JP4748281B2 - Wiring board manufacturing method and wiring board - Google Patents

Description

  The present invention relates to a method for manufacturing a wiring board having vias and the wiring board.

  2. Description of the Related Art In recent years, multilayer wiring boards in which a plurality of wiring patterns are formed in multiple layers have been used with the high density mounting of components. As a method for manufacturing such a multilayer wiring board, Patent Document 1 discloses that a wiring pattern is formed on one surface of a hard substrate, an adhesive layer is formed on the other surface, and the hard substrate and the adhesive layer are penetrated. A method of forming a hole in contact with the wiring pattern and filling the hole with a conductive paste is disclosed.

  FIG. 9 shows an example of the manufacturing method disclosed in Patent Document 1. As shown in (a), a hard resin substrate 50 having a metal foil 51 attached to the upper surface is prepared, and the metal foil 51 is etched to form a wiring pattern 51a as shown in (b). Next, an adhesive layer 52 is laminated on one surface of the resin substrate 50 as shown in (c), and then laser is irradiated from the adhesive layer side as shown in (d), thereby the adhesive layer 52 and the resin substrate. 50 via holes 53 are formed. Furthermore, a single-sided wiring board can be obtained by filling the via hole 53 with the conductive paste 54 as shown in FIG. At this time, the adhesive layer 52 and the conductive paste 54 are uncured.

  After a plurality of single-sided wiring boards 55a to 55d formed by the same method as described above are stacked as shown in FIG. 10, the adhesive layer 52 and the conductive paste 54 are thermally cured at the same time, as shown in FIG. A multilayer wiring board can be obtained.

  As described above, when the bottomed via hole 53 having the wiring pattern 51 a as the bottom surface is formed on the resin substrate 50 by laser processing, the laser beam is reflected by the wiring pattern 51 a and cuts the inner wall of the via hole 53. The shape is tapered. In the case of the tapered via hole 53, the diameter of the bottom surface of the via hole is reduced. Therefore, in order to secure the connection area between the conductive paste 54 and the wiring pattern 51a on the bottom surface of the via hole, it is necessary to increase the diameter of the opening of the via hole 53. is there. In particular, since the adhesive layer 52 is formed on the resin substrate 50, the thickness of the substrate 50 is increased by the amount of the adhesive layer 52, and when the laser is irradiated from above, the diameter of the opening of the via hole 53 is It gets bigger. As a result, there is a drawback that the pitch between vias cannot be narrowed and hinders fine wiring.

  Moreover, in the said conventional manufacturing method, since the laser is irradiated with respect to the resin substrate 50 which adhere | attached the adhesive bond layer 52 like FIG.9 (d), the unhardened adhesive bond layer 52 is irradiated with a laser beam. As a result of heat melting, the diameter of the via hole 53 of the adhesive layer 52 becomes larger than necessary. Such enlargement of the diameter, combined with the taper shape of the via hole 53, becomes a further obstacle to miniaturization.

  Furthermore, since the resin removed by laser irradiation may adhere to the periphery of the via hole 53 or the surface of the wiring pattern 51a, it is necessary to remove it by desmearing or plasma processing. However, in such a method of removing smear, the uncured adhesive layer 52 is also removed at the same time. For this reason, there is a concern that smear cannot be appropriately removed and electrical reliability is lowered.

The conductive paste 54 filled in the via hole of the resin substrate 50 and the via hole of the adhesive layer 52 is cured after being multilayered as shown in FIG. However, since the conductive paste filled in these via holes is completely surrounded by the resin substrate 50 and the adhesive layer 52 and hardens without being exposed to the outside, the solvent contained in the conductive paste 54 is sufficient. There is a possibility of remaining without being emitted. In the subsequent process, when the entire substrate is heated, the remaining solvent expands, which may reduce the connection reliability between the via and the wiring.
JP-A-9-36551

  An object of a preferred embodiment of the present invention is to provide a method of manufacturing a wiring board that can process a via hole without enlarging the diameter more than necessary, can be easily miniaturized, and can improve the connection reliability between the via and the wiring. It is to provide a wiring board.

The method for manufacturing a wiring board according to the present invention includes a first step of preparing a cured first resin layer having a conductor pattern and having a bottomed first via hole having the conductor pattern as a bottom surface. A second step of filling the first via hole with the first conductive paste so that a part of the first via hole protrudes from the surface of the first resin layer, and curing the conductive paste; A third step of polishing the protruding portion of the first conductive paste filled in the via hole, and a second uncured state in which a second via hole penetrating in a position corresponding to the first via hole is formed A fourth step of preparing a resin layer, and a fifth step of laminating the first resin layer and the second resin layer so that the first via hole and the second via hole are continuous. , After the fifth step, the second via hole A sixth step of filling the second conductive paste le are those comprising a.

The wiring board according to the present invention has a conductor pattern, a first resin layer having a bottomed first via hole with the conductor pattern as a bottom surface, and embedded in the first resin layer, And a circuit component mounted on the conductor pattern, a first conductive paste that is filled and cured in the first via hole, and the surface exposed on the upper surface of the first resin layer is polished, and a first conductive paste that penetrates vertically. 2 via holes are formed, the upper end opening of the second via hole is formed with a smaller diameter than the upper end opening of the first via hole, and the diameter of the upper end opening of the second via hole is the diameter of the lower end opening. a larger tapered bore than the lower end opening of the second via hole is laminated on the first resin layer so as to correspond to the upper end opening portion of the first via hole, and the first resin the first is thinner than the layer A second conductive paste filled and cured in the second via hole and electrically connected to the first conductive paste, and on the second resin layer so as to cover the second via hole And a wiring pattern electrically connected to the second conductive paste.

  A method for manufacturing a wiring board according to the present invention will be described. First, in a first step, a cured first resin layer having a conductor pattern and having a bottomed first via hole having the conductor pattern as a bottom surface is prepared. In order to obtain such a first resin layer, for example, after bonding an uncured resin layer to the surface of the core substrate on which the conductor pattern is formed, the first resin layer is formed by curing the resin layer. May be. A first via hole having a conductor pattern as a bottom surface is formed in the first resin layer, and laser processing can be used at that time. When the first via hole having the conductor pattern as the bottom surface is formed by laser processing, the via hole inevitably becomes a taper shape, but the first resin layer before the second resin layer is laminated is formed. Since laser processing is sufficient, the depth of the first via hole can be made relatively shallow, and an increase in the diameter of the opening can be suppressed. The resin removed by laser irradiation may adhere to the periphery of the via hole or the surface of the wiring pattern, but the first resin layer is a cured resin plate, so that it is well known such as wet desmear treatment or dry plasma treatment The smear can be easily removed by this method.

  Next, the first via hole is filled with a conductive paste, and the conductive paste is cured. At this time, since the conductive paste is cured in a state of being exposed to the outside, the solvent contained in the conductive paste is easily diffused, and a decrease in reliability due to the remaining solvent can be prevented. After the conductive paste is cured, an uncured second resin layer having a second via hole is laminated on the cured first resin layer, and the second via hole is filled with the conductive paste to form the first paste. Conduction with the hardened conductive paste filled in the via hole. At this time, the surface of the cured conductive paste is likely to be resin-rich, and when an uncured conductive paste is brought into contact with this conductive paste, the conduction resistance may increase at the interface between both conductive pastes. However, in the present invention, since the surface of the cured conductive paste is physically polished before contacting the uncured conductive paste, the resin-rich surface layer is removed to expose the conductive portion on the surface. And the conduction resistance at the interface of the conductive paste can be lowered.

  Since the second via hole of the second resin layer is formed separately from the first via hole of the first resin layer, the second via hole is not affected by the enlargement of the diameter as in the case of forming both via holes simultaneously. In other words, even if the opening diameter of the first via hole is increased by laser processing, the diameter of the second via hole can be made smaller than the opening diameter of the first via hole, and fine wiring can be realized. Since the second via hole is a through hole, the second via hole is not limited to laser processing, and can be formed by other methods such as drilling or punching. Since the uncured second resin layer is laminated on the first resin layer and the second via hole is filled with the conductive paste in a state where they are in close contact with each other, the conductive paste becomes the first resin layer and the second resin layer. Therefore, a highly reliable wiring board can be obtained.

  When filling the first via hole with the conductive paste, a part of the first resin layer may protrude from the surface, and the protruding portion of the conductive paste may be polished. In this case, since only the protruding portion of the conductive paste needs to be polished, the polishing operation is simplified. In order to make the conductive paste partly protrude from the surface of the first resin layer, a film having a through hole is laminated on the first resin layer, and the first via hole and the film of the first resin layer are laminated. The conductive paste may be filled with the conductive paste at the same time, and then the film may be peeled off so that the conductive paste partially protrudes from the surface of the first resin layer. In this case, by forming the protrusion using a film thicker than the resin-rich layer, the resin-rich layer can be entirely accommodated in the protrusion, and the conductive material can be easily exposed by a subsequent polishing process. become.

  The diameter of the through-hole of the film is preferably larger than the opening diameter of the first via hole. By enlarging the diameter of the through-hole, when polishing in the third step, the conductive paste filled in the first via hole can be cut without being damaged. In the third step, buffing can be used as a method for polishing the surface of the conductive paste. Buffing is suitable when there are steps on the polished surface.

  In the fourth step, the bottom diameter of the second via hole is preferably made smaller than the opening diameter of the first via hole. By reducing the diameter of the second via hole, the wiring pattern formed on the second resin layer can be formed more finely. Further, the pitch of the first via hole and the pitch of the second via hole need to correspond accurately, but when the diameter of the second via hole is made smaller than the opening diameter of the first via hole, Can be absorbed.

  When wiring is formed on the second resin layer, a metal foil is pressure-bonded to the uncured second resin layer, and the metal foil is applied to an uncured conductive paste filled in the second via hole. You may further provide the 7th process made to contact and the 8th process of hardening simultaneously the electrically conductive paste with which the 2nd via hole was filled, and the 2nd resin layer. Thus, the metal foil is fixed to the second resin layer, and the metal foil and the conductive paste are electrically connected. Thereafter, a metal foil may be patterned. In addition, you may crimp | bond to the 2nd resin layer in the state in which the metal foil was pattern-formed beforehand. The wiring formed on the second resin layer can be sequentially multilayered by appropriately mounting circuit components and forming a resin layer thereon. Further, instead of the method of pressure bonding the metal foil on the uncured second resin layer, a multilayer substrate may be formed by pressure bonding a substrate having a wiring pattern formed on the lower surface.

  The first resin layer and the second resin layer in the present invention may be composed of various resin materials such as epoxy-based, polyimide-based, acrylate-based, phenol-based, etc., thermosetting resin and inorganic filler, Or a composite of carbon fiber or glass fiber impregnated with resin.

  According to a preferred embodiment, a conductor pattern is formed on a core substrate, a circuit component is mounted on the conductor pattern, and an uncured first resin layer is pressure-bonded and cured from the first circuit layer. The resin layer and the core substrate may be integrated, and the circuit component may be embedded in the first resin layer. Furthermore, a conductor pattern is formed on the carrier, circuit components are mounted on the conductor pattern, and an uncured first resin layer is pressure-bonded and cured from above to form a first resin layer. After the circuit component is embedded in the carrier, the carrier may be peeled off from the first resin layer. In this case, the conductor pattern is exposed on the bottom surface of the first resin layer.

Effects of preferred embodiments of the invention

  According to the method for manufacturing a wiring board according to the present invention, when the first via hole of the first resin layer is filled with the conductive paste and cured, the conductive paste is cured while being exposed to the outside. It is easy to remove the solvent contained in the solvent, and it is possible to prevent a decrease in reliability due to residual solvent. Further, in the present invention, since the surface of the cured conductive paste filled in the first via hole is polished to remove the resin-rich surface layer, the uncured second layer is removed from the first resin layer. When the resin layer is laminated and the second via hole is filled with the conductive paste, the conduction resistance at the interface of the conductive paste of both via holes can be lowered. Further, since the second via hole of the second resin layer is formed separately from the first via hole of the first resin layer, even if the opening diameter of the first via hole is increased, the second via hole is formed. In addition to the opening diameter of the first via hole, the diameter can be made smaller, and fine wiring can be realized. Since the smear generated during the processing of the first via hole can be removed before the second resin layer is laminated, the smear can be easily removed by a known method, and a wiring board having high electrical reliability can be obtained. .

  According to the wiring board according to the present invention, the surface of the first conductive paste filled in the first via hole of the first resin layer is polished to remove the resin-rich surface layer. The conduction resistance at the interface between the conductive paste and the second conductive paste can be reduced, and a wiring board with high electrical reliability can be obtained. In addition, since the upper end opening diameter of the second via hole formed in the second resin layer is smaller than the upper end opening diameter of the first via hole formed in the first resin layer, the opening of the first via hole is not performed. Even if the aperture is increased, the wiring pattern formed on the upper surface of the second resin layer can be miniaturized.

It is sectional drawing of 1st Example of the wiring board concerning this invention. It is a figure which shows the 1st step of the manufacturing process of the wiring board of FIG. It is a figure which shows the 2nd step of the manufacturing process of the wiring board of FIG. It is a figure which shows the last step of the manufacturing process of the wiring board of FIG. It is a partial manufacturing process figure of 2nd Example of the wiring board concerning this invention. It is a partial manufacturing process figure of 3rd Example of the wiring board concerning this invention. It is sectional drawing of the example which multilayered the wiring board concerning this invention. It is sectional drawing of the other example of the wiring board concerning this invention. It is a figure which shows the first half of the manufacturing process of the conventional multilayer wiring board. It is a figure which shows the second half of the manufacturing process of the conventional multilayer wiring board. It is sectional drawing which shows the structure of the conventional multilayer wiring board.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, preferred embodiments of the present invention will be described with reference to examples.

  FIG. 1 is a sectional view of a first embodiment of a wiring board according to the present invention. The wiring board A of the present embodiment is configured as a component built-in board having circuit components built therein.

  The wiring board A is obtained by laminating three resin layers. The lowermost resin layer is a wired core substrate 1 (for example, a printed wiring board), and a conductive pattern 2 having mounting lands 2a and via lands 2b for mounting circuit components is formed on the surface thereof. ing. Although not shown in the drawing, wiring may be provided as appropriate on the back surface or inside of the core substrate 1 so as to be electrically connected via the land and via on the surface. A circuit component 3 is mounted on the mounting land 2a by soldering or the like. Although FIG. 1 shows an example in which the circuit component 3 is a two-terminal chip component, it may be a multi-terminal electronic component (for example, an integrated circuit). The core substrate 1 is not limited to a resin substrate, and may be a ceramic substrate such as LTCC.

  A first resin layer 4 is formed on the core substrate 1, and the circuit component 3 is embedded in the first resin layer 4. The resin layer 4 is composed of a thermosetting resin such as an epoxy resin or a phenol resin, a mixture in which an inorganic filler is mixed with a thermosetting resin, or a composite material in which a glass fiber or carbon fiber is impregnated with a thermosetting resin. . A via hole 4a penetrating in the thickness direction is formed at a position of the resin layer 4 corresponding to the via land 2b of the core substrate 1, and the conductive paste 5 is filled and cured in the via hole 4a. The via hole 4a is a tapered hole that is formed by laser processing and expands in diameter upward.

  A second resin layer 6 thinner than the resin layer 4 is laminated and fixed on the first resin layer 4. The second resin layer 6 is preferably made of the same thermosetting resin as the first resin layer 4. A via hole 6a penetrating vertically is formed at a position of the second resin layer 6 corresponding to the via hole 4a of the first resin layer 4, and the conductive paste 7 is filled and cured in the via hole 6a, so that the inside of the via hole 4a Is electrically connected to the conductive paste 5 filled therein. A wiring pattern 8 is formed on the upper surface of the second resin layer 6. Here, the wiring pattern 8 is composed of two via lands 8a formed at positions corresponding to the via holes 6a and one electrode 8b, but the wiring pattern shape is arbitrary. Via land 8 a on the upper surface of second resin layer 6 and via land 2 b of core substrate 1 are electrically connected to each other via conductive pastes 7 and 5. In this example, not only the first via hole 4a but also the second via hole 6a is a tapered hole whose diameter increases upward, but the second via hole 6a may be a straight hole having the same upper end opening diameter and lower end opening diameter. . The upper end opening diameter D2 of the second via hole 6a is smaller than the upper end opening diameter D1 of the first via hole 4a.

  Next, an example of a method for manufacturing the wiring board A having the above configuration will be described with reference to FIGS. 2 shows the first stage of the manufacturing process, FIG. 3 shows the second stage of the manufacturing process, and FIG. 4 shows the final stage of the manufacturing process. Here, the manufacturing method of the wiring board A in the sub-board state will be described, but in actuality, it is manufactured in the collective board state and then divided into the sub-boards.

  As shown in FIG. 2A, the core substrate 1 having the conductor pattern 2 formed on the upper surface is prepared, and the circuit component 3 is mounted on the mounting land 2a. The core substrate 1 is created by a known printed wiring technique.

  Next, as shown in FIG. 2B, the uncured first resin layer 4 thicker than the component height is stacked on the core substrate 1 and pressure-bonded. The thickness of the 1st resin layer 4 is 400-500 micrometers, for example. Uncured means a semi-cured (for example, B stage) state or a softer state. When the resin layer 4 is pressure-bonded, the softened resin enters the gap between the circuit component 3 and the core substrate 1, and the circuit component 3 is embedded in the resin layer 4. By heating at the same time as or after the pressure bonding of the resin layer 4, the resin layer 4 is cured and the core substrate 1 and the resin layer 4 are integrated. The embedding condition is, for example, a temperature of 80 to 140 ° C. and a pressure of 1.0 to 5.0 MPa is preferably applied. Furthermore, the conditions at the time of hardening are good to apply a heat | fever about 160-200 degreeC. As a result, the first resin layer 4 having the mounting land 2a and the via land 2b on the bottom surface is formed.

  Next, as shown in FIG. 2C, laser light is irradiated from above the cured resin layer 4 to process the bottomed via hole 4a having the via land 2b as the bottom surface. At the time of laser processing, since the laser beam is reflected by the via land 2b and cuts the inner wall of the via hole 4a, the shape of the via hole 4a becomes a tapered shape whose diameter increases upward. After the laser processing, a desmear process is performed for cleaning the surface of the land 2b which is the bottom surface of the bottomed via hole 4a. The desmear treatment may be either dry or wet.

  Next, as shown in FIG. 2 (d), a film 10 with an adhesive having a through hole 10a at the same position as the via hole 4a is prepared and affixed on the resin layer 4 with a laminator or a hand. For example, a PET film can be used as the film 10. The thickness of the film 10 is desirably about 25 to 100 μm, and the through hole 10a formed in the film 10 is desirably equal to or larger than the opening diameter of the via hole 4a. In place of (c) and (d) in FIG. 2, the film 10 is attached on the cured resin layer 4, and the via hole 4 a and the through hole 10 a are simultaneously formed by irradiating the laser beam. You may perform a desmear process.

  Next, as shown in FIG. 2E, with the film 10 attached to the upper surface of the resin layer 4, the conductive paste 5 is filled into the via holes 4a and the through holes 10a by the printer 11 and cured. The conductive paste 5 is cured by heating at about 160 to 200 ° C. Since the hardening of the conductive paste 5 can be performed in a state exposed to the outside, the solvent component contained in the conductive paste 5 can be surely volatilized.

  Next, as shown in FIG. 3A, when the conductive paste 5 is cured and then the film 10 is peeled off, a part 5 a of the conductive paste 5 is formed in a state protruding from the upper surface of the resin layer 4. The conductive paste 5 contains a conductive filler in a resin, and when cured, the surface tends to be resin-rich. The projecting portion 5a is made by sticking the film 10 in this manner in order to prevent the resin layer 4 from being polished in the subsequent polishing step by projecting a resin-rich portion having a small conductive component. is there. For example, when the conductive paste 5 is filled in the via hole 4a having a depth of 400 to 500 [mu] m and cured, the upper 10 to 30 [mu] m is considered to be a resin-rich layer. Therefore, if the protruding portion 5a is formed using the film 10 thicker than the resin-rich layer, the resin-rich layer can be entirely accommodated in the protruding portion 5a, and the conductive material can be easily exposed by a subsequent polishing process. Become.

  Next, as shown in FIG. 3B, the protruding portion 5a of the conductive paste 5 protruding in a protruding shape on the upper surface of the resin layer 4 is removed by physical polishing, and the resin layer 4 and the top surface of the conductive paste 5 are separated. Make it coplanar. Polishing can be performed with a buff 12 of about # 200 to # 600, for example. By polishing the protruding portion 5 a of the resin rich surface layer, the conductive portion is exposed on the surface of the conductive paste 5.

  Next, as shown in FIG. 3C, an uncured resin layer 6 with a protective film 13 having a via hole 6a and a through hole 13a at the same position as the via hole 4a on the upper surface of the resin layer 4 is prepared, and pin lamination is performed. The resin layer 6 is pressure-bonded onto the resin layer 4 with a press machine in a state where the positions are aligned. The pressing conditions are performed by applying a temperature of about 50 to 120 ° C. and a pressure of about 0.1 to 5.0 MPa. The thickness of the protective film 13 is desirably about 12.5 to 50 μm. As the resin layer 6, a thin semi-cured resin sheet having a thickness of 10 to 50 μm can be used. The via hole 6a and the through hole 13a are not limited to laser processing, and can be processed by a known method such as punching or drilling. The via hole 6a can be a hole having a smaller diameter than the diameter of the opening of the via hole 4a. Therefore, the via holes 6a can be formed with a narrow pitch corresponding to the via lands 8a formed thereon. In FIG. 3C, the shape of the via hole 6a is also drawn as a taper shape, but it goes without saying that it may be a straight shape.

  Next, as shown in FIG. 3D, the conductive paste 7 is filled into the via hole 6a and the through hole 13a by a printing machine (not shown), and then the protective film 13 is peeled off. As a result, the conductive paste 7 is formed on the surface of the resin layer 6 so as to protrude by the thickness of the protective film 13. At this time, both the resin layer 6 and the conductive paste 7 are in an uncured state.

  Next, as shown in FIG. 4A, the copper foil 8 is pressure-bonded to the release surface of the resin layer 6 by a press machine. The pressing conditions are performed by applying a temperature of about 50 to 120 ° C. and a pressure of about 0.1 to 5.0 MPa. Thereby, while the copper foil 8 and the resin layer 6 adhere, the copper foil 8 and the electrically conductive paste 7 adhere. Thereafter, the resin layer 6 and the conductive paste 7 are collectively cured by heating at 160 to 200 ° C. When the conductive paste 7 protrudes from the surface of the resin layer 6, the density of the conductive paste 7 in the via hole 6 a is increased by crimping the copper foil 8, the conductivity of the conductive paste 7 itself is improved, and the conductive paste 5 Connection reliability is improved.

  Finally, as shown in FIG. 4B, the wiring board A is completed by patterning (8a, 8b) the copper foil 8 by, for example, a subtractive method that is a photolithographic technique.

  As mentioned above, by using conductive paste and copper foil for three-dimensional wiring, less wet processing compared to plating wiring etc. which is a representative wiring method, that large scale equipment such as plating equipment is not required, Since it can be formed without a permanent hole filling process, the process can be simplified, for example, the number of steps can be reduced. Since the via diameter can be individually set by using the cured resin layer 4 and the uncured resin layer 6 and creating the via holes 4a and 6a individually, the via diameter of the uncured resin layer 6 corresponding to the surface side is reduced. By doing so, the surface wiring pattern 8 can be miniaturized. Furthermore, the surface of the cured conductive paste 5 tends to be resin-rich, and when the uncured conductive paste 7 is brought into contact with the conductive paste 5, there is a possibility that the conduction resistance becomes high at the interface between both conductive pastes. However, since the surface of the cured conductive paste 5 is physically polished before contacting the uncured conductive paste 7, the resin-rich surface layer can be removed to expose the conductive portion on the surface. The conduction resistance at the interface between the conductive pastes 5 and 7 can be lowered. Therefore, the conduction reliability in the via can be improved.

  FIG. 5 shows a second embodiment of the method of manufacturing the wiring board A. Portions corresponding to those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. In the first embodiment, the copper foil 8 is patterned after being attached to the second resin layer 6. However, in this embodiment, the method uses a copper foil with a carrier in which a wiring pattern is formed in advance. The pin lamination method is used for the alignment of the wiring.

  FIG. 5A shows a state in which the carrier 20 is attached to the back surface of the copper foil 8. The copper foil 8 is patterned as shown in FIG. 5B, and the copper foil 8 patterned as shown in FIG. 5C is pressed onto the uncured second resin layer 6 and cured. The uncured second resin layer 6 is, for example, the resin layer 6 at the stage of (d) in FIG. In this case, since it is not necessary to carry out the pattern formation process of the copper foil 8 on the resin layers 4 and 6, it is not necessary to perform the wet treatment on the resin layers 4 and 6; The influence of moisture absorption etc. can be suppressed.

  FIG. 6 shows a third embodiment of the method of manufacturing the wiring board A. Portions corresponding to those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The process up to the formation of the cured resin layer 4 (FIG. 3B) is the same as in the first embodiment, but the uncured resin layer 6 is not pressure-bonded to the resin layer 4, but is not applied to the copper foil 8. In this method, the cured resin layer 6 is pressure-bonded and the conductive paste 7 is filled, and then the resin layer 4 is pressure-bonded.

  6A, the copper foil 8 is pressure-bonded to the uncured resin layer 6 with the protective film 13 having the via hole 6a and the through hole 13a. Next, as shown in FIG. 6B, the conductive paste 7 is filled into the via holes 6 a and the through holes 13 a from the protective film 13 by the printing machine 21. Next, as shown in FIG. 6C, the protective film 13 is peeled off, and the conductive paste 7 partially protrudes from the surface of the second resin layer 6. At this time, both the resin layer 6 and the conductive paste 7 are in an uncured state. Next, as shown in FIG. 6D, the surface from which the conductive paste 7 protrudes is pressure-bonded to the cured first resin layer 4. The first resin layer 4 is obtained by physically polishing the surface of the conductive paste 5 as shown in FIG. At this time, a pin lamination method is used for alignment of the vias at the time of crimping. Thereafter, the copper foil 8 may be patterned.

  In this method, since the paste filling process can be separated into the cured resin layer 4 and the uncured resin layer 6, there is an advantage that the process efficiency can be improved. In addition, pattern formation of the copper foil 8 can also be implemented in the stage (state which stuck the copper foil on the carrier) before crimping | bonding to the resin layer 6 similarly to FIG.

  FIG. 7 shows an example in which a multilayer wiring board is configured using the wiring board A manufactured as described above. The circuit component 15 is mounted between one land 8a and the electrode 8b, the third resin layer 16 is formed thereon, and the circuit component 15 is embedded in the resin layer 16. A fourth resin layer 17 is formed thereon, and a wiring 18 is formed thereon. In this case, the wiring board A of the first embodiment corresponds to the core substrate, the third resin layer 16 corresponds to the first resin layer, and the fourth resin layer 17 corresponds to the second resin layer. . On one via land 8a, the via hole 16a of the resin layer 16 corresponds, and the conductive paste 19 filled in the via hole 16a and the via land 8a are electrically connected. Further, a via hole 17a of the resin layer 17 corresponds to the conductive paste 19, and the conductive paste 20 filled in the via hole 17a is connected to the via land 18a thereon. In this way, multiple layers can be sequentially formed.

  FIG. 8 shows another example of the wiring board. In this wiring board B, the core substrate 1 in the wiring board A of FIG. 1 is omitted, and the mounting land 2a and the via land 2b are directly formed on the lower surface of the first resin layer 4. In this case, the mounting land 2a and the via land 2b are formed by, for example, forming the mounting land 2a and the via land 2b on the carrier and forming the resin layer 4 on the mounting land 2a. The carrier may be peeled off from the resin layer 4. A multilayer wiring board can also be configured by stacking such a wiring board B on the uncured resin layer 6 instead of the copper foil in FIG. Also in this example, the second via hole 6a is a tapered hole whose diameter increases upward, but may be a straight hole having the same diameter at the upper end and the same diameter at the lower end. Since the upper end opening diameter D2 of the second via hole 6a is smaller than the upper end opening diameter D1 of the first via hole 4a, the via land 8a formed on the upper surface of the conductive paste 7 can be miniaturized and the conductor pattern 8 can be miniaturized.

Explanation of symbols

A, B Wiring board 1 Core board 2 Conductor pattern 2a Mounting land 2b Via land 3 Circuit component 4 Resin layer (first resin layer)
4a Via hole 5 Conductive paste 6 Adhesive layer (second resin layer)
6a Via hole 7 Conductive paste 8 Wiring pattern (metal foil)
8a Via land 8b Electrode

Claims (9)

A first step of preparing a cured first resin layer having a conductor pattern and having a bottomed first via hole having the conductor pattern as a bottom surface;
A second step of filling the first via hole with the first conductive paste so that a part of the first via hole protrudes from the surface of the first resin layer, and curing the conductive paste;
A third step of polishing the protruding portion of the first conductive paste filled in the first via hole;
A fourth step of preparing an uncured second resin layer in which a second via hole penetrating in a position corresponding to the first via hole is formed;
A fifth step of laminating the first resin layer and the second resin layer so that the first via hole and the second via hole are continuous;
And a sixth step of filling the second via hole with a second conductive paste after the fifth step. In the second step, a film having a through hole is laminated on the first resin layer, and the first conductive paste is simultaneously filled in the first via hole of the first resin layer and the through hole of the film. Then, by peeling the film, the first conductive paste is in a state in which a part protrudes from the surface of the first resin layer,
The method for manufacturing a wiring board according to claim 1 , wherein in the third step, the protruding portion of the first conductive paste is polished. The method for manufacturing a wiring board according to claim 2 , wherein a diameter of the through hole of the film is larger than an opening diameter of the first via hole. Wherein in the third step, the manufacturing method of the wiring substrate according to any one of claims 1 to 3, characterized in that polishing the surface of the first conductive paste by buffing. In the fourth step, the bottom diameter of the second via hole, manufacturing of the wiring board according to any one of claims 1 to 4, wherein the smaller than the opening diameter of the first via hole Method.   A seventh step of pressing a metal foil against the uncured second resin layer and bringing the metal foil into contact with an uncured second conductive paste filled in the second via hole; The manufacturing of the wiring board according to any one of claims 1 to 5, further comprising an eighth step of simultaneously curing the second conductive paste filled in the second via hole and the second resin layer. Method. The method for manufacturing a wiring board according to claim 6 , wherein the metal foil is patterned after completion of the eighth step. In the seventh step, the metal foil is pre-patterned in a state of being stuck on a carrier, and the patterned metal foil is pressure-bonded to the second resin layer,
The method for manufacturing a wiring board according to claim 6 , wherein the carrier is peeled after the eighth step is finished. A first resin layer having a conductor pattern and having a bottomed first via hole having the conductor pattern as a bottom surface;
A circuit component embedded in the first resin layer and mounted on the conductor pattern;
A first conductive paste that is filled and cured in the first via hole and the surface exposed on the upper surface of the first resin layer is polished;
A second via hole penetrating vertically is formed, the upper end opening of the second via hole is formed with a smaller diameter than the upper end opening of the first via hole, and the diameter of the upper end opening of the second via hole is smaller. A tapered hole larger than the diameter of the lower end opening, and is laminated on the first resin layer so that the lower end opening of the second via hole corresponds to the upper end opening of the first via hole; and A second resin layer that is thinner than the first resin layer;
A second conductive paste filled and cured in the second via hole and electrically connected to the first conductive paste;
A wiring board comprising: a wiring pattern formed on the second resin layer so as to cover the second via hole, and electrically connected to the second conductive paste.

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