JP2012248798A - Manufacturing method of wiring board and wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a wiring board capable of reducing inclination of an electrode on a top face around a recess, and a wiring board.SOLUTION: A manufacturing method of a wiring board comprises the steps of: preparing a first ceramic green sheet 1 and a second ceramic green sheet 2; providing a low shrinkage member 3; manufacturing a laminate 7 by laminating the second ceramic green sheet 2 on a top face of the first ceramic green sheet 1; and burning the laminate 7. The first ceramic sheet 1 has a first through hole 1a. The second ceramic green sheet 2 has a second through hole 2a smaller than the first through hole 1a. The low shrinkage member 3 has a burning shrinkage ratio smaller than the first ceramic green sheet 1 and is provided in the first through hole 1a. The laminate 7 is manufactured by laminating the second ceramic green sheet 2 on the top face of the first ceramic green sheet 1 so that the first through hole 1a overlaps with the second through hole 2a.

Description

  The present invention relates to a method of manufacturing a wiring board and a wiring board for housing and mounting an electronic component such as a semiconductor element or a crystal vibration element.

  Conventionally, a circuit board made of ceramic is used as a wiring board for mounting an electronic component and being mounted on a printed circuit board incorporated in an electronic device, and has a shape having a recess for accommodating the electronic component on the upper surface. is there.

  The bottom surface of such a recess is used as an electronic component mounting area. The electrode formed on the upper surface of the side wall portion around the recess and each electrode of the electronic component mounted in the electronic component mounting area are electrically connected via a connecting member such as solder or a bonding wire. With such a configuration, it is possible to manufacture an electronic device in which the electronic component is accommodated in the recess and the electronic component is prevented from being damaged by contact between the electronic component and an external member of the wiring board.

  Such a ceramic wiring board is manufactured by a green sheet lamination method. For example, a ceramic green sheet containing ceramic powder and an organic binder as main components is prepared. Next, a first ceramic green sheet in which a wiring conductor pattern is formed by printing a conductive paste containing metal powder as a main component and the like, and forming a through hole to form a frame and an electrode around the through hole A second ceramic green sheet on which a pattern is formed is prepared. Next, a second ceramic green sheet is laminated on the first ceramic green sheet and pressed to form a laminate. Thereafter, the laminated body is fired to produce a ceramic wiring board (see, for example, Patent Document 1).

JP 2001-260120 A

  However, in the wiring board having the conventional concave portion as described above, the concave portion on the upper surface of the side wall portion around the concave portion may be an inclined surface inclined toward the bottom surface of the concave portion. This is because when the ceramic green sheets are stacked and pressed, the plate-like pressing member in contact with the ceramic green sheets is bent and a part of the pressing member enters the recess. That is, the pressing member is brought into contact with the concave portion on the top surface of the ceramic green sheet serving as the side wall portion obliquely toward the bottom surface of the concave portion, so that the concave portion on the top surface of the side wall portion of the wiring board is inclined as described above. It was a surface.

  In addition, with the downsizing of electronic devices, the width of the upper surface of the side wall portion of the wiring board is becoming shorter. The length of the electrode formed on the upper surface of such a side wall portion and the length between the inner wall of the side wall and the end portion of the electrode on the concave portion side are becoming shorter. Therefore, the electrode formed on the upper surface of the inclined side wall portion is inclined toward the bottom surface of the concave portion, and when the electronic component and the electrode are connected with the bonding wire, the bonding wire is well connected on the electrode. It was difficult.

  The present invention has been devised in view of the above problems of the prior art, and an object thereof is to provide a method of manufacturing a wiring board and a wiring board that can reduce the inclination of the upper surface around the recess.

  According to one aspect of the present invention, there is provided a method of manufacturing a wiring board comprising: preparing a first ceramic green sheet and a second ceramic green sheet; providing a low-shrinkage member; and an upper surface of the first ceramic green sheet. And a step of laminating the second ceramic green sheets to produce a laminate, and a step of firing the laminate. The first ceramic green sheet has a first through hole. The second ceramic green sheet has a second through hole that is smaller than the first through hole. The low shrinkage member has a firing shrinkage rate smaller than that of the first ceramic green sheet, and is provided in the first through hole. The laminated body is produced by laminating and pressing the second ceramic green sheet so that the first through hole and the second through hole overlap the upper surface of the first ceramic green sheet.

  A wiring substrate according to another aspect of the present invention includes an insulating substrate provided with a recess, and a low-shrinkage member that is larger than the recess in plan view and is embedded in the insulating substrate so as to face the recess.

  The method for manufacturing a wiring board according to the present invention includes a step of providing a low-shrinkage member having a firing shrinkage rate smaller than that of the first ceramic green sheet in the first through-hole, and a top surface of the first ceramic green sheet. A second ceramic green sheet is laminated and pressed so that the through hole and the second through hole overlap, and a laminate is produced and fired. Since it is such a manufacturing method, even when laminated, even when the concave portion on the upper surface of the side wall portion around the concave portion becomes an inclined surface inclined toward the bottom surface of the concave portion, Shrinkage is smaller than that of the first ceramic green sheet. When such a laminated body is fired, the laminated body has a first ceramic green sheet and a second ceramic green sheet, rather than a region where the low-shrinkage member and the second ceramic green sheet overlap in a plan view. The overlapping area contracts more greatly. Thus, the low shrinkage member suppresses the concave side of the upper surface of the side wall portion of the multilayer body from being deformed to the low shrinkage member side, thereby reducing the inclination of the upper surface of the side wall portion of the multilayer body. Therefore, for example, when the electrode is formed on the upper surface of the side wall, the inclination of the electrode can be suppressed.

  The wiring board of the present invention has an insulating substrate provided with a recess and a low-shrinkage member that is larger than the recess in plan view and embedded in the insulating substrate so as to face the recess. The inclination of the upper surface of the part can be suppressed. Therefore, for example, when the electrode is formed on the upper surface of the side wall, the tilt of the electrode can be suppressed, and the bonding wire can be satisfactorily connected to the electrode.

(A) is a top view which shows an example of 1 process of embodiment of the manufacturing method of the wiring board of this invention, (b) is sectional drawing in the AA of (a). (A) is a top view which shows an example of 1 process of embodiment of the manufacturing method of the wiring board of this invention, (b) is sectional drawing in the AA of (a). (A) is a top view which shows an example of 1 process of embodiment of the manufacturing method of the wiring board of this invention, (b) is sectional drawing in the AA of (a). (A), (b) and (c) are sectional drawings which show an example of 1 process of embodiment of the manufacturing method of the wiring board of this invention. (A) is a top view which shows an example of 1 process of embodiment of the manufacturing method of the wiring board of this invention, (b) is sectional drawing in the AA of (a). It is a top view which expands and shows the A section of Fig.5 (a). It is sectional drawing which shows an example of embodiment of the wiring board of this invention. (A) is a top view which shows the other example of 1 process of embodiment of the manufacturing method of the wiring board of this invention, (b) is sectional drawing in the AA of (a).

  A method for manufacturing a wiring board and a wiring board according to the present invention will be described in detail with reference to the drawings. 1 to 8, 1 is a first ceramic green sheet, 1a is a first through hole, 2 is a second ceramic green sheet, 2a is a second through hole, 3 is a low shrinkage member, and 4 is an electrode. Pattern 5 is a through conductor pattern, 6 is a wiring conductor pattern, 7 is a laminate, 7a is a recess, 8 is a third ceramic green sheet, 11 is an insulating substrate, 14 is an electrode, 15 is a through conductor, 16 is a wiring conductor It is.

  First, a first ceramic green sheet 1 and a second ceramic green sheet 2 are prepared. The first ceramic green sheet 1 and the second ceramic green sheet 2 have a thickness corresponding to the wiring board to be produced.

  The first ceramic green sheet 1 and the second ceramic green sheet 2 are obtained by adding an organic binder and a solvent to a ceramic powder, and adding a predetermined amount of a plasticizer and a dispersing agent as required to obtain a slurry, (Polyethylene terephthalate) is applied on a resin or paper support by a doctor blade method, lip coater method or die coater method, and formed into a sheet, and then dried in hot air, vacuum or far infrared It is produced by drying by a drying method such as.

Examples of the ceramic powder include aluminum oxide (Al ₂ O ₃ ) powder, aluminum nitride (AlN) powder, glass ceramic powder, and the like, which are appropriately selected according to the characteristics required for the wiring board.

When the ceramic powder is an aluminum oxide powder or aluminum nitride powder, a powder of a component serving as a sintering aid such as silicon oxide (SiO ₂ ) or magnesium oxide (MgO) is added, and manganese oxide (MnO) is used as a colorant. ) Etc. may be added.

The glass ceramic powder is a mixture of glass powder and filler powder in a mass ratio of 10:90 to 99: 1, preferably 40:60 to 80:20. The glass powder of the glass ceramic powder, may be used those conventionally used in glass ceramics, for example, _SiO 2 _-B 2 _{O 3 based, SiO 2 -B 2 O 3 -Al} 2 O 3 system, SiO _{2 -B 2 O 3 -Al 2 O 3} -MO -based (where, M represents Ca, Sr, Mg, Ba, or _{Zn.), SiO 2 -Al 2} O 3 -M1O-M2O -based (where, M1 and M2 Are the same or different and indicate Ca, Sr, Mg, Ba or Zn.), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M 1 and M 2 are the same as above). , SiO ₂ —B ₂ O ₃ —M3 ₂ O system (where M3 represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M3 ₂ O system (where M3 is Same as above In a.), Pb-based, powder glass Bi system and the like are used.

Further, as the filler powder of the glass ceramic powder, what is conventionally used for glass ceramics may be used, for example, a composite oxide of Al ₂ O ₃ , SiO ₂ , ZrO ₂ and an alkaline earth metal oxide, Ceramic powders such as composite oxides of TiO ₂ and alkaline earth metal oxides, composite oxides containing at least one of Al ₂ O ₃ and SiO ₂ (cristobalite, quartz) (for example, spinel, mullite, cordierite) Can be mentioned.

As the organic binder, those conventionally used for ceramic green sheets may be used. For example, acrylic (acrylic acid, methacrylic acid or a single aggregate or copolymer of esters thereof, specifically, acrylic ester. Copolymer, methacrylic acid ester copolymer, acrylic acid ester-methacrylic acid ester copolymer, etc.), polyvinyl butyral type, polyvinyl alcohol type, acrylic-styrene type, polypropylene carbonate type, cellulose type homopolymer or the like A copolymer is mentioned. In view of decomposability and volatility in the firing step, an acrylic binder is more preferable. The amount of the organic binder added varies depending on the ceramic powder, but it may be an amount that is easy to be decomposed and removed during firing, and the ceramic powder is dispersed, and the green sheet is easy to handle and process. About 10 to 20% by mass is desirable.

The solvent contained in the slurry is made of organic materials such as hydrocarbons, ethers, esters, ketones, alcohols, etc. so that a slurry having a viscosity suitable for green sheet molding can be obtained by dispersing ceramic powder and organic binder. A solvent and water are mentioned. Among these, solvents having a high evaporation coefficient such as toluene, methyl ethyl ketone, and isopropyl alcohol are preferable because the drying process after slurry application can be completed in a short time. The solvent is added in an amount of 30 to 100% by mass with respect to the ceramic powder, so that the viscosity is such that the slurry can be satisfactorily coated on the support, specifically about 3 to 100 cps. It is desirable to make it.

  Next, as in the example shown in FIG. 1, the first through hole 1 a is formed in the first ceramic green sheet 1. Thereafter, as in the example shown in FIG. 2, the first through-hole 1 a has substantially the same shape as the first through-hole 1 a and has a smaller shrinkage in firing in the thickness direction than the first ceramic green sheet 1. The low shrinkage member 3 is disposed.

  Further, as in the example shown in FIG. 3, the second through hole 2 a is formed in the second ceramic green sheet 2.

  The first through hole 1a and the second through hole 2a can be formed by stamping or laser processing using a die or punching.

  Next, as in the example shown in FIGS. 2 and 3, conductor patterns such as an electrode pattern 4, a through conductor pattern 5, and a wiring conductor pattern 6 are formed on the first ceramic green sheet 1 and the second ceramic green sheet 2. Form.

  Note that any of the step of forming the first through hole 1a, the step of forming the second through hole 2a, and the step of forming the conductor pattern may be performed first. Moreover, the formation of the first through hole 1a or the second through hole 2a and the formation of the through hole for the through conductor pattern 5 may be performed simultaneously, or the formation of the conductor pattern may be performed simultaneously.

  The low shrinkage member 3 is a material having a firing shrinkage rate smaller than that of the first ceramic green sheet 1 in the thickness direction, and is embedded in the wiring board after firing. As such a low shrinkage member 3, for example, a metal sheet or a ceramic green sheet having a firing shrinkage rate smaller than that of the first ceramic green sheet 1 is embedded in the first through hole 1 a of the first ceramic green sheet 1. By forming. The low-shrinkage member 3 has, for example, a rectangular shape, a circular shape, or an elliptical shape in which the corners are arcuate in plan view, and is provided so as to fill the first through hole. Note that the low shrinkage member 3 may have a stepped shape in a cross-sectional view. The low shrinkage member 3 can be efficiently produced by embedding the first through hole 1a in the first ceramic green sheet 1 at the same time as the punching process.

When the low shrinkage member 3 is a ceramic green sheet, the ceramic green sheet can be manufactured in the same manner as the first ceramic green sheet 1 and the second ceramic green sheet 2. The ceramic green sheet as the low shrinkage member 3 is thicker than the first ceramic green sheet 1 by adjusting the amount of ceramic powder added, the size of the ceramic powder, the amount of organic binder and solvent added, and the like. The firing shrinkage rate in the direction is adjusted to be small.

  When the low shrinkable member 3 is made of a metal sheet, the metal sheet is produced, for example, as follows. First, an organic binder and an organic solvent are added to the metal powder, and a predetermined amount of a plasticizer and a dispersant are added as necessary to obtain a slurry. Such a slurry is applied to a resin or paper support such as PET (polyethylene terephthalate) by a molding method such as a doctor blade method, a lip coater method, or a die coater method to form a sheet. Thereafter, the slurry formed into a sheet is dried by a drying method such as hot air drying, vacuum drying, or far infrared drying to produce a metal sheet. The metal sheet is the same as the ceramic green sheet as the low-shrinkage member 3 by adjusting the addition amount of the metal powder, the size of the metal powder, the addition amount of the organic binder and the solvent, etc. The firing shrinkage rate in the thickness direction is adjusted to be smaller than that of the green sheet 1.

  The low shrinkage member 3 may have a shape that protrudes toward the second ceramic green sheet 2 in a region overlapping the second ceramic green sheet 2. At the time of lamination, the second ceramic green sheet 2 is deformed so as to be pushed up by the low shrinkage member 3, which is effective in reducing the inclination of the upper surface around the recess 7a. Further, even if the difference between the firing shrinkage rate of the first ceramic green sheet 1 and the firing shrinkage rate of the low shrinkage member 3 is reduced, the inclination can be reduced.

  Examples of the metal powder for the low shrinkage member 3 include tungsten (W), molybdenum (Mo), manganese (Mn), gold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum ( Examples thereof include powders of one type or two or more types such as Pt), which are appropriately selected in accordance with required characteristics. In addition, when a metal powder consists of 2 or more types, any form, such as mixing, an alloy, and a coating, may be sufficient. For example, when using the low shrinkage member 3 containing a material in which Cu powder and W powder are mixed and using the low shrinkage member 3 as a heat radiating part after firing, the low shrinkage member 3 is made of copper having excellent heat dissipation. Since tungsten (CuW) is used, it is effective to improve heat dissipation when heat generated by the electronic component mounted on the wiring board is released to the outside through the low shrinkage member 3.

  The electrode pattern 4 is an electrode electrically connected to each electrode of the electronic component by wire bonding. Since such an electrode is connected to the other wiring conductor 16 through the through conductor 15, the first ceramic green sheet 1 and the second ceramic green sheet 2 have a through conductor pattern 5 and a through conductor 15. A wiring conductor pattern 6 to be a wiring conductor is formed. In the example shown in FIG. 3, only the through conductor pattern 5 is formed. The wiring conductor 16 includes a connection pad for connecting to an external circuit board via a bonding material such as solder and an internal wiring layer routed in the board.

  The electrode pattern 4 and the wiring conductor pattern 6 are formed, for example, by forming a through hole for the through conductor pattern 5 in the first ceramic green sheet 1 and the second ceramic green sheet 2 by punching, punching with a mold, or laser processing. In this through hole, a conductive paste for the through conductor pattern 5 is embedded by screen printing or press filling to form the through conductor pattern 5, and the upper surface or the lower surface of the first ceramic green sheet 1 and the second ceramic green sheet 2 10 μm to 20 μm by printing a conductive paste for the electrode pattern 4 and the wiring conductor pattern 6 on the exposed portion of the through conductor pattern 5 in a predetermined pattern shape by a printing method such as a screen printing method or a gravure printing method. The thickness is formed.

  Conductor paste is added to the metal powder by adding an appropriate organic binder and solvent, and uniformly dispersed by a kneading means such as a ball mill or a planetary mixer. It is produced by adjusting the viscosity to be suitable for.

  The metal powder used for the conductor paste is a metal powder that is sintered by co-firing with the first ceramic green sheet 1 and the second ceramic green sheet 2 in a subsequent firing step, such as tungsten (W), molybdenum ( Examples thereof include one or more of Mo), manganese (Mn), gold (Au), silver (Ag), copper (Cu), palladium (Pd), platinum (Pt) and the like. In the case of two or more kinds, any form of mixing, alloy, coating, etc. may be used.

  As the organic binder for the conductive paste, those conventionally used for the conductive paste can be used. For example, acrylic (acrylic acid, methacrylic acid or their homopolymers or copolymers, specifically, Acrylic ester copolymer, methacrylic ester copolymer, acrylic ester-methacrylic ester copolymer, etc.), polyvinyl butyral, acrylic-styrene, polypropylene carbonate, cellulose, etc. homopolymer or copolymer Coalescence is mentioned. In view of decomposability and volatility in the firing step, acrylic and alkyd organic binders are more preferable. The amount of the organic binder added varies depending on the metal powder, but may be any amount that can be easily decomposed and removed during firing and can disperse the metal powder. It is desirable that the amount of

The solvent used for the conductor paste is not particularly limited as long as the metal powder and the organic binder can be well dispersed and mixed, and examples thereof include terpineol and butyl carbitol acetate. In view of formability after printing and drying properties, it is preferable to use a low boiling point solvent. Specifically, the solvent is added in an amount of 4 to 15% by mass with respect to the metal powder, and specifically, for the electrode pattern 4 and the wiring conductor pattern 6 so as to have a viscosity enough to form these conductor pastes. The conductive paste is adjusted to about 3000 to 40000 cps, and the conductive paste for the through conductor pattern 5 is adjusted to about 15000 to 40000 cps.

  In order to match the firing shrinkage behavior and shrinkage rate of the first ceramic green sheet 1 or the second ceramic green sheet 2 during firing, or to ensure the bonding strength of the wiring conductor after firing, the conductor paste is made of glass. Or ceramic powder may be added.

The electrode pattern 4 may be formed away from the through hole 2a of the second ceramic green sheet 2 as in the example shown in FIG. 3, or may be formed to extend to the through hole 2a. Absent. When the electrode pattern 4 is formed after the through hole 2a is formed, the conductive paste is applied to the inner wall of the through hole 2a by forming the electrode pattern 4 so as to be separated from the through hole 2a by about 0.1 mm. It can reduce that electrode pattern 4 connects and an electrode short-circuits. When the through hole 2a is formed after the electrode pattern 4 is formed, the electrode pattern 4 extending to the through hole 2a is punched out so as to overlap the end portion of the electrode pattern 4. And can.

After that, as in the example shown in FIG. 5, the second ceramic green sheet 2 is laminated on the first ceramic green sheet 1 and pressed to produce the laminate 7 having the recesses 7 a. . At this time, the low-shrinkage member 3 and the electrode pattern 4 are laminated so as to overlap in a plan view. The pressurization at this time is performed while heating as necessary. The pressure and heating conditions vary depending on the type and amount of the organic binder used, but are generally a pressure of 2 to 20 MPa and a temperature of 30 to 100 ° C. In order to improve the adhesiveness between the first ceramic green sheet 1 and the second ceramic green sheet 2, an adhesive obtained by mixing a solvent with an organic binder, a plasticizer, or the like may be used. Moreover, the laminated body 7 may be pressurized by the elastic body which consists of rubber | gum etc. corresponding to the shape of the recessed part 7a.

  In addition, the length (L shown in FIG. 6) of the portion where the low shrinkage member 3 and the second ceramic green sheet 2 overlap in plan view is the length of the upper surface of the second ceramic green sheet 2 by the low shrinkage member 3. In order to reduce the inclination, although it depends on the composition of the first ceramic green sheet 1 and the second ceramic green sheet 2 or the low shrinkage member 3, it is preferable that L ≧ 0.05 mm.

  A plurality of electrode patterns 4 are usually formed along the through hole 2a. In the example shown in FIG. 3, a plurality of electrode patterns 4 are arranged in 12 pieces along two opposing sides of the square through hole 2a, but are formed along the four sides of the through hole 2a. May be. Moreover, when the through-hole 2a is circular shape, the several electrode pattern 4 should just be arranged in alignment along the through-hole 2a.

  In the example shown in FIG. 5, the laminate 7 is formed by laminating a total of two ceramic green sheets, one each of the first ceramic green sheet 1 and the second ceramic green sheet 2. However, one or both of the ceramic green sheets may be formed by a plurality of sheets, and the laminate 7 may be manufactured by stacking three or more ceramic green sheets.

  Further, the surface of the low shrinkage member 3 may be covered with a metallized paste or ceramic paste wider than the low shrinkage member 3 in plan view. For example, when such a metallized paste or ceramic paste is formed by a screen printing method or the like, the metallized paste or ceramic paste is formed around the opening of the first through hole 1 a with the low shrinkage member 3 and the first ceramic green sheet 1. It is possible to prevent the low-shrinkage member 3 from falling out of the first ceramic green sheet 1 by entering between the minute gaps. The metallized paste may be the same conductive paste as the conductive paste for the electrode pattern 4 or the wiring conductor pattern 6. As the ceramic paste, a ceramic paste prepared by adding an appropriate organic binder and solvent to the ceramic powder used for the first ceramic green sheet 1 or the second ceramic green sheet 2 may be used.

The laminate 7 thus produced is fired to produce a wiring board 11 as shown in the example of FIG. The firing step consists of removing organic components and sintering the ceramic powder. The organic component is removed by decomposing and volatilizing the organic component by heating the laminate 7 in a temperature range of about 100 to 1000 ° C. The sintering temperature varies depending on the ceramic composition and is performed within a range of about 800 to 1600 ° C. In addition, the firing atmosphere varies depending on the ceramic powder and the conductor material, and is performed in the air, in a reducing atmosphere, or in a non-oxidizing atmosphere, etc. Even if water or the like is included in the atmosphere in order to effectively remove organic components. Good.

  When such a laminated body 7 is fired, the laminated body 7 has the first ceramic green sheet 1 and the second ceramic sheet 2 in a plan view, rather than the region where the low-shrinkage member 3 and the second ceramic green sheet 2 overlap. The region where the ceramic green sheet 2 overlaps contracts more greatly. Therefore, the low-shrinkage member 3 prevents the recess 7a side of the upper surface of the side wall portion of the multilayer body 7 from being deformed to the low-shrinkage member 3 side, and the inclination of the upper surface of the side wall portion of the multilayer body 7 can be reduced.

The low-shrinkage member 3 is inserted into the first through hole 1a at any time before or after the step of laminating and pressurizing the first ceramic green sheet 1 and the second ceramic green sheet 2 described later. As long as the low-shrinkage member 3 is embedded in the first through hole 1a before the step of stacking and pressurizing as in the example shown in FIG. This is effective in reducing the inclination of the upper surface.

After the laminated body 7 is fired, a plating layer is deposited on the exposed surfaces of the electrode 14 and the wiring conductor 16 by an electrolytic plating method or an electroless plating method. By such a plating layer, it is possible to firmly fix the wiring conductor 16 and the electronic component, the connection between the wiring conductor 16 and the wiring conductor of the external circuit board, and the bonding between the electrode 14 and the bonding wire. For the plating layer, a metal having excellent corrosion resistance such as nickel or gold is used. For example, a nickel plating layer with a thickness of about 1 to 10 μm and a thickness of 0.1 to 3
A gold plating layer of about μm is sequentially deposited.

  When the low shrinkage member 3 is made of a metal member, or when a metal layer is disposed so as to cover the low shrinkage member 3, a plating layer is formed on the exposed surface of the low shrinkage member 3 or the metal layer. It is good to leave. For the plating layer, in addition to the metal having excellent corrosion resistance, a metal having excellent reflectivity such as silver or a metal having excellent thermal conductivity such as copper may be used. Use of silver or copper for the base plating layer is effective for conducting heat generated in the electronic component to the outside through the low shrinkage member 3. For example, when a light emitting element is mounted on the bottom surface of the recess 7a as an electronic component, using silver as the plating layer is effective in increasing the reflectance of light emitted from the light emitting element to the plating layer.

  When the third ceramic green sheet 8 is disposed on the upper surface and the lower surface of the first ceramic green sheet 1 as in the example shown in FIG. 8, the low-shrinkage member 3 becomes the first ceramic green sheet. It is possible to suppress falling off from 1. Further, if the third ceramic green sheet 8 is arranged on the lower surface of the first ceramic grease sheet 1, the wiring conductor pattern 6 can be formed in a large area on the lower surface, so that the wiring conductor 16 of the wiring board 11 and the external electric circuit can be formed. Connection reliability with the wiring of the substrate can be improved.

  When the third ceramic green sheet 8 is disposed between the first ceramic green sheet 1 and the low shrinkage member 3 and the second ceramic green sheet 2, the thickness of the third ceramic green sheet 8 is , 0.2 mm or less is preferable. If it exceeds 0.2 mm, the effect of reducing the inclination of the inclined surface on the concave portion 7a side of the second ceramic green sheet 2 is reduced by the third ceramic green sheet 8.

  The wiring substrate according to one aspect of the present invention includes an insulating substrate 11 provided with a recess 7a, a low-shrinkage member 3 that is larger than the recess 7a in plan view and embedded in the insulating substrate 11 so as to face the recess 7a. Have With such a configuration, the inclination of the electrode 14 formed on the upper surface of the side wall around the recess 7a can be suppressed. Therefore, for example, when an electronic component is mounted on the bottom surface of the recess 7a and the electrode of the electronic component and the electrode 14 are connected by wire bonding, the bonding wire and the electrode 14 are firmly connected.

  Further, the outer edge of the low shrinkage member 3 is held by the second ceramic green sheet 2 and is shrunk so that the central portion of the low shrinkage member 3 is thicker than the outer edge, and the bottom surface of the recess 7a is convex. Thus, when the electronic component is arranged on the bottom surface of the recess 7a, it is effective to suppress the resin for joining the electronic component to the bottom surface of the recess 7a from flowing out to the top surface of the side wall around the recess.

  In addition, it is preferable that the shape of the low shrinkage member 3 is the same as the shape of the recess 7a in plan view. For example, as in the example shown in FIG. 5 and FIG. 8, if the concave portion 7 a is a quadrangular shape in plan view, the low-shrinkage member 3 is a rectangular shape with corners arcuate in plan view. If the recess 7a is circular in plan view, the low-shrinkage member 3 is circular in plan view. When the laminate 7a is fired, the second ceramic green sheet 2 around the recess 7a is fired. This is effective for reducing the variation in the inclination of the second ceramic green sheet 2 by suppressing the deformation uniformly.

In addition, this invention is not limited to the example of the above-mentioned embodiment, A various change is possible. For example, a so-called castellation conductor in which a conductor is formed on the inner surface of a groove formed on the side surface of the wiring board may be formed as the wiring conductor. Further, as in the example shown in FIG. 8, the wiring conductor may be led out to the outer periphery of the upper surface of the wiring board. Moreover, you may manufacture as what is called a multi-cavity board | substrate which provided the some wiring board area | region used as a wiring board in the laminated body 7. FIG.

  Further, as in the example shown in FIG. 8, when the third ceramic green sheet 8 is arranged on the upper surface or the lower surface of the first ceramic green sheet 1, the bottom surface of the recess 7 a and the lower surface of the first ceramic green sheet 1 are used. A metallized paste for the metal layer may be formed. This is effective for enhancing the heat dissipation of the wiring board and the reliability of bonding with the external electric circuit board.

  Further, as in the example shown in FIG. 8, a frame-shaped third ceramic green sheet 8 may be disposed on the upper surface of the second ceramic green sheet 2. Alternatively, the metallized paste for the reflective layer may be formed on the inner wall surface of the frame-shaped third ceramic green sheet 8, and the reflective layer may be formed on the inner wall surface of the recess 7 a of the wiring substrate 11.

DESCRIPTION OF SYMBOLS 1 ... The 1st ceramic green sheet 1a ... The 1st through-hole 2 ... The 2nd ceramic green sheet 2a ... The 2nd through-hole 3 ... Low-shrinkage member 4 ... Electrode pattern 5 ... Penetration conductor pattern 6 ... Wiring conductor pattern 7 ... Laminate 7a ... ..Recess 8 ... Third ceramic green sheet
11 ・ ・ ・ ・ ・ ・ Insulating substrate
14 ・ ・ ・ ・ ・ ・ Electrodes
15 ・ ・ ・ ・ ・ ・ Penetration conductor
16 ・ ・ ・ ・ ・ ・ Wiring conductor

Claims (2)

  Preparing a first ceramic green sheet having a first through hole in plan view and a second ceramic green sheet having a second through hole smaller than the first through hole in plan view; A step of providing a low shrinkage member having a firing shrinkage smaller than that of the first ceramic green sheet in one through hole; and the first through hole and the second on the upper surface of the first ceramic green sheet. A method of manufacturing a wiring board, comprising: a step of stacking and pressing the second ceramic green sheet so as to overlap with a through hole, and a step of firing the laminate, and a step of firing the laminate. .   A wiring board comprising: an insulating substrate provided with a recess; and a low-shrinkage member embedded in the insulating substrate so as to be opposed to the recess and larger than the recess in plan view.

Images