JP2005005684A - Multilayer board and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer board and a manufacturing method therefor, which obtain stable electric connection by sufficiently compressing a conductive paste at the time of hot pressing and allow a thermosetting resin to be charged into spaces between wiring patterns in inner layers without leaving any gap. <P>SOLUTION: A multilayer board (215) has multiple wiring substrates (206 and 210) that are laminated. At least one wiring substrate (210) located outside has holes which penetrate through the substrate in the thickness direction. A conductive material (209) is charged into the holes and is cured. The multiple wiring substrates (206 and 210) have wiring layers (211') that are electrically connected through the cured conductive material (209). The wiring layers (211'), which are positioned outside the cured conductive material (209), protrude outside the surrounding areas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a multilayer board that performs electrical connection in the thickness direction of a wiring board by a conductor such as a conductive paste and a method for manufacturing the same.

  In recent years, with the miniaturization and high performance of electronic devices, the supply of multilayer wiring circuit boards capable of mounting semiconductor chips such as LSIs at high density not only for industrial use but also in the field of consumer equipment at low cost. Is strongly demanded. In such a multilayer printed circuit board, it is important to electrically connect a plurality of wiring patterns formed at a fine wiring pitch with high reliability. In response to such market demand, instead of the metal plated conductor on the inner wall of the through hole, which has been the mainstream for interlayer connection of multilayer wiring boards in the past, any electrode on the multilayer printed wiring board can be placed at any wiring pattern position. There is what is called an all-layer IVH structure resin multilayer substrate using an inner via hole connection method that can be connected (see, for example, Patent Document 1 below). According to such a substrate, it is possible to fill the via holes of the multilayer printed wiring board with a conductive paste to electrically connect only necessary layers, and to provide an inner via hole (IVH) directly under the component land. For this reason, it is possible to reduce the substrate size and achieve high-density mounting. In addition, since the conductive paste is used for the electrical connection in the inner via hole, the stress applied to the via hole can be relieved, and a stable electrical connection can be realized against dimensional changes due to thermal shock or the like. Can do.

In this all-layer IVH structure resin multilayer substrate, a paste filling method as shown in FIGS. 5A to 5D was used for the purpose of realizing high-density interlayer connection with high productivity by reducing the size of the inner via hole. Conventionally, wiring boards have been proposed. A method for manufacturing a wiring board using conventional paste filling will be described below. First, FIG. 5A shows an inner layer substrate 106 in which a wiring layer 102 is formed on both surfaces of an electrically insulating base material 101 and the layers are connected by a conductive paste 103 or electrolytic plating. The electrically insulating base material 101 is made by impregnating a thermosetting resin 105 on both sides of the core material 104. As a core material, a glass woven fabric impregnated with a thermosetting resin such as an epoxy resin is generally used as a glass epoxy substrate. FIG. 5B shows a base material A110 in which the core material 107 is impregnated with an uncured thermosetting resin 108 on both sides of the inner layer substrate 106, through holes are formed, and the conductive paste 109 is filled. The inner layer substrate 106 and the base material A110 disposed on both sides are aligned at a predetermined position and temporarily fixed with an adhesive or the like (not shown). Further, wiring layers 111 for outer layers are arranged on both sides of the base material A110. After that, the uncured thermosetting resin 108 and the conductive paste 109 are cured by hot pressing, and the conductive paste 109 is compressed to adhere the wiring layer of the inner substrate and the wiring layer for the outer layer, so that electric The substrate shown in FIG. Thereafter, the outer wiring layer is patterned by a photolithography method to obtain a four-layer substrate 112 shown in FIG. 5D. 111 ′ is a patterned wiring.
JP-A-6-268345

  In the conventional method for manufacturing a wiring board as described above, when the degree of cure of the uncured thermosetting resin used (gel time, resin flowability, minimum viscosity value in the curing process, etc.) is low, The conductive paste flows together with the resin during hot pressing, and a sufficient compression effect cannot be obtained, resulting in poor connection. Further, if the degree of curing is high, insufficient adhesive strength with the inner layer substrate or sufficient resin does not flow between the inner layer wiring patterns, resulting in whitening, and defects in the moisture absorption reflow test occur.

  The present invention solves the above-mentioned problem, and a multilayer capable of sufficiently compressing a conductive paste during hot pressing to obtain a stable electrical connection and filling a thermosetting resin between the inner layer patterns without any gaps. A substrate and a method for manufacturing the same are provided.

  In the multilayer substrate of the present invention, a plurality of wiring substrates are laminated, and at least one wiring substrate located outside is filled with a conductive substance in a hole penetrating in the thickness direction and cured, The wiring layer of the single wiring board is a multilayer board electrically connected by the hardened conductive material, and the wiring layer located outside the hardened conductive material protrudes outside from the surroundings. It is characterized by that.

  The method for producing a multilayer substrate according to the present invention includes a core material including a thermosetting resin layer in an uncured state on at least one surface of a wiring substrate including wiring layers provided on both surfaces of an electrically insulating substrate, and both surfaces thereof. An uncured base material filled with conductive paste is placed in a hole penetrating in the thickness direction, including an uncured thermosetting resin layer, and the wiring layer is stacked from the outside, and the whole is compressed in the thickness direction. The uncured base material is deformed along the irregularities due to the wiring on the surface of the adjacent wiring board, and then the uncured base material and the wiring layer of the adjacent wiring board are heated by heating press the conductive paste. The wiring layer located outside the hardened conductive material is protruded outside from the surroundings by being electrically connected by the hardened conductive material.

  According to the present invention, it is possible to produce a product in which a thermosetting resin is deformed so that there is no gap in the inner wiring layer, and there is an effect that it is possible to eliminate the occurrence of defects due to the swelling phenomenon in the moisture absorption reflow test. . Further, by pressing the press sheet material using a material having a higher modulus of elasticity than the core material, the conductive paste and the wiring layer can be joined and alloyed, and a stable electrical connection can be obtained. Further, by using a thermosetting resin sheet or a composite sheet of a thermoplastic sheet and a rigid sheet, it can be created without increasing the number of steps. In addition, the conventional problem can be solved without using an indirect material such as a composite sheet by using a method in which a thermosetting resin is filled between inner layer wiring patterns with an elastic sheet or elastic roll in advance and then heat pressing is applied. In addition, it is possible to provide a method for manufacturing a multilayer substrate in consideration of productivity. The invention is preferably selected in consideration of the number of production, the size of the workpiece, the physical properties of the thermosetting resin, and the like. Due to the above-described effects, it is possible to greatly reduce defects due to the swelling phenomenon when mounting components on the wiring board, and it is possible to obtain a multilayer board with sufficiently high reliability in electrical connection reliability.

  In the multilayer board of the present invention, a plurality of wiring boards are laminated, and the wiring layer located outside the cured conductive material of at least one wiring board located outside protrudes outward from the periphery. This structure includes a core material including an uncured thermosetting resin layer on at least one surface of the wiring board, and an uncured thermosetting resin layer on both surfaces of the core material, and a hole penetrating in the thickness direction. Place the uncured base material filled with conductive paste, stack the wiring layers from the outside, compress the whole in the thickness direction, and deform the uncured base material along the irregularities due to the wiring on the adjacent wiring board surface Then, it is obtained by electrically connecting the uncured base material and the wiring layer of the wiring board adjacent to the uncured base material with a conductive material obtained by heat-curing the conductive paste.

  As a result, it is possible to provide a multilayer substrate capable of sufficiently compressing the conductive paste during hot pressing to obtain a stable electrical connection and filling the thermosetting resin between the wiring patterns of the inner layer without any gap, and a method for manufacturing the same. .

  Further, the protruding structure of the wiring layer increases the bonding strength between the wiring layer and the via made of a conductive material obtained by curing the conductive paste, and can improve the via reliability. Further, when another wiring layer is bonded to the outside of the wiring layer, it becomes easy to bond.

  The protrusion height to the outside of the wiring layer is preferably in the range of 1 μm to 100 μm.

  The wiring board from which the wiring layer projects outwards is composed of a core material and thermosetting resin layers on both sides thereof, and the core material and thermosetting resin layers on both sides thereof are formed by wiring on the surface of the adjacent wiring board. It is preferable to be deformed along the unevenness. By this deformation, the resin can be filled with no gap between the inner layer wiring patterns.

  The unevenness of the core material and the thermosetting resin layers on both sides thereof can be formed by press molding, compression molding or vacuum molding before hot pressing.

  It is preferable that the plurality of wiring boards are laminated with three or more wiring boards, and the wiring boards located on both outer layers are composed of a core material and thermosetting resin layers on both sides thereof.

  The core material is preferably a resin film or a resin-impregnated fiber sheet.

  The present invention provides a rigid sheet on both sides of an uncured resin sheet using a thermosetting resin as a method for embedding a thermosetting resin between the wiring patterns of the inner layer without a gap and simultaneously compressing the conductive paste. By arranging the press sheet with the outer side of the outermost wiring layer at the time of hot pressing, the viscosity decreases as the temperature rises from normal temperature, and the shape follows the inner layer pattern of the resin sheet. Furthermore, by hardening after that, it becomes possible to compress an electrically conductive paste and to solve the said subject. According to the present invention, it is possible to obtain a multilayer substrate that can sufficiently withstand the moisture absorption reflow test and has high connection reliability. Further, the same effect can be obtained by disposing a composite press sheet in which a rigid sheet is disposed on both sides of the thermoplastic sheet on the outside of the wiring layer at the time of hot pressing. However, at this time, it is necessary to carefully match the relationship between the thermoplastic sheet and the elastic sheet to the base material. That is, it is necessary to balance the degree of softening of the thermoplastic sheet and the elastic modulus (rigidity) of the rigid sheet. When the thermoplastic sheet is greatly softened, the rigidity of the rigid sheet is increased, or the rigidity is increased by increasing the thickness. However, if the rigidity is excessively high, the embedding property of the resin in the inner layer pattern is hindered to cause whitening.

  The structure of the uncured electrical insulating material is applied to a base material impregnated with an uncured resin of a core material made of woven or non-woven fabric, or on both surfaces of a core material made of an organic resin film sheet. When applying a base material on which a cured resin is disposed, a method in which a press sheet material having a higher elastic modulus than the core material of the electrical insulating material and lower than the wiring layer is disposed outside the wiring layer during hot pressing Is used.

  Further, on both sides of the inner layer substrate having a wiring layer provided on both surfaces of the electrically insulating base material, a base material filled with a conductive paste is disposed in a hole penetrating the uncured electrical insulating base material, Wiring layers are stacked on both sides and heat-pressed to obtain an electrical connection between the outermost layer and the inner layer with the conductive paste. In the inner layer substrate, the core material is impregnated with an uncured resin, and a through hole is formed. After aligning the base material filled with the conductive paste, and laminating in the temperature range where the uncured thermosetting resin is not completely cured in the state where the wiring layer for the outer layer is overlapped on both sides thereof A method of curing and electrically connecting the thermosetting resin and the conductive paste by a hot press is used.

  As a method of performing the lamination, pressing is performed in a state where elastic sheets having an elastic modulus lower than that of the core material are arranged on both surfaces, or a laminator device including an elastic roll having an elastic modulus lower than that of the core material is used. It is also effective to perform the lamination in a reduced pressure or vacuum.

  As a result, due to the compressive effect of the conductive paste, it is possible to eliminate the whitening phenomenon due to high electrical connection reliability and poor wraparound of the resin, and to obtain a multilayer substrate that can sufficiently withstand the moisture absorption reflow test. As described above, according to the multilayer substrate manufacturing method of the present invention, the degree of cure (control width) of the uncured electrical insulating resin can be increased, and the high electrical connection can be achieved without complicating the manufacturing process. A reliable multilayer substrate can be manufactured.

(Embodiment 1)
The manufacturing method of the multilayer substrate in 1st Embodiment of this invention is demonstrated with reference to FIG. 1A-FIG. 2B. FIG. 1A shows an inner layer substrate 206 in which wiring layers 202 are formed on both surfaces of an electrically insulating base material 201 and the layers are connected by a conductive paste 203 or electrolytic plating. The electric insulating base material 201 is formed by impregnating a thermosetting resin 205 on both sides of a core material 204.

  In FIG. 1B, the base material A 210 is disposed on both sides of the inner layer substrate 206. The base material A210 is obtained by bonding an uncured thermosetting resin 208 to a core material 207, opening a through hole, and filling with a conductive paste 209. The core material is preferably a heat-resistant synthetic resin film such as a polyimide film having a thickness in the range of 3 to 50 μm, a polyamide film, or a fluororesin film (for example, polytetrafluoroethylene). Moreover, you may form with materials, such as a prepreg which impregnated the epoxy resin to the aramid fiber nonwoven fabric of thickness 10-200 micrometers.

  The uncured thermosetting resin is preferably formed of a material such as a polyimide resin, an epoxy resin, or a polyimide resin into which an epoxy group is introduced in a thickness range of 5 to 30 μm, for example.

  The inner layer substrate 206 and the base material A210 disposed on both sides are aligned (aligned) at a predetermined position and temporarily fixed with an adhesive or the like (not shown). Further, wiring layers 211 for outer layers are arranged on both sides of the base material A210. Furthermore, the composite type press sheet 214 which arrange | positions the rigid sheet | seat 213 is arrange | positioned at the both sides of the resin sheet 212 of the uncured state using a thermosetting resin on the outer side. The thermosetting resin is, for example, an epoxy resin corresponding to FR-4 or FR-5 having a thickness in the range of 10 to 100 μm, and the rigid sheet is, for example, a copper foil, stainless steel foil, or fluorine-based resin having a thickness in the range of 10 to 100 μm. A resin sheet, a polyimide film, or the like is used. However, the condition is that the elastic modulus is higher than the material used for the core material. This is because the core material is finally compression-compressed.

  As shown in FIG. 1C, during the subsequent hot pressing, as the temperature rises from room temperature in a pressurized state, the viscosity of the resin sheet 212 decreases and follows the pattern of the inner wiring layer. Furthermore, it becomes possible to compress an electrically conductive paste by hardening after that. As a result, the inner wiring layer 202 and the outer wiring layer 211 can be bonded and integrated, and sufficient electrical connectivity can be obtained. In addition, since the resin sheet 212 follows the inner wiring pattern, a whitening phenomenon is suppressed, and a multilayer substrate that does not cause defects in the moisture absorption reflow test can be obtained. Preferable conditions for the hot press are heat press using a hot press at a press temperature of 200 ° C. and a pressure of 5 to 20 MPa for 60 minutes.

  As shown in FIG. 2A, a substrate after hot pressing in which no gap is generated between the inner layer wiring patterns is obtained. Thereafter, the outer wiring layer is patterned by a photolithography method to obtain a four-layer substrate 215 shown in FIG. 2B. 211 'is a patterned wiring. The height at which the wiring 211 ′ protrudes from the periphery was about 50 μm. Further, the outer substrate 210 was deformed along the uneven shape of the inner wiring pattern 202.

  When a thermoplastic sheet is used as the resin sheet 212, it is necessary to sufficiently consider the degree of softening with respect to the temperature of the sheet and the temperature during hot pressing. That is, if the degree of softening is high, the core material becomes soft and the pressure escapes to the resin sheet side, so that the conductive paste cannot be sufficiently compressed. Although some measures can be taken with rigid sheets placed on both sides, caution is required. In order to fully exhibit the effect of this embodiment, it is necessary to consider the type and thickness of the resin sheet so that both the followability to the inner layer pattern and the compression effect of the conductive paste can be achieved. As a material suitable for the purpose, for example, a polytetrafluoroethylene (PTFE) sheet having a thickness in the range of 25 to 200 μm and other fluororesin-based sheets can be used.

  Further, in order to achieve both of the effects described above, instead of the resin sheet 212 and the rigid sheet 213, a press sheet material having higher rigidity than the core material of the uncured electrical insulating material and lower than the wiring layer is heated. It is also possible to arrange it outside the wiring layer during pressing. Examples of the sheet that can achieve the effect include a metal sheet such as an aluminum sheet having a thickness in the range of 12 to 100 μm, a nickel sheet, and a resin sheet having a thickness in the range of 12 to 100 μm, such as a fluorine-based, PTFE-based, and polyimide-based sheet. There is a stack of multiple sheets. Further, as the base material A210, for example, a woven or non-woven organic or inorganic (for example, glass) fiber and a thermosetting resin (for example, epoxy resin) are used as the core material. Those using an epoxy resin as a thermosetting resin are generally prevalent as a glass epoxy material and are advantageous in price. Further, those using an aramid fiber as a fiber and an epoxy resin as a thermosetting resin are characterized by excellent processability with a laser and easy production. Further, when an organic resin film is used as the core material, the thickness of the multilayer substrate can be made thin and flexible. As the organic resin film, an aramid film, a polyimide film, a liquid crystal polymer film, or the like is used. An organic resin film having a thickness of about 10 μm can be easily obtained, and a thin multilayer substrate can be realized. When the thickness of the organic resin film is thin, it is possible to connect wiring with small vias accordingly, and as a result, a high-density multilayer substrate can be realized.

  For example, in the case of a film having a thickness of 30 μm, the via diameter is preferably in the range of 30 to 70 μm, and more preferably in the vicinity of 50 μm.

  Further, when a thermosetting organic resin is used as an adhesive layer on both sides of the organic resin film, the stability with respect to the reliability test can be increased.

  In addition, an electrolytic copper foil is generally used for the wiring layer, and the conductive paste is made of at least a conductive powder and a thermosetting resin. Examples of the conductive powder include metal powders such as copper powder, silver powder, nickel powder, and aluminum powder, and powders having a coating layer of the above metal, and the form thereof is resin-like, flake-like, spherical, and amorphous. Any form may be sufficient. Thermosetting resins include known resins such as phenol resins, naphthalene resins, urea resins, amino resins, alkyd resins, silicon resins, furan resins, unsaturated polyester resins, epoxy resins, polyurethane resins, etc. Can be combined as appropriate. In addition, an additive or a solvent can be added to adjust the oxidation stability and viscosity of the conductive paste. In addition, examples of the method for reducing the conductive paste include, but are not limited to, adding a reducing agent and using an amine curing agent. Examples of the reducing agent include known reducing agents such as fatty acids, but are not limited thereto.

  When the wiring layer is formed of copper foil by hot pressing, the copper powder mainly causes mutual adhesion and can be electrically connected. Further, when silver-coated particles are used for silver powder or copper powder, adhesion and alloying are performed, and a strong electrical connection reliability can be obtained with a strong connection.

  Next, in the base material A210, the conductive paste 209 is formed in a projecting shape from the thermosetting resin. This is because the absolute amount of particles is easy to obtain a connection by compressing the wiring layer and the conductive paste. The purpose is to increase. Although not necessarily required, the manufacturing method thereof is, for example, as shown in Japanese Patent Application Laid-Open No. 06-268345, after performing hole processing with a cover film placed on an uncured resin, It can be easily obtained by filling the adhesive paste and peeling off the cover film.

  According to the present invention, the resin sheet 212 follows the inner wiring layer at the time of hot pressing, and the phenomenon of whitening can be suppressed and defects due to swelling in the moisture absorption reflow test can be eliminated. Furthermore, since the resin sheet 212 is cured, it is possible to compress the conductive paste without applying a process, and a multilayer substrate with high electrical connection reliability can be obtained.

(Embodiment 2)
The multilayer substrate manufacturing method of Embodiment 2 does not use a composite sheet at the time of hot pressing, but includes a step of laminating with an elastic sheet in a temperature range in which an uncured cured resin is not completely cured in advance, And the step of curing and electrically connecting the electrically insulating substrate and the conductive paste, which is different from the first embodiment described above. Hereinafter, the manufacturing method of the 2nd Embodiment of this invention is demonstrated with reference to FIG. FIG. 3A shows a state in which a plurality of base materials created in the same manner as FIG. 1B described in Embodiment 1 are sandwiched between elastic sheets 320. The plurality of base materials include a base material A310 impregnated with an uncured thermosetting resin 303 on both sides of the inner layer substrate 301 on both sides of the inner layer substrate 301, opened through holes and filled with the conductive paste 304, and The wiring layer 305 is disposed on both sides thereof. Thereafter, the elastic sheet 320 is pressed and laminated in a temperature range in which the uncured thermosetting resin 303 is not completely cured. As the elastic sheet, for example, an aluminum foil, a nickel foil, a fluororesin film, a silicone rubber sheet, a fluororubber sheet, a urethane rubber sheet having a thickness in the range of 12 to 100 μm can be used.

  FIG. 3B is a cross-sectional view showing a state after lamination. As shown in the figure, the thermosetting resin 303 is pushed by the elastic sheet 320 and penetrates between the inner layer patterns. At this time, the conductive paste 304 is in close contact with the wiring layers on both sides and is hardly connected. Further, the uncured thermosetting resin 303 is hardly cured. At this time, if it is performed under a high temperature condition, the resin does not flow into the remaining gap even if hot pressing is performed later, and the effect of compressing the conductive paste cannot be obtained sufficiently, and electrical connection cannot be obtained.

  Next, the thermosetting resin 303 and the conductive paste 304 are cured by hot pressing, and the conductive paste is compressed to obtain electrical connection. At this time, the gap with the inner wiring layer generated in FIG. 3A is filled with resin. The preferable conditions for the hot press are hot press using a hot press at a press temperature of 200 ° C. and a pressure of 5 to 20 MPa for 60 minutes.

  Thereafter, as shown in FIG. 3C, the outer wiring layer is patterned by photolithography to obtain a four-layer substrate. Reference numeral 305 'denotes a patterned wiring. The height at which the wiring 305 ′ protrudes from the periphery was about 50 μm. Further, the thermosetting resin 303 was deformed along the uneven shape of the inner wiring pattern 306.

(Embodiment 3)
The manufacturing method of the multilayer substrate of Embodiment 3 does not use a composite sheet at the time of hot pressing, but includes a step of laminating with an elastic roll in a temperature range in which an uncured cured resin is not completely cured in advance, The second embodiment differs from the first and second embodiments in that it includes a step of curing and electrically connecting the electrically insulating substrate and the conductive paste. Hereinafter, the manufacturing method of the 3rd Embodiment of this invention is demonstrated with reference to FIG. FIG. 4A shows a state in which a plurality of base materials created in the same manner as FIG. 1B described in Embodiment 1 are sandwiched between elastic rolls 420. As the elastic roll, a roll of silicone rubber, urethane rubber or the like can be used.

  The plurality of base materials include a base material A410 that impregnates both sides of the core member 402 with an uncured thermosetting resin 403 on both sides of the inner layer substrate 401, opens through holes, and is filled with the conductive paste 404; The wiring layer 405 is disposed on both sides thereof. Thereafter, the elastic roll 420 is laminated in a temperature range in which the uncured thermosetting resin 403 is not completely cured. The preferable conditions for the laminate are a temperature of 70 to 120 ° C., a linear pressure of 0.1 to 0.3 Kg / cm, and a roll passing speed of 30 mm / min. FIG. 4B is a cross-sectional view showing a state after lamination. As shown in the figure, the uncured thermosetting resin 403 is pushed by the elastic roll 420 and penetrates between the inner layer patterns. At this time, the conductive paste 404 is in close contact with the wiring layers on both sides and is hardly connected. Further, the curing of the uncured thermosetting resin 403 has hardly progressed. If the temperature is increased at this time, the resin does not flow into the remaining gap even if hot pressing is performed later, and the compression effect of the conductive paste cannot be obtained sufficiently, and electrical connection cannot be obtained. This is the same as in the second embodiment. Next, hot pressing is performed to cure the uncured thermosetting resin 403 and the conductive paste 404, and the conductive paste 404 is compressed to obtain electrical connection. At this time, the gap with the inner wiring layer generated in FIG. 4A is filled with resin.

  Thereafter, as shown in FIG. 4C, the outer wiring layer 405 is patterned by photolithography to obtain a four-layer substrate. Reference numeral 405 'denotes a patterned wiring. The height at which the wiring 405 ′ protrudes from the periphery was about 50 μm. Further, the outer substrate 410 was deformed along the uneven shape of the inner wiring pattern 406.

  Since the present embodiment performs lamination using an elastic roll as compared to the second embodiment, continuous operations can be performed, and productivity is improved. Further, in comparison with the first embodiment, an indirect material such as a composite sheet is not necessary, and a multilayer substrate can be obtained at low cost.

  In the multilayer substrate of this embodiment manufactured by the manufacturing method as described above, it is possible to suppress the whitening phenomenon due to insufficient flow into the thermosetting resin, compared to the multilayer substrate manufactured by the conventional manufacturing method. In addition, the electrical connection by the conductive paste was able to obtain a stable product as before.

FIGS. 8A to 8C are cross-sectional views illustrating the first half of the method for manufacturing a multilayer substrate according to Embodiment 1 of the present invention. FIGS. FIGS. 9A to 9B are cross-sectional views illustrating the latter half of the method for manufacturing a multilayer substrate according to Embodiment 1 of the present invention. FIGS. AC is sectional drawing explaining the manufacturing method of the multilayer substrate based on Embodiment 2 of this invention. A to C are cross-sectional views illustrating a method for manufacturing a multilayer substrate according to Embodiment 3 of the present invention. A to D are cross-sectional views illustrating a method for manufacturing a multilayer substrate according to a conventional embodiment.

Explanation of symbols

101,201 Electrically insulating substrate
102,202,111,211,305,405 Wiring layer
103,109,203,209,304,404 Conductive paste
104,107,204,207,302,402 Core material
105,205 Thermosetting resin
106,206,301,401 Inner layer substrate
108,208,212,303,403 Uncured thermosetting resin
110,210 Base material A
112,215 4-layer board
213 Rigid sheet
214 Combined press sheet
320 Elastic sheet
420 Elastic roll
211 ', 305', 405 ', 111' wiring

Claims (22)

Multiple wiring boards are stacked,
At least one wiring board located outside is filled and hardened with a conductive substance in a hole penetrating in the thickness direction, and the wiring layers of the plurality of wiring boards are made of the hardened conductive substance. A multi-layer board that is electrically connected,
The multilayer substrate is characterized in that the wiring layer located outside the cured conductive material protrudes outside from the surroundings.   The multilayer substrate according to claim 1, wherein a protruding height of the wiring layer to the outside is in a range of 1 μm to 100 μm.   The wiring board from which the wiring layer projects outwards is composed of a core material and thermosetting resin layers on both sides thereof, and the core material and thermosetting resin layers on both sides thereof are formed by wiring on the surface of the adjacent wiring board. The multilayer substrate according to claim 1, wherein the multilayer substrate is deformed along the unevenness.   The multilayer substrate according to claim 3, wherein the irregularities of the core material and the thermosetting resin layers on both sides thereof are formed by press molding, compression molding or vacuum molding before hot pressing. The plurality of wiring boards are laminated with three or more wiring boards,
The multilayer substrate according to claim 1, wherein the wiring boards located in both outer layers are constituted by a core material and thermosetting resin layers on both sides thereof.   The multilayer substrate according to claim 1, wherein the core material is a resin film or a resin-impregnated fiber sheet. On at least one side of the wiring board including the wiring layer provided on both sides of the electrically insulating base material,
An uncured base material including a core material including an uncured thermosetting resin layer and an uncured thermosetting resin layer on both surfaces thereof and filled with a conductive paste in a hole penetrating in the thickness direction. Place and
Overlay the wiring layer from the outside,
Compress the whole in the thickness direction, deform the uncured base material along the unevenness due to the wiring on the adjacent wiring board surface,
Then, by electrically connecting the uncured base material and the wiring layer of the adjacent wiring board by a heat press with a conductive material obtained by thermosetting the conductive paste, the outside of the cured conductive material A method for manufacturing a multilayer substrate, wherein a wiring layer located at a position protrudes outward from the surroundings.   The method for producing a multilayer substrate according to claim 7, wherein the deformation of the uncured base material before the heat pressing is performed by press molding, compression molding, or vacuum molding.   The method for producing a multilayer substrate according to claim 8, wherein the press molding or compression molding is performed by placing a press sheet material outside the wiring layer of the outer layer and performing hot pressing from the outside.   The method for producing a multilayer board according to claim 9, wherein the press sheet material is a composite press sheet including a rigid sheet on both sides of an uncured resin sheet of a thermosetting resin.   The method for producing a multilayer substrate according to claim 10, wherein an elastic modulus of the rigid sheet is higher than that of the uncured electrically insulating base material.   The method for manufacturing a multilayer board according to claim 10, wherein the elastic modulus of the rigid sheet is higher than that of the core material and lower than that of the wiring layer.   The method for producing a multilayer substrate according to claim 10, wherein the rigid sheet is a metal foil.   The method for producing a multilayer substrate according to claim 10, wherein the rigid sheet is a fluororesin or a polyimide resin sheet.   The method for producing a multilayer substrate according to claim 9, wherein the press sheet material has higher rigidity than the core material of the uncured electrically insulating substrate and is lower than the wiring layer.   The method for producing a multilayer substrate according to claim 15, wherein the press sheet material is a single sheet or a plurality of stacked sheets.   The method for producing a multilayer substrate according to claim 7, wherein the deformation of the uncured base material before the heat pressing is performed by laminate molding in a temperature range in which the uncured base material is not completely cured.   The method for producing a multilayer substrate according to claim 17, wherein when laminating, pressing is performed in a state where sheets having a lower elastic modulus than the core material are arranged on both sides.   The method for producing a multilayer substrate according to claim 17, wherein a laminator device composed of a roll having a lower elastic modulus than that of the core material is used when laminating.   The method for producing a multilayer substrate according to claim 17, wherein the inside of the press sheet material is depressurized when the lamination is performed.   The method for producing a multilayer substrate according to claim 7, wherein the uncured base material is a base material in which a core material made of a woven fabric or a nonwoven fabric is impregnated with an uncured resin.   The method for producing a multilayer substrate according to claim 7, wherein the uncured base material has an uncured resin disposed on both surfaces of a core material made of an organic resin film sheet.

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