JP5383585B2 - Aluminum nitride firing jig - Google Patents

Description

  The present invention relates to a novel jig for firing aluminum nitride. Specifically, in a jig that is used in contact with aluminum nitride at the time of firing, adhesion with the sintered aluminum nitride after firing at the contact point can be prevented, and the resulting fired product is extremely less contaminated by the jig. An aluminum nitride firing jig is provided.

  In recent years, higher output of semiconductor elements such as laser diode elements and light emitting diode elements has progressed, and accordingly, heat generation of these elements has increased. Therefore, there is a problem that the element is overheated due to the accumulation of heat and the life thereof is shortened. In order to solve such a problem, an aluminum nitride sintered body having high heat dissipation characteristics has been adopted as a substrate for mounting elements.

  When the aluminum nitride sintered body is used as an element mounting substrate, wiring patterns such as electrodes and wirings are formed on the surface of the substrate for the purpose of joining the elements and supplying power to the joined elements. The wiring pattern is formed by drawing a wiring pattern on a substrate surface made of an aluminum nitride sintered body or a green body using a metallized paste containing tungsten and then firing the wiring pattern. In addition, in order to protect the wiring pattern to be formed and to provide insulation to the surface, an insulating paste containing aluminum nitride powder is generally applied on the metallized layer, and baked with the metallized paste for insulation. A method of forming a layer has been adopted.

  However, in the production of a substrate made of an aluminum nitride sintered body, the substrate obtained due to material shrinkage or the like may be warped during firing, particularly when a wiring pattern is formed with the conductive paste. The occurrence of warping was a problem. Therefore, in order to suppress the warpage, conventionally, a method has been proposed in which a jig made of boron nitride is used and the insulating layer surface made of aluminum nitride is pressed and fired (Patent Document 1).

  Although a warp of a substrate made of an aluminum nitride sintered body having a metallized layer (hereinafter also referred to as a metallized aluminum nitride substrate) obtained by this method can be reduced, such a jig (pressing plate) made of boron nitride. Is applied to the firing of a metallized substrate in which a wiring pattern made of tungsten and an insulating pattern made of aluminum nitride are formed on a part thereof, tungsten and boron nitride react to produce tungsten boride. There was a problem.

  As a jig that does not react with tungsten, a method using an aluminum nitride sintered body that does not contain a sintering aid (Patent Document 2) and a method using a tungsten plate have been proposed (Patent Document 3).

  However, when an aluminum nitride sintered body is used as a jig, there is a problem that adhesion occurs with the insulating layer in contact with the jig after firing. In addition, when using a tungsten plate, there is no problem of adhesion with the insulating layer, but part of tungsten constituting the jig is scattered during firing and adheres to the surface of the aluminum nitride sintered body between the wiring patterns. However, there arises a problem that the insulation between the wiring patterns is deteriorated, or the plating growth is likely to occur on the tungsten adhered on the object to be fired when the electroless plating process is performed as a subsequent process.

Japanese Patent No. 2661258 JP-A-5-13617 JP-A-7-247171

  Therefore, the object of the present invention is to contact the aluminum nitride at the time of firing as in the case where an insulating pattern made of a wiring pattern and an aluminum nitride sintered body is formed on the aluminum nitride sintered body or green body by firing. To provide an aluminum nitride firing jig that can prevent adhesion with a sintered aluminum nitride body after firing at a contact location in the jig to be used, and that is extremely less contaminated by the jig on the obtained fired object. It is in.

  As a result of repeated research to achieve the above object, the inventors of the present invention, in a jig that has conventionally been composed of only a sintered body of tungsten or a melt-formed body, at least the surface thereof is combined with aluminum nitride, And by adjusting the area ratio occupied by the aluminum nitride to a specific value, it was found that contamination with tungsten during firing can be effectively reduced while preventing adhesion with the aluminum nitride sintered body, The present invention has been completed.

That is, according to the present invention, when an insulating pattern made of a wiring pattern and an aluminum nitride sintered body is formed on an aluminum nitride sintered body or green body by firing, the jig for pressing the insulating pattern forming surface during firing. The aluminum nitride firing treatment is characterized in that at least the surface in contact with the insulating pattern forming surface is composed of a composite surface of tungsten and aluminum nitride in which the abundance ratio of aluminum nitride is 15 to 35%. Tools are provided.

  The composite surface is preferably formed of a composite sintered body of tungsten and aluminum nitride.

  When the jig according to the present invention is used, when a metallized substrate having a wiring pattern made of tungsten and an insulating pattern made of aluminum nitride formed on a part of the wiring pattern is fired, adhesion between the jig and the object to be fired is performed. Can be prevented, and contamination of the object to be fired by tungsten can be reduced.

Schematic showing an embodiment (one step) at the time of firing a metallized substrate using the jig of the present invention Schematic showing another embodiment (multi-stage) when firing a metallized substrate using the jig of the present invention Schematic diagram showing a typical wiring pattern unit

  The jig according to the present invention has a wiring pattern made of tungsten on an aluminum nitride sintered body and an insulating pattern made of aluminum nitride thereon, or an aluminum nitride green body containing aluminum nitride powder and an organic binder. This is effective when firing a metallized substrate having a wiring pattern made of tungsten and an insulating pattern made of aluminum nitride formed thereon.

  Specifically, a wiring pattern is formed on a substrate made of an aluminum nitride sintered body or a green sheet by a paste or the like containing mainly a refractory metal such as tungsten or molybdenum, and nitriding is further performed thereon. When firing the metallized substrate precursor coated and laminated with an aluminum nitride sheet or a paste containing aluminum nitride, an aluminum nitride green sheet formed on the wiring paste so that the substrate does not warp during firing, or It is used as a firing jig that contacts the surface of the paste layer containing aluminum nitride.

  The feature of the jig of the present invention is that at least the surface in contact with the object to be fired is composed of a composite surface of tungsten and aluminum nitride in which aluminum nitride is present in an area ratio of 15 to 35%. .

  That is, when the area ratio of aluminum nitride on the surface of the jig is greater than 35%, adhesion occurs between the object to be fired and the jig during firing. The reason why such adhesion occurs is that a sintering aid for accelerating sintering is generally added to the object to be fired. This sintering aid forms a liquid phase during firing, and the aluminum nitride grains In order to promote the growth, it is considered that the aluminum nitride contained in the object to be fired and the jig grows and adheres in the liquid phase. Preferably, the area ratio of the aluminum nitride is 29% or less from the viewpoint of reducing adhesion between the jig and the object to be fired.

  On the other hand, when the area ratio of aluminum nitride on the surface of the jig is too small, a part of tungsten of the jig adheres to the object to be fired during firing, and the object to be fired is contaminated and subjected to electroless plating treatment. Tungsten adhering to the metal tends to undergo plating growth, impairing the appearance, and lowering the electrical insulation. Therefore, it is desirable that it is as large as possible within the range of the upper limit of the area ratio of aluminum nitride on the jig surface from the viewpoint of preventing contamination of the object to be fired. Specifically, the area ratio of aluminum nitride is 15% as the lower limit. It is necessary to.

  As described above, it is possible to solve the problem by confirming the influence of contamination of the firing object of the jig whose surface is made only of tungsten, and forming the surface by the surface made of the composite of aluminum nitride as described above. It is proposed for the first time by the present invention.

  In other words, tungsten is a metal that has a low vapor pressure even at a high temperature and is difficult to evaporate, and is considered to be a metal that does not easily react with aluminum nitride. However, in actual use, tungsten is an oxide. Vapor pressure becomes high and it becomes easy to evaporate even at 1000 ° C. or lower. The present invention succeeded in suppressing such a phenomenon by making aluminum nitride exist as a composite at the specific area ratio.

  The area ratio of the aluminum nitride is obtained by quantifying the existing area ratio of the aluminum nitride with an image analyzer after the surface of the jig is photographed with a scanning electron microscope. Moreover, in order to quantify the existing area ratio, observation of about 1000 times is sufficient.

  The area ratio of the aluminum nitride on the jig surface only needs to be achieved at least on the surface in contact with the object to be fired. For example, a jig having the above-described area ratio on all surfaces of the jig may be used, or only the surface of the jig that contacts the object to be fired may have the above-mentioned area ratio.

  Moreover, the jig | tool of this invention does not restrict | limit especially the material of parts other than the said surface. For example, an aluminum nitride sintered body, particularly an aluminum nitride sintered body that does not contain a sintering aid, is preferred, but it may be composed of a tungsten sintered body or a melt-formed body. Of course, the whole may be a composite sintered body of aluminum nitride and tungsten as described above.

  The aspect which comprises the composite surface of tungsten and aluminum nitride which made aluminum nitride exist only in the specific ratio only in the surface layer part of a jig | tool is not restrict | limited.

  For example, as an aspect in which the composite surface is formed on the surface of the aluminum nitride sintered body, there is a method of forming a layer of a composite sintered body of aluminum nitride and tungsten on the surface of the aluminum nitride sintered body.

  In addition, as an aspect of constituting the composite surface on the surface of a sintered or melt-formed body of tungsten, in addition to the above-described method of forming a composite sintered body layer of aluminum nitride and tungsten, aluminum nitride is sputtered, etc. And a method of partially vapor-depositing by the vapor phase method.

  Among these, those using aluminum nitride as the base material are more preferable because they are lighter than those using tungsten as the base material, and therefore can be easily stacked in multiple stages when the object to be fired is fired.

  The method for producing the composite sintered body of tungsten and aluminum nitride is not particularly limited, and a known method can be applied without any limitation. For example, an aluminum nitride powder blended in an amount such that the area ratio of aluminum nitride falls within the above range with respect to the tungsten powder, and an organic binder, and if necessary, an organic solvent for viscosity adjustment, a dispersant, etc. It can be manufactured by molding or applying a paste composition mixed with defatted and fired.

  Specifically, in the embodiment of manufacturing a metallized substrate using such a firing jig, a wiring pattern 2 made of tungsten is formed on the substrate 1 as shown in FIG. 1, and an insulating layer made of aluminum nitride is further formed thereon. The aspect which formed the pattern 3 is mentioned.

  The pattern may be formed by, for example, screen-printing and drying a paste containing the composition. In order to make the composition into a paste, in addition to the essential components, a solvent, a binder, a dispersant, and a plasticizer as necessary may be added and kneaded sufficiently using a mixer, three rolls, or the like. At this time, the ratio of each compounding component of the paste is applied without any particular reproducibility. For example, the drying may be performed in air within a temperature range of 60 ° C. to 200 ° C. for about 1 minute to 60 minutes. Moreover, you may degrease this dry body within the range of 100 to 1000 degreeC as needed. At this time, if tungsten formed for the wiring pattern is oxidized, evaporation and deposition of tungsten oxide occurs during firing. Therefore, degreasing is performed at a low temperature so that tungsten is not oxidized, or in a non-oxidizing atmosphere such as nitrogen or hydrogen. It is preferable to degrease with.

  The obtained metallized substrate precursor is charged together with the firing jig 4 into a setter 5 made of, for example, boron nitride, and is fired by holding it at a temperature of 1600 to 2000 ° C. for 30 minutes or more in a normal pressure nitrogen atmosphere. . The substrate and the jig 4 may be stacked and charged alone as shown in FIG. 1, or may be charged in multiple stages as shown in FIG.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these Examples.

Example 1
100 parts by mass of tungsten powder having an average particle diameter of 3.0 μm, 5 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, 2 parts by mass of ethyl cellulose, and 10 parts by mass of terpineol were sufficiently kneaded to prepare tungsten paste 1. Next, the tungsten paste 1 containing the aluminum nitride powder was applied by screen printing on a plate of an aluminum nitride sintered body containing 5 parts by weight of yttrium oxide, and dried at 100 ° C. for 10 minutes. The dried body was baked at 1800 ° C. for 8 hours in a nitrogen atmosphere to obtain a plate-shaped jig. The aluminum nitride area ratio on the jig surface was 16.4%.

  Next, a method for producing a metallized substrate suitable for using the jig of the present invention will be described. A tungsten paste 2 was prepared by kneading 100 parts by mass of tungsten powder having an average particle diameter of 3.0 μm, 5 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, 2 parts by mass of ethyl cellulose, and 10 parts by mass of terpineol. Next, 100 parts by mass of aluminum nitride powder having an average particle size of 1.5 μm, 5 parts by mass of yttrium oxide, 10 parts by mass of ethyl cellulose, and 40 parts by mass of terpineol were mixed to prepare an aluminum nitride paste. After forming the wiring pattern by screen printing the tungsten paste 2 on the aluminum nitride sintered body substrate containing 5 parts by weight of yttrium oxide, the insulating pattern is formed by screen printing the aluminum nitride paste thereon. did. At this time, pattern formation was performed so that 10 pattern units as shown in FIG. 3 were arranged in a lattice shape on the aluminum nitride sintered body substrate, 10 pieces each in length and width. The metallized substrate obtained by the above method was degreased in air at 200 ° C. for 2 hours, and then sandwiched with a jig according to the present invention, and fired at 1800 ° C. for 8 hours in a nitrogen atmosphere. The obtained metallized substrate was subjected to electroless plating treatment, and then the plated body was cut to obtain 100 pattern units.

  The appearance inspection of the pattern unit obtained by the above process was observed with a 20-fold stereo microscope, and the occurrence rate of adhesion marks of 20 μm or more and the occurrence rate of abnormal plating deposition were investigated. The results are shown in Table 1.

Example 2
The composition of the tungsten paste 1 used for manufacturing the jig is 100 parts by mass of tungsten powder having an average particle size of 3.0 μm, 10 parts by mass of aluminum nitride powder having an average particle size of 1.5 μm, 2 parts by mass of ethyl cellulose, and 12 parts by mass of terpineol. A jig was prepared. The aluminum nitride area ratio on the jig surface was 28.5%. Table 1 shows the results of the metallized substrate and the pattern unit produced by the same method as in the example using this jig and the same evaluation.

Comparative Example 1
A jig in which the composition of the tungsten paste 1 used for producing the jig was 100 parts by mass of tungsten powder having an average particle size of 3.0 μm, 1 part by mass of ethyl cellulose, and 6 parts by mass of terpineol was produced. The aluminum nitride area ratio on the jig surface was 0%. Table 1 shows the results of the metallized substrate and the pattern unit produced by the same method as in the example using this jig and the same evaluation.

Comparative Example 2
The composition of the tungsten paste 1 used for manufacturing the jig is 100 parts by mass of tungsten powder having an average particle diameter of 3.0 μm, 2 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, 2 parts by mass of ethyl cellulose, and 9 parts by mass of terpineol. A jig was prepared. The area ratio of aluminum nitride on the jig surface was 8.2%. Table 1 shows the results of the metallized substrate and the pattern unit produced by the same method as in the example using this jig and the same evaluation.

Comparative Example 3
The composition of the tungsten paste used for manufacturing the jig was 100 parts by mass of tungsten powder having an average particle diameter of 3.0 μm, 25 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, 4 parts by mass of ethyl cellulose, and 18 parts by mass of terpineol. A jig was produced. The aluminum nitride area ratio on the jig surface was 40.6%. Table 1 shows the results of the metallized substrate and the pattern unit produced by the same method as in the example using this jig and the same evaluation.

DESCRIPTION OF SYMBOLS 1 Substrate made of aluminum nitride sintered body or aluminum nitride green body 2 Wiring pattern made of tungsten 3 Insulating pattern made of aluminum nitride 4 Jig 5 Setter made of boron nitride

Claims (2)

A jig for pressing the insulating pattern forming surface at the time of firing when forming an insulating pattern made of a wiring pattern and an aluminum nitride sintered body on an aluminum nitride sintered body or green body by firing, and at least the insulating pattern The aluminum nitride baking jig characterized in that the surface in contact with the forming surface is composed of a composite surface of tungsten and aluminum nitride in which the abundance ratio of aluminum nitride is 15 to 35%. The aluminum nitride firing jig according to claim 1, wherein the composite surface is formed of a composite sintered body of tungsten and aluminum nitride.

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