Wiring board and method for manufacturing a wiring board

Abstract

To provide a method for manufacturing a wiring board with excellent flatness. [Solution] The manufacturing method of the wiring board of the embodiment is a manufacturing method of a wiring board 100 comprising a circuit pattern region A and a frame region B surrounding the circuit pattern region A, and includes laminating an adhesive sheet on a substrate within the circuit pattern region A and the frame region B, and forming a first insulating layer on the substrate by heat pressing the adhesive sheet to the substrate, wherein the first pressure during heat pressing in the circuit pattern region A is greater than the second pressure during heat pressing in the frame region B, the heat pressing includes forming a first protrusion on the adhesive sheet due to the pressure difference between the first pressure and the second pressure, and forming the first insulating layer includes curing the adhesive sheet including the first protrusion by heating, and the first protrusion is formed within the frame region B at a position where it is not exposed to the end face of the first insulating layer.

Description

Technical Field

[0001] The present invention relates to a wiring board and a method for manufacturing the wiring board.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a wiring board, which includes laminating a resin insulating layer having a protective film on a substrate, and removing a portion protruding from the outer edge of the protective film in the resin insulating layer while the resin insulating layer has the protective film, using a solvent.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method disclosed in Patent Document 1, since it is necessary to additionally perform a step of removing a portion protruding from the outer edge of the protective film in the resin insulating layer, there is a risk of reducing the production efficiency of the wiring board.

Means for Solving the Problems

[0005] The present invention relates to a method for manufacturing a wiring board comprising a circuit pattern region and a frame region surrounding the circuit pattern region, and includes laminating an adhesive sheet on a substrate within the circuit pattern region and the frame region, and thermocompressing the adhesive sheet to the substrate by heating and pressing to form a first insulating layer on the substrate. The first pressure during thermocompression in the circuit pattern region is greater than the second pressure during thermocompression in the frame region, the thermocompression includes forming a first protrusion on the adhesive sheet due to the pressure difference between the first and second pressures, and forming the first insulating layer includes curing the adhesive sheet including the first protrusion by heating, the first protrusion is formed within the frame region at a position where it is not exposed to the end face of the first insulating layer.

[0006] The wiring board of the present invention comprises a circuit pattern region and a frame region surrounding the circuit pattern region. The wiring board has a first insulating layer and a second insulating layer on the first insulating layer, the first insulating layer having a first protrusion formed in the frame region and not exposed from the end face of the wiring board, and the second insulating layer covering the first protrusion.

[0007] According to embodiments of the present invention, it is possible to manufacture wiring boards with improved flatness from the edge of the resin insulating layer of the wiring board to the center of the product area in a high yield. [Brief explanation of the drawing]

[0008] [Figure 1] A partial cross-sectional view showing an example of a wiring board according to an embodiment. [Figure 2] A partial cross-sectional view showing another example of the wiring board of the embodiment. [Figure 3] A plan view showing an example of a wiring board according to the embodiment. [Figure 4A] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4B] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4C]A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4D] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4E] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4F] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4G] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4H] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4I] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4J] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Figure 4K] A cross-sectional view showing an example of a wiring board being manufactured using the manufacturing method of the embodiment of the wiring board. [Modes for carrying out the invention]

[0009] A method for manufacturing a wiring board according to one embodiment of the present invention and an example of a wiring board according to the embodiment will be described with reference to the drawings. Figures 1 and 2 show partial cross-sectional views of wiring boards 100 and 110, which are examples of wiring boards according to this embodiment. A method for manufacturing one embodiment is shown in Figures 4A to 4K. As shown in Figures 1 and 2, the wiring boards 100 and 110 have a circuit pattern area A and a frame area B formed around the circuit pattern area A. Figure 3 is a plan view showing the circuit pattern area A and the frame area B around the circuit pattern area A in the wiring boards 100 and 110.

[0010] The wiring boards 100 and 110 in Figures 1 and 2 are merely examples of wiring boards in the embodiment. That is, by the manufacturing method of the wiring board in the embodiment, it is possible to manufacture wiring boards having a different structure from the laminated structure of wiring boards 100 and 110, and / or containing a different number of resin insulating layers and wiring layers than the number of wiring layers and resin insulating layers in wiring boards 100 and 110. Note that in the drawings referenced in the following description, certain parts may be enlarged to facilitate understanding of the disclosed embodiment, and the size and length of each component may not be depicted in the exact proportions relative to each other.

[0011] As shown in Figure 1, the wiring board 100 includes a core substrate 3 and, sequentially laminated on the first surface 31 of the core substrate 3, a resin insulating layer 11, a wiring layer 21, a resin insulating layer 12, a wiring layer 22, a resin insulating layer 13, a wiring layer 23, and a solder resist 41. Furthermore, the wiring board 100 includes, sequentially formed on the second surface 32 of the core substrate 3, a resin insulating layer 15, a wiring layer 25, a resin insulating layer 16, a wiring layer 26, a resin insulating layer 17, a wiring layer 27, and a solder resist 42 (hereinafter, "resin insulating layer" will also be simply referred to as "insulating layer"). The core substrate 3 is composed of an insulating layer 19 and wiring layers 28 and 29 formed on both sides of the insulating layer 19, respectively. The core substrate 3 has through-hole conductors 51 that penetrate the insulating layer 19 and connect the wiring layers 28 and 29. The inside of the cylindrical through-hole conductors 51 is filled with a filler 51a made of epoxy resin or the like.

[0012] In the description of the manufacturing method of the wiring board according to the embodiments described below, the side of the wiring board 100 furthest from the insulating layer 19 in the thickness direction (lamination direction) is referred to as the "outside," "upper side," or "upper," or simply "upper," while the side closer to the insulating layer 19 is referred to as the "inside," "lower side," or "downward," or simply "lower." Furthermore, for each component such as the wiring layer and the insulating layer, the surface facing away from the insulating layer 19 is also referred to as the "upper surface," and the surface facing the insulating layer 19 is also referred to as the "lower surface."

[0013] In each of the insulating layers 11 to 13, 15 to 17, a via conductor 5 is formed through each of these insulating layers to connect the wiring layers on both sides of each insulating layer. The wiring layers 21 to 23, 25 to 27, 28, and 29 each contain an arbitrary conductor pattern such as a wiring pattern or a conductor pad. In the example of FIG. 1, the wiring layer 28 and the wiring layer 29 each contain dummy patterns 2a and 2b in the frame region B.

[0014] The insulating layers 11 to 13, 15 to 17, and 19 can each be formed using an insulating resin. Examples of the insulating resin include thermosetting resins such as epoxy resin, bismaleimide triazine resin (BT resin), or phenolic resin, and thermoplastic resins such as fluororesin, liquid crystal polymer (LCP), ethylene fluoride (PTFE) resin, polyester (PE) resin, and modified polyimide (MPI) resin. On the other hand, the solder resists 41 and 42 can be formed using, for example, a photosensitive epoxy resin or polyimide resin. The insulating layers 11 to 13, 15 to 17, and 19 can include an inorganic filler (not shown) such as silica or alumina, and / or a reinforcing material (core material) such as glass fiber not shown.

[0015] The wiring layers 21 to 23, 25 to 27, 28, 29, the via conductor 5, and the through-hole conductor 51 are formed using an arbitrary metal such as copper or nickel. In FIG. 1, these are depicted as having only one layer for simplicity, but they can have a multilayer structure of two or more layers including, for example, an electroless plating film, a sputter film, and an electrolytic plating film.

[0016] The wiring layers 28 and 29 contain the dummy pattern 2a and the dummy pattern 2b. The dummy pattern 2b is formed in a region on the circuit pattern region A side from the dummy pattern 2a in the frame region B. In the example shown in FIG. 1, the dummy pattern 2a is a solid pattern, and the dummy pattern 2b is formed as a mesh pattern.

[0017] The insulating layers 11-13 and 15-17 do not extend to the outer edge of the frame region B, and are missing on a portion of the outer edge of the dummy pattern 2a. That is, in the wiring board 100, the insulating layers 11-13 and 15-17 form end faces 100a inward from the outer edge of the frame region B so as to expose the edge of the core substrate 3. The insulating layers 11-13 and 15-17 each include protrusions 11a-13a and 15a-17a that rise in the frame region B of the wiring board 100, respectively, in a direction away from the core substrate 3. The protrusions 11a-13a and 15a-17a are formed within the region of the frame region B where the dummy pattern 2a is formed. However, the protrusions 11a-13a and 15a-17a are not exposed on the end face 100a. The protrusions 11a-13a and 15a-17a are formed away from the end face 100a. As shown in Figure 1, the insulating layers 11-13 and 15-17 have flat portions between the protrusions 11a-13a and 15a-17a and the end face 100a. The height h of each of the protrusions 11a-13a and 15a-17a from the flat portion is, for example, 15 μm or less. The protrusions 11a-13a and 15a-17a may each have similar height h.

[0018] The insulating layers 11-13 and 15-17 on the dummy pattern 2b are each formed to be approximately flat. The area of ​​the frame region B on which the dummy pattern 2a is formed is also called the adjustment region C. The protrusions 11a-13a and 15a-17a are positioned between the circuit pattern region A and the adjustment region C.

[0019] As shown in Figure 3, the circuit pattern area A is surrounded by the frame area B. Specifically, the circuit pattern area A is surrounded by the adjustment area C, which is part of the frame area B. The wiring board 100 has an end face 100a that lies inward from the outer edge of the frame area B.

[0020] Solder resist 41 is formed on the resin insulating layer 13 and the wiring layer 23. As shown in Figure 1, the solder resist 41 does not extend to the end face 100a, but covers only a portion of the protrusion 13a. Solder resist 42 is formed on the resin insulating layer 17 and the wiring layer 27. As shown in Figure 1, the solder resist 42 does not extend to the end face 100a, but covers only a portion of the protrusion 17a. The thickness of the solder resists 41 and 42 is greater than the height h of the protrusions 13a and 17a.

[0021] Figure 2 shows a wiring board 110 as another example of a wiring board manufactured by the manufacturing method of the embodiment. On the wiring layers 21-23 and 25-27 of the wiring board 110, a solid dummy pattern 2c is formed in the frame region B, excluding the adjustment region C. In a plan view, the dummy pattern 2c is formed on each insulating layer 11-13 and 15-17 at a position that overlaps with the dummy pattern 2a up to the end face 100a. Here, "plan view" means viewing the object with a line of sight parallel to the thickness direction of the wiring board 110. That is, each dummy pattern 2c covers the entire surface of each of the protrusions 11a-13a and 15a-17a. In the adjustment region C of the wiring board 110, a dummy pattern 2d with a mesh pattern similar to dummy pattern 2b is formed on each insulating layer 11-13 and 15-17.

[0022] Solder resists 41 and 42 are formed on the resin insulating layer 13 and wiring layer 23 of the wiring board 110, and on the resin insulating layer 17 and wiring layer 27, respectively, similar to the wiring board 100. Solder resist 41 covers a portion of the dummy pattern 2c laminated on the protrusion 13a. Solder resist 42 covers a portion of the dummy pattern 2c laminated on the protrusion 17a. The combined thickness of the heights h of the protrusions 13a and 17a (see Figure 1) and the thickness of the dummy pattern 2c is less than the thickness of the solder resists 41 and 42.

[0023] Using the example of the wiring board 100 shown in Figure 1, the manufacturing method of the wiring board according to the embodiment will be described below with reference to Figures 4A to 4K.

[0024] As shown in Figures 4A and 4B, the manufacturing method of the wiring board of this embodiment includes laminating a semi-cured insulating layer 11, which has a support film 61 on its surface 11s, onto a substrate (in the example of Figure 4A, a core substrate 3). When the wiring board 100 of Figure 1 is manufactured, a core substrate 3 is prepared, the insulating layer 11 is laminated on the first surface 31 of the core substrate 3, and the insulating layer 15 is laminated on the second surface 32. The core substrate 3 has a circuit pattern region A where a circuit pattern is densely formed, and a frame region B that surrounds the outside of the circuit pattern region A. The frame region B includes an adjustment region C in the area on the circuit pattern region A side within the frame region B. Laminating the insulating layer 11 may include laminating an adhesive sheet 6a onto a prepared substrate such as the core substrate 3, as shown in Figure 4A.

[0025] A substrate that serves as the base for the insulating layer 11, such as the core substrate 3, can be prepared by any method. For example, when the core substrate 3 is prepared, a double-sided copper-clad laminate is prepared, which includes an insulating layer that will become the insulating layer 19 and metal foils bonded to both sides of it. After forming through holes by drilling, through-hole conductors 51 are formed in the through holes by electroless plating and electrolytic plating. After a filler 51a is formed by filling the inside of the through-hole conductors 51 with epoxy resin or the like, wiring layers 28 and 29, which include predetermined conductor patterns such as dummy patterns 2a and dummy patterns 2b, are formed by a subtractive method including electroless plating and electrolytic plating, for example. Dummy pattern 2a is formed in the frame region B other than the adjustment region C. Dummy pattern 2b is formed in the adjustment region C. For example, the core substrate 3 including the wiring layers 28 and 29 and the insulating layer 19 is prepared in this way. Note that the substrate prepared to serve as the base for the insulating layer, such as the insulating layer 11, may also be a support substrate. Furthermore, the substrate used as the base is not necessarily a so-called core substrate, but may be, for example, a single insulating layer or a laminate of an insulating layer and a wiring layer that has already been formed using a build-up method.

[0026] As shown in Figure 4A, the adhesive sheet 6a has a support film 61 on its surface that is removable from the adhesive sheet. The support film 61 also functions as a protective film during the subsequent formation of the through hole 5a. The adhesive sheet 6a with the support film 61 is laminated onto the first surface 31 and the second surface 32 of the core substrate 3, respectively. In the example in Figure 4A, the adhesive sheet 6a and the support film 61 are smaller than the core substrate 3 in plan view.

[0027] The adhesive sheet 6a is, for example, a resin film and is composed of a material containing one of the resins mentioned above as the material for the insulating layers 11 and 15, such as a thermosetting resin like epoxy resin or a thermoplastic resin like fluororesin. The adhesive sheet 6a may contain these resins in a so-called B-stage state, which is semi-cured or dry. Polyethylene terephthalate (PET) is an example of a material for the support film 61. However, the material for the support film 61 is not limited to PET.

[0028] After the adhesive sheet 6a is laminated onto the core substrate 3, it is heated and pressed together with the support film 61. As a result, the adhesive sheets 6a laminated on both sides of the core substrate 3 are heat-pressed to the core substrate 3, and an insulating layer 11 or insulating layer 15 is formed on each surface of the core substrate 3. The surface 11s of the insulating layer 11 and the surface 15s of the insulating layer 15 are each covered with the support film 61, which also functions as a protective film.

[0029] In the thermocompression bonding of the adhesive sheet 6a (see Figure 4A), the resin constituting the adhesive sheet 6a is softened by heating, and pressure is applied to the first surface 31 or second surface 32 of the core substrate 3 by a pressure plate. In the manufacturing method of the wiring board of this embodiment, a pressure plate having recesses at positions corresponding to the positions where the protrusions 11a and 15a (see Figure 4B) are to be formed can be used in the thermocompression bonding process. By allowing the softened resin of the adhesive sheet 6a and the support film 61 to flow into the recesses of the pressure plate, a semi-cured resin layer (insulating layer 11, 15) having raised portions that form the protrusions 11a and 15a of the insulating layers 11, 15 is formed. The raised portions are composed of the semi-cured resin and the support film 61 on the resin.

[0030] During the thermocompression bonding of the adhesive sheet 6a (see Figure 4A), the pressure applied to the wiring board 100 by the pressure plate may differ between the circuit pattern region A in the center of the wiring board 100 and the frame region B surrounding the outside of the circuit pattern region A. In the circuit pattern region A in the center of the wiring board 100, the circuit pattern is densely formed on the wiring layers 28 and 29, and the surface of the pressure plate is flat, so a relatively large first pressure can be applied to the wiring board 100. On the other hand, in the frame region B outside the circuit pattern region A, a dummy pattern 2b, which is a mesh pattern, is formed in the adjustment region C, and the pressure plate outside the adjustment region C is provided with a recess. Therefore, due to the pressure applied by the pressure plate, a second pressure, which is smaller than the first pressure in the circuit pattern region A, can be applied in the frame region B. Specifically, when pressure is applied by the pressure plate, the softened resin of the adhesive sheet 6a and the support film 61 are pushed outwards from the center towards the outer edge of the frame region B, where a second pressure less than the first pressure is applied, by the first pressure applied to the central part of the wiring board 100. The softened resin and support film 61 flowing outwards accumulate in the adjustment region C where the pressure from the pressure plate is low, and then flow further outwards into the recess of the pressure plate. It is thought that the flow velocity is reduced in the adjustment region C by the pressure difference between the first and second pressures and the dummy pattern 2b which is relatively roughly formed on the wiring layers 28 and 29, thereby efficiently allowing the resin and support film 61 to flow into the recess of the pressure plate.

[0031] Instead of a pressure plate with recesses, an adhesive sheet 6a with recesses formed in the support film 61 may be used. In this case, the pressure from the pressure plate causes the softened resin of the adhesive sheet 6a to flow into the recesses in the support film 61, forming a semi-cured resin layer (insulating layers 11, 15) with raised portions that form the convex portions 11a, 15a of the insulating layers 11, 15.

[0032] After the adhesive sheet 6a is heat-pressed, the semi-cured insulating layers 11 and 15 are fully cured. This fully cured state causes the resin constituting the insulating layers 11 and 15 to harden to the final stage of curing, the so-called C stage. The insulating layers 11 and 15 are fully cured, for example, by heating them at a temperature suitable for the fully curing of the resin constituting the insulating layers 11 and 15 for an appropriate amount of time. The insulating layers 11 and 15 may be fully cured by any other method, such as ultraviolet irradiation, rather than by heat curing. The insulating layers 11 and 15 are formed, each having protrusions 11a and 15a and having surfaces 11s and 15s covered with a support film 61.

[0033] The protrusions 11a and 15a are located within the area of ​​the frame region B where the dummy pattern 2a is formed, and are separated from the end face 100a. That is, the protrusions 11a and 15a are formed in a position such that there is a flat portion between the protrusions 11a and 15a and the end face 100a where the insulating layer is formed substantially flat. Forming the protrusions 11a and 15a in such a position prevents the softened resin of the adhesive sheet 6a from spreading beyond the position where the end face 100a is formed to the outer edge of the core substrate 3. When the resin flows to the outside of the support film 61 and reaches the edge of the core substrate 3, it is thought that the resin will rise in the opposite direction to the core substrate 3 due to surface tension. Therefore, there is a risk that a part of the resin will rise near the edge of the core substrate 3 so as to cover the surface of the support film 61, or that an insulating layer will be formed that is excessively raised compared to the surface 11s of the insulating layer 11 and the surface 15s of the insulating layer 15. It is thought that processes such as skiving to remove the raised areas and flattening the insulating layer will be necessary, which is expected to reduce production efficiency.

[0034] By forming the protrusions 11a and 15a at positions separated from the end face 100a, the protrusions 11a and 15a can be made into a smooth shape. As described above, when a bulge is formed on the edge of the core substrate 3, the shape of the bulge tends to be steep. When such a bulge is formed, not only does a large variation in thickness occur in the insulating layer from the edge of the core substrate 3 to the frame region B, but this variation may also worsen the flatness of the insulating layer portion from the frame region B to the center of the circuit pattern region A. It is thought that the yield will worsen due to the deterioration of flatness. Forming the protrusions 11a and 15a in a smooth shape is thought to suppress the variation in thickness in the insulating layer, and as a result, an insulating layer with improved flatness can be manufactured. It is thought that the lamination of the subsequent wiring layers 21 and 25 (see Figure 4E) and the resin layer can be carried out properly.

[0035] In the manufacturing method of the wiring board of this embodiment, a flat adjustment area C is formed within the frame area B, so the influence of the protrusions 11a and 15a on the thickness of the circuit pattern area A is reduced. It is considered that insulating layers 11 and 15 with excellent flatness are formed in the circuit pattern area A.

[0036] Next, as shown in Figure 4C, via through-holes 5a for forming via conductors 5 (see Figure 1) are formed in the insulating layer 11 and the insulating layer 15, respectively, penetrating through the insulating layers 11 and 15. The through-holes 5a are formed by irradiation with laser light, such as a carbon dioxide laser or a UV laser. In the example shown in Figure 4C, the through-holes 5a are formed in the insulating layers 11 and 15 while the support film 61 is still in place. That is, through-holes 5a are formed that penetrate the support film 61 along with the insulating layers 11 and 15, respectively, while the support film 61 is still in place. Because the support film 61 remains in place, the adhesion of resin debris generated from the insulating layers 11 and 15 to the surface 11s of the insulating layer 11 or the surface 15s of the insulating layer 15 is prevented during the formation of the through-holes 5a. Furthermore, since the irradiation surface for laser processing is the surface of the support film 61 and not the surfaces 11s and 15s, the formation of excessively large through-holes 5a in the insulating layer 11 or insulating layer 15 due to the impact during irradiation is prevented.

[0037] A resin residue removal treatment (so-called desmear treatment) may be performed inside the through-hole 5a to remove resin residue generated during the formation of the through-hole 5a. The resin residue removal treatment is performed while the insulating layer 11 and insulating layer 15 are still fitted with the support film 61. This is thought to prevent the surface 11s of the insulating layer 11 and the surface 15s of the insulating layer 15 from being subjected to any chemical and / or mechanical stress.

[0038] The removal process may be a wet process, for example, involving immersion in a dissolving solution such as a permanganate solution. Alternatively, the removal process may be carried out as a dry process without using a dissolving solution. The dry process for removing the resin residue may be a plasma treatment using a plasma gas such as argon, methane tetrafluoride, a mixture of methane tetrafluoride and oxygen, or sulfur hexafluoride.

[0039] Subsequently, the support film 61 is removed. The support film 61 may be removed by any method; for example, it may be peeled from the insulating layers 11 and 15 by simply pulling the support film 61 in the opposite direction to the insulating layers 11 and 15, respectively. Alternatively, the support film 61 may be removed by dissolution using a suitable solvent.

[0040] Removing the support film 61 exposes the surface 11s of the insulating layer 11 and the surface 15s of the insulating layer 15, as shown in Figure 4D. Because they were protected by the support film 61, there is no adhesion of resin debris or other materials during the processes up to this point, and clean, smooth surfaces 11s and 15s with little stress history are exposed.

[0041] Next, as shown in Figure 4E, a wiring layer 21 is formed on the surface 11s of the exposed insulating layer 11. A wiring layer 25 is formed on the surface 15s of the insulating layer 15. In addition, a via conductor 5, which is integrated with the wiring layer 21, is formed in a through-hole 5a that penetrates the insulating layer 11. A via conductor 5, which is integrated with the insulating layer 15, is formed in a through-hole 5a that penetrates the insulating layer 15.

[0042] The wiring layers 21, 25 and via conductors 5 can be formed using any method for forming the wiring layers and via conductors. For example, each wiring layer 21, 25 and via conductor 5 may be formed by a general semi-additive method. That is, a seed layer (not shown) made of a metal film such as copper is formed on the surfaces 11s, 15s of each insulating layer and within the through-holes 5a by electroless plating or sputtering. A plating resist (not shown) with appropriate openings is formed on the formed seed layer, and an electroplated film (not shown) is formed within the openings of the plating resist, using the seed layer as a power supply layer. The via conductor 5 is formed within the through-holes 5a. Then, the wiring layers 21, 25 having the desired conductor pattern are formed by removing the exposed portion of the seed layer by peeling off the plating resist and quick etching.

[0043] Next, as shown in Figures 4F and 4G, the adhesive sheet 6a with the support film 61 is heat-pressed onto the insulating layer 11 and the wiring layer 21, and onto the insulating layer 15 and the wiring layer 25, in the same manner as described in Figure 4A. The semi-cured resin is fully cured in the same manner as the method for forming the insulating layers 11 and 15 described earlier, forming insulating layers 12 and 16, each with the support film 61. On insulating layer 12, a protrusion 12a of approximately the same size as the protrusion 11a is formed at a position that overlaps with the protrusion 11a in a plan view. On insulating layer 16, a protrusion 16a of approximately the same size as the protrusion 15a is formed at a position that overlaps with the protrusion 15a in a plan view.

[0044] Next, as shown in Figure 4H, the through-hole 5a is formed, the support film 61 (see Figure 4G) is removed, and the wiring layers 22, 26 and via conductors 5 having the desired conductor pattern are formed in a manner similar to that described in Figures 4C, 4D, and 4E.

[0045] Next, as shown in Figures 4I and 4J, the adhesive sheet 6a with the support film 61 is heat-pressed onto the insulating layer 12 and wiring layer 22, and onto the insulating layer 16 and wiring layer 26, respectively, in the same manner as described in Figures 4A and 4F. The semi-cured resin is then fully cured in the same manner as the methods for forming the insulating layers 11, 15 and insulating layers 12, 16 described earlier, forming insulating layers 13 and 17, each with the support film 61. On insulating layer 13, a protrusion 13a is formed at a position that overlaps with the protrusions 11a and 12a in a plan view, and is approximately the same size as the protrusions 11a and 12a. On insulating layer 17, a protrusion 17a is formed at a position that overlaps with the protrusions 15a and 16a in a plan view, and is approximately the same size as the protrusions 15a and 16a.

[0046] Next, as shown in Figure 4K, the through-hole 5a is formed, the support film 61 (see Figure 4J) is removed, and the wiring layers 23, 27 and via conductors 5 having the desired conductor pattern are formed in a manner similar to that described in Figures 4C, 4D, and 4E.

[0047] Subsequently, as shown in Figure 1, solder resist 41 is formed on the insulating layer 13 and the wiring layer 23, and solder resist 42 is formed on the insulating layer 17 and the wiring layer 27. Solder resists 41 and 42 are formed, for example, by supplying a photosensitive epoxy resin or polyimide resin onto each insulating layer and each wiring layer by methods such as lamination or spraying.

[0048] In the wiring board 100, as shown in Figure 1, protrusions 13a and 17a are formed in the frame region B of the resin insulating layer 13 and the wiring layer 17. Therefore, it is considered that the spread of the resin forming the solder resist to the outer edge of the frame region B can be suppressed by the protrusions 13a and 17a during the formation of the solder resist.

[0049] As shown in Figure 1, openings that expose a portion of the wiring layer 23 or wiring layer 27 are formed in the solder resists 41 and 42 by photolithography or laser irradiation. Through these steps, the wiring substrate 100 shown in Figure 1 is obtained.

[0050] The method for manufacturing the wiring board of the embodiment is not limited to the method described with reference to each drawing. As stated above, the method for manufacturing the wiring board of the embodiment may produce a wiring board having a different structure from the laminated structure shown in each drawing, or a wiring board containing a different number of wiring layers than the number of wiring layers shown in each drawing. For example, a wiring board without a core substrate may be manufactured using the method for manufacturing the wiring board of the embodiment. Also, the wiring board does not have to have an adjustment region C. In the wiring board shown in Figure 2, all wiring layers from the second layer onward do not have to include dummy patterns 2c and dummy patterns 2d. The circuit pattern region A may be one or more consecutive product areas, and a laminate containing one wiring board may be formed in each product area, and the formed laminate may be divided according to the product areas to manufacture the wiring board. In addition to the steps described above, any additional steps may be added to the method for manufacturing the wiring board of the embodiment, and some of the steps described above may be omitted. [Explanation of Symbols]

[0051] 100, 110 Wiring board 100a end face 11-13, 15-17, 19 Resin insulating layer (insulating layer) 11a~13a, 15a~17a Convex parts 21~23, 25~29 wiring layer 2a~2d Dummy Patterns 3 Core board (board) A Circuit pattern area B. Frame area C Adjustment area 41, 42 Solder Resist 5 via conductors 5a Through hole for via (through hole) 6a Adhesive sheet 61 Support film

Claims

1. A method for manufacturing a wiring board comprising a circuit pattern region and a frame region surrounding the circuit pattern region, Laminating adhesive sheets onto the substrate within the circuit pattern region and the frame region, The adhesive sheet is heat-pressed onto the substrate by heating and pressing to form a first insulating layer on the substrate. Includes, The first pressure during thermocompression bonding in the circuit pattern region is greater than the second pressure during thermocompression bonding in the frame region. The heat-pressing process includes forming a first protrusion on the adhesive sheet due to the pressure difference between the first pressure and the second pressure. Forming the first insulating layer includes curing the adhesive sheet including the first protrusion by heating, The first protrusion is formed within the frame region at a position that does not expose the end face of the first insulating layer.

2. A method for manufacturing a wiring board according to claim 1, further comprising forming a wiring layer on the first insulating layer including the first protrusion.

3. A method for manufacturing a wiring board according to claim 1, The adhesive sheet is provided with a support film on its upper surface that is detachably attached from the adhesive sheet. The heat-pressing process includes heating and pressing the adhesive sheet together with the support film to form the first protrusion whose surface is covered by the support film.

4. A method for manufacturing a wiring board according to claim 1, The method further includes forming a second insulating layer on the first insulating layer, Forming the second insulating layer includes forming the second protrusion at a position that overlaps with the first protrusion in a plan view.

5. A wiring board comprising a circuit pattern area and a frame area surrounding the circuit pattern area, The aforementioned wiring board has a first insulating layer and a second insulating layer on the first insulating layer. The first insulating layer is formed in the frame region and has a first protrusion that is not exposed from the end face of the wiring board. The second insulating layer covers the first protrusion.

6. A wiring board according to claim 5, The second insulating layer is formed in the frame region and has a second protrusion that is not exposed from the end face of the wiring board. The first and second protrusions overlap in a plan view.

7. A wiring board according to claim 5, A wiring layer is provided between the first insulating layer and the second insulating layer. The wiring layer covers the entire first protrusion within the frame region.

8. A wiring board according to claim 6, The facility comprises a wiring layer formed on the second insulating layer, and a solder resist covering the wiring layer and the second insulating layer exposed from the wiring layer. The solder resist is formed within the region surrounded by the second protrusion.

9. A wiring board according to claim 5, A wiring layer is provided between the first insulating layer and the second insulating layer. The wiring layer is located within the frame region and has a mesh pattern between the first protrusion and the circuit pattern region.

Images