JP4959950B2 - Sintered body and wiring board - Google Patents

Description

The present invention relates to a sintered body and a wiring board which is fired at a firing temperature of 1050 ° C. or less.

Conventionally, a sintered body or a wiring board manufactured using a ceramic material has B as a sintering aid.
2O3, alkali element oxides, and alkaline earth element oxides have been used. Alternatively, glass powder containing boron, alkali element and alkaline earth element is used as a sintering aid, and by using these sintering aids, the firing temperature is reduced to 1050 ° C. or lower, There is an advantage that energy saving and shortening of the firing time are achieved (see Patent Document 1).

In order to further improve the productivity, for example, a sintered body or a wiring board is continuously produced by passing the molded body through a space maintained at a predetermined temperature using a tunnel furnace ( Patent Document 2).
JP 2003-002682 A JP-A-1992-268187

  However, while such low-temperature firing is possible, B2O3, alkali element oxides, and alkaline earth element oxides are likely to volatilize from the surface of the sintered body during firing, and the surface of the sintered body is exposed from the inside. There was also a problem that it was difficult to densify.

  In particular, in a manufacturing method using a tunnel furnace capable of continuous firing in which the temperature changes with respect to the traveling direction of the molded body, an atmosphere gas (hydrogen + nitrogen mixed gas, nitrogen gas, air, etc.) is introduced into the furnace. Since the exhaust gas is discharged outside the furnace, volatilization from the surface of the molded body of the boron, alkali element and alkaline earth element is remarkable as compared with a batch-type firing furnace in which the atmospheric gas stays in the furnace. Therefore, the density of the surface layer of the sintered body tends to decrease, and the dimensional accuracy of the sintered body is significantly deteriorated. For example, compared with the conventional alumina ceramics fired in a temperature range of about 1500 ° C. There is a problem that the sinterability of the surface of the bonded body is greatly influenced by factors such as a firing furnace.

  This problem is also a problem in a wiring board using the sintered body as an insulating layer.

Accordingly, the present invention aims to provide a sintered body and a wiring board which surface layer is sufficiently densified.

The sintered body of the present invention is a sintered body that contains at least one of boron, an alkali element, and an alkaline earth element, and is fired at a temperature of 1050 ° C. or less. The total content of boron, alkali element and alkaline earth element oxides in the surface layer is the content of boron, alkali element and alkaline earth element oxides inside the sintered body. It is characterized by being 5% by mass or more than the total.

  Moreover, as for the sintered compact of this invention, it is desirable that the sum total of content converted into the oxide of the boron, an alkali element, and an alkaline-earth element in the said sintered compact is 50 mass% or less.

The wiring board of the present invention contains at least one of boron, an alkali element, and an alkaline earth element and is sintered at a temperature of 1050 ° C. or lower, and at least the insulating layer. And a wiring layer formed on the surface of the wiring board, wherein the content of the wiring substrate is converted to an oxide of boron, alkali element and alkaline earth element in the surface layer of the wiring board. The total is more than 5% by mass more than the total content of boron, alkali element and alkaline earth element converted to oxides inside the wiring board.

  In the wiring board of the present invention, the total content of boron, alkali element and alkaline earth element in the wiring board is preferably 50% by mass or less.

The sintered body and the wiring board of the present invention are more than 5% by mass of the total content converted to the oxide of boron, alkali element and alkaline earth element in the surface layer from the inside, In the surface layer, it is possible to solve the problem that the densification of the surface layer that occurs because these elements are reduced from the inside is inhibited. In particular, in the case of a wiring board provided with a wiring layer on the surface layer, to solve the problem of deterioration of the bonding strength between the wiring layer and the surface layer, which has been conventionally caused by the densification of the surface layer. Therefore, the wiring board is excellent in reliability.

  Further, when the total content of the sintered body and the wiring board in terms of boron, alkali element and alkaline earth element oxides is 50% by mass or less, the chemical stability of the sintered body and the wiring board is improved. For example, damage to the sintered body and the wiring board due to chemicals in the plating process can be suppressed.

  The sintered body and wiring board of the present invention are shown in FIG.

As shown in FIG. 1A, the sintered body 1 of the present invention is fired at a temperature of 1050 ° C. or less, and is formed on the inside of the sintered body 1a and the surface of the sintered body inside 1a. And a surface layer 1b of the sintered body. The surface layer 1b of the sintered body contains at least one of boron, an alkali element, and an alkaline earth element, and the oxide of any element of the boron, alkali element, and alkaline earth element is used as the oxide. It is important that the total converted content is contained by 5% by mass or more than the inside 1a of the sintered body.

  As shown in FIG. 1B, the wiring board 3 of the present invention includes an insulating layer 5, a wiring conductor 7 formed on at least one of the surface and the inside of the insulating layer 5, and an insulating layer. 5 and a through conductor 9 that connects the wiring conductors 7 formed on the front and back of the insulating layer 5. And the insulating layer 5 may be laminated | stacked two or more, for example.

The insulating layer 5 is formed of an insulating layer inside 5 a made of ceramics and a surface layer 5 b of the wiring board formed so as to cover a portion exposed on the surface of the wiring board 3. The surface layer 5b of the wiring board contains at least one of boron, an alkali element, and an alkaline earth element, and an oxide of any element of the boron, alkali element, and alkaline earth element . It is important that the sum of the contents converted into is more than 5% by mass than the inside 5a of the insulating layer.

And the total of the content converted into the oxide of boron, an alkali element, and an alkaline-earth element of the surface layer 1b of a sintered compact or the surface layer 5b of a wiring board is boron in the sintered compact inside 1a or the insulating layer inside 5a. It is desirable that the content is 6 mass% or more, and more preferably 7 mass% or more than the total content converted to oxides of alkali elements and alkaline earth elements.

  The total content of the sintered body inside 1a or the insulating layer inside 5a in terms of boron, alkali element and alkaline earth element oxides is 50% by mass or less, particularly 40% by mass or less, and further 30% by mass. The following is desirable.

In the present invention, the inside means 20 μm deeper than the surface of the sintered body 1 or the wiring board 3.
The surface layer means a region up to a depth of 20 μm from the surface.

Next, a method for producing the sintered body and the wiring board of the present invention will be described.

First, a ceramic material used for the sintered body and the insulating layer of the wiring board is prepared. In order to obtain a dense body at 1050 ° C. or less, there are a method of mixing glass powder and ceramic filler powder, a method of mixing powders such as B ₂ O ₃ , PbO, and BaO.

For example, the glass powder contains SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO, PbO, alkaline earth metal oxide, alkali metal oxide, etc., for example, SiO ₂ —B Borosilicate glass such as ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO system (where M represents Ca, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —MO system Examples thereof include glass, alkali silicate glass, Ba glass, titanate glass, Pb glass, and Bi glass.

On the other hand, as ceramic filler powder, SiO ₂ such as quartz and cristobalite, Al ₂ O ₃ , ZrO ₂ , mullite, forsterite, enstatite, spinel, magnesia and the like are preferably used.

In order to increase the dielectric constant of the insulating layer 5 after firing, MgTiO ₃ , CaTiO ₃ , SrTiO ₃ , BaTiO ₃ , TiO ₂ , La ₂ Ti ₂ O ₇ , ZrO _2, etc. may be added.

  The ceramic molded body 11 for obtaining the sintered body 1 is prepared by granulating a powder for pressing mixed with an organic binder using these raw materials, and filling the mold, for example, in a mold. Obtainable.

  Moreover, the wiring board molded body 13 for obtaining the wiring board 3 can be obtained through the following steps. After adding an organic binder etc. to the inorganic composition which mixed the raw material mentioned above in a predetermined ratio, the green sheet of desired thickness is produced by the sheet forming method represented by the doctor blade method.

  Next, a through hole is formed in the green sheet by laser or punching, and a via paste is formed by filling the through hole with a conductive paste.

  Next, a conductor paste is similarly printed on the surface of the green sheet on which the via-hole conductor is formed to form a wiring conductor. The conductor paste is formed by mixing at least one metal component selected from Cu, Ag, and the like, and an organic binder or organic solvent made of an acrylic resin or the like. Note that some glass powder or the like may be added to the conductor paste. In some cases, the wiring conductor can be formed using a metal foil instead of the conductor paste. Finally, a plurality of green sheets are laminated and pressure-bonded to form the wiring board molded body 13.

  And the sintered compact 1 and the wiring board 3 are producible by baking this ceramic molded object 11 and the wiring board molded object 13 by a predetermined | prescribed firing pattern of 1050 degrees C or less.

When firing a sintered body or a ceramic molded body 11 containing at least one of boron, alkali element and alkaline earth element and a wiring board molded body 13 including a metal wiring layer to be a sintered body or a wiring board as shown in FIG. For example, as shown in FIG. 2 (a), a baking shelf 31 on which a molded body is placed is prepared, and a ceramic molded body 11 or a wiring board molded body 13 is placed thereon, and the ceramic molded body 11 is placed around the ceramic molded body 11. The co-material molded body 33 having a higher content of any one of boron, alkali elements, and alkaline earth elements than that is disposed, or as shown in FIG. On top of this, the wiring board molded body 13 or the ceramic so as to cover the wiring board molded body 13 or the ceramic molded body 11 provided with the insulating layer molded body 15 and the metal wiring layers 17 and 19. Boron than form 11 to place one of the sheet materials 35 of high content of element selected from alkali element and alkaline earth element is also to you fired.

According to such a manufacturing method, it is possible not only to suppress the volatilization of boron, alkali elements and alkaline earth elements from the surface of the ceramic molded body 11 or the wiring board molded body 13, but also the co-material molded body 33 or the sheet. Since boron, alkali element and alkaline earth element volatilized from the shaped molded body 35 can be supplied to the surface of the co-formed molded body 33 or the sheet-shaped molded body 35, The surface can be fired densely.
That is, the co-material is fired together with the molded body, and the co-material molded body having a higher content of any one element of boron, alkali element and alkaline earth element than the sintered body and the molded body to be the wiring board. Boron, alkali elements and alkaline earth elements volatilized from the molded body adhere to the surface of the molded body during the firing process, and as a result, the content of boron, alkali elements and alkaline earth elements in the surface layer of the molded body is reduced. Therefore, the sinterability of the molded body is not impaired, and a sintered body and a wiring board that are dense in both the surface layer and inside and excellent in dimensional accuracy can be manufactured. In particular, when a wiring board is manufactured, since the bonding strength of the wiring layer formed on the surface layer of the wiring board is improved, the wiring board is excellent in reliability.
In addition, the sintered body and the molded body to be the wiring board are wrapped with a sheet-shaped molded body having a higher content of any one of boron, alkali elements and alkaline earth elements, and fired together. Therefore, it is possible to increase the content of boron, alkali elements and alkaline earth elements in the surface layer as compared to the inside of the sintered body and the wiring board, and to prevent the occurrence of deposits on the sintered body and the wiring board. it can.

  Therefore, according to such a manufacturing method, the sintered body and the wiring board of the present invention can be easily produced.

  Note that when the sheet-shaped molded body 35 is used, the space can be used more effectively than when the co-material molded body 33 is used, so that more products can be produced. It is more desirable than using the body 33.

  On the other hand, when the common material molded body 33 is used, there is an advantage that preparation for firing is easier than when the sheet-shaped molded body 35 is used.

In particular, the effect of the above manufacturing method is remarkable in the plate-like sintered body 1 or the wiring board 3 having a large surface area compared to the volume.

  First, a sintered body and a wiring board were produced and evaluated.

First, for an insulating layer, diopsite crystallized glass (glass composed of SiO ₂ : 50% by mass, Al ₂ O ₃ : 15% by mass, MgO: 20% by mass, CaO: 15% by mass) as a glass powder, Alumina was prepared as a filler powder. The glass powder and alumina are mixed in a ratio of glass: alumina = 60% by mass: 40% by mass, and a ball mill is used to add 12% by mass of organic binder and 5% by mass of a plasticizer to sufficiently mix and grind the slurry. Then, a green sheet having a thickness of 150 μm was produced using the slurry by a doctor blade method.

  Next, via holes having a diameter of 150 μm were formed in a predetermined portion of the ceramic green sheet by an NC punching machine, and a conductor paste containing Cu was filled therein by screen printing to form an interlayer conductor, thereby forming an interlayer conductor. A circuit was formed by applying a conductive paste containing Cu to the surface of the ceramic green sheet by screen printing. This conductor paste was prepared by blending glass powder at a ratio of 4% by mass with respect to 100% by mass of Cu powder, and adding and mixing an organic binder, a plasticizer and a solvent to this mixture.

  Seven ceramic green sheets each having the wiring circuit layer thus prepared were laminated, and a split groove was formed by a mold having a V-shaped cutting edge on one main surface, and a size of 80 mm × 80 mm. The substrate was cut into pieces to produce a wiring board molded body.

  In addition, seven layers of ceramic green sheets not forming a circuit are laminated, a dividing groove is formed by a mold having a V-shaped cutting edge on one main surface, and cut into a size of 80 mm × 80 mm. A ceramic compact was produced.

As a raw material of the sheet-like molded body for covering the wiring board molded body and the ceramic molded body thus produced, (1) Diopsite crystallized glass used for the green sheet, (2) Borosilicate zinc-based glass- (1) (SiO ₂ : 43% by mass, Al ₂ O ₃ : 6% by mass, B ₂ O ₃ : 9% by mass, CaO: 5% by mass, BaO: 37% by mass) ), (3) Zinc borosilicate glass- (2) (SiO ₂ : 44 mass%, Al ₂ O ₃ : 28 mass%, B ₂ O ₃ :: 10 mass%, MgO: 11 mass%, ZnO: 7) A glass composed of mass%) and alumina as a filler powder were prepared.

  These glass powders and alumina are prepared in a ratio of glass: alumina = 10% by mass: 90% by mass, an organic binder and a plasticizer are added using a ball mill, and sufficiently mixed and pulverized to prepare a slurry. A sheet-like molded body having a thickness of 300 μm was produced.

  Here, (1) sheet A using a diopsite crystallized glass, (2) zinc borosilicate glass-sheet (1) using sheet B, (3) zinc borosilicate glass- ( A sheet C was prepared using 2).

(3) Zinc borosilicate glass--sheet D prepared by mixing (2) and alumina in a ratio of glass: alumina = 15% by mass: 85% by mass, (3) zinc borosilicate glass- (2): alumina = 20% by mass: Sheet E prepared at a ratio of 80% by mass was also prepared. Further, (3) Zinc borosilicate glass- (2) and alumina are added to the glass: alumina = 20 mass%: 80 mass% ratio as an alkali component and 1 mass part of sodium carbonate in terms of Na ₂ O is added. F also prepared.

  Next, the wiring board molded body and the ceramic molded body are sandwiched between the sheet-like molded bodies and placed on a 300 mm □ porous alumina baking shelf, and this baking shelf is used as a movable belt of a tunnel furnace. The firing process was carried out by passing through a region heated to the desired temperature. Specifically, the binder removal / decarbonization treatment is performed by heating and holding at 720 ° C. in a nitrogen atmosphere containing water vapor, and sintering as a final ceramic is performed at 900 ° C. in a nitrogen atmosphere containing water vapor. And heated for 1 hour. The firing process from entering the furnace to leaving the furnace was 8 hours.

  Moreover, the co-material molded object for baking with a wiring board molded object and a ceramic molded object was produced using the raw material powder which produced the sheet-like molded object.

The common material molded body was obtained by adding 60% by mass of alumina powder to 40% by mass of the glass powders (1) to (3) described above. This is referred to as a material molded body C.

  Further, (3) zinc borosilicate glass- (2) and alumina powder, each of 45 mass%: 55 mass%, is referred to as a co-molded product D, and 50 mass%: 50 mass%, This was designated as a co-material molded body E. Moreover, what added 1 mass part of sodium carbonate as an alkali component with respect to the common material molded object E in Na2O conversion was described with the common material molded object F. FIG.

  These co-material molded bodies were produced by press molding a powder obtained by mixing a raw material powder and a binder.

  These co-material molded bodies are placed on a shelf for firing at a ratio of 20% by mass with respect to the wiring board molded body and the ceramic molded body, and fired under the same firing conditions as those used for the sheet-shaped molded body. did.

  An Au electrode protective film was further formed on the fired wiring board by plating.

  The sintered body and the wiring board thus produced were subjected to the following measurements, and the evaluation results of the sintered body and the wiring board produced using the sheet-like molded body are shown in Table 1, using the co-material molded body. Table 2 shows the evaluation results of the produced sintered body and wiring board.

  About the produced sintered compact and the wiring board, the open porosity was measured by the Archimedes method. In addition, about the sample using the same sheet-like molded object and a co-material molded object, since it became a value substantially the same with a sintered compact and a wiring board, Table 1, 2 shows open porosity of a sintered compact. Was described.

  The evaluation of the bonding strength between the insulating layer on the surface of the wiring board and the surface wiring circuit layer was performed by soldering a lead made of Cu wire (φ0.8 mm) plated with Sn on the surface wiring circuit layer of 2 mm □ on the surface of the wiring board. Then, after fixing the wiring board, when the Cu wire was pulled up under the condition of 10 mm / min, the load at which the insulating layer and the surface wiring circuit layer bonding portion were broken was measured and compared.

  The composition analysis of the surface layer and the inside of the sintered body and the wiring board is carried out by grinding the 10 μm thick part and the inner part of the surface of the sintered body and the wiring board, and then performing chemical analysis. The composition was analyzed. Also in this composition analysis, there was no substantial difference between the wiring board and the sintered body, so the measured values of the sintered body are listed in the table.

The evaluation of dimensional accuracy was obtained from the dimensional change rate of the conductor pattern before and after firing on the surface of the ceramic wiring board as shown in FIG. That is, it was calculated from the shrinkage variation (6σ (σ: standard deviation)) before and after firing at three measurement points x1 to x3 in the direction perpendicular to the moving direction of the movable belt of the tunnel furnace.

As shown in Table 1, the total amount of boron, alkali element, and alkaline earth element contents of the wiring board and sintered body surface layer outside the scope of the present invention is the wiring board and sintered body. The sample No. is smaller than the sum of the contents of boron, alkali element and alkaline earth element as oxides. In Nos. 1 and 2, the open porosity of the wiring board and the sintered body was 1% or more, the bonding strength was less than 50 N / 2 mm □, and sufficient bonding strength was not obtained, and the variation in shrinkage was large.

On the other hand, a ceramic molded body and a wiring board molded body are sandwiched and fired between sheet-shaped molded bodies having a higher content of any one of boron, alkali elements and alkaline earth elements than these molded bodies. Sample No. of the present invention. In 3-7, the sintered compact and wiring board which were precise | minute and excellent in the dimensional accuracy were obtained. Moreover, in the wiring board, the bonding strength between the insulating layer on the surface of the wiring board and the surface wiring circuit layer could be sufficiently increased.

As shown in Table 2, the total of the content of boron, alkali element and alkaline earth element in the surface layer of the wiring board and sintered body, which are outside the scope of the present invention, is the wiring board and sintered body. The sample No. is smaller than the sum of the contents of boron, alkali element and alkaline earth element as oxides. In Nos. 1 and 8, the open porosity of the wiring board and the sintered body was 1% or more, the bonding strength was less than 50 N / 2 mm □, sufficient bonding strength was not obtained, and the shrinkage variation was large.

  On the other hand, a ceramic molded body and a wiring board molded body are sandwiched and fired between sheet-shaped molded bodies having a higher content of any one of boron, alkali elements and alkaline earth elements than these molded bodies. Sample No. of the present invention. In Nos. 9 to 13, a dense sintered body and a wiring board having excellent dimensional accuracy were obtained. Moreover, in the wiring board, the bonding strength between the insulating layer on the surface of the wiring board and the surface wiring circuit layer could be sufficiently increased.

(A) is sectional drawing which shows the sintered compact of this invention, (b) is sectional drawing which shows the wiring board of this invention. It is a schematic diagram which shows the method to manufacture the sintered compact and wiring board of this invention. It is a schematic diagram for dimension measurement of the wiring board in the real施例.

DESCRIPTION OF SYMBOLS 1 Sintered body 1a Sintered body inside 1b Sintered body surface layer 3 Wiring board 5 Insulating layer 5a Insulating layer inside 5b Wiring board surface layer 7 Wiring conductor 9 Through conductor 11 Ceramic molded body 13 Wiring board molded body 33 Common material Molded body 35 Sheet-shaped molded body

Claims (4)

A sintered body containing at least one of boron, an alkaline element, and an alkaline earth element and fired at a temperature of 1050 ° C. or less , wherein boron and an alkaline element in a surface layer of the sintered body And the sum total of the content converted into the oxide of alkaline-earth element is 5 mass% or more more than the sum total of the content converted into the oxide of the boron in the said sintered compact, an alkali element, and an alkaline-earth element A sintered body characterized by that. 2. The sintered body according to claim 1, wherein the total content of boron, alkali element and alkaline earth element in the sintered body is 50% by mass or less. At least boron, an insulating layer containing at least one kind of alkali element and alkaline earth element, at least the surface of the insulating layer, together with formed by and a wiring layer formed on either internal, 1050 A wiring board of a sintered body fired at a temperature of ℃ or less , wherein the total content in terms of boron, alkali element and alkaline earth element oxide in the surface layer of the wiring board is the wiring board A wiring board characterized in that the content is 5% by mass or more than the total content of boron, alkali element and alkaline earth element oxide in the interior. 4. The wiring board according to claim 3 , wherein the total content of boron, alkali element and alkaline earth element in the wiring board is 50% by mass or less.

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