JP3236769B2 - Ceramic substrate, method of manufacturing the same, and divided circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate which becomes a divided circuit board having a plurality of end electrodes when divided into unit blocks, a method of manufacturing the same, and a divided circuit board.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller, lighter and more portable, and the circuit blocks used therein have been reduced in size, weight, and thickness, surface-mounted, and composited in accordance with the trend. .

[0003] In such a trend, ceramic circuit boards have been widely used because of their excellent heat dissipation properties and low dielectric loss, and have been widely applied mainly to hybrid ICs for surface mounting. .

Conventionally, hybrid ICs for surface mounting are used by being soldered to a ceramic circuit board. The ceramic circuit board has an end face electrode from the viewpoints of joining confirmation and maintaining reliability. From the viewpoint of the manufacturing method, the structure of the end face electrode can be roughly classified into 3
There are different types of manufacturing methods.

[0005] First, in a structure called a through-hole thick film structure, an unfired or fired ceramic substrate on which a through-hole for an end face electrode has already been formed is combined with a technique such as suction to form a thick film. Conductive paste is converted to sulfo by printing technology, etc.
This is a structure achieved by a method of coating and baking on the inner wall surface of the fuel tank. The advantage of this method is that a plurality of substrates can be processed, that is, when divided into unit blocks, each becomes a divided circuit substrate having a plurality of end face electrodes, which is advantageous in reducing the number of steps.

[0006] The second structure is a so-called single structure, in which end electrodes are patterned on a divided circuit board divided into unit blocks, basically using a thick film printing technique or the like.
This is a structure achieved by lining and baking.
The advantage of this method is that there is no dead space due to a through hole when viewed in a mounting projection area, and the method is suitable for miniaturization.

[0007] The third structure is an application of the first structure. When the ceramic substrate has a multilayer structure, a through hole is formed for each unfired green sheet layer. This structure is achieved by coating a conductive paste on the inner wall surface of the hole and laminating and integrating the through-hole thick film structure. This advantage is in that the connection between the internal wiring and the end face electrode can be easily made.

[0008]

However, the above 3)
Each of the structures according to the various manufacturing methods has the following disadvantages. That is, in the first through-hole thick film structure, when the ceramic substrate has the internal wiring, the connection reliability between the internal wiring and the end face electrode is lacking. If the target is an unfired ceramic substrate, the through-hole is punched by a punching method or the like.
Although it is necessary to form a hole, the internal wiring collapses during the formation, making it difficult to make contact with the end face electrode.

Further, if a fired ceramic circuit board is the target, a flux component or the like for adjusting shrinkage contained in the internal wiring floats on the inner wall surface of the through hole which is a free surface, and it is difficult to join the end surface electrode. Occurs.
In order to solve this problem, an etching process or the like may be performed, but this process may corrode the ceramics and leads to an increase in cost. Further, when a wide end face electrode is required, it is difficult to completely coat the required width because a flux component and the like float on the inner wall surface of the through hole which is a free surface.

In the second single formation structure, since the end face is exposed, a large number of pieces cannot be formed. Therefore, when components are mounted on the surface of the ceramic circuit board, the mounting efficiency is greatly reduced.

As in the first structure, the third structure becomes unsuitable when the width of the end face electrode is increased. That is, in this structure,
It is difficult to coat only the inner wall surface of the through hole, but when the conductive paste is filled in the through hole formed in the green sheet, it is necessary to remove the conductive paste to leave the conductive paste only on the inner wall surface of the through hole. There is a problem that an operation is required, and if the conductor paste is left as it is, an extra conductor paste is required. Further, since the through holes are formed for each layer by punching or the like, there is a problem that the inner wall surface of the through holes becomes uneven, and the surface of the end face electrode is also likely to be uneven.

Further, in the first and third structures, as shown in FIG.
When the substrate 1 was divided, it passed through the cylindrical conductive member 43 serving as an end surface electrode. Therefore, when the substrate 1 was divided by the dividing groove 41, the conductive member 43 was directly cut, and the force required to divide the conductive member 43 was reduced. Act, and the connection reliability between the conductive member 43 and the insulating base 40 is reduced, such as the conductive member 43 peeling off.

Furthermore, various end face structures and conductor shapes have conventionally been used. However, when end face electrodes are formed by a punching method using a mold, design using a simple shape such as a circle and an ellipse is forced, and a conductive member is formed. An end face structure excellent in connection reliability and mass productivity between the insulating substrate 43 and the insulating base 40 was not obtained.

[0014]

According to the present invention, there is provided a ceramic substrate comprising: an insulating base formed by laminating a plurality of insulating layers made of ceramic; an internal wiring formed between the insulating layers; and a surface formed on the surface of the insulating base. A divided circuit board, comprising: a dividing groove; and a conductive member that forms an end face electrode formed in a thickness direction of the insulating base, and each of the divided circuit boards includes a plurality of end face electrodes when the insulating base is divided by the dividing groove. In the ceramic substrate to be formed, the conductive members are formed in a substantially U shape, and are formed at predetermined intervals so that ends of the conductive members of adjacent divided circuit boards face each other with the division groove interposed therebetween. In addition, a protruding portion in which the dividing groove is formed is interposed between opposing ends of the pair of conductive members.

Further, a method of manufacturing a ceramic substrate according to the present invention comprises: an insulating base formed by laminating a plurality of insulating layers made of ceramic; and an internal wiring formed between the insulating layers. In the method of manufacturing a ceramic substrate to be a divided circuit board each having a plurality of end face electrodes when divided by the divided groove, the insulating layer material made of ceramics, photocurable monomer, slip material containing an organic binder A step of forming an insulating layer molded body by thinning and drying; a step of exposing the surface of the insulating layer molded body except for a position where the end face electrode is formed; and a step of exposing the insulating layer molded body Forming a pair of substantially U-shaped end surface electrode through grooves at predetermined positions at positions where the end surface electrodes are to be formed so that the end portions thereof face each other; and A step of filling a conductive paste in the electrode through-groove, a step of printing a conductive paste on the surface of the insulating layer molded body to form an internal wiring pattern, and a step of forming a conductive paste in the end face electrode through-groove. A step of laminating the insulating layer molded body before the exposure processing on the insulating layer molded body filled with Forming a divided groove for passing through between the pair of substantially U-shaped end surface electrode through-grooves, and firing the laminated molded body having the divided groove formed therein. It is. After firing, it is desirable to plate the surface of the end face electrode with a metal having good solder wettability.

Further, according to the divided circuit board of the present invention, in the divided circuit board formed by forming an end face electrode along the concave portion formed on the outer peripheral surface of the insulating base, the concave portion is formed in the concave portion. And a protrusion that protrudes toward the end and covers the end of the end face electrode.

In the insulating layer made of the ceramic of the present invention, the term "ceramic" includes glass ceramic.

[0018]

According to the ceramic substrate of the present invention, since the dividing groove for dividing each unit block is formed so as to pass between two opposed U-shapes serving as end face electrodes, the dividing groove is divided along the dividing groove. Even if the conductive member serving as the end face electrode is not directly divided, peeling of the conductive member from the insulating base is suppressed, and connection reliability between the conductive member and the insulating base can be improved.

Further, the reliability of connection between the internal wiring and the end face electrode is good, the number of manufacturing steps is small, and a ceramic substrate which can be formed in a large number can be realized. Furthermore, since a large number of devices can be formed, there is an advantage that mounting efficiency is improved when components are mounted on the surface of the ceramic substrate.

In the method for manufacturing a ceramic substrate according to the present invention,
The idea of forming the end face electrodes in the thickness direction of the insulating layer for each insulating layer is basically the same as the third method described in the related art. However, unlike the case where the through hole is formed as in the third method, a feature is that the formation method is such that the end face electrode conductor is buried in a portion corresponding to the end face electrode (through groove for the end face electrode). In the through-hole method, a wide end face electrode can be formed, for example, an end face electrode having a width of 1 mm is formed on an end face of a substrate having a thickness of 1 mm, which cannot be manufactured due to a problem that an embedded conductor is separated.

According to the divided circuit board of the present invention, the end of the semi-cylindrical end face electrode is covered by the protrusion protruding inward from the recess formed on the outer peripheral surface of the insulating base, The end face electrode is not exposed on the outer peripheral surface of the divided circuit board,
There is almost no direct force acting from the outside,
Problems such as peeling off of the end face electrodes when handling the divided circuit board are also improved.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION A ceramic substrate according to the present invention is formed by forming a pair of U-shaped conductive members at predetermined intervals so that the ends thereof face each other across a dividing groove formed in an insulating base. It is. The insulating substrate of the ceramic substrate according to the present invention is configured by laminating a plurality of insulating layers made of ceramic or glass ceramic, and internal wiring is formed between these insulating layers. And a division groove is formed in this ceramic substrate, and this division groove
It is formed between a pair of substantially U-shaped conductive members formed so that their ends face each other. By dividing the ceramic substrate along the dividing groove, a protrusion is formed in the recess formed on the outer peripheral surface of the insulating substrate, and the protrusion protrudes inward of the recess. A divided circuit board having a plurality of end face electrodes coated with is obtained.

In the method of manufacturing a ceramic substrate according to the present invention, the insulating layer molded body is exposed and developed to form a substantially U-shaped end face electrode through groove at a position to be an end face electrode, and a conductive paste is filled in this groove. This is a method of manufacturing a ceramic substrate in which a plurality of divided circuit boards each having an end face electrode are formed when filling and dividing are performed by repeating the above steps.

Further, in the manufacturing method of the present invention, the inside of the pair of semi-cylindrical conductive members formed with the ends facing each other is the same as the insulating layer molded body after the lamination and integration of the insulating layer molded body. Columns of composition are present. If the structure is divided along the dividing groove with this structure, an end face electrode cannot be formed. Therefore, the columnar body inside the conductive member must be removed before the division, but this removing step uses a ceramic substrate as a hybrid IC unit block. Any process may be used before (before division). For example, it may be performed after lamination and integration and before firing, or after firing.

Since the divided circuit boards are finally mounted by soldering, the end electrodes of the divided circuit boards must be able to be joined by soldering. Therefore, considering simultaneous firing with ceramics including glass ceramics, ceramics are materials that can be fired at about 800 to 1,000 ° C., and the constituent metals of the terminal electrodes are silver,
The main component is one of palladium, platinum, copper, and an alloy of silver and palladium. Among them, a silver alloy or copper is preferable. Because silver is eroded by solder,
It is preferable to apply tin plating or the like on a nickel base.
Further, since tungsten or molybdenum or the like cannot be directly connected by soldering, it is preferable to apply plating or the like to the surface of tungsten or molybdenum in this case as well.

The production method of the present invention will be described in detail.

First, the slip material serving as the insulating layer is a solvent-based slip material obtained by homogeneously kneading a glass ceramic or ceramic material, a photocurable monomer, an organic binder, and an organic solvent.

When so-called low-temperature fired ceramics fired at 850 to 1050 ° C. is used as the composite circuit block, a ceramic material and a glass material (both are referred to as a solid component) are generally used for the insulating layer. .

The ceramic material is a powder such as cristobalite, quartz, corundum (α-alumina), mullite, zirconia, cordierite, etc., having an average particle size of preferably 1.0 to 6.0 μm, more preferably 1 to 6.0 μm. 0.5 to 4.0 μm. These ceramic materials may be used in combination of two or more. Here, 1.0-6.
When the ceramic material having a thickness of 0 μm is used, when the average particle size of the ceramic material is less than 1.0 μm, it is difficult to form a slip, and the exposure light is diffusely reflected at the time of exposure described below, and sufficient exposure cannot be performed. Conversely, the average particle size is 6.0 μm
This is because if it exceeds 300, it becomes difficult to obtain a dense insulating layer.

The glass material is a glass frit containing a plurality of metal oxides, and after firing at 850 to 1050 ° C., cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, petalite and its replacement. As long as at least one derivative crystal is deposited, an insulating layer with high strength can be obtained. In particular, when a crystallized glass frit that precipitates anorthite or Celsian is used, an insulating layer with higher strength is obtained, and when a crystallized glass frit that can precipitate cordierite or mullite is used, thermal expansion after firing is performed. Since the rate is low, it is optimal as a circuit board for arranging a silicon chip such as an IC on the circuit board.

The most preferred glass materials in consideration of the strength of the insulating layer and the coefficient of thermal expansion are B ₂ O ₃ , SiO ₂ , Al
It is a glass frit containing ₂ O ₃ , ZnO, and alkaline earth oxide. Since such a glass frit has a wide vitrification range and a yield point around 600 to 800 ° C.,
When firing at about 850 to 1050 ° C., it is suitable for the sintering behavior of copper-based, silver-based, and gold-based conductive materials serving as internal wiring and via-hole conductors used for low-temperature fired multilayer ceramic circuit boards.

As an action of each component, B ₂ O ₃ , Si
O ₂ is mainly as a network former, Al ₂ O
₃ mainly acts as an intermediate, and ZnO and alkaline earth oxides mainly act as a network modifier.

Such a glass material can be obtained by mixing the above-mentioned predetermined components at a predetermined ratio, heating and melting, quenching and then pulverizing. The average particle size of the crushed glass frit is 1.0 to 5.0 μm, preferably 1.
5 to 3.5 μm.

Here, the average particle size of the ground glass frit is set to 1.0 to 5.0 μm because the average particle size is 1.
If the thickness is less than 0 μm, it is difficult to form a slip,
Exposure light is irregularly reflected at the time of exposure to be described later, so that sufficient exposure cannot be performed. Conversely, if the average particle size exceeds 5.0 μm, dispersibility is impaired, and specifically, the powder is uniformly dissolved between ceramic powders, which are insulating materials. This is because they cannot be dispersed and the strength is extremely reduced.

The composition ratio of the above-mentioned ceramic material and glass material is such that the ceramic material is 10% by weight to 50% by weight,
It is preferably 20% to 35% by weight, and the glass material is 90% to 50% by weight, preferably 80% to 6% by weight.
5% by weight.

Here, the ceramic material is 10% by weight to 5% by weight.
The reason why the weight is 0% by weight and the glass material is 90% by weight to 50% by weight is that if the ceramic material is less than 10% by weight and the glass material exceeds 90% by weight, the glass quality of the insulating layer is excessively increased, and It is inappropriate even from the strength of
When the amount of the ceramic material exceeds 50% by weight and the amount of the glass material is less than 50% by weight, the exposure light is irregularly reflected at the time of exposure to be described later, so that sufficient exposure cannot be performed, and the denseness of the insulating layer after firing is also impaired. is there.

In addition to the above ceramic materials, the constituent materials of the slip material include a photocurable monomer, an organic binder, and an organic solvent, which are lost by sintering. A water-based slip material may be used instead of the solvent-based slip material.

The photo-curable monomer of the solvent-based slip material must be excellent in thermal decomposability in order to cope with a low-temperature and short-time baking step. As a photocurable monomer, a monomer having a secondary or tertiary carbon, which needs to be photopolymerized by exposure after application of a slip material and drying, capable of forming free radicals and chain growth addition polymerization. For example, alkyl acrylates such as butyl acrylate having at least one polymerizable ethylenic group and the corresponding alkyl methacrylates are effective. Further, polyethylene glycol diacrylates such as tetraethylene glycol diacrylate and methacrylates corresponding thereto are also effective. The photo-curable monomer is added in such a range that it can be cured by exposure and a portion other than the exposure can be easily removed by development, and is, for example, 5 to 15% by weight or less based on the solid component.

The organic binder of the solvent-based slip material must have good thermal decomposability like the photo-curable monomer. Specifically, thermal decomposition must be possible at 600 ° C. or lower. More preferably, the temperature is 500 ° C. or lower. If the thermal decomposition temperature exceeds 600 ° C., it remains in the insulating layer and is trapped as carbon, discoloring the substrate to gray, and lowering the insulation resistance and Q value of the insulating layer. In addition, it may become a void and cause delamination.

As a slip material, a sensitizer, a photo-initiating material or the like may be added as required. For example,
Examples of the photoinitiating material include benzophenones and acyloin ester compounds.

As described above, a glass-ceramic or ceramic material, a photocurable monomer, an organic binder, and an organic solvent are mixed and kneaded to form a solvent-based slip material serving as an insulating layer. The method of mixing and kneading may be a conventionally used method, for example, a method using a ball mill. The method of thinning the slip material is, for example, a doctor blade method (knife coat method), a roll coat method, a printing method, and the like. A blade method or the like is suitable. The slip material is adjusted to a predetermined viscosity according to the method of thinning.

The conductive paste of the conductive material used as the end face electrode is obtained by homogeneously kneading a powder of at least one metal material of a silver alloy or copper, a low melting point glass component, an organic binder and an organic solvent. Is preferably used. The conductive paste of the conductor material to be the internal wiring and via-hole conductor may be the same as that of the end face electrode,
A material containing silver as a main component may be used. Since these materials have a firing temperature of 850 to 1050 ° C. in particular, a metal material having a relatively low melting point and a low resistance material is selected. Taking into account the sintering behavior with a body (one coated with a slip material and dried), one having a deformation point of about 700 ° C. is used.

In the method of manufacturing a ceramic circuit board according to the present invention, first, a slip material is thinned on a support substrate (hereinafter, referred to as a “slip material”).
(The coating is simply referred to as coating.) Drying to form an insulating layer molded body that becomes an insulating layer.

Examples of the support substrate include a glass substrate, an organic film, and an alumina ceramic. This support substrate is removed before the firing step.

The coating is performed by a doctor blade method, a roll coating method, a printing method using a screen having a coating area approximately the same as that of the support substrate, or the like.

Next, a substantially U-shaped through groove for an end face electrode serving as an end face electrode and a through hole serving as a via hole conductor are formed on the insulating layer formed body formed on the support substrate, if necessary. In practice, the lower portions of the through-groove and the through-hole are closed by a support substrate or the like, but are referred to as the through-groove and the through-hole for convenience.

The method for forming the through-grooves and through-holes is performed using exposure and development. The formation of the through hole and the subsequent filling of the conductive paste are omitted for the insulating layer molded body that does not require the formation of the via hole conductor.

In the exposure processing, for example, a photo target is brought close to or placed on the molded article of the insulating layer, and a region other than the through groove and the through hole is irradiated with exposure light of a low-pressure, high-pressure, or ultra-high-pressure mercury lamp system. . As a result, the photocurable monomer causes a photopolymerization reaction in a region other than the through groove and the through hole. Therefore, only the through-groove and the through-hole portion become the fusible portion that can be removed by the developing process. At this time, the shape of the end surface electrode through-groove is such that a pair of substantially U-shaped end surface electrode through-grooves are formed at predetermined intervals so that the end portions face each other.

In the developing treatment, a solvent such as chlorocene is brought into contact with the exposed and solubilized portion which is a through groove or a through hole by, for example, a spray developing method or a paddle developing method to perform development. A pair of U
A part of the insulating layer molded body remains between the ends of the U-shaped end face electrode through groove.

Thereafter, washing and drying are performed as required.

Next, a conductive member to be an end face electrode and a via hole conductor is formed by filling a through-hole and a through-hole of the insulating layer molded body with a conductive paste and drying. The filling method is performed by, for example, a screen printing method.

Next, a pattern to be an internal wiring is printed and dried using a conductive paste. The printing method is, for example, a screen printing method. If no internal wiring is required, this step is omitted. The internal wiring pattern may be formed after the formation of the through groove.

As described above, the formation of the insulating layer molded body by applying and drying the slip material, the formation of the through-grooves and the through-holes by exposure and development, the formation of the conductive member and the pattern to be the internal wiring by the printing of the conductive paste, Basically, the formation of the insulating layer molded body and the internal wiring pattern for one layer is completed, and this is repeated a desired number of times to complete the unfired laminated molded body. Thereafter, the shape is adjusted by performing pressing or the like as necessary.

Thereafter, the laminated molded body is divided into divided circuit boards so that the divided grooves pass between one substantially U-shaped end surface electrode through-grooves formed so that the ends are opposed to each other. To form a dividing groove. This step of forming the dividing groove is desirably performed before removing the columnar body inside the semi-cylindrical conductive member formed inside the pair of substantially U-shaped end face electrode through grooves.

Next, the columnar bodies inside the pair of semi-cylindrical conductive members filled in the through-holes for the end face electrodes are removed. It is not limited in the present invention that the present step is performed in the unfired state of the ceramic circuit board as described above, but it is preferable to remove the laminated molded body after forming it from the viewpoint of easiness of processing. As a method, a punching method using a die or the like is preferable, but a method using a drill or the like is also practical.

Finally, firing is performed. The firing step includes a binder removal step and a firing step.
C), the organic components of the insulating layer molded body, the internal wiring pattern, the end face electrode, and the conductive member of the via-hole conductor disappear. Thereafter, the insulating layer molded body serving as the insulating layer and the internal wiring pattern, the end surface electrode, and the conductive member serving as the via hole conductor are fired at a predetermined atmosphere and at a predetermined temperature.

[0057]

FIG. 1 is a perspective view of a divided circuit board obtained by dividing a ceramic substrate manufactured by the manufacturing method of the present invention along a dividing groove. In FIG. 1, reference numeral 1 denotes a divided circuit board, and terminals such as input / output terminals, power supply terminals, and ground terminals are shown as end face electrodes 2. FIG.
In the example, the end face electrodes 2 are formed at a total of ten places on the four side surfaces of the divided circuit board 1. A surface electrode (wiring) 3 is formed on the surface of the divided circuit board 1, and a chip component 4 such as a resistor or a capacitor is connected to the surface electrode 3. A cavity 5 is formed in the divided circuit board 1, and a semiconductor bare chip 6 is accommodated in the cavity 5, and is connected to the surface electrode 3 by a wire.

Such a divided circuit board 1 is obtained by dividing a ceramic substrate as shown in FIG. 2 on which the divided circuit boards 1 are assembled along the dividing grooves.

In this embodiment, a case will be described in which the ceramic substrate is formed of a low-temperature fired ceramic using a gold-based, silver-based, or copper-based conductor as the internal wiring conductor.

As shown in FIG. 3, the ceramic substrate of the present invention comprises insulating layers 10a to 10g, internal wirings 11, via hole conductors 12, and conductive members 21 to be the end face electrodes 2, and is insulated by the insulating layers 10a to 10g. A base 13 is formed, and a surface electrode 3 is formed on the surface. In FIG. 2, illustration of the surface electrode 3 is omitted.

The insulating layers 10a to 10g are made of a glass ceramic material, and each has a thickness of 40 to 150 μm. Such an insulating layer 10a, an insulating layer 10b, an insulating layer 1
The internal wiring 11 is disposed between the insulating layer 10c and the insulating layer 10d, between the insulating layer 10e and the insulating layer 10f, and between the insulating layer 10f and the insulating layer 10g. The internal wiring 11 is made of a gold-based, silver-based, or copper-based metal material, for example, a silver-based conductor. Further, the internal wiring 11 includes a via-hole conductor 12 penetrating through the thickness of the insulating layer 10g.
Some are connected in a distributed manner by capacitive coupling or the like. The via-hole conductor 12 is also made of a gold-based, silver-based, or copper-based metal material, for example, a silver-based conductor, like the internal wiring 11.

A surface electrode 3 connected to the via-hole conductor 12 of the insulating layer 10g is formed on the surface of the insulating substrate 13, and a thick resistor film or a thick film is formed on the surface electrode 3 as necessary. If a protective film is formed, plated,
Further, as shown in FIG. 1, various electronic components including an IC are joined by solder or a thin bonding wire.

The divided circuit board of the present invention is manufactured through the intermediate structure shown in FIGS. First, the insulating layer 10
A slip material of a to 10 g is prepared.

Solvent-based slip materials include, for example, glass materials such as SiO ₂ , Al ₂ O ₃ , ZnO, MgO, and B ₂ O.
_A glass-ceramic powder comprising 50% by weight of a crystallized glass powder containing ₃ as a main component and 50% by weight of an alumina powder as a ceramic material, a photocurable monomer such as polyoxyethylated trimethylolpropane triacrylate, It is prepared by mixing an organic binder such as alkyl methacrylate and a plasticizer with an organic solvent such as ethyl carbitol acetate, and kneading the mixture in a ball mill for about 48 hours.

In this embodiment, a solvent-based slip material is prepared. However, as described above, a photocurable monomer having a hydrophilic functional group added thereto, for example, a polyfunctional methacrylate monomer, an organic binder such as carboxylic acid Using a modified alkyl methacrylate, an aqueous slip material kneaded with ion-exchanged water may be prepared.

The internal wiring 11 and the via-hole conductor 1
2. A conductive paste to be the end face electrode 2 is prepared. The conductive paste includes a low melting point and low resistance metal material such as silver powder and a borosilicate low melting point glass such as B ₂ O _3.
—SiO ₂ —BaO glass, CaO—B ₂ O ₃ —SiO
₂ glass, and _{CaO-Al 2 O 3 -B 2} O 3 -SiO 2 glass, an organic binder, such as ethyl cellulose,
It is prepared by mixing with an organic solvent, for example, 2,2,4-trimethyl-1,3-pentadiolmonoisobutyrate, and kneading it homogeneously with a ball mill.

Then, first, as shown in FIG.
The slip material described above is applied to the prepared support substrate 14 and dried to form the lowermost insulating layer molded body 20a. Specifically, first, the above-mentioned slip material is applied on the support substrate 14 by a doctor blade method, and then dried, and then the insulating layer 10a to be the lowermost layer of the fired insulating layers 10a to 10g is formed. The body 20a is formed. Here, a mylar film is used as the support substrate 14,
Removed before firing process. Drying conditions after application are 60
Drying is performed at -80 ° C for 20 minutes, and the thickness of the thinned and dried insulating layer molded body 20a is 120 µm.

Since the conductive member 21 corresponding to the end face electrode 2 is formed in the insulating layer molded body 20a, the end face electrode through groove 23 is formed as shown in FIG. 4B. When viewed from the plane, the pair of end surface electrode through-grooves 23 is shown in FIG.
As shown in FIG. 3, the ends 24 are formed facing each other at a predetermined interval. The end surface electrode through groove 23 is formed by performing an exposure process, a development process, and a cleaning / drying process.

In the exposure processing, for example, a photo target is brought close to or placed on the insulating layer molded body 20a, and low-pressure, high-pressure, and ultra-high-pressure mercury lamp-based exposure light is applied to regions other than the end surface electrode through-grooves 23. Irradiate. As a result, the photocurable monomer causes a photopolymerization reaction in a region other than the end surface electrode through groove 23. Accordingly, only the portion of the through-hole 23 for the end face electrode is a fusible portion that can be removed by the developing process.

Specifically, the exposure treatment is performed on the insulating layer molded body 2
A photo target is placed on Oa so that the region where the end face electrode through groove 23 is formed is shielded from light, and exposure is performed using an ultra-high pressure mercury lamp (10 mW / cm ² ) as a light source.

As a result, the photopolymerization reaction of the photocurable monomer does not occur in the insulating layer molded body 20a in the region where the end face electrode through groove 23 is formed, and the end face electrode through groove 2
The photopolymerization reaction occurs in the insulating layer molded body 20a other than the region where 3 is formed. Here, the part where the photopolymerization reaction has occurred is called an insolubilized part, and the part where the photopolymerization reaction does not occur is called a solubilized part. In addition, the insulating layer molded body of about 120 μm
Exposure can be performed by irradiating an ultra-high pressure mercury lamp (10 mW / cm ² ) for about 20 to 30 seconds.

In the developing treatment, a solvent such as chlorocene is brought into contact with the exposed and solubilized portion, which is the insulating layer molded body 20a, by, for example, a spray developing method or a paddle developing method to perform development. Thereafter, washing and drying are performed as necessary. The development process is
This is for removing the solubilized portion of the insulating layer molded body 20a with a developer, and specifically, 1,1,1-trichloroethane is developed by a spray method.

By this developing treatment, the insulating layer molded body 20a
U-shaped end face electrode through groove 2 having a width of 100 to 200 μm
3 can be formed. Then, the insulating layer molded body 20
Unnecessary residue generated by development a is completely removed by washing and drying processes. In addition, the through groove 23 for the end face electrode
Any shape may be used as long as it is partially open (U-shaped) in plan view, and may be, for example, an elliptical shape, a square shape, or another closed-loop shape with a partially open shape. .

Next, a conductive paste is filled in the through-hole 23 for the end face electrode and dried to form a conductive member 21 for forming the end face electrode 2 as shown in FIG. 4C. Specifically, the above-described conductive paste is filled in the end surface electrode through-groove 23 formed in the above-described step, and dried. The conductive member 21 which becomes the end face electrode 2 by printing using a screen which can be printed only on the portion corresponding to the end face electrode through groove 23
And then dried at 50 ° C. for 10 minutes.

Next, a pattern to be the internal wiring 11 after firing is printed and dried. More specifically, as shown in FIG. 4C, an internal wiring pattern 26 serving as the internal wiring 11 disposed between the insulating layer 10a and the insulating layer 10b is formed by a screen printing method and dried. .

Then, the steps from the formation of the insulating layer molded body 20a to the formation of the internal wiring pattern 26 are repeated. In this manner, as shown in FIG. 5, the uppermost insulating layer molded body 20g is formed, and through-holes for forming the through-holes 23 for the end face electrodes and the via holes are formed by exposure and development processes. The conductive paste that becomes the through-grooves 23 and the via-hole conductors 12 is printed and filled to form a seven-layer laminated body 27. If the internal wiring pattern 26 is unnecessary, the above-described step of manufacturing the internal wiring pattern 26 is omitted.

Subsequently, a conductor film to be the surface electrode 3 is printed and
It is formed by drying. This is because each of the insulating layer molded bodies 20a-
At the time of firing the 20 g, the wiring pattern 26 to be the internal wiring 11, the via hole conductor 12, and the conductive member 21 to be the end face electrode 2, the conductive film to be the surface electrode 3 is also to be fired at a time.

Next, if necessary, the shape of the laminated molded body 27 is adjusted by pressing, the dividing groove 7 is formed, and the support substrate 14 is removed. The division groove 7 is formed so as to pass through the columnar body 29 inside the pair of end surface electrode through grooves 23 formed facing the laminated molded body 27 as shown in FIGS. 2 and 6. Such division grooves 7 are formed by using a dicing saw.

Next, the columnar body 29 surrounded by the pair of semi-cylindrical conductive members 21 to be the end surface electrodes 2 is removed.
Removal is performed by punching with a die. At this time, the inner surfaces of the pair of conductive members 21 are removed with a slight thickness together with the columnar bodies 29 while taking into account the clearance of the mold. It is not limited in the present invention that this step is performed in the unfired state as described above, but it is preferable to remove after forming the laminated molded body 27 from the viewpoint of easiness of processing. As a method, a punching method using a die or the like is preferable as described above, but a method using a drill or the like is also practical.

Next, firing is performed. The firing includes a binder removal step and a main firing step. The binder removal step is performed in a temperature range of about 600 ° C. or less, and the insulating layer molded body 20 a
-20 g, the internal wiring pattern 26, the organic binder contained in the conductive member 21, and the photo-curable monomer are eliminated.
This is a baking process at 50 ° C., for example, at 900 ° C. for 30 minutes, and the insulating layer molded bodies 10 a to 10 g serving as the insulating layer, the internal wiring pattern 26, the end face electrode 2, and the via hole conductor 12
The conductive member 21 to be formed is fired collectively.

As a result, as shown in FIG. 3, the internal wiring 11, the via-hole conductor 12, and the conductive member 21 serving as the end face electrode 2 are formed between predetermined portions of the seven insulating layers 10a to 10g. The ceramic substrate of the present invention on which 3 is formed is manufactured.

Thereafter, as a surface treatment, printing and baking of a thick-film resistive film and a thick-film protective film, plating, and bonding of electronic components including an IC chip are further performed. After that, by dividing along the dividing groove 7, the divided circuit board 1 as shown in FIG. 1 is obtained. That is, as shown in FIG. 7, the divided circuit board 1 protrudes inward of the concave portion 31 formed on the outer peripheral surface of the insulating base, and
A projection 33 covering the end 24 of the end face electrode 2 is provided and formed.

According to the method for manufacturing a ceramic substrate of the present invention, since the through holes and the through grooves for the end face electrodes are formed by exposure and development using a photo target, complicated shapes and various shapes can be obtained depending on the pattern of the photo target. Is formed, and can be formed in a shape and size corresponding to the mating member to be connected.

Further, the conventional manufacturing method, that is, the mold and the NC
It is possible to form a through groove or a through hole having a large diameter or a small diameter that cannot be obtained by punching a punch, and it is possible to form a through hole with high relative positional accuracy.

Further, since the insulating layer molded body is formed by applying the slip material serving as the insulating layer, the surface of the insulating layer molded body is irrespective of the lamination state of the wiring pattern of the internal wiring.
The planar state can always be maintained, and the precision in forming the wiring pattern on the molded insulating layer becomes extremely high.

Further, in the divided circuit board of the present invention, the end of the end face electrode is covered by the projecting portion projecting inward from the recess formed on the outer peripheral surface of the insulating base, and the end face electrode is divided. It is not exposed to the outer peripheral surface of the circuit board, and there is almost no possibility that a force is directly applied from the outside. Thus, it is possible to improve the problem that the end face electrode peels off when the divided circuit board is handled. In addition, even when the ceramic substrate is divided, the conductive member serving as the end face electrode is not directly divided, so that no force acts and separation of the end face electrode can be prevented.

In the above embodiment, the internal wiring 11 is
The method of manufacturing a low-temperature sintering ceramic substrate using a Au-based, Ag-based, or Cu-based low-melting-point metal material has been described, but a high-melting-point metal material such as tungsten or molybdenum is used as the internal wiring 11 at around 1300 ° C. The manufacturing method of the present invention may be applied to a ceramic substrate fired in the above.
In this case, it is necessary to set the composition of the glass material of the slip material as a predetermined component, and further set the mixing ratio with the ceramic material to a predetermined value.

[0088]

According to the present invention, the connection reliability between the internal wiring and the end face electrode is good, and the problem that the conductor of the end face electrode peels off at the time of division and use is improved. Further, the number of manufacturing steps is small, and a ceramic circuit board that can be manufactured in large numbers can be realized. In addition, since a large number of individual components can be obtained, there is an advantage that mounting efficiency is increased when components are mounted on the surface of the ceramic circuit board.

[Brief description of the drawings]

FIG. 1 is a perspective view of a divided circuit board obtained by dividing a ceramic substrate manufactured by a manufacturing method of the present invention.

FIG. 2 is a perspective view showing a ceramic substrate obtained by the manufacturing method of the present invention.

FIG. 3 is a sectional view taken along line A in FIG. 2;

FIG. 4 is a process chart for explaining the manufacturing method of the present invention.

FIG. 5 is a cross-sectional view showing a laminated molded body before firing.

FIG. 6 is a perspective view showing the vicinity of a pair of substantially U-shaped conductive members in FIG. 3;

FIG. 7 is an enlarged perspective view showing an end face electrode portion of the divided circuit board.

FIG. 8 is an enlarged plan view showing a conductive member portion of a conventional ceramic substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Divided circuit board 2 ... End surface electrode 4 ... Chip product 7 ... Divided groove 10a-10g ... Insulating layer 11 ... Internal wiring 12 ... Via-hole conductor 13 ... Insulated Substrate 14 Support substrate 20a to 20g Insulating layer molded body 21 Conductive member 23 End surface electrode through groove 24 End 26 Wiring pattern 27 Lamination molding Body 29: Column 31: Recess 33: Projection

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-37109 (JP, A) JP-A 7-192961 (JP, A) JP-A-7-15143 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H05K 3/46 H05K 1/02 H05K 3/00

Claims (4)

(57) [Claims] An insulating substrate formed by laminating a plurality of insulating layers made of ceramic; an internal wiring formed between the insulating layers; a dividing groove formed on a surface of the insulating substrate; A conductive member that forms the formed end surface electrode, wherein when the insulating substrate is divided by the division groove, each of the ceramic substrates becomes a divided circuit board having a plurality of end surface electrodes, wherein the conductive member is substantially U-shaped, formed at predetermined intervals such that ends of the conductive members of adjacent divided circuit boards are opposed to each other across the division groove, and opposed ends of a pair of the conductive members. A ceramic substrate, characterized in that a projection in which the division groove is formed is interposed between the portions. 2. An insulating substrate comprising a plurality of insulating layers made of ceramics, and an internal wiring formed between the insulating layers, each of which is divided by a dividing groove formed in the insulating substrate. Is a method of manufacturing a ceramic substrate to be a divided circuit board having a plurality of end surface electrodes, comprising: forming an insulating layer material made of ceramics, a photocurable monomer, and a slip material containing an organic binder; Forming an end surface electrode, exposing the surface of the insulating layer molded body to an exposure process except for the position where the end face electrode is formed, and developing the exposed insulating layer molded body to form an end face electrode. Forming a pair of substantially U-shaped end face electrode through-grooves at predetermined positions such that their ends face each other, and filling the end face electrode through-grooves with a conductive paste. A step of printing a conductive paste on the surface of the insulating layer molded body to form an internal wiring pattern; and a step of exposing the insulating layer molded body filled with the conductive paste into the end face electrode through-grooves before an exposure process. And a pair of substantially U-shaped dividing grooves for dividing the divided circuit boards on the surface of the laminated molded body formed by repeating the steps of laminating the insulating layer molded body and exposing to laminating. A method of manufacturing a ceramic substrate, comprising: a step of forming between the through-holes for end surface electrodes in a shape of a circle; and a step of firing the laminated molded body in which the divided grooves are formed. 3. After the firing, the surface of the end face electrode is plated with a metal having good solder wettability.
The manufacturing method of the ceramic substrate described in the above. 4. A divided circuit board having an end surface electrode formed in a concave portion formed on an outer peripheral surface of an insulating base along the concave portion, wherein the concave portion protrudes inward of the concave portion and the end surface A divided circuit board provided with a protrusion for covering an end of an electrode.