductor element usually differ by several to several tens of times. Therefore, in order to electrically connect the semiconductor element and the circuit board, an interposer, which is a relay substrate for connection, is used. A semiconductor element is mounted on one surface of the interposer, and a circuit board is connected to the other surface. ​​​​​​​​​​To address the phenomenon of back cracking in the glass plate described above, methods have been proposed such as forming holes that penetrate both the front and back surfaces of the glass plate and filling them with resin (see Patent Document 1), coating the glass plate with a mixture of resin and inorganic filler (see Patent Document 2), modifying the glass plate by irradiating it with a laser (see Patent Document 3), and forming a resin layer on the glass plate and then cutting the glass plate with a rotating blade (dicing blade) (see Patent Document 4).

[0007] The methods described in Patent Documents 1 and 2, among others, have shown some effectiveness in preventing back cracking during glass plate processing. However, these methods increase the number of steps required during the manufacturing process, such as drilling holes in the glass plate, resin filling, and coating with various materials, and are not necessarily simple. Furthermore, due to breakage during the manufacturing of glass-resin substrates, further improvement in production efficiency is desired.

[0008] Methods such as those described in Patent Documents 3 and 4 also exhibit a certain degree of effectiveness against back cracking during glass plate processing. However, the laser irradiation method described in Patent Document 3 requires considerable time to process the glass plate, thus limiting production efficiency. Patent Document 4 improves production efficiency by employing a rotary blade (dicing blade). However, cutting the glass plate with a rotary blade while avoiding the resin layer present in the glass plate and paying attention to back cracking is not easy in terms of precision. Furthermore, there is a risk of back cracking defects occurring in load tests that simulate repeated heating and cooling during use of wiring boards utilizing glass plates.

[0009] Japanese Patent Publication No. 2016-157982, Japanese Patent Publication No. 2020-182006, Japanese Patent Publication No. 2019-021720, International Publication WO / 149374

[0010] The inventor, based on the premise of manufacturing glass wiring substrates, reviewed and diligently improved the manufacturing process, thereby developing an effective countermeasure against the back cracking phenomenon that is unavoidable during the processing of glass plates, and succeeded in developing glass wiring substrates and a method for manufacturing glass wiring substrates.

[0011] The present invention has been made in view of the above points, and provides a glass wiring substrate and a method for manufacturing a glass wiring substrate that can eliminate problems during manufacturing and use and improve productivity by eliminating the phenomenon of the glass plate itself splitting in layers inside itself (back splitting) due to the action that occurs on the resin film (resin layer) when manufacturing a glass wiring substrate by cutting a glass plate to which a resin film is attached or a resin layer is laminated.

[0012] In other words, the glass wiring substrate of the embodiment is characterized by comprising: through holes formed in the thickness direction from the first surface to the second surface of the glass substrate; a conductive material embedded in the through holes; a plurality of resin layers formed on the first surface and the second surface of the glass substrate, respectively; grooves formed on the first surface and the second surface of the glass substrate, in which the plurality of resin layers are cut to a predetermined width; a close-contact portion that forms the bottom of the groove and leaves a resin layer portion that adheres closely to the glass substrate and covers the glass substrate; and a resin layer cut-off portion consisting of the groove and the close-contact portion.

[0013] Furthermore, in the glass wiring substrate of the embodiment, the groove portion may be formed on a second surface portion that is symmetrical to the first surface portion in the thickness direction of the glass substrate.

[0014] Furthermore, in the glass wiring substrate of this embodiment, the glass substrate may be rectangular, and the resin layer cut-off portions may be provided on the four sides of the first surface and the four sides of the second surface of the glass substrate, respectively.

[0015] Furthermore, in the glass wiring substrate of the embodiment, the resin layer cut-off portion may be provided with an inclined portion that widens the width of the groove in the direction away from the glass substrate.

[0016] Furthermore, in the glass wiring substrate of the embodiment, the multiple resin layers may be multiple resin film portions.

[0017] Furthermore, the manufacturing method of the glass wiring substrate according to the embodiment is characterized by comprising: a through-hole forming step of forming through-holes in the thickness direction from the first surface to the second surface of the glass substrate; a conductive material embedding step of embedding conductive material in the through-holes; a forming step of forming a plurality of resin layers on the first surface and the second surface of the glass substrate; a groove forming step of forming grooves of a predetermined width and predetermined depth in the plurality of resin layers formed on the first surface and the second surface of the glass substrate, while leaving a closest-contact portion that adheres to the glass substrate and covers the glass substrate; and a cutting step of cutting the glass substrate in the thickness direction in the groove, separating the closest-contact portion of the first surface, the glass substrate, and the closest-contact portion of the second surface.

[0018] Furthermore, in the manufacturing method of the glass wiring substrate according to the embodiment, the formation of the grooves in the groove formation step may be done by cutting or melting.

[0019] Furthermore, in the manufacturing method of the glass wiring substrate according to the embodiment, the groove portion may be formed on a second surface portion that is symmetrical to the first surface portion in the thickness direction of the glass substrate.

[0020] Furthermore, in the manufacturing method of the glass wiring substrate according to the embodiment, in the groove formation step, an inclined portion is formed in the groove that increases the width of the groove in the direction away from the glass substrate.

[0021] Furthermore, in the manufacturing method of the glass wiring substrate of the embodiment, the multiple resin layers may be multiple resin film portions.

[0022] In addition, the glass wiring substrate manufacturing apparatus used in the manufacturing method of the embodiment is characterized by comprising: a first rotating blade that forms grooves of a predetermined width and depth in a plurality of resin layers; a second rotating blade that cuts from the grooves toward the thickness direction of the glass substrate; and a control unit that controls the positions of the first rotating blade and the second rotating blade.

[0023] The glass wiring substrate of the present invention comprises through-holes formed in the thickness direction from the first surface to the second surface of the glass substrate, a conductive material embedded in the through-holes, a plurality of resin layers formed on the first surface and the second surface of the glass substrate, grooves formed on the first surface and the second surface of the glass substrate by cutting out the plurality of resin layers to a predetermined width, a close-contact portion that forms the bottom of the groove and leaves behind a resin layer that adheres closely to the glass substrate and covers the glass substrate, and a resin layer cut-off portion consisting of the groove and the close-contact portion. Therefore, the phenomenon of the glass substrate itself splitting in layers internally (back cracking) during manufacturing and use can be eliminated due to the action that occurs on the plurality of resin layers and resin film when manufacturing a glass wiring substrate by cutting a glass plate having a plurality of resin layers and a resin film.

[0024] Furthermore, the present invention provides a method for manufacturing a glass wiring substrate, which includes a through-hole forming step to form through-holes in the thickness direction from the first surface to the second surface of the glass substrate, a conductive material embedding step to embed conductive material in the through-holes, a forming step to form a plurality of resin layers on the first surface and the second surface of the glass substrate, a groove forming step to form grooves of a predetermined width and depth in the plurality of resin layers formed on the first surface and the second surface of the glass substrate, while leaving a closest-contact portion that adheres to the glass substrate and covers the glass substrate, and a cutting step to cut the glass substrate in the thickness direction in the groove, separating the closest-contact portion of the first surface, the glass substrate, and the closest-contact portion of the second surface. Therefore, the invention provides a method for manufacturing a glass wiring substrate, which includes a through-hole forming step to form through-holes in the thickness direction from the first surface and the second surface of the glass substrate, which is caused by the action of the plurality of resin layers and resin films when cutting a glass plate equipped with a plurality of resin layers and resin films to manufacture a glass wiring substrate, thereby eliminating defects during manufacturing, increasing productivity, and improving durability during use.

[0025] In addition, the glass wiring substrate manufacturing apparatus used in the method for manufacturing a glass wiring substrate of the present invention includes a first rotating blade that forms grooves of a predetermined width and depth in a plurality of resin layers, a second rotating blade that cuts from the grooves toward the thickness direction of the glass substrate, and a control unit that controls the positions of the first rotating blade and the second rotating blade. Therefore, it is possible to eliminate the phenomenon of the glass plate itself splitting in layers inside (back splitting) due to the action that occurs in the resin film (resin layer) when manufacturing a glass resin substrate by cutting a glass plate to which a resin film has been attached or resin layers have been laminated, thereby eliminating manufacturing defects and providing a manufacturing apparatus that increases productivity.

[0026] Figure 3(B) shows a schematic cross-sectional view illustrating the layered cracking phenomenon (back cracking) of a glass substrate. (A) First schematic cross-sectional view, (B) Second schematic cross-sectional view, and (C) Third schematic cross-sectional view. Figure 3 shows a schematic cross-sectional view of a glass wiring substrate according to an embodiment. (A) First enlarged schematic view of the film cut-off section, and (B) Second enlarged schematic view of the film cut-off section. Figure 3(B) is an enlarged photograph (200x magnification). Figures 3(B) show the manufacturing process of a glass wiring substrate, with (A) First schematic cross-sectional view, (B) Second schematic cross-sectional view, and (C) Third schematic cross-sectional view. Figure 3 shows a schematic cross-sectional view illustrating the manufacturing process of a glass wiring substrate. Figures 3(B) show the manufacturing process of a glass wiring substrate, with (A) a schematic cross-sectional view when using the first rotary blade and (B) a schematic cross-sectional view when using the second rotary blade. Figure 3 shows a schematic cross-sectional view illustrating the manufacturing process of a glass wiring substrate. Figure 3 shows an overall perspective view from above of the glass wiring substrate manufacturing apparatus according to an embodiment. (A) A cross-sectional photograph of a glass wiring substrate with one layer of 40 μm thick resin film formed on it, and (B) A cross-sectional photograph of a glass wiring substrate with two layers of 20 μm thick resin film formed on it. (A) A magnified cross-sectional photograph of a glass wiring substrate with three layers of 20 μm thick resin film formed on it, and (B) A magnified cross-sectional photograph of a glass wiring substrate with three layers of 40 μm thick resin film formed on it. (A) A magnified cross-sectional photograph of a glass wiring substrate with three layers of 40 μm thick resin film formed on it and a film trimmed section formed on it, and (B) A magnified cross-sectional photograph of a glass wiring substrate with eight layers of 20 μm thick resin film formed on it and a film trimmed section formed on it. A magnified cross-sectional photograph of a glass wiring substrate with three layers of 40 μm thick resin film formed on it and cut without forming a film trimmed section.

[0027] The glass wiring substrate of this embodiment is a glass substrate having through-holes that penetrate both the front and back surfaces of the glass substrate, with a conductive metal material placed in these through-holes, and is primarily used as an interposer. A glass interposer, in this context, is a component that serves as a relay substrate for electrically wiring and connecting various semiconductor elements such as memory, CPU, and GPU mounted on a circuit board to the circuit board itself. In particular, since the glass interposer itself is formed only from glass and a conductive material for wiring, it does not contain materials with different coefficients of thermal expansion, such as resin, thus reducing deformation due to thermal exposure during use. Of course, the glass wiring substrate of this embodiment can be applied to various uses other than as an interposer.

[0028] First, using the schematic cross-sectional diagram in Figure 1, we will explain the number of glass substrates 10 and resin film portions 20 laminated onto the glass substrates 10, as well as the phenomenon of layered cleavage (back cracking). The same principle is considered to apply when a resin coating is applied multiple times to create layers instead of the resin film portions 20.

[0029] Figure 1(A) is a schematic cross-sectional view of the glass substrate 10 being cut in the thickness direction when there is no resin film portion 20 (0 pieces). When there is no resin film portion 20, the glass substrate 10 is cut as is and no particular problems occur.

[0030] Figure 1(B) is a schematic cross-sectional view of the glass substrate 10 being cut in the thickness direction when only one resin film portion 20 is attached to the glass substrate 10. When there is only one resin film portion 20, even if stress is applied to the resin film portion 20 during cutting, the glass substrate 10 is relatively thicker, so the deformation force of the resin film portion 20 does not affect the glass substrate 10. As a result, the glass substrate 10 is cut as is, and no particular problems occur.

[0031] Figure 1(C) is a schematic cross-sectional view of a glass substrate 10 cut in the thickness direction when four resin film portions 20 are attached to the glass substrate 10. When there are four resin film portions 20, the deformation of the multiple resin film portions 20 that occurs during cutting becomes stress, and the attached glass substrate 10 is pulled by the stress of the multiple resin film portions 20. As a result, a phenomenon of layered cracking (so-called back cracking) occurs inside the glass substrate 10. The back cracking area C is shown in the figure.

[0032] Thus, whether or not back cracks occur in the glass substrate 10 depends on the number of layers of resin film 20 stacked. Based on this finding, when cutting the glass substrate 10 to divide it into individual substrates, it is considered possible to reduce the stress applied to the glass substrate 10 from multiple resin film 20 (multiple resin layers) by reducing the number of layers of resin film 20 stacked as much as possible, and similarly by reducing the number of layers of resin layers stacked by painting or the like. Therefore, in order to suppress back cracks, the glass wiring substrate and its manufacturing method of the embodiment are characterized by reducing the number of layers of resin film 20 stacked at the cutting location of the glass substrate 10 (the number of layers of resin layers stacked) in advance.

[0033] Furthermore, in this embodiment, the number of layers of the resin film portion 20 on the cutting area of ​​the glass substrate 10 is reduced, so the resin film portion 20 is not completely eliminated. Even after reducing the resin film portion 20, some resin film portion 20 remains on the cutting area of ​​the glass substrate 10, and the glass substrate 10 is cut together with the resin film portion 20 while covered with the resin film portion 20, as described later.

[0034] Based on the findings in Figure 1, the structure of the glass wiring board 1 of the embodiment will be explained using the schematic cross-sectional diagrams in Figures 2 and 3. The glass wiring board 1 is equipped with a glass substrate 10 that constitutes the main structure of the substrate. The material of the glass substrate 10 is alkali glass, alkali-free glass, borosilicate glass, etc. Through holes 13 are formed in the thickness direction from the first surface portion 11 to the second surface portion 12 of the glass substrate 10. Resin film portions 20, 20 are attached to the first surface portion 11 and the second surface portion 12 of the glass substrate 10, respectively. In the figures, multiple resin film portions 20, 20 (four resin film portions 21, 22, 23, and 24, respectively) are attached to the first surface portion 11 and the second surface portion 12. The resin film portion 20 is made of a material with good stretchability and insulating properties, and a film such as epoxy resin is used.

[0035] In addition to the aforementioned lamination of multiple resin film portions 20, the glass wiring substrate 1 of the embodiment can also employ a configuration in which a resin coating agent is applied multiple times to form layers, thereby creating a resin layer of a predetermined thickness. Therefore, the "resin layer portion" is a configuration that encompasses both the form of the "resin film portion" and the form of the "resin layer" derived from the resin coating agent. Of course, as mentioned above, materials such as epoxy resin are used as the resin coating agent. The following explanation and drawings illustrate and describe the resin layer portion as being in the form of the resin film portion. Regarding the closely adhering portion and the resin layer cut-off portion, which will be discussed later, the closely adhering portion and the resin layer cut-off portion are configurations that encompass both the form of the "resin film portion" and the form of the "resin layer" derived from the resin coating agent. When the resin layer portion is in the form of a resin film portion, the closely adhering portion becomes the closely adhering film portion, and the resin layer cut-off portion becomes the film cut-off portion.

[0036] The through-holes 13 in the glass substrate 10 are formed using known methods such as laser irradiation or etching with an acid or alkali solution. A conductive material 14 is embedded inside the through-holes 13. The conductive material 14 is a conductive resin paste containing fine particles of metals such as copper, silver, gold, platinum, nickel, and lead. This ensures conductivity of the through-holes 13 from the first surface 11 to the second surface 12. Alternatively, copper or silver plating is formed inside the through-holes 13 to achieve conductivity.

[0037] Wiring sections 15 are formed on the resin film sections (resin layer sections) 20, 20 (resin film sections 21, 22, 23, 24, respectively), thereby providing conductivity on both the first surface 11 and the second surface 12 of the glass substrate 10. The structure and position of the wiring sections 15 are appropriate according to the design of the glass wiring substrate 1, and the illustration is merely a schematic example.

[0038] A structural feature of the glass wiring substrate 1 of this embodiment is that grooves 31 of a predetermined width are formed in multiple resin film portions 20, 20 (multiple resin layers) that are laminated by adhesion to the first surface portion 11 and the second surface portion 12 of the glass substrate 10. In Figure 1, the grooves 31 are formed by removing some of the resin film portions 20 (multiple resin layers) from the multiple resin film portions 20 (multiple resin layers), leaving a close-adhesion film portion 34 (closest-adhesion portion) that is in close contact with the glass substrate 10 and covering the glass substrate 10. The close-adhesion film portion shown corresponds to the resin film portion 21.

[0039] Then, a film cut-off portion 30 is formed from the vertical groove portion 31 and the horizontal close-adhesion film portion (resin film portion 21). The film cut-off portion 30 has a structure in which multiple resin film portions 20 (multiple resin layers) are cut from the side edge 10e of the glass substrate 10 in the width direction of the glass substrate 10 while leaving the close-adhesion film portion.

[0040] The groove 31 is formed by cutting a predetermined width into the second surface 12, which is symmetrical (line symmetrical) to the first surface 11 in the thickness direction of the glass substrate 10. As described in the manufacturing method below, the glass substrate 10 is cut together with the closest-adhesion film portion 34 (closest-adhesion portion) of the resin film portions 20, 20 (resin layer portions). Therefore, in order to separate the substrate in the center of the groove 31 during a single cut, it is necessary to align the positions of the groove 31, and the formation positions of the groove 31 are aligned on both the front and back surfaces of the glass substrate 10.

[0041] The glass wiring substrate 1 of this embodiment is square or rectangular to match the shape of the semiconductor elements mounted on the circuit board. Therefore, the glass substrate 10 is rectangular (square or rectangular). The film trimming portions 30 are provided around the perimeter of the rectangular glass substrate 10, on the four sides of the first surface portion 11 and the four sides of the second surface portion 12, respectively. Figure 2 is a schematic cross-sectional view of the glass wiring substrate 1. As can be seen from the figure, the film trimming portions 30 are provided at the four corners on the first surface portion 11 side and the four corners on the second surface portion 12 side of the glass substrate 10 (the figure is a partial disclosure of the cross-section). In other words, at each of the four corners on the first surface portion 11 side and the four corners on the second surface portion 12 side of the glass substrate 10, the film trimming portions 30 (resin layer trimming portions) are formed in a long, L-shaped cross-sectional view on the laminated resin film portions 20, 20 (resin layer portions). The film trimming portions 30 are formed by the vertical wall surface of the groove portion 31 and the surface of the closest-adhesion film portion 34.

[0042] There are two types of film trimming portions 30, as shown in the enlarged schematic diagram in Figure 3. The film trimming portion 30 in Figure 3(A) is formed perpendicular to the multiple resin film portions 20, 20 (resin film portions 21, 22, 23, 24) (multiple resin layer portions). In contrast, the film trimming portion 30a in Figure 3(B) is provided with an inclined portion 32 that widens the width of the groove portion 31a in the direction away from the glass substrate 10 (in the order of resin film portions 21, 22, 23, 24). The method for forming the film trimming portions 30, 30a (resin layer trimming portions) in Figures 3(A) and 3(B) will be described later in the manufacturing method section.

[0043] In the film trimmed portion 30a of Figure 3(B) compared to the film trimmed portion 30 of Figure 3(A), the opening of the film trimmed portion 30a gradually increases. In other words, the amount of resin film 20 layered gradually decreases. From this, it can be considered that the stress generated in the resin film portion 20 (resin layer portion) decreases as it moves away from the glass substrate 10, and the force acting on the glass substrate 10 decreases.

[0044] Figure 4 is a magnified photograph (200 times magnification) taken by prototyping the film cutting portion 30a of FIG. 3(B). In the photograph, the thickness of the glass substrate is 495.52 μm, the film thickness of the closest contact film portion is 25.07 μm on the upper side and 27.60 μm on the lower side, and the layer thickness of the resin film portion excluding the closest contact film portion is 210.79 μm on the upper side and 177.08 μm on the lower side. As can be understood from the photograph, the opening amount of the film cutting portion 30a gradually increases, and in a side view (cross-sectional view), the film cutting portion 30a has an approximately "J" shape.

[0045] In the glass wiring board 1 of the embodiment, a plurality of resin film portions 20, 20 (a plurality of resin layer portions) are cut out leaving a part. However, the closest contact film portion 34 (closest contact portion) that remains in contact with the glass substrate 10 and covers the glass substrate 10 is left. Thus, the intentional formation of the closest contact film portion 34 (closest contact portion) is, as is clear from the verification of the following examples, to prevent back cracking when cutting the glass substrate 10. Furthermore, it also has the effect of maintaining durability considering the repeated use conditions of heating and cooling of the glass wiring board 1.

[0046] Subsequently, the manufacturing method of the glass wiring board 1 of the embodiment will be described using each schematic diagram of FIGS. 5 to 8. In FIG. 5(A), the glass substrate 10 constituting the glass wiring board 1 of the embodiment is prepared. In FIG. 5(B), a through-hole portion 13 is formed in the glass substrate 10 in the thickness direction from the first surface portion 11 to the second surface portion 12 ("through-hole portion forming step"). The formation of the through-hole portion 13 in the glass substrate 10 is by either punching by immersion (etching) in a chemical solution of an acid such as hydrofluoric acid or a chemical solution of an alkali such as caustic soda, or punching by laser light irradiation, or a combination of both.

[0047] In FIG. 5(C), after the through-hole portion 13 is formed, a conductive material is embedded in the through-hole portion 13 (the "conductive material embedding step"). The conductive material 14 is a conductive resin paste containing fine particles of a metal such as copper, silver, gold, platinum, nickel, or lead. Thus, the conductivity of the through-hole portion 13 from the first surface portion 11 to the second surface portion 12 is ensured by the conductive material 14. Alternatively, copper or silver plating is formed inside the through-hole portion 13 to make the through-hole portion 13 conductive.

[0048] In FIG. 6, a plurality of resin layer portions are formed on each of the first surface portion 11 and the second surface portion 12 of the glass substrate 10. In the embodiment, a resin film portion 20 is adhered to each of the first surface portion 11 and the second surface portion 12 (the "formation step / adhesion step"). Similar to the example shown in FIG. 1, wiring portions 15 are formed in the resin film portions 20, 20 (respective resin film portions 21, 22, 23, 24), and conductivity is achieved on both the first surface portion 11 side and the second surface portion 12 side of the glass substrate 10. The illustrated resin film portion 21 corresponds to the closest adhesion film portion (closest adhesion portion) that adheres closely to the glass substrate 10.

[0049] In FIGS. 7(A) and 7(B), among the plurality of resin film portions 20, 20 adhered to the first surface portion 11 and the second surface portion 12 of the glass substrate 10, groove portions 31, 31a having a predetermined width and a predetermined depth for forming the closest adhesion film portion 34 (in the illustration, the resin film portion 21) (closest adhesion portion) that remains with at least the resin film portion 20 that adheres closely to the glass substrate 10 and covers the glass substrate 10 are formed in the plurality of resin film portions (plural resin layer portions) (the "groove portion forming step"). When forming the groove portions 31, 31a, in the embodiment, cutting grindstones 50, 50a (rotary blades, dicing blades) containing diamond powder are brought into contact with the plurality of resin film portions 20, 20 and are cut (ground) so as to leave the closest adhesion film portion 34 (closest adhesion portion).

[0050] In the case of a cutting wheel 50 (rotating blade), position control is accurate and easy, making it preferable for forming the groove 31 in the groove formation process. Note that cutting while leaving the closest-adhering film portion does not mean being so precise as to leave only the closest-adhering film portion, but also includes cases where cutting reaches a part of the closest-adhering film portion, and even cases where cutting ends in the middle of other resin film portions laminated to the closest-adhering film portion. Of course, when forming the groove 31 in the groove formation process, known methods such as dissolving the resin portion using chemical solutions such as organic solvents for resins, or cutting the resin portion by irradiation with laser light (cutting by melting) may be employed.

[0051] In forming the groove 31 in Figure 7(A), a cutting wheel 50 (rotating blade) with a square-shaped end is used. This corresponds to the creation of the film trimming section 30 (resin layer trimming section) in Figure 3(A). In forming the groove 31a in Figure 7(B), a cutting wheel 50a (rotating blade) with a rounded chamfered end is used. This corresponds to the creation of the film trimming section 30a (resin layer trimming section) in Figure 3(B). Due to the shape of the cutting wheel 50a (rotating blade, dicing blade), an inclined section 32 that widens the groove 31a is simultaneously formed. In this case, in cross-sectional view, the groove 31a is approximately "U" shaped.

[0052] When forming the grooves 31, 31a, the positions of the grooves 31 relative to each other are formed on the second surface 12, which is symmetrical (line symmetrical) with respect to the first surface 11 in the thickness direction of the glass substrate 10. This is to ensure that the positions are aligned during cutting, as described below. The size of the grooves with a predetermined width and depth in the multiple resin film sections (multiple resin layers) that leave the closest-adhering film section (resin film section 21 in the figure) (closest-adhering section) in the groove formation process is influenced by various factors such as the type of resin, the amount of thermal expansion, elasticity, and the groove formation method, so it is not easy to define a range for the size of the grooves in general.

[0053] In Figure 8, at the grooves 31 and 31a, the closest-adhesion film portion (resin film portion 21) of the first surface portion 11, the glass substrate 10, and the closest-adhesion film portion (resin film portion 21) of the second surface portion 12 are cut in the thickness direction of the glass substrate 10 ("cutting process"). A cutting wheel 50 (rotary blade, dicing blade) with a square-shaped end is used for cutting. The closest-adhesion film portion corresponds to the closest-adhesion portion.

[0054] In the cutting process shown in Figure 8, when the groove 31 in Figure 7(A) is cut by the cutting wheel 50, the film trimmed portion 30 (resin layer trimmed portion) in Figure 3(A) is formed on the end face. In other words, the rectangular groove 31 forms an L-shaped film trimmed portion 30 on the end face. Also, in the cutting process, when the groove 31a in Figure 3(B) is cut by the cutting wheel 50, the film trimmed portion 30a (resin layer trimmed portion) in Figure 3(B) is formed on the end face. In other words, the U-shaped groove 31 forms a J-shaped film trimmed portion 30 on the end face.

[0055] As can be seen from the illustration, film trimming portions 30, 30a (resin layer trimming portions) originating from grooves 31, 31a are formed on the first surface 11 side and the second surface 12 side of the glass substrate 10, respectively. In other words, in the film trimming portions 30, 30a, the resin film portion (resin layer portion) that adheres to the glass substrate 10 is limited to the minimum closest-adhesion film portion (closest-adhesion portion). Therefore, when the cutting wheel 50 (rotating blade, dicing blade) contacts the closest-adhesion film portion, the stress generated in the closest-adhesion film portion is small compared to the entirety of the multiple laminated resin film portions 20, 20 (multiple resin layers), and the propagation of stress from the closest-adhesion film portion (closest-adhesion portion) to the glass substrate 10 is suppressed. By reducing the volume of the resin film portion 20, 20 (resin layer portion) at the cutting location in advance, the influence of excess stress generated from the resin film portion 20, 20 (resin layer portion) on the glass substrate 10 is mitigated, and deformation of the glass substrate 10 is avoided. As a result, this method is effective in preventing the aforementioned phenomenon of the glass plate itself splitting in layers internally (back cracking).

[0056] To reiterate, in the embodiment, the glass wiring substrate 1 has multiple resin film portions 20, 20 (multiple resin layers) that are partially removed, leaving only a portion intact. However, a close-contact film portion 34 (closest contact portion) remains, which is the resin film portion 20 that adheres closely to and covers the glass substrate 10. The purpose of intentionally forming this close-contact film portion 34 (closest contact portion) is to prevent back cracking when cutting the glass substrate 10, as will be clear from the verification of the embodiments described later. In other words, by intentionally thinning the multiple resin film portions 20, 20 (multiple resin layers), the stress applied from the resin film portions 20, 20 to the glass substrate 10 is reduced.

[0057] Here, if the closest-adhesion film portion 34 (closest-adhesion portion) is completely removed and only the glass substrate 10 is exposed and cut with a cutting wheel 50 (rotating blade, dicing blade), the stress caused by the resin film portions 20, 20 will be further reduced, and it seems that back cracking when cutting the glass substrate 10 will be further reduced. However, in a state where the glass substrate 10 is exposed without the closest-adhesion film portion 34 (closest-adhesion portion) of the resin film portions 20, 20 interposed, a fine-grit cutting wheel 50 (rotating blade, dicing blade) must be used to cut the hard glass substrate 10, resulting in significant wear of the cutting wheel 50. Here, if a coarse cutting wheel 50 (rotating blade, dicing blade) is used, fine cracks are likely to occur at the cutting site, and these cracks will enlarge with repeated heating and cooling, resulting in damage and defects such as back cracking in the glass wiring board 1, thereby reducing its durability. Therefore, considering the improvement of the cutting efficiency of the glass substrate 10 and the improvement of the durability of the glass wiring board 1 after it becomes a product, the glass substrate 10 is cut while the closest-adhesion film portion 34 (closest-adhesion portion) is still present.

[0058] Figure 9 is a perspective view showing an example of a glass wiring board manufacturing apparatus 500 for manufacturing the glass wiring board 1 described above. The glass wiring board manufacturing apparatus 500 includes a first rotating blade 501 that forms grooves 31, 31a of a predetermined width and depth in a plurality of resin layer portions 20 (resin film portions 21, 22, 23, 24) of the glass substrate 10, and a second rotating blade 502 that cuts the grooves 31, 31a of the glass substrate 10 in the thickness direction.

[0059] Furthermore, the glass wiring substrate manufacturing apparatus 500 includes a control unit 505 inside the base unit 507 that controls the positions of the first rotating blade 501 and the second rotating blade 502. The control unit 505 is a control device or control board on which known computing elements such as a microcomputer or programmable logic controller are mounted.

[0060] In the illustrated glass wiring substrate manufacturing apparatus 500, the workpiece W is placed at a predetermined position on the turntable 508 of the base 507. The workpiece W is rotated through the turntable 508 in accordance with the cutting process performed by the first rotating blade 501 and the second rotating blade 502. The workpiece W is a glass wiring substrate 1.

[0061] The first rotating blade 501 is held by the first arm 503, and the second rotating blade 502 is held by the second arm 504. The first rotating blade 501 and the second rotating blade 502 are known rotating blades (cutting wheels, dicing blades) used for processing glass, silicon wafers, etc., such as grinding wheels containing diamond or the like. The first rotating blade 501 is a thick (thick and wide) rotating blade used to form grooves 31, 31a of a predetermined width in the resin film portion 20 (resin film portions 21, 22, 23, 24). In contrast, the second rotating blade 502 is a thinner (thinner) rotating blade than the first rotating blade 501 used to sequentially cut each glass substrate 10 of the laminate 45.

[0062] The base portion 507 is equipped with a motor (servo motor, stepping motor, etc.) for rotating the turntable 508 (not shown). The base portion 507 is also equipped with a case portion 509, which is equipped with rails and motors (servo motor, stepping motor, etc.) (not shown) for the vertical, horizontal, and vertical movement (see arrows) of the first arm 503 and the second arm 504. The amount of movement of the first arm 503 and the second arm 504 is controlled under the control of the control unit 505.

[0063] The glass wiring substrate manufacturing apparatus 500 of this embodiment can ultimately manufacture a glass wiring substrate 1 by using the first rotary blade 501 and the second rotary blade 502 depending on the desired groove width and the workpiece. Since the processing is done using only rotary blades, it is possible to process faster than laser irradiation processing. This is particularly advantageous for mass production of glass wiring substrates 1.

[0064] Based on the manufacturing method for glass wiring substrates disclosed in the embodiments, the inventors fabricated glass wiring substrates while varying the thickness (film thickness) and number of layers of the epoxy resin film. They then observed the condition of each glass wiring substrate and conducted temperature endurance tests to evaluate the occurrence of defects such as back cracks in the glass wiring substrates. Figures 10, 11, 12, and 13 are magnified cross-sectional photographs of the fabricated glass wiring substrates. All photographs are magnified 150 times.

[0065] Figure 10(A) shows a glass wiring board manufactured by laminating one layer of epoxy resin film (40 μm thick) on both sides of a glass substrate and cutting it with a dicing blade. After cutting, the glass wiring board was subjected to a thermal shock test consisting of 160 cycles of cooling at -65°C for 30 minutes and heating at 125°C for 30 minutes each. This is a magnified cross-sectional photograph of the glass wiring board after the same thermal shock test was performed 160 cycles. Figure 10(B) shows a glass wiring board manufactured by laminating two layers of epoxy resin film (20 μm thick) on both sides of a glass substrate of the same specifications and cutting it with a dicing blade. This is a magnified cross-sectional photograph of the glass wiring board manufactured by doing the same thermal shock test 160 times. In both the glass wiring boards in Figure 10(A) and (B), no back cracks occurred in the glass substrate and no delamination of the resin film occurred.

[0066] Figure 11(A) shows a glass wiring board manufactured by laminating three layers of epoxy resin film (20 μm thick) on both sides of a glass substrate of the same specifications and cutting it with a dicing blade. The image is a magnified cross-sectional photograph after a heat resistance test was conducted on the glass wiring board by heating it at 260°C for 60 minutes after cutting. At this time, a black streak appeared within the ellipse shown. This is a delamination phenomenon that occurred in the glass substrate, known as back cracking. It is likely that the difference in thermal expansion coefficients between the glass substrate and the resin film caused strain deformation.

[0067] Figure 11(B) shows a glass wiring board manufactured by laminating three layers of epoxy resin film (40 μm thick) onto one side of a glass substrate of the same specifications and cutting it with a dicing blade. When the glass substrate was cut together with the resin film, a large back crack occurred in the glass substrate, as shown within the ellipse in the figure. This is thought to be due to the glass substrate being pulled together by stress caused by the elasticity of the resin film.

[0068] Thus, experiments have shown that the problem of back cracking increases as the thickness of the resin film layer formed on the surface of the glass substrate increases. Therefore, we investigated the effect of reducing the thickness of the pre-laid resin film layer when cutting with a dicing blade.

[0069] Figure 12(A) shows a glass wiring board fabricated by laminating three layers of epoxy resin film (40 μm thick) on both sides of a glass substrate, leaving approximately 30 μm of resin film on both sides of the glass substrate, and then cutting off the resin film with a dicing blade. The glass substrate was then cut together with the resin film using the dicing blade. The image shows a magnified cross-sectional photograph of the glass wiring board after 160 cycles of a temperature shock test, in which one cycle consists of cooling at -65°C for 30 minutes and heating at 125°C for 30 minutes.

[0070] Figure 12(B) shows a glass wiring board fabricated by laminating eight layers of epoxy resin film (20 μm thick) on both sides of a glass substrate of the same specifications, leaving approximately 30 μm of resin film on both sides of the glass substrate, and then cutting off the resin film with a dicing blade. The glass substrate was then cut together with the resin film using the dicing blade to produce the glass wiring board. The image is a magnified cross-sectional photograph of the glass wiring board after undergoing a similar temperature shock test for 160 cycles following the cutting.

[0071] In the glass wiring substrates shown in Figures 12(A) and (B), the resin film portion is removed while the closely adhering film portion remains. This allows for lamination of the resin film portion while enabling cutting with a dicing blade, and in particular, it was able to withstand damage caused by thermal shock testing.

[0072] Figure 13 shows a glass wiring board fabricated by laminating three layers of epoxy resin film (40 μm thick) on both sides of a glass substrate, then completely cutting away the resin film from both sides of the glass substrate using a dicing blade. The glass substrate was then cut together with the resin film using the dicing blade. The image shows a magnified cross-section of the glass wiring board after 160 cycles of a thermal shock test, each cycle consisting of cooling at -65°C for 30 minutes and heating at 125°C for 30 minutes. Although no back crack occurred during the cutting of the glass substrate, a large back crack occurred in the glass substrate as shown within the ellipse in the figure after the thermal shock test. This is thought to be due to the difference in thermal expansion coefficients between the glass substrate and the resin film, which caused strain deformation.

[0073] Based on the test results in Figures 10 to 13, we further investigated the frequency and variability of back crack occurrence during manufacturing. Specifically, five prototypes were manufactured for the following examples, and the percentage of defects such as back cracks among them was confirmed (either zero defects or five defects). The confirmation was performed at three time points: (a) when cutting the glass substrate, (b) after conducting a heat resistance test by heating at 260°C for 60 minutes, and (c) after conducting 160 cycles of a temperature shock test consisting of one cycle of cooling at -65°C for 30 minutes and heating at 125°C for 30 minutes.

[0074] (Prototype Example 1) Only the glass substrate was cut using a dicing blade. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance testing: 0 defects were found in 5 samples. (c) After thermal shock testing: 0 defects were found in 5 samples.

[0075] (Prototype Example 2) A single layer of epoxy resin film (40 μm thick) was laminated onto both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance testing: 0 defects were found in 5 samples. (c) After thermal shock testing: 0 defects were found in 5 samples.

[0076] (Prototype Example 3) Two layers of epoxy resin film (40 μm thick) were laminated on both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects occurred out of 5 samples (b) After heat resistance test: 5 defects occurred out of 5 samples (c) After thermal shock test: Measurement impossible

[0077] (Prototype Example 4) Three layers of epoxy resin film (40 μm thick) were laminated on both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 5 out of 5 samples had defects. (b) After heat resistance test: Measurement impossible. (c) After thermal shock test: Measurement impossible.

[0078] (Prototype Example 5) A single layer of epoxy resin film (20 μm thick) was laminated onto both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance testing: 0 defects were found in 5 samples. (c) After thermal shock testing: 0 defects were found in 5 samples.

[0079] (Prototype Example 6) Two layers of epoxy resin film (20 μm thick) were laminated on both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance test: 0 defects were found in 5 samples. (c) After thermal shock test: 0 defects were found in 5 samples.

[0080] (Prototype Example 7) Three layers of epoxy resin film (20 μm thick) were laminated on both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects occurred out of 5 samples (b) After heat resistance test: 5 defects occurred out of 5 samples (c) After temperature shock test: Measurement impossible

[0081] (Prototype Example 8) Four layers of epoxy resin film (20 μm thick) were laminated on both sides of a glass substrate, and then the glass substrate was cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 5 out of 5 samples had defects. (b) After heat resistance test: Measurement impossible. (c) After thermal shock test: Measurement impossible.

[0082] (Prototype Example 9) Three layers of epoxy resin film (40 μm thick) were laminated on both sides of a glass substrate. Then, the resin film was completely removed from both sides of the glass substrate using a dicing blade. The glass substrate was then cut together with the resin film using a dicing blade. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance test: 0 defects were found in 5 samples. (c) After thermal shock test: 5 defects were found in 5 samples.

[0083] (Prototype Example 10) Three layers of epoxy resin film (40 μm thick) were laminated on both sides of a glass substrate. Approximately 30 μm of resin film remained on both sides of the glass substrate, and the resin film was removed using a dicing blade. The glass substrate was then cut together with the resin film using a dicing blade to produce the product. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance test: 0 defects were found in 5 samples. (c) After thermal shock test: 0 defects were found in 5 samples.

[0084] (Prototype Example 11) Eight layers of epoxy resin film (20 μm thick) were laminated on both sides of a glass substrate. Approximately 30 μm of resin film remained on both sides of the glass substrate, and the resin film was removed using a dicing blade. The glass substrate was then cut together with the resin film using a dicing blade to produce the product. (a) During glass substrate cutting: 0 defects were found in 5 samples. (b) After heat resistance test: 0 defects were found in 5 samples. (c) After thermal shock test: 0 defects were found in 5 samples.

[0085] In the case where there is no resin film portion, as in prototype example 1, it is not necessary to consider the stress caused by the resin film portion. As shown in the comparison between prototype examples 2, 5, and 6 and prototype examples 3, 4, 7, and 8, the defect of back cracking increases as the thickness of the resin film portion increases.

[0086] Based on Prototype Example 1, Prototype Example 9, in which the resin film portion was completely removed, showed significant degradation after the thermal shock test. It is presumed that microscopic cracks formed in the glass substrate when the exposed glass substrate was cut with a dicing blade triggered the cracking, and the repeated expansion and contraction of the resin film portion due to temperature changes led to stress and ultimately back cracking.

[0087] In contrast, as shown in prototype examples 10 and 11, the presence of an intentionally close-adhesion film portion (close-adhesion section) moderately mitigates the impact on the glass substrate during cutting by the dicing blade, thereby preventing the formation of minute cracks in the glass substrate. Therefore, the advantages of the glass wiring substrate and its manufacturing method, which are provided in the embodiments, can be demonstrated.

[0088] 1 Glass wiring board 10 Glass substrate 10e Side edge 11 First surface 12 Second surface 13 Through hole 14 Conductive material 15 Wiring section 20 (21, 22, 23, 24) Resin film section (resin layer section) 30, 30a Film trimming section (resin layer trimming section) 31, 31a Groove section 32 Inclined section 34 Closest-adhesion film section (closest-adhesion section) 50, 50a Cutting wheel (rotating blade) 500 Glass wiring board manufacturing apparatus 501 First rotating blade 502 Second rotating blade 503 First arm 504 Second arm 505 Control unit 506 Rotating blade moving section 507 Base section 508 Turntable C Back split section W Workpiece

Claims

1. A method for manufacturing a glass wiring substrate, comprising: a through-hole forming step of forming through-holes in the thickness direction from a first surface to a second surface of a glass substrate; a conductive material embedding step of embedding a conductive material in the through-holes; a forming step of forming a plurality of single-type resin layers on each of the first and second surfaces of the glass substrate; a groove forming step of forming grooves of a predetermined width and depth on the plurality of resin layers, with the closest-contact portion remaining in close contact with the glass substrate and covering the glass substrate, and the closest-contact portion being formed on the second surface of the glass substrate symmetrical to the first surface in the thickness direction of the glass substrate; and a cutting step of cutting the closest-contact portion of the first surface, the glass substrate, and the closest-contact portion of the second surface in the thickness direction of the glass substrate, while both the closest-contact portion of the first surface and the closest-contact portion of the second surface are in close contact with the glass substrate in the grooves.

2. The method for manufacturing a glass wiring substrate according to claim 1, wherein the formation of the groove in the groove formation step is by cutting or melting.

3. The method for manufacturing a glass wiring substrate according to claim 1, wherein, in the groove forming step, an inclined portion is formed in the groove that increases the width of the groove in a direction away from the glass substrate.

4. The method for manufacturing a glass wiring substrate according to claim 1, wherein the multiple resin layers of a single type are multiple resin film portions of a single type.

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