JP2007250679A - Ceramic wiring board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a ceramic wiring board with which the ceramic wiring board of high quality is easily be manufactured, and also to provide the easily manufactured ceramic wiring board of high quality. <P>SOLUTION: For manufacturing the ceramic wiring board 10, a conduction layer 3 passing through a ceramic substrate in a thickness direction is formed in the planar ceramic substrate 1, and a wiring pattern 5 in a prescribed shape comprising wiring connected to the conduction layer is formed in at least one face of the ceramic substrate. A through-hole in a shape whose horizontal cross section in the ceramic substrate gradually reduces from one main face 1a-side to the other main face 1b-side is formed in the ceramic substrate. The through-hole is filled with conductive paste from an opening end-side with a wider area in the through-hole, conductive paste is baked, and the conductive layer is formed in the through-hole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a ceramic wiring board having a flat ceramic base material, a conductive layer penetrating the ceramic base material in the thickness direction, and a wiring pattern including wiring connected to the conductive layer, And the ceramic wiring board.

  Wiring boards used for mounting electronic components and connecting between electronic components can be classified into many types according to the layer configuration and material of the base material constituting the wiring board, or the layout specifications of the wiring pattern. In one of them, a pattern of a predetermined shape or a whole surface conductive film is formed on one main surface of a flat ceramic substrate, and a predetermined shape of a wiring pattern and a predetermined number of pads are formed on the other main surface. There is a wiring board (hereinafter, this wiring board is referred to as a “ceramic wiring board”).

  The ceramic wiring board is provided with a conductive layer that penetrates the ceramic base material in the thickness direction, and is formed on one main surface of the ceramic base material and the other main surface. The wiring pattern is electrically connected by the conductive layer. Conventionally, such a ceramic wiring board is manufactured by the following method.

  First, a desired inorganic powder used as a raw material for the ceramic substrate is mixed with an organic binder or solvent to obtain a paste. This paste is thinly coated with a doctor blade or squeegee to obtain a green sheet, and then calcined and fired. To obtain a ceramic substrate. Next, a laser beam is irradiated from one main surface side of the ceramic substrate to form a first through hole at a predetermined location, and further, abrasive grains are sprayed from the other main surface side to perform sandblasting. The ceramic molten solidified material adhering to the wall surface of the first through hole is removed to obtain a second through hole.

  The shape of the second through hole is, for example, a columnar shape similar to a through via hole (a through hole penetrating the laminated substrate in the thickness direction) formed in the laminated substrate described in Patent Document 1. Moreover, the center part may be made into the shape of a constricted column. By making the main surface that emits the laser beam and the main surface that blows abrasive grains different from each other, it is easy to form a conductive layer with a very small exposed surface on the wiring pattern surface on the ceramic substrate. As a result, it becomes easy to obtain a ceramic wiring substrate having a high wiring density in the wiring pattern.

  Next, a metal mask having a predetermined shape is arranged on the ceramic substrate formed up to the second through hole, and a conductive paste is applied from above the metal mask, and the conductive paste is placed in the second through hole. Fill. The conductive paste is applied in a state where the ceramic substrate is placed on a flat stage. Next, the conductive paste filled in the second through hole is subjected to a heat treatment to remove the binder component in the conductive paste, and then further heated to fire the conductive paste. Thereby, a conductive layer is formed.

  Thereafter, a conductive film is formed on both main surfaces of the ceramic substrate, and the conductive film is patterned into a predetermined shape on one main surface to obtain a pattern. The conductive film is patterned by, for example, forming a resist pattern having a predetermined shape on the conductive film by a photolithography method or the like, and etching the conductive film using the resist pattern as an etching mask. In addition, on the other main surface of the ceramic substrate, a predetermined-shaped wiring pattern and a predetermined number of pads are formed. Thus, a ceramic wiring board is obtained by forming a wiring pattern etc. in both the main surfaces of a ceramic base material.

JP 2003-273520 A

  However, in the conventional ceramic wiring board, since the shape of the second through hole is a columnar shape or a columnar shape with a constricted central portion, voids (voids) are generated in the conductive paste filled in the second through hole. The adhesion between the conductive paste filled in the second through hole and the ceramic base material tends to be insufficient. For this reason, voids are generated inside the conductive layer obtained by firing the conductive paste filled in the second through-hole, or the adhesion between the ceramic substrate and the conductive layer is insufficient, and the ceramic substrate And a gap is easily generated between the conductive layer and the conductive layer.

  In addition, since the conductive paste is applied with the ceramic base placed on a flat stage and the second through hole is filled with the conductive paste, the ceramic base is removed from the stage after the conductive paste is filled. When picked up, a part of the conductive paste adheres to the stage, and the upper surface of the conductive paste in the second through hole (the surface opposite to the side coated with the conductive paste) is likely to fall and be depressed. When the conductive paste having the upper surface dropped and thus baked is obtained by baking, the upper surface (the surface opposite to the side coated with the conductive paste) also has a recessed shape, and the appearance of the ceramic wiring board is impaired. It is.

  The generation of voids inside the conductive layer, the generation of voids between the ceramic base material and the conductive layer, or the depression on the upper surface of the conductive layer are all factors that degrade the quality of the ceramic wiring board.

  The present invention has been made in view of the above, and an object of the present invention is to provide a method for manufacturing a ceramic wiring board that is easy to manufacture a high-quality ceramic wiring board, and a ceramic wiring board that is easy to manufacture a high-quality one.

  The method of manufacturing a ceramic wiring board according to the present invention that achieves the above object includes: a conductive layer formed on a flat ceramic base material, the conductive layer penetrating the ceramic base material in the thickness direction, and connected to the conductive layer; Is a method for manufacturing a ceramic wiring board in which a wiring pattern having a predetermined shape is formed on at least one surface of a ceramic substrate, the ceramic substrate being covered from one main surface side to the other main surface side of the ceramic substrate. A through-hole forming step for forming a through-hole having a shape in which the horizontal cross-sectional area gradually decreases, and the conductive paste is baked after filling the through-hole from the opening end side having the larger area in the through-hole. And a conductive layer forming step of forming a conductive layer in the through hole.

  In another method of manufacturing the ceramic wiring board of the present invention that achieves the above object, a conductive layer that penetrates the ceramic base material in the thickness direction is formed on a flat ceramic base material. A method of manufacturing a ceramic wiring board in which a wiring pattern of a predetermined shape including connected wiring is formed on at least one surface of a ceramic substrate, and the ceramic substrate is penetrated through the ceramic substrate in the thickness direction. A through hole forming step of forming a hole, and a ceramic substrate is arranged on the stage so that a gap is formed below the through hole, and after the conductive paste is filled in the through hole, the conductive paste is baked, And a conductive layer forming step of forming a conductive layer in the through hole.

  In the method for manufacturing a ceramic wiring board according to the present invention, a through hole having a shape in which the horizontal cross-sectional area gradually decreases from one main surface side to the other main surface side in the ceramic base material is formed in the ceramic base material. Since the conductive paste is filled into the through-hole from the opening end side with the larger area, the entire wall surface of the through-hole is conductive compared to the case where the shape of the through-hole is a columnar shape or a columnar shape with a constricted central portion. The paste will be pressed relatively strongly. For this reason, it is suppressed that voids are generated in the conductive paste in the through-hole or the adhesiveness between the conductive paste and the ceramic substrate is insufficient, and even in the conductive layer obtained by firing the conductive paste, It is possible to suppress the formation of voids and insufficient adhesion to the ceramic substrate. As a result, it becomes easy to manufacture a high-quality ceramic wiring board.

  In another method of manufacturing a ceramic wiring board according to the present invention, the ceramic base is placed on the stage so that a gap is formed below the through hole formed in the ceramic base, and the conductive paste is placed in the through hole. Since it fills, when picking up a ceramic base material from a stage after filling with a conductive paste, it can prevent easily that a part of conductive paste in a through-hole adheres on a stage. For this reason, it is easy to prevent a depression from occurring on the upper surface of the conductive layer obtained by firing the conductive paste filled in the through hole (the surface opposite to the side coated with the conductive paste). Become. As a result, it becomes easy to manufacture a high-quality ceramic wiring board.

  Hereinafter, each of the ceramic wiring board and the method of manufacturing the ceramic wiring board according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

Embodiment 1 FIG.
1-1 is a perspective view schematically showing an example of the ceramic wiring board of the present invention, FIG. 1-2 is a plan view schematically showing the ceramic wiring board shown in FIG. 1-1, FIG. 1-3 is a schematic diagram of a cross section taken along line II shown in FIG.

  A ceramic wiring substrate 10 shown in these drawings is formed on a flat ceramic base material 1, a conductive layer 3 penetrating the ceramic base material 1 in the thickness direction, and one main surface 1a of the ceramic base material 1. Wiring pattern 5 and conductive film 7 formed on the other main surface 1 b of ceramic substrate 1.

  The ceramic substrate 1 is a substrate having a single-layer structure or a multilayer structure made of, for example, aluminum oxide (alumina sintered body), aluminum nitride, silicon nitride, or the like. Are selected as appropriate. For example, when the ceramic wiring board 10 is used for connection between electronic components, the outer dimensions of the ceramic substrate 1 can be about 3 mm in length, 4 mm in width, and about 0.1 to 1 mm in thickness. . One main surface 1a and the other main surface 1b of the ceramic substrate 1 are substantially parallel to each other.

  The conductive layer 3 is formed by firing, for example, a conductive paste containing silver (Ag) paste or silver (Ag) and palladium (Pd), and is a through hole provided at a predetermined position of the ceramic substrate 1. Is buried. The conductive layer 3 is provided in a shape in which the horizontal cross-sectional area gradually decreases from the main surface 1a side to the main surface 1b side, for example, a truncated cone-shaped through hole TH whose bottom surface is located on the main surface 1a side. Each end surface of the conductive layer 3 is substantially flat, and the conductive layer 3 has a shape in which the horizontal cross-sectional area gradually decreases from the main surface 1a side to the main surface 1b side. The size of the conductive layer 3 can be appropriately selected according to the size of the ceramic substrate 1 and the use of the ceramic wiring substrate 10. For example, when the ceramic substrate 1 has a size of about 3 mm in length, 4 mm in width, and about 0.1 to 1 mm in thickness, and the conductive layer 3 has a truncated cone shape, the conductive layer 3 on the main surface 1a side The exposed surface can be circular with a diameter of about 0.1 to 1 mm.

  The wiring pattern 5 formed on the main surface 1a of the ceramic base 1 is arranged with contact points such as terminals and pads formed on an electronic component to be mounted on the ceramic wiring substrate 10 in consideration of electrical characteristics. Or a plurality of wirings provided according to the installation of contacts or wirings in each of two electronic components to be connected by the ceramic wiring board 10, and these wirings. One of the wirings is connected to the conductive layer 3. In the illustrated example, a wiring pattern 5 is constituted by four wirings 5 a, 5 b, 5 c and 5 d, and the wiring 5 d among these four wirings 5 a to 5 d is connected to the conductive layer 3. In many cases, the wiring pattern in an actual ceramic wiring board is more complicated and fine. On the other hand, the conductive film 7 formed on the main surface 1 b of the ceramic substrate 1 covers the main surface 1 b and the exposed surface of the conductive layer 3 on the main surface 1 b side.

  Each of the wirings 5a to 5d and the conductive film 7 described above can have a single layer structure or a multilayer structure. Examples of the material include gold (Au), lead (Pb), and nickel. (Ni), chromium (Cr), aluminum (Al), copper (Cu), silver (Ag), platinum (Pt), zinc (Zn), cobalt (Co), iron (Fe), palladium (Pd), titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), or the like is used.

  Since the ceramic wiring substrate 10 having the above-described structure has the conductive layer 3 whose horizontal cross-sectional area gradually decreases from the main surface 1a side to the main surface 1b side in the ceramic substrate 1, for example, the following Embodiment 2 It can be obtained by the method for manufacturing a ceramic wiring board of the present invention described in the above. And by obtaining the ceramic wiring board 10 by this manufacturing method, it is suppressed that a space | gap arises inside the conduction | electrical_connection layer 3, or the adhesiveness of the conduction | electrical_connection layer 3 and the ceramic base material 1 becomes inadequate. Becomes easier. That is, it becomes easy to obtain a high quality product.

Embodiment 2. FIG.
In the method for manufacturing a ceramic wiring board according to the present invention, a through-hole forming step and a conductive layer forming step, which will be described below, are performed in this order, and the ceramic substrate is penetrated in the thickness direction through a flat ceramic substrate. A ceramic wiring board is obtained in which a conductive layer is formed, and a wiring pattern having a predetermined shape including wiring connected to the conductive layer is formed on at least one surface of the ceramic base. Hereinafter, it explains in full detail for every process.

(Through hole forming process)
In the through hole forming step, a through hole having a shape in which the horizontal cross-sectional area gradually decreases from one main surface side to the other main surface side of the ceramic base material is formed in the flat ceramic base material. Such a through hole can be formed, for example, by performing the following first sub-step and second sub-step in this order.

  In the first sub-process, one main surface of the ceramic base material is irradiated with a laser beam to form a first through hole penetrating the ceramic base material in the thickness direction. The first through hole preferably has a shape in which the horizontal cross-sectional area gradually decreases from one main surface side to the other main surface side in the ceramic substrate. Such a first through hole is, for example, a laser. It can be obtained by appropriately adjusting the focal position of the beam. Irradiation of the laser beam to the ceramic substrate is performed, for example, so that the incident angle on the main surface is 0 °.

FIG. 2-1 is a cross-sectional view schematically illustrating an example of a ceramic base material in which a first through hole is formed. In the ceramic substrate 11 shown in the figure, the first through hole TH ₁ is formed by irradiating a predetermined portion of one main surface 11 a of the ceramic substrate 11 with the laser beam LB. The first through hole TH ₁ penetrates the ceramic substrate 11 in the thickness direction and is open on the other main surface 11b of the ceramic substrate 11. Further, the wall surface of the first through hole TH ₁ is covered with a melted and solidified material MS generated by solidification after part of the ceramic base material 11 is melted by irradiation with the laser beam LB.

  In the second sub-process, a mask having a predetermined shape is arranged on the main surface on the side irradiated with the laser beam in the first sub-process, and the sandblasting process is selectively performed around the first through hole through the mask. As a result, the first through hole is expanded to form a second through hole having a shape in which the horizontal cross-sectional area gradually decreases from the main surface side where the mask is disposed to the other main surface side. At this time, the shape of the second through hole can be controlled by appropriately selecting the shape of the opening in the mask, the spraying time and strength of the abrasive grains in the sandblasting process, and the like.

  As the mask, a metal mask or a resist mask can be used. When the resist mask is formed by patterning a resist coated on the ceramic substrate 11 or a dry film resist applied on the ceramic substrate 11, the cost is lower than the cost of the metal mask. It becomes easy to suppress the manufacturing cost of the wiring board. In addition, when the resist mask is formed by patterning a dry film resist, the conductive paste enters between the mask and the ceramic substrate when the conductive paste is applied in a conductive layer forming process described later. As a result, it is easy to suppress the conductive paste from adhering to the vicinity of the second through hole in the main surface of the ceramic substrate. The conductive paste adhering to the main surface of the ceramic substrate is usually removed after the formation of the conductive layer in order to prevent unnecessary short circuit in the wiring pattern or to improve the appearance of the ceramic wiring board. Therefore, it is desired to suppress the adhesion of the conductive paste to an undesired location as much as possible.

  FIG. 2-2 is a cross-sectional view schematically showing an example of a dry film resist used when forming a resist mask in the second sub-step, and FIG. 2-3 is obtained by patterning the dry film resist. It is sectional drawing which shows schematically an example of the resist mask used.

As shown in Figure 2-2, the dry film resist 13A is attached on the ceramic substrate 11 so as to cover the main surface 11a and the first through-hole TH ₁ of the ceramic substrate 11. Also, as shown in FIG. 2-3, the resist mask 13 is obtained by patterning the dry film resist 13A to form an opening OP at a predetermined location. The opening OP is formed above the first through hole TH ₁ , and the first through hole TH ₁ appears at the bottom of the opening OP, and the first through hole is formed on the upper surface of the ceramic substrate 11. A region located around TH ₁ also appears. The patterning of the dry film resist 13A is performed, for example, by selectively exposing the dry film resist 13A using an exposure mask having a predetermined shape and then performing development processing. Such mask 13 disposed on the ceramic substrate 11 in the is used to apply selectively sandblasted around the first through-hole TH _1.

FIG. 2-4 is a cross-sectional view schematically illustrating an example of a second through hole formed by sandblasting in the second sub-process. As shown in the drawing, sandblasting is performed by blowing a predetermined mask, abrasive grains Pa around the first through-hole TH ₁ through a mask 13 shown in Figure 2-3. By this sandblasting process, the melted solid MS shown in FIG. 2-1 is removed and the surrounding ceramic substrate 11 is removed. As a result, the first through hole TH ₁ shown in FIG. 2-3 is expanded. The second through hole TH ₂ is obtained. In the second through hole TH _2, a horizontal cross-sectional area is gradually reduced from the main surface 11a (see FIG. 2-3) side of arranging the mask 13 to the other main surface 11b (see FIG. 2-3) side.

Since the ceramic base material 1 shown in FIG. 1 is obtained by forming the second through hole TH ₂ , the ceramic base material is denoted by reference numeral “1” in FIG. 1, the main surface on which the mask 13 is disposed is indicated by reference numeral “1a”, and the other main surface of the ceramic substrate 1 is indicated by reference numeral “1b”. After the sandblasting process, the abrasive grains adhering to the surface of the mask 13 and the surface of the ceramic substrate 1 are removed by a method such as ultrasonic cleaning.

(Conductive layer formation process)
In the conductive layer forming step, the conductive paste is filled into the through hole from the opening end side having the larger area in the through hole (second through hole) formed in the ceramic substrate, and then the conductive paste is baked. Then, a conductive layer is formed in the through hole.

  Examples of the conductive paste include silver (Ag) paste and conductive paste containing silver (Ag) and palladium (Pd). From the viewpoint of forming a conductive layer having excellent adhesion to the ceramic substrate, it is preferable to use a conductive paste having a heat shrinkage rate as small as possible.

  The filling of the conductive paste into the through hole (second through hole) is performed, for example, by applying a desired conductive paste using a squeegee or a doctor blade. When the mask used in the sandblasting process is a resist mask, the resist mask is preferably used as it is as a mask for coating a conductive paste without peeling off. By using the mask used in the sand blasting process as a mask for applying the conductive paste, the mask alignment work for applying the conductive paste becomes unnecessary, and the productivity is improved.

  The filling of the conductive paste into the through-hole (second through-hole) can be performed, for example, by placing the ceramic substrate directly on the stage as in the conventional case, but the conductive layer obtained by firing the conductive paste From the viewpoint of obtaining a high-quality ceramic wiring board by preventing the formation of dents on the upper surface (the surface opposite to the side coated with the conductive paste), the bottom of the through hole (second through hole) It is preferable to carry out by placing the ceramic substrate on the stage so that a gap is formed in the substrate.

FIG. 3A is a cross-sectional view schematically illustrating an example of a method of filling a conductive paste into a through hole (second through hole). In the method shown in the figure, the ceramic base material 1 such that a gap is generated in the lower second through hole TH ₂ is placed on the stage 20, the conductive paste for coating the mask 13 used in the through hole forming step by applying the conductive paste 23 by the squeegee 22 while using as a mask, filling the conductive paste 23 to the second through hole TH _2. A plurality of spacers 20 a having a predetermined height are provided on the upper surface of the stage 20, and a gap is formed between the second through hole TH ₂ and the stage 20 by supporting the ceramic substrate 1 on the spacer 20 a. Is formed. Note that an arrow A in the figure indicates the moving direction of the squeegee 22.

Since the shape of the second through hole TH ₂ is the above-described shape, when the conductive paste 23 is imprinted in the second through hole TH ₂ by the squeegee 22, the conductive paste 23 in the second through hole TH ₂ is used. A relatively large load is applied. Therefore, a possible second through hole TH ₂ is compared with the case where the columnar constricted columnar shape and central portion, the conductive paste 23 over the entire wall surface of the second through-holes TH ₂ is pressed relatively strongly Become. As a result, the formation of voids in the conductive paste 23 filled in the second through hole TH ₂ is suppressed, and the conductive paste 23 is formed on the wall surface (ceramics) of the second through hole TH _2. Adhere to the substrate 1).

Further, since the ceramic substrate 1 such that a gap is generated in the lower second through hole TH ₂ is placed on the stage 20, when the ceramic substrate 1 was taken from the stage 20 to move to the next step, the 2. It is easy for a part of the conductive paste 23 in the through hole TH ₂ to adhere to the stage and the upper surface of the conductive paste 23 (the surface opposite to the side coated with the conductive paste) falls off and is easily depressed. Can be prevented. As a result, that the depression in the upper surface of the conductive layer obtained by firing the conductive paste 23 filled in the second through-hole TH in ₂ (surface opposite to the side where the coating a conductive paste) occurs It becomes easy to prevent, and it becomes easy to obtain a high-quality ceramic wiring board.

The baking of the conductive paste 23 filled in the second through hole TH ₂ is preferably performed after the conductive paste 23 is planarized after the mask 13 is peeled off. FIG. 3-2 is a cross-sectional view schematically illustrating an example of a state of the conductive paste after the mask is physically peeled. As shown in the figure, the conductive paste 23 filled in the second through hole TH ₂ is peeled from the ceramic substrate 1 by the thickness of the mask 13 after the mask 13 (see FIG. 3A) is peeled off. It protrudes. The conductive paste 23 protrudes from the ceramic substrate 1 also on the main surface 1 b side of the ceramic substrate 1.

FIG. 3-3 is a cross-sectional view schematically illustrating an example of a planarized conductive paste. As shown in the drawing, the conductive paste 23 filled in the second through hole TH ₂ is flattened so that the upper surface thereof is substantially flush with the main surface 1a of the ceramic substrate 1, and the lower surface thereof is ceramic base. It is preferable to carry out so as to be substantially flush with the main surface 1 b of the material 1. This flattening is performed by, for example, scrubbing the conductive paste 23 using a cloth or the like. In this case, the region located around the second through hole TH ₂ among the second area located around the through hole TH ₂ and the main surface 1b, among main surfaces 1a, respectively, thin conductive paste The layer 23a is inevitably generated. In FIG. 3-3, are exaggerated thin conductive paste layer 23a which is formed around the second through hole TH _2.

In firing the conductive paste 23 filled in the second through hole TH ₂ , first, the conductive paste 23 is subjected to a heat treatment at about 150 ° C. to remove the binder component, and then the composition of the conductive paste 23. And firing treatment at a predetermined temperature according to the composition of the ceramic substrate 1. The firing temperature at this time is such that the conductive fine particles contained in the conductive paste are sintered from the viewpoint of enhancing the adhesion between the conductive layer formed by firing the conductive paste and the ceramic substrate 1. In addition, it is preferable to set the temperature at which the conductive fine particles in contact with the ceramic substrate 1 and the ceramic substrate 1 are sintered. For example, when the ceramic substrate 1 is made of aluminum oxide (alumina sintered body), the firing temperature is preferably about 850 ° C. By performing the firing process in this manner, the conductive paste 23 in the second through hole TH ₂ is converted into a solid metal, and a conductive layer having high adhesion to the ceramic substrate 1 is obtained. Also, a thin conductive layer a thin electrically conductive paste layers 23a that are formed around the second through hole TH ₂ also solid metallization is formed.

FIG. 3-4 is a cross-sectional view schematically illustrating an example of each of the conductive layer formed in the second through hole and the conductor layer formed around the conductive layer. As shown in the figure, the conductive paste 23 (see FIG. 3-3) filled in the second through hole TH ₂ is solidified by the above-described baking treatment, and a conductive layer is formed in the second through hole TH _2. 3 is formed. Further, (see Figure 3-3) the second through hole TH ₂ thin conductive paste layer 23a which has been formed around even if solid metallized thin conductive layer 3a is formed.

  Thereafter, the thin conductor layer 3a is removed by, for example, ion milling or the like, and the ceramic substrate 1 having only the conductive layer 3 as the conductor layer, that is, the ceramic substrate 1 having the conductive layer 3 shown in FIG. obtain. FIG. 3-5 is a cross-sectional view schematically illustrating an example of a ceramic substrate having only a conductive layer as a conductor layer. The ceramic substrate 1 shown in the figure is obtained by removing the thin conductor layer 3a from the ceramic substrate 1 shown in FIG. 3-4 by ion milling. As the conductor layer, only the conduction layer 3 is obtained. Have.

  The target ceramic wiring board has a wiring pattern and a pad formed on at least one main surface of the ceramic base material in which the conductive layer is formed in the through hole (second through hole) as described above, and the other main surface. It is obtained by forming a pattern or a conductive film on the entire surface. The wiring pattern at this time is formed so as to include wiring connected to the conductive layer, and the pad is formed so as to cover the conductive layer or to be in contact with the conductive layer. When a wiring pattern is formed only on one main surface of the ceramic substrate, the main surface of the ceramic substrate on which the wiring pattern is formed depends on the wiring density of the wiring pattern to be formed, etc. Can be selected as appropriate.

  The above wiring pattern is formed by forming a conductive film as a base by, for example, a physical vapor deposition method such as a vacuum deposition method or a sputtering method, or a plating method, and then forming a photoresist layer thereon, for example. The resist layer can be formed into a predetermined shape by photolithography or the like to obtain a resist pattern, and the resist film can be used as an etching mask to etch the conductive film.

  Each of the wiring pattern, the pad, and the conductive film may have a single layer structure or a multilayer structure. Examples of the material include gold (Au) and lead (Pb). ), Nickel (Ni), chromium (Cr), aluminum (Al), copper (Cu), silver (Ag), platinum (Pt), zinc (Zn), cobalt (Co), iron (Fe), palladium (Pd) ), Titanium (Ti), molybdenum (Mo), tungsten (W), zirconium (Zr), or the like.

FIG. 4 is a cross-sectional view schematically showing an example of a ceramic substrate having a conductive film formed on both sides. The ceramic substrate 1 shown in the figure has a conductive layer 3 formed in the second through hole TH ₂ , and a conductive film is formed on one main surface 1 a of the ceramic substrate 1 so as to cover the conductive layer 3. 5A is formed, and another conductive film 7 is formed on the other main surface 1b so as to cover the conductive layer 3. The ceramic wiring substrate 10 shown in FIGS. 1-1 to 1-3 is obtained by patterning the conductive film 5A into a predetermined shape.

When the ceramic wiring board is manufactured by the manufacturing method described above, as already described in the description of the conductive layer forming step, the conductive paste 23 filled in the second through hole TH ₂ (see FIG. 3A). ) with voids that may occur is suppressed in, since the conductive paste 23 is pressed relatively strongly in the second through-hole TH ₂ of the wall (ceramic substrate 1), then the conductive paste 23 When the conductive layer 3 (see FIGS. 3-4 and 3-5) is obtained by baking, voids are generated in the conductive layer 3 or the adhesion between the conductive layer 3 and the ceramic substrate 1 is insufficient. Is suppressed. Therefore, according to this manufacturing method, it becomes easy to manufacture a high-quality ceramic wiring board.

Further, as already described in the description of the conductive layer forming step, the ceramic is formed so that a gap is formed below the second through hole TH ₂ when the conductive paste 23 is filled in the second through hole TH _2. placing the substrate 1 on the stage 20, when the ceramic substrate 1 was taken from the stage 20 to move to the next step, a portion of the second through-hole TH ₂ in the conductive paste 23 on the stage It becomes easy to prevent the upper surface of the conductive paste 23 (the surface opposite to the side coated with the conductive paste) from dropping and sinking. As a result, it becomes easy to prevent the upper surface of the conductive layer 3 (the surface opposite to the side coated with the conductive paste) from being depressed, and it becomes easy to obtain a high-quality ceramic wiring board.

Embodiment 3 FIG.
A high-quality ceramic wiring board as compared with the prior art can be obtained by another method for manufacturing a ceramic wiring board of the present invention. In this manufacturing method, a through-hole forming step and a conductive layer forming step described below are performed in this order, and a conductive layer that penetrates the ceramic base material in the thickness direction is formed on a flat ceramic base material. A ceramic wiring board is obtained in which a wiring pattern having a predetermined shape including wiring connected to the conductive layer is formed on at least one surface of a ceramic base material. Hereinafter, it explains in full detail for every process.

(Through hole forming process)
In the through hole forming step, a through hole that penetrates the ceramic base material in the thickness direction is formed in the ceramic base material. In this through-hole forming step, after irradiating a laser beam from one main surface side of the ceramic base material to form a first through hole at a predetermined location, the sand blast treatment is performed from the other main surface side as in the conventional case. Thus, the first through hole can be expanded to form a columnar second through hole having a cylindrical shape or a constricted central portion. Of course, a through hole (second through hole) may be formed in the same manner as the through hole forming step in the manufacturing method described in the second embodiment.

(Conductive layer formation process)
In the conductive layer forming step, the ceramic base material is arranged on the stage so that a gap is formed below the through hole (second through hole) formed in the ceramic base material in the through hole forming step, and the through hole (second through hole) After the conductive paste is filled in the holes), the conductive paste is baked to form a conductive layer in the through hole (second through hole).

  When the second through-hole formed in the through-hole forming step has a columnar shape or a columnar shape with a constricted central portion, the filling of the conductive paste into the second through-hole is performed at the two open ends of the second through-hole. It can be done from either side. Further, when the second through hole is a through hole formed in the through hole forming step of the manufacturing method described in the second embodiment, as described above, the one with the larger area in the second through hole. It is preferable to fill the conductive paste from the opening end side. The firing of the conductive paste and the subsequent treatment are performed in the same manner as the firing of the conductive paste and the subsequent treatment in the conductive layer forming step in the manufacturing method described in the second embodiment.

  The target ceramic wiring board is formed up to the conductive layer formation step described above, and then a wiring pattern and a pad are formed on at least one main surface of the ceramic base, and a pattern or a whole conductive film is formed on the other main surface Can be obtained. Each of the wiring pattern, the pad, and the conductive film is formed in the same manner as the wiring pattern, the pad, or the conductive film when the ceramic wiring substrate is obtained based on the manufacturing method described in the second embodiment. .

  When the ceramic wiring board is manufactured in this way, the ceramic base is placed on the stage so that a gap is formed below the second through hole formed in the ceramic base, and in this state, the conductive material is conductive in the second through hole. Since the conductive paste is filled, when the ceramic substrate is picked up from the stage to move to the next step, a part of the conductive paste in the second through hole is placed on the stage regardless of the shape of the second through hole. It becomes easy to prevent the upper surface of the conductive paste (the surface opposite to the side coated with the conductive paste) from dropping and sinking. As a result, it is easy to prevent the upper surface (the surface opposite to the side coated with the conductive paste) of the conductive layer obtained by firing the conductive paste filled in the second through hole from being depressed. It becomes easy to obtain a high-quality ceramic wiring board.

  The ceramic wiring board and the method for manufacturing the ceramic wiring board according to the present invention have been described with reference to the three embodiments. However, as described above, the present invention is not limited to the three embodiments.

For example, the shape of the through hole (second through hole) formed in the ceramic base material in the method for manufacturing a ceramic wiring board described in the second embodiment is the horizontal cross-sectional area from one main surface to the other main surface in the ceramic base material. The horizontal cross-sectional shape on the one main surface side and the horizontal cross-sectional shape on the other main surface side may be the same or different from each other. Further, the rate of change of the horizontal cross-sectional area of the second through hole does not have to be constant from one main surface to the other main surface in the ceramic substrate, but is a step from one main surface to the other main surface. Or continuously. Moreover, the second through-hole, as in the second through-hole TH ₁₂ shown in FIG. 5, area horizontal cross-sectional area from the one main surface 31a of the ceramic substrate 31 to the other main surface 31b does not substantially change R May be included.

  Further, each end face of the conductive layer is preferably flush with the main surface of the ceramic base material, but does not hinder the formation of a desired wiring pattern, pad, or conductive film on the main surface of the ceramic base material. If so, there may be a step between the end face of the conductive layer and the main surface of the ceramic substrate. The removal of the thin conductive layer 3a (see FIG. 3-4) inevitably generated in the vicinity of the conductive layer is omitted if it is within an allowable range for obtaining a ceramic wiring board of desired quality. It is also possible. In addition, various modifications, modifications, combinations, and the like are possible for the method for manufacturing a ceramic wiring board and the ceramic wiring board of the present invention.

It is a perspective view which shows roughly an example of the ceramic wiring board of this invention. It is a top view which shows schematically the ceramic wiring board shown to FIGS. 1-1. It is the schematic of the II sectional view shown to FIGS. It is sectional drawing which shows roughly an example of the ceramic base material in which the 1st through-hole was formed at the through-hole formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the dry film resist used when forming a resist mask at the through-hole formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the resist mask obtained by patterning a dry film resist at the through-hole formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the 2nd through-hole formed at the through-hole formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the filling method at the time of filling a conductive paste in a through-hole at the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the state of the electrically conductive paste after peeling the mask used for application | coating of the electrically conductive paste at the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the electrically conductive paste by which it filled in the through-hole at the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention, and was planarized. It is sectional drawing which shows roughly an example of each of the conduction | electrical_connection layer formed in the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention, and the conductor layer formed in the circumference | surroundings. It is sectional drawing which shows roughly an example of the ceramic base material produced through the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly an example of the ceramic base material in which the electrically conductive film was formed in both surfaces after passing through the conduction | electrical_connection layer formation process in the manufacturing method of the ceramic wiring board of this invention. It is sectional drawing which shows roughly the other example of the 2nd through-hole formed at the through-hole formation process in the manufacturing method of the ceramic wiring board of this invention.

Explanation of symbols

1, 11, 31 Ceramic base material 1a One main surface 1b of the ceramic base material Other main surface 3,33 of the ceramic base material Conductive layer 5 Wiring pattern 7 Conductive film 10 Ceramic wiring substrate 13A Dry film resist 13 Mask 20 Stage 20a Spacer 23 Conductive paste TH Through hole TH ₁ First through hole TH ₂ , TH ₁₂ Second through hole

Claims (6)

A conductive layer penetrating the ceramic base material in the thickness direction is formed on a flat ceramic base material, and a predetermined-shaped wiring pattern including wiring connected to the conductive layer is formed on at least one surface of the ceramic base material A method of manufacturing a ceramic wiring board, comprising:
A through hole forming step of forming a through hole having a shape in which a horizontal cross-sectional area gradually decreases from one main surface side to the other main surface side in the ceramic base material;
A conductive layer forming step of forming the conductive layer in the through-hole by firing the conductive paste after filling the through-hole into the through-hole from the opening end side having the larger area in the through-hole;
A method for producing a ceramic wiring board, comprising: The through hole forming step includes
A first sub-process of irradiating one main surface of the ceramic substrate with a laser beam to form a first through hole penetrating the ceramic substrate in a thickness direction thereof;
A mask having a predetermined shape is arranged on the main surface on the side irradiated with the laser beam, and the first through hole is expanded by selectively performing sandblasting around the first through hole through the mask. A second sub-step of forming a second through hole having a shape in which the horizontal cross-sectional area gradually decreases from the main surface side where the mask is disposed to the other main surface side;
The manufacturing method of the ceramic wiring board of Claim 1 characterized by the above-mentioned.   3. The method of manufacturing a ceramic wiring board according to claim 2, wherein the mask is a dry film resist having an opening at a predetermined location.   The filling of the conductive paste into the through hole in the conductive layer forming step is performed by arranging the ceramic base material on a stage so that a gap is formed below the through hole. The manufacturing method of the ceramic wiring board of any one of 1-3. A conductive layer penetrating the ceramic base material in the thickness direction is formed on a flat ceramic base material, and a predetermined-shaped wiring pattern including wiring connected to the conductive layer is formed on at least one surface of the ceramic base material A method of manufacturing a ceramic wiring board, comprising:
A through-hole forming step for forming a through-hole penetrating the ceramic base material in the thickness direction of the ceramic base material;
The ceramic substrate is arranged on a stage so that a gap is formed below the through hole, and the conductive paste is baked after filling the through hole with the conductive paste, and the conductive layer is formed in the through hole. A conductive layer forming step of forming
A method for producing a ceramic wiring board, comprising: A flat ceramic substrate, a conductive layer penetrating the ceramic substrate in a thickness direction thereof, and a wiring pattern having a predetermined shape including wiring connected to the conductive layer, wherein the wiring pattern is the ceramic substrate. A ceramic wiring board formed on at least one side of the material,
The ceramic wiring board, wherein the conductive layer is provided in a through hole having a shape in which a horizontal cross-sectional area gradually decreases from one main surface side to the other main surface side in the ceramic base material.

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