JP2014075498A - Method of manufacturing ceramic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a ceramic substrate including a ceramic substrate body and a heat dissipation via conductor of relative large diameter penetrating the substrate body, capable of dissipating heat generated from a mounted element generating a lot of heat, e.g., a light-emitting element mounted on the upper end face of the heat dissipation via conductor, efficiently to the outside from the back side of the substrate body, and having stabilized electrical conductivity.SOLUTION: A method of manufacturing a ceramic substrate 1 includes the steps of: preparing a molding S1 with a sheet material formed by laminating a plurality of green sheets G1-G3, in which at least one surface (back surface) 4 of a green sheet molding 2a becoming a substrate body 2 having a pair of surfaces 3, 4 is covered with a sheet material 20; forming via holes 12, 13 penetrating the molding S1 with a sheet material in the thickness direction thereof; filling the via holes 12, 13 with a conductor-containing paste 10a becoming a heat dissipation via conductor 10; and peeling the sheet material 20 after drying the conductor-containing paste 10a.

Description

  The present invention relates to a method for manufacturing a ceramic substrate having a heat radiating via conductor for radiating heat generated by a mounting element such as a light emitting element or a power semiconductor element to the outside of the substrate.

In order to improve the heat dissipation and mounting reliability of the light emitting element to be mounted, the insulating base is made of a flat ceramic, and the central portion of the insulating base passes through the central portion and has a relatively large diameter of 200 μm to more than 1 mm. There has been proposed a light-emitting element wiring board including a through metal body (thermal via conductor) and a mounting portion for mounting the light emitting element on the upper end surface of the through metal body (for example, Patent Document 1). reference).
Furthermore, a wiring board for a light-emitting element is also proposed which includes the same insulating base, a relatively large-diameter penetrating metal body, and a mounting portion, and is provided with an inclined portion or a step portion on a side surface of the penetrating metal body that contacts the insulating base. (For example, refer to Patent Document 2).

However, when forming a relatively large-diameter penetrating metal body that penetrates the insulating base as in the light-emitting element wiring boards described in Patent Documents 1 and 2, the comparison is provided on the green sheet serving as the insulating base. After the conductive paste containing W powder or the like is filled in the large-diameter through hole, for example, when natural drying is allowed to stand for several hours at room temperature, the previously contained solvent evaporates. Spherical dents are formed vertically symmetrically on the upper end surface and the lower end surface. In addition, when the insulating base is formed by laminating a plurality of green sheets in which individual through holes are filled with a conductive paste in advance, a cross section formed by the pair of recesses at the boundary between adjacent green sheets. A convex lens-shaped gap may be further formed inside the penetrating metal body.
When the dent and the internal gap are formed, a large amount of heat generated from the light emitting element mounted on the mounting portion located on the upper end surface of the through metal body passes through the through metal body and passes through the back surface side of the insulating substrate. There is a problem that heat conduction is difficult and electrical continuity with the light emitting element may become unstable.

Japanese Patent Laying-Open No. 2006-66409 (pages 1 to 21, FIG. 1) Japanese Patent Laying-Open No. 2006-93565 (pages 1 to 21, FIG. 1)

  The present invention solves the problems described in the background art, and includes a substrate body made of ceramic and a relatively large-diameter radiating via conductor penetrating the substrate body, and the light emitting device mounted on the upper end surface of the radiating via conductor It is an object of the present invention to provide a method for manufacturing a ceramic substrate that can efficiently dissipate heat from a mounting element that generates a large amount of heat, such as an element, from the back side of the substrate body to the outside and that has stable electrical conductivity.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-described problems, the present invention provides a heat dissipation via conductor in a via hole formed by covering at least one surface of a green sheet serving as a substrate body and penetrating the green sheet including the sheet material. After filling and drying the conductor-containing paste, the sheet material is peeled off to form the protruding portion of the conductor-containing paste on the one surface.
That is, a method for manufacturing a ceramic substrate according to the present invention (Claim 1) is a ceramic including a substrate body having a pair of surfaces and made of ceramic, and a heat dissipation via conductor penetrating between the pair of surfaces in the substrate body. A method of manufacturing a substrate, comprising a single green sheet or a laminate of a plurality of green sheets, and a sheet material on at least one surface of a green sheet molded body that becomes a substrate body having a pair of surfaces A step of preparing a molded body with a sheet material coated with a sheet, a step of forming a via hole penetrating along the thickness direction of the molded body with a sheet material, and a conductor-containing paste serving as a radiating via conductor is filled in the via hole And a step of peeling the sheet material after drying the conductor-containing paste.

  According to this, a relatively large via hole penetrating between the front and back surfaces of a molded body with a sheet material in which at least one surface of the green sheet molded body in which a single green sheet or a plurality of green sheets is laminated is coated with a sheet material. After the conductor material containing paste is filled in the via hole, the sheet material is peeled off. As a result, even if dents are formed on both end faces of the conductor-containing paste due to natural drying or the like, a protruding portion of the conductor-containing paste that protrudes from the surface of the green sheet molded body appears after the sheet material is peeled off. Therefore, by utilizing the projecting portion, it is possible to eliminate the dent and reliably form the flat mounting surface and the flat surface conductor layer of the mounting element on the pair of surfaces of the green sheet molded body. Become.

The green sheet is made of a material containing a high-temperature fired ceramic such as alumina, or a glass-ceramic that is a kind of low-temperature fired ceramic, and is obtained, for example, by blending ceramic powder such as alumina, a binder resin, or a solvent. This ceramic slurry is made into a sheet by the doctor blade method or the like.
In addition, a light emitting element (light emitting diode or semiconductor laser) or a power semiconductor element that has a relatively large amount of heat generation is mounted on one surface of a pair of surfaces in the green sheet or the plurality of green sheets serving as the substrate body. A surface conductor layer (back surface pad) connected to the heat radiating via conductor is formed on the other surface of the pair of surfaces, the surface including the end face of the heat radiating via conductor made of the conductor-containing paste constituting the surface. It becomes the back side. The pair of front surfaces are relative names for distinguishing each other, and for example, one of them may be referred to as a front surface and the other may be referred to as a back surface.
Furthermore, the via hole has a circular shape, a rectangular shape (a square shape or a rectangular shape, or a curved portion at each corner thereof), an oval shape, an oval shape, or the like in plan view. The inner diameter, the long diameter, or the length of one side of the via hole is at least 0.5 mm or more, for example, 0.8 mm or more or about 1 mm or more. Two or more via holes may be provided on the green sheet serving as one substrate body. However, the size refers to the inner diameter of a relatively small via hole in the case where a plurality of via holes having different inner diameters are communicated.
In addition, the sheet material may be made of, for example, polyethylene terephthalate (hereinafter referred to as “PET”) and the like, and may also be a resin carrier film having flexibility.

Further, in the present invention, the green sheet molded body in which a plurality of green sheets are laminated is a laminate of a plurality of green sheets so that via holes of different sizes formed for the respective green sheets communicate with each other. Also included is a method for manufacturing a ceramic substrate (Claim 2) in which the conductor-containing paste is filled into the via hole.
According to this, even if a relatively large via hole (different diameter via hole or deformed via hole) having a different inner diameter or different side length is formed for each of the plurality of green sheets, the plurality of via holes are connected concentrically. As described above, the plurality of green sheets are laminated, and the conductor-containing paste is filled into the via hole having the above-described configuration. Therefore, a heat radiation via conductor with stable thermal conductivity and electrical conductivity can be reliably disposed between a pair of surfaces in a green sheet molded body in which a plurality of green sheets are laminated.
In addition, on one surface of the green sheet molded body in which a single green sheet or a plurality of green sheets are laminated, a through hole having a conical shape, a cylindrical shape, a long conical shape, a long cylindrical shape or the like surrounding the surface as a bottom surface It is also possible to form a cavity on the surface side by further laminating separate green sheets having

Furthermore, in the present invention, after the step of peeling off the sheet material, a surface conductor layer covering the protruding portion of the conductor-containing paste protruding from the surface on the surface of the green sheet molded body from which the sheet material has been peeled off Also included is a method for manufacturing a ceramic substrate (Claim 3) in which the step of forming is performed.
According to this, after the sheet material is peeled off, the surface of the protruding portion of the conductor-containing paste and the surface on the opposite side are dried to form a spherical recess due to evaporation of a solvent or the like. For example, a surface conductor layer such as an electrode pad is formed by printing. Therefore, the indentation pressure is eliminated along the thickness direction by a squeegee used at the time of printing the surface conductor layer, and the conductor-containing paste and the surface conductor layer can be brought into surface contact with each other on the entire boundary surface between them. .
The protruding portion of the conductor-containing paste protruding on the surface of the green sheet molded body after peeling the sheet material is, for example, natural drying (room temperature x several hours) or removal of the solvent by forced drying by heating, A shallow spherical recess is formed on the surface of the protruding portion, and the surface conductor layer (back surface pad) formed so as to cover the protruding portion is used when screen-printing the same conductor-containing paste as described above or using a metal mask. The surface of the surface conductor layer can be flattened by the pressing action accompanying the movement of the squeegee used.
Further, prior to the screen printing or the like, it is also possible to perform a pressing step of compressing the conductor-containing paste including the projecting portions together with a pair of surfaces of the green sheet molded body by applying pressure along these thicknesses.
Further, after the step of forming the surface conductor layer, a step of removing the binder and firing the green green sheet molded body including the surface conductor layer and the heat dissipation via conductor is performed.

In addition, the present invention also includes a method for manufacturing a ceramic substrate (Claim 4) in which the thickness of the sheet material is twice or more the depth of the dent generated on the surface of the protruding portion of the conductor-containing paste. .
According to this, even if spherical recesses resulting from the drying of the conductor-containing paste occur on the surface of the protrusion and the surface opposite to the protrusion, the thickness of the sheet material and the periphery of the protrusion The thickness is twice or more the depth of the dent generated on the surface of the protrusion. Therefore, in the step of forming the surface conductor layer, the dent can be surely eliminated by the pressure along the thickness direction when the conductor layer is printed. Therefore, it is possible to reliably manufacture a heat radiating via conductor without a gap between a pair of surfaces in the substrate body obtained after firing.
The sheet material may be coated on both surfaces of the green sheet molded body. In this case, the sum of the thicknesses of the protrusions of the pair of conductor-containing pastes that appear after the sheet material is peeled is It is necessary to be not less than the sum of the depths of the recesses formed on the surface of each protrusion.

In other words, according to the present invention, the filling of the conductor-containing paste includes an opening of the via hole in a pair of surfaces of the molded body with the sheet material formed by laminating a plurality of green sheets and a sheet material. A method of manufacturing a ceramic substrate, which is performed from the surface side of the larger side, can also be included.
In this case, for example, even when a ring-shaped step portion is located at the boundary between via holes having different inner diameters, a gap is not generated in the vicinity of the step portion. The conductor-containing paste can be reliably filled.
In addition, each said process can also be performed by the method of taking many pieces using what is called a large format green sheet. In this case, after the firing step, an individual substrate body is separated into individual ceramic substrates, and a plurality of ceramic substrates are formed. Further, by forming the same paste in a cylindrical shape along the inner wall surface of the through-hole provided along the thickness direction on the boundary surface of each adjacent substrate body, electrical conduction is established between a pair of surfaces in each substrate body. A concave conductor (connection wiring) having a semicircular cross section or a circular arc shape is formed.

Schematic of 1 step of the process of preparing the molded object with a sheet material of this invention. Schematic which shows the step following FIG. 1 of the process of preparing the said molded object. Schematic which shows the step etc. following FIG. 2 of the process of preparing the said molded object. Schematic which shows the molded object with a sheet material prepared by each said step. Schematic which shows the process of filling a conductor containing paste in the via hole of the said molded object. The schematic of the said molded object which shows the state after drying of the said conductor containing paste. Schematic which shows the process of peeling a sheet | seat material from the surface of the said molded object. Schematic which shows the process of forming a surface conductor layer in the protrusion part side of the said paste. Schematic which shows the cross section of the green sheet molded object in which the surface conductor layer was formed. The vertical sectional view of the ceramic substrate obtained through each said process. The top view of the said ceramic substrate. Schematic which shows the process of preparing the molded object with a sheet material for obtaining the ceramic substrate of a different form. Schematic which shows the process of filling a conductor containing paste in the via hole of the said molded object. The schematic of the said molded object which shows the state after drying of the said conductor containing paste. Schematic which shows the process of peeling a sheet | seat material from the surface of the said molded object. Schematic which shows the process of forming a surface conductor layer in the protrusion part side of the said paste. Furthermore, the schematic which shows the process of preparing the molded object with a sheet material for obtaining the ceramic substrate of a different form. Schematic which shows the process of filling a conductor containing paste in the via hole of the said molded object. The schematic of the said molded object which shows the state after drying of the said conductor containing paste. Schematic which shows the process of peeling a sheet | seat material from the surface of the said molded object. Schematic which shows the process of forming a surface conductor layer in the protrusion part side of the said paste.

Hereinafter, modes for carrying out the present invention will be described.
1 to 4 are schematic cross sections showing a step of preparing a molded body S1 with a sheet material and a step of forming a via hole according to the present invention.
As shown in FIG. 1, a green sheet G1 having a thickness similar to the above on one surface of a carrier film (sheet material: hereinafter referred to as a sheet material) 20 having a thickness of about 30 μm and coated with an Si film. And green sheets G2 and G3 having a thickness of about 150 μm each were prepared. The green sheets G1 to G3 are formed by forming a ceramic slurry made of ceramic powder such as alumina, a binder resin, and a solvent into a sheet shape by a doctor blade method, and are partitioned by a boundary surface 21 in FIG. This is a large-sized product for multi-piece production in which square product regions A each having a side of about 3 mm in a plan view are arranged in a lattice shape along the vertical and horizontal directions.
The sheet material is made of a PET film having flexibility.

Next, as shown in FIG. 2, a lower layer green sheet G1 and an intermediate layer green sheet G2 disposed on the sheet material 20 were laminated so that the boundary surface 21 was continuous. In this state, as shown in FIG. 3, a relatively large via hole 12 having an inner diameter of about 1 mm is formed at the center of the upper green sheet G3 by punching using a punch and a die. A relatively large via hole 13 having an inner diameter of about 1.2 mm was formed by punching at the center of the green sheets G2 and G1 and the sheet material 20 in the lower layer.
The reason for providing the via holes 12 and 13 having different inner diameters as described above is that the surface (one surface) 3 and the back surface (the other surface) of the green sheet molded body (2a) to be described later, which will be the substrate body (2). This is because it corresponds to the area and arrangement of each surface conductor layer to be formed in (4). Alternatively, a wiring layer having a predetermined pattern may be formed in advance by screen-printing a paste similar to a conductor-containing paste described later on the upper surface of the intermediate green sheet G2 or the lower surface of the upper green sheet G3.

Next, as shown in FIG. 4, the boundary layer 21 is continuous with the upper green sheet G3 on the lower and middle green sheets G1 and G2 including the sheet material 20, and the via holes 12 and 13 are concentric. The layers were laminated so as to communicate with each other.
As a result, as shown in the drawing, for each product region A, a plurality of green sheets G1 to G3 are laminated, and subsequently formed on a green sheet molded body 2a that becomes a substrate body (2) and its back surface (the other surface) 4. A molded body with sheet material S1 coated with the sheet material 20 was obtained (step of preparing a molded body with sheet material). At the same time, via holes 12, 13 penetrating concentrically along the thickness direction of the molded body S1 with sheet material were formed (step of forming via holes).
A ring-shaped step portion 14 is located inside two via holes 12 and 13 having different inner diameters and communicating concentrically (hereinafter referred to as different diameter via holes). Moreover, the laminated body of the green sheets G1-G3 for multi-piece | units which has the molded object S1 with a sheet material for every product area | region A is also called a green sheet laminated body below.

Further, as shown in FIG. 5, the conductor-containing paste 10a was filled from the opening on the sheet material 20 side in each product region A by screen printing or the like (step of filling the conductor-containing paste). At this time, the surface 8 of the conductor-containing paste 10a was flush with the surface 3 of the green sheet molded body 2a, and the back surface 9 of the conductor-containing paste 10a was flush with the back surface of the sheet material 20. .
The said conductor containing paste 10a consists of conductors, such as W powder and Mo powder, binder resin, a solvent, etc., for example. Such a conductor-containing paste 10a has an opening on the sheet material 20 side as indicated by an arrow in FIG. 5 in a state where the surface 3 of the upper green sheet G3 having a small inner diameter is closed with a flat plate (not shown). Filled from. Thus, by filling from the side of the sheet material 20 having a large inner diameter of the opening and the green sheets G1 and G2 of the lower and middle layers, it is possible to prevent a situation in which an inadvertent gap is generated immediately below the stepped portion 14. I was able to.

After the step of filling the conductor-containing paste 10a, natural drying was performed by allowing the paste 10a to stand at room temperature for about several hours (about 1 to 3 hours). At that time, a volatile solvent or the like evaporated from the conductor-containing paste 10a filled in the different diameter via holes 12 and 13 to the outside. As a result, as shown in FIG. 6, shallow spherical recesses 8h and 9h were formed on the front surface 8 and the back surface 9 of the conductor-containing paste 10a.
Next, as shown in FIG. 7, the multi-piece sheet material 20 was peeled so that the Si coating surface side was separated from the back surface 4 of the lower green sheet G1 for each of the plurality of product regions A (the sheet material was peeled off). Process).

As a result, as shown in FIG. 7, the protruding portion 11 of the conductor-containing paste 10 a, which has a substantially crater shape as a whole, appeared on the back surface 4 of the green sheet molded body 2 a in each product region A. The thickness t1 in the peripheral portion of the protruding portion 11 is the same as the thickness t1 of the sheet material 20, and the depth d1 at the central portion (the deepest portion) of the protruding portion 11 is less than half of the thickness t1. It was. Furthermore, even if the depth d2 at the center (deepest part) of the recess 8h located on the surface 8 of the conductor-containing paste 10a exposed on the surface 3 side of the green sheet molded body 2a is added to the depth d1, The total depth value (d1 + d2) was equal to or less than the thickness t1 of the protruding portion 11 or the sheet material 20.
That is, the thickness t1 of the sheet material 20 was previously selected so as to be twice or more the depth d1 generated on the front surface 8 of the conductor-containing paste 10a or the depth d2 generated on the back surface 9.

  Next, as shown in FIG. 8, the green sheet laminate including the plurality of green sheet molded bodies 2 a was turned upside down and placed on the surface plate 15 and fixed. In this state, on the back surface 4 of the green sheet molded body 2a for each of the plurality of product regions A, there is a circular opening on the center side of the back surface 4 for each product region A, and the whole in plan view is a lattice. A metal mask 19 having a frame shape was arranged. Further, by using the squeegee 17 that moves in the horizontal direction in an oblique posture along the upper surface of the metal mask 19, the same conductor-containing paste 16 is passed through the opening of the metal mask 19 and green sheets for each product region A. Printing was performed so as to cover the back surface 4 of the molded body 2a and the conductor-containing paste 10a protruding from the back surface 4 to form a back surface pad (surface conductor layer) 18 having a circular bottom view and a thin film shape (surface conductor) Forming the layer).

As a result, as the squeegee 17 was horizontally moved, pressure was applied to the squeegee 17 along the thickness direction of the green sheet molded body 2a, so that the protruding portion 11 disappeared and the flat back surface as shown in FIG. At the same time, the back surface pad 18 and the conductor-containing paste 10a in the different diameter via holes 12 and 13 were in surface contact with each other on the entire boundary surface between them. At the same time, as a result of the disappearance of the dent 8h on the surface 8 side of the conductor-containing paste 10a, it returned to the flat surface 8 similar to the above.
As described above, the conductor-containing paste 10a is filled in the different-diameter via holes 12 and 13 without gaps and has the flat front surface 8 and the back surface 9, and the back pad 18 can be brought into surface contact with the entire back surface 9. This is presumably because the thickness t1 of the protruding portion 11 which is the same thickness as the thickness t1 of the sheet material 20 is set to be equal to or greater than the total value of the depths d1 and d2 of the recesses 8h and 9h. .

Further, for each product region A, the green sheet molded body 2a, the conductor-containing paste 10a in the different diameter via holes 12 and 13, and the multi-sheet green sheet laminate formed with the back surface pad 18 are separated from the product regions A and A. A blade (not shown) is inserted along the thickness direction along the boundary surface 21 that divides the gap, and a dividing groove (not shown) having a V-shaped cross section is formed on at least one of the front surface 3 side and the back surface 4 side. It was formed in a lattice shape. In addition, the insertion depth of the said cutter was about 1/2 of the thickness of the green sheet laminated body in the case where the depths of the dividing grooves for the front and back sides were totaled.
In this state, the green sheet laminate was heated to a predetermined temperature zone, subjected to binder removal treatment, and subsequently fired (binder removal and firing step). And the ceramic laminated body after baking applied the bending stress along the said division | segmentation groove | channel, and was separated into pieces for every said product area | region A. FIG.
As a result, as shown in FIGS. 10 and 11, a substrate body 2 having a regular surface 3 and a back surface 4 and a plurality of ceramic layers C <b> 1 to C <b> 3 are laminated, and the surface 3 of the substrate body 2, A relatively large-diameter heat-dissipating via conductor 10 made of W or Mo filled in different-diameter via holes 12 and 13 penetrating between the back-surface 4 and a back-surface pad connected to the back-surface 4 side of the heat-dissipating via conductor 10 The ceramic substrate 1 provided with 18 was obtained.
In the firing step, the green sheets G1 to G3 become the ceramic layers C1 to C3, the conductor-containing paste 10a becomes the heat dissipating via conductor 10, and the raw back surface pad 18 is mainly composed of W or Mo. Thus, the baked back surface pad 18 was obtained.

As shown in FIGS. 10 and 11, the ceramic substrate 1 has, for example, a light emitting diode (light emitting element) 24 at the center of the surface 8 of the heat radiating via conductor 10 located near the center of the surface 3 of the substrate body 2. In the vicinity of the periphery of the surface 8 of the heat radiating via conductor 10, a surface pad 22 which is a pair of electrodes with the heat radiating via conductor 10 is formed. The front surface pad 22 is formed, for example, by screen-printing the same conductor-containing paste after the back surface pad 18 is formed.
Further, a recess 6 having a circular arc cross section is formed between the front surface 3 and the back surface 4 at the four corners of the substrate body 2, and a concave conductor 7 made of W or Mo is formed along the inner wall surface of each recess 6. Is formed. Such a concave conductor 7 sucks the conductor-containing paste into a relatively small diameter through hole that is perforated near each intersection of the boundary surfaces 21 and 21 orthogonal to each other in the green sheet laminate, using negative pressure, After the cylindrical connection conductor is formed, it is divided into four along the axial direction in the singulation after firing.
The surface 8 of the heat dissipation via conductor 10 and, for example, a pair of adjacent concave conductors 7 are connected by a wiring (not shown) formed on the surface 3 of the substrate body 2. Another pair of concave conductors 7 are connected by another wiring (not shown) formed on the surface 3 of the substrate body 2.
Further, the light emitting diode 24 mounted on the surface 8 of the heat radiating via conductor 10 is sealed from the outside by a light-transmitting sealing resin (not shown) formed in a dome shape on the surface of the substrate body 2. The Each concave conductor 7 may be connected to a wiring layer formed in advance between the green sheets G2 and G3.

According to the manufacturing method of the ceramic substrate 1 which passes through each process as described above, the sheet material 20 is coated on the back surface 4 of the green sheet molded body 2a in which a plurality of green sheets G1 to G3 are laminated, and the molded body with sheet material S1. A relatively large-diameter via hole 12, 13 penetrating between the front surface 3 and the back surface 4 side of the molded body S1 is formed, and the conductor containing paste 10a is filled in the via holes 12, 13. Then, after the sheet material 20 is peeled off, the back surface pad (surface) covers the protruding portion 11 of the conductor-containing paste 10a protruding from the back surface 4 on the back surface 4 of the green sheet molded body 2a from which the sheet material 20 has been peeled off. The process of forming the conductor layer 18 is performed.
Moreover, after the sheet material 20 is peeled off, the thickness t1 of the protrusion 11 protruding from the back surface 4 side of the green sheet molded body 2a and the thickness t1 of the sheet material 20 that defines the thickness t1 are different diameter via holes 12 and 13. It is more than the total value of the dent 9h of the back surface 9 and the dent 8h of the front surface 8 after the natural drying of the conductor-containing paste 10a filled therein. As a result, when the back surface pad 18 is printed by covering the protrusion 11, the protrusion 11 and the recesses 8h and 9h are eliminated, and the conductor-containing paste 10a and the back surface pad 18 are in contact with each other and There is no gap between the front surface 8 and the back surface 9.

Therefore, the ceramic substrate 1 obtained by firing and separating the green sheet molded body 2a is the inside of a relatively large-diameter heat radiating via conductor 10 penetrating between the front surface 3 and the back surface 4 of the substrate body 2. In addition, since there is no gap in the connection portion between the heat radiation via conductor 10 and the back surface pad 18, a large amount of heat generated by the light emitting diode 24 and the like mounted on the surface 8 of the heat radiation via conductor 10 is effectively removed from the back surface of the substrate body 2. In addition to being able to transmit to the four sides, it is possible to stably take electrical continuity between the light emitting diode 24 and the outside.
In addition, after peeling of the said sheet | seat material 20, a pair of flat plate is pinched | interposed and approached along the thickness direction with respect to the surface 3 and the back surface 4 of the green sheet molded object 2a containing the protrusion part 11 of the conductor containing paste 10a, and pressure It is also possible to eliminate the protruding portion 11 and make the conductor-containing paste 10a having the flat front and back surfaces 8 and 9 and then to form the back surface pad 18 by printing.

FIGS. 12-16 are related with the manufacturing process for obtaining the ceramic substrate (1a) of a different form.
First, as shown in FIG. 12, a single green sheet G for each product area A in a multi-sheet green sheet G having a thickness of about 150 μm and made of the same material as above and having a plurality of product areas A. Is formed into a green sheet molded body 2a having a front surface 3 and a back surface 4, and the back surface 4 is coated with the same sheet material 20 as described above to obtain a molded body with sheet material S2 (preparing a molded body with sheet material). Process).
Next, as shown in FIG. 12, a punching process similar to that described above is performed on the vicinity of the center portion of the molded body S2 with a sheet material for each product region A to form a via hole 12 having a relatively large inner diameter of about 1 mm. (Step of forming a via hole).

Next, as shown in FIG. 13, the same conductor-containing paste 10a was filled into the via hole 12 from one of the openings (step of filling the conductor-containing paste). At this time, the surface 8 of the conductor-containing paste 10a was flush with the surface 3 of the green sheet molded body 2a, and the back surface 9 of the conductor-containing paste 10a was flush with the back surface of the sheet material 20. In this state, the filled conductor-containing paste 10a was naturally dried as described above. As a result, as shown in FIG. 14, spherical recesses 8h and 9h similar to those described above were formed on the front surface 8 and the back surface 9 of the conductor-containing paste 10a.
Furthermore, the said sheet material 20 was peeled from the back surface 4 of the green sheet molded object 2a (process of peeling a sheet material). As a result, as shown in FIG. 15, the protruding portion 11 of the conductor-containing paste 10 a that has a substantially crater shape as a whole appeared at the center of the back surface 4 of the green sheet molded body 2 a in each product region.
The thickness t1 in the peripheral portion of the protruding portion 11 is the same as the thickness t1 of the sheet material 20, and the depth d2 at the central portion (the deepest portion) of the protruding portion 11 is less than or equal to half of the thickness t1. It was. Furthermore, even if the depth d2 at the center (the deepest part) of the recess 8h located on the surface 8 of the conductor-containing paste 10a is added to the depth d2, the thickness t1 of the protruding portion 11 or the sheet material 20 is added. It was the following.

Further, as shown in FIG. 16, the conductor-containing paste 16 is printed on the center portion of the back surface 4 of the green sheet molded body 2a so as to cover the protruding portion 11 of the conductor-containing paste 10a by the same method as described above. Thus, a back surface pad (surface conductor layer) 18 having a circular bottom view and a thin film shape was formed (step of forming the surface conductor layer). In this step, the protrusion 11 and the recesses 8h and 9h disappeared in the same manner as described above, and a flat back surface pad 18 was obtained.
Thereafter, the same binder removal and firing process as that described above and an individualization process were performed. As a result, as shown in FIG. 16, in each product region A, the green sheet G is composed of the fired ceramic layer C, the substrate body 2 having the front surface 3 and the back surface 4, and the conductor-containing paste 10a are fired and contained therein. A ceramic substrate (1a) provided with the cylindrical heat-radiating via conductor 10 having no voids and the fired back surface pad 18 was obtained. Also by this, the heat generated by the light emitting diode 24 mounted on the front surface 8 of the heat radiating via conductor 10 can be effectively transmitted to the back surface 4 side of the substrate body 2 and the electrical conduction between the light emitting diode 24 and the outside is stable. Can be taken.

FIG. 17 to FIG. 21 relate to a manufacturing process for obtaining a ceramic substrate (1b) of still another form.
First, as shown in FIG. 17, a single green sheet G for each product region A is formed on the surface of a green sheet G that is made of the same material and thickness as described above and includes a plurality of product regions A. 3 and a green sheet molded body 2a having a back surface 4, and the surface 3 and the back surface 4 are individually coated with a relatively thin sheet material 20a, 20b having a thickness (t2) of about 10 to 20 μm. S3 was prepared (step of preparing a molded body with a sheet material).
Next, as shown in FIG. 17, the same punching process is performed on the vicinity of the center of the molded body S3 with sheet material for each product region A to form the same via hole 12 (step of forming the via hole). ).

Next, as shown in FIG. 18, the via-hole 12 was filled with the same conductor-containing paste 10 a from either one of the openings (step of filling the conductor-containing paste). At this time, the surface 8 of the conductor-containing paste 10a was flush with the surface 3 of the green sheet molded body 2a, and the back surface 9 of the conductor-containing paste 10a was flush with the back surface of the sheet material 20. In this state, the filled conductor-containing paste 10a was naturally dried as described above. As a result, as shown in FIG. 19, spherical recesses 8h and 9h similar to those described above were formed on the front surface 8 and the back surface 9 of the conductor-containing paste 10a.
Further, the sheet materials 20a and 20b were peeled off from the front and back surfaces 3 and 4 of the green sheet molded body 2a (step of peeling the sheet material). As a result, as shown in FIG. 20, a pair of crater-like protrusions 11 made of the conductor-containing paste 10a are vertically symmetrical at the center of the front surface 3 and the back surface 4 of the green sheet molded body 2a in each product region A. Appeared.

The thickness t2 in the peripheral portion for each protrusion 11 is the same as the thickness t2 of the sheet materials 20a and 20b, and the depth d2 at the center (the deepest portion) for each protrusion 11 is equal to or less than the thickness t2. Met. Furthermore, even when the two depths d2 were summed, the total value (2 × t2) of the thickness t2 of the two upper and lower protrusions 11 (sheet material 20) was not more.
Further, as shown in FIG. 21, the conductor-containing paste is applied to the central portion of the back surface 4 of the green sheet molded body 2a so as to cover the protruding portion 11 on the back surface 4 side of the conductor-containing paste 10a by the same method. 16 was printed to form a back surface pad (surface conductor layer) 18 having a circular bottom view and a thin film shape (step of forming a surface conductor layer). In this process, the two protrusions 11 and the recesses 8h and 9h disappeared, and a flat back pad 18 was obtained.

Thereafter, the same binder removal and firing process as that described above and an individualization process were performed. As a result, as shown in FIG. 21, in each product region A, the green sheet G is composed of the fired ceramic layer C, the substrate body 2 having the front surface 3 and the back surface 4, the conductor-containing paste 10a is fired, and the inside A ceramic substrate (1b) provided with the cylindrical heat-radiating via conductor 10 having no voids and the fired back pad 18 was obtained. Also by this, the heat generated by the light emitting diode 24 mounted on the front surface 8 of the heat radiating via conductor 10 can be effectively transmitted to the back surface 4 side of the substrate body 2 and the electrical conduction between the light emitting diode 24 and the outside is stable. Can be taken.
Note that the conductor-containing paste 16 is also printed on the central portion of the surface 3 of the green sheet molded body 2a so as to cover the protruding portion 11 on the surface 3 side of the conductor-containing paste 10a. A surface pad (surface conductor layer) may be formed. In this case, the light emitting diode 24 is mounted on the surface pad.

The present invention is not limited to the embodiments described above.
For example, also in the process of manufacturing the ceramic substrate 1, the front and back surfaces 3 and 4 of the green sheet molded body 2a are individually coated with relatively thin sheet materials 20a and 20b, and the same molded body with sheet material S3 as described above. The pair of upper and lower protrusions 11 having the surfaces 8 and 9 including the recesses 8 and 9 may be formed on both surfaces of the conductor-containing paste 10a filled in the different diameter via holes 12 and 13 penetrating therethrough.
In the process of manufacturing the ceramic substrates 1 and 1a, a surface pad may be formed on the surface 3 side of the green sheet molded body 2a.
Further, the green sheets G and G1 to G3 may be ceramic materials that are high-temperature fired ceramics other than alumina, or ceramic materials that are glass-ceramics that are a kind of low-temperature fired ceramics. When the green sheets G and G1 to G3 are low-temperature fired ceramics, the conductor-containing paste 10a is made of a conductor powder such as Ag or Cu, a binder resin, and a solvent.

In addition, the green sheet molded body may have a form in which two layers of green sheets are laminated or a form in which four or more green sheets are laminated, and a molding with a sheet material in which only the back surface 4 is coated with the sheet material 20. It is good also as a body, or it is good also as a molded object with a sheet | seat material which coat | covered the said sheet | seat materials 20a and 20b on the front and back surfaces 3 and 4.
Further, the green sheet molded body has another through-hole having a cylindrical shape or a conical shape on the center side on the uppermost green sheet G3 having the surface 3 or the surface 3 of the single-layer green sheet G. It is good also as a form which has a cavity which laminates | stacks a green sheet | seat and has the surface pad formed on the surface 8 and the surface 8 of the said thermal radiation via conductor 10 on the bottom face.
Further, a plurality of the via holes 12 and the different diameter via holes 12 and 13 may be formed in the same product region A, and a conductor containing paste 10a may be formed on each of them to form a ceramic substrate having a plurality of heat dissipating via conductors. Is possible.

Further, the via hole has a conical shape between the front surface 3 and the back surface 4 of the green sheet molded body 2a with a small diameter on the front surface 3 side and a large diameter on the back surface 4 side, and forms a heat radiation via conductor similar to this. It is also possible. Alternatively, by forming a via hole having a square cross section and a side length of 1 mm or more, or a rectangular shape and a short side length of 1 mm or more, a heat dissipation via conductor having a cross section similar to these is formed. Is also possible. At this time, a plurality of via holes each having a rectangular cross-section and having one side or a different dimension on each side may be connected concentrically to form a deformed via hole.
Further, the sheet material may be made of a resin film other than PET, and may have required strength, flexibility, and appropriate peelability.
Furthermore, not only the light emitting diode 24 but also a semiconductor laser or a power semiconductor element can be mounted on the surface 8 of the heat radiating via 10 or on a surface pad formed thereon.
In addition, the present invention is not limited to the multi-cavity configuration described above, and can also be applied to a method of manufacturing a single ceramic substrate.

  According to the present invention, a mounting element having a large amount of heat generation, such as a light emitting element mounted on the surface side of a heat dissipation via conductor, comprising a substrate main body made of ceramic and a relatively large-diameter heat dissipation via conductor penetrating the main body. Therefore, it is possible to efficiently dissipate heat from the back surface of the substrate body and to reliably manufacture a ceramic substrate having stable electrical conductivity.

1, 1a, 1b ... Ceramic substrate 2 ............... Substrate body 2a ............ Green sheet molded body 3 ............... Surface (one of a pair of surfaces)
4 ………………… Back (the other of the pair of fronts)
8 ………………… Conductor-containing paste / surface of protruding portion 9 ………………… Back surface of protruding portion 8h, 9h ……… Dent 10 ……………… Heat dissipation via conductor 10a ………… … Conductor-containing paste 11 ……………… Protrusions 12, 13 ……… Via hole / different diameter via hole 18 ……………… Back pad (surface conductor layer)
20 ……………… Carrier film (sheet material)
G, G1 to G3 ... Green sheets S1 to S3 ......... Molded body with sheet material t1, t2 ... ... Thickness d1, d2 ... ... Depth

Claims (4)

A method of manufacturing a ceramic substrate, comprising a substrate body having a pair of surfaces and made of ceramic, and a heat dissipation via conductor penetrating between the pair of surfaces in the substrate body,
A molded body with a sheet material, which is made of a single green sheet or formed by laminating a plurality of green sheets, and in which a green sheet molded body that is a substrate body having a pair of surfaces is coated with a sheet material. The process of preparing
Forming a via hole penetrating along the thickness direction of the molded body with the sheet material;
Filling the via-hole with a conductor-containing paste to be a heat-dissipating via conductor;
A step of peeling the sheet material after drying the conductor-containing paste,
A method for manufacturing a ceramic substrate. The green sheet molded body in which a plurality of green sheets are laminated is obtained by laminating a plurality of green sheets so that via holes of different sizes formed for the respective green sheets communicate with each other, and the conductors are formed in the via holes. Containing paste is filled,
The method for producing a ceramic substrate according to claim 1. After the step of peeling off the sheet material, a step of forming a surface conductor layer covering the protruding portion of the conductor-containing paste protruding from the surface is performed on the surface of the green sheet molded body from which the sheet material has been peeled off. ,
The method for producing a ceramic substrate according to claim 1 or 2, wherein The thickness of the sheet material is at least twice the depth of the dent generated on the surface of the protruding portion of the conductor-containing paste.
The method for producing a ceramic substrate according to claim 3.

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