JP6936040B2 - Metallized substrate and its manufacturing method - Google Patents

Description

The present invention relates to a metallized substrate which is used for an electronic substrate of various electronic devices and has a surface conductor layer, and a method for manufacturing the same.

Conventionally, electronic boards used for arranging functional parts and forming wiring circuits are manufactured by laminating a conductive layer such as a circuit pattern made of conductive metal on an insulating substrate such as ceramics. Has been done. In particular, since the affinity and reactivity between an insulating material such as ceramics and a metal is low, an active metal such as titanium is used as a method for manufacturing an electronic substrate, and the adhesiveness (bonding strength) between the insulating substrate and the conductive layer is used. ) Is widely used. Examples of the method using the active metal include a method of forming a conductive layer by interposing an active metal layer on an insulating substrate, a method of mixing active metal particles in a conductor paste for forming the conductive layer, and the like. Are known.

In the former method, an active metal thin film such as Ti is formed on the surface of an insulating substrate such as ceramics by a physical vapor deposition method such as sputtering, and then a highly conductive conductor film such as Cu, Pd, or Au is further formed on the surface of the active metal film. The method of forming is used in the field of electronics industry. However, this method requires film formation under vacuum and has a low film formation rate, so that the manufacturing cost is high. As a result, it is mainly used only for products having a conductor film thickness of several μm or less, and it is difficult to apply it to versatile applications. As a method for solving the problem, a conductor thin film containing an active metal is formed on the surface of an insulating substrate such as a ceramic plate by a physical vapor deposition method such as sputtering, and then Cu, Ag, Ni, etc. are formed on the surface of the conductor thin film by a wet plating method. A method of forming a conductor film such as Au is widely used. The plating method can easily obtain a desired film thickness and is suitable for mass production, so that the manufacturing cost is low. The disadvantage of this method is that a long-time plating process is required to produce a conductor film having a large film thickness, and the burden on the environment such as treatment of a chemical solution is large. Further, when a conductor film having a large film thickness is formed by plating, the stress between the conductor film and the ceramic substrate is large, which may be disadvantageous in terms of reliability.

As the latter method, Japanese Patent Application Laid-Open No. 6-99199 (Patent Document 1) describes an alloy containing at least one selected from titanium, zirconium and hafnium, and silver and copper as essential components on an aluminum nitride sintered body. An aluminum nitride substrate having a conductive metallized layer made of the same material is disclosed. This conductive metallized layer is produced by applying and firing a paste containing a powder of a metal or compound for forming the conductive metallized layer and a medium such as ethyl cellulose.

However, when active metal particles such as titanium are blended in the conductor paste, the properties such as conductivity and solder wettability of the conductor paste after firing may be significantly deteriorated. Further, in order to react the active metal with the substrate and develop adhesion, it is necessary to bake in a vacuum, and the productivity is low. Further, active metal particles such as titanium may grow into coarse particles during firing, which may greatly reduce the smoothness of the conductor film.

On the other hand, as a method of forming a conductor pattern on an insulating substrate such as ceramics, there is a thick film paste method. For example, Japanese Patent Application Laid-Open No. 2008-226771 (Patent Document 2) uses a thick film paste method in which glass powder is mixed with a conductive metal powder to form a paste without using the above-mentioned adhesion by an active metal. After applying this paste to the surface of the ceramic substrate, it is fired above the softening temperature of the glass powder and the sintering temperature of the metal powder, and the metal powder is sintered and the glass powder is melted to melt the sintered metal film and the ceramic substrate. A method of adhering to and is disclosed.

However, in the case of a conductor paste for a thick film, in order to secure the adhesion to the substrate mainly by the glass component mixed in the paste, the adhesion strength is as strong as that of bonding with an active metal (Ti, etc.) by the thin film method or the plating method. I can't get it. As a result, long-term reliability such as thermal shock resistance may be insufficient. Further, in the thick film method screen printing, the pattern resolution is limited to about 100 μm, and it is difficult to form a fine pattern of 100 μm or less. Further, since the cross-sectional shape of the pattern is semi-cylindrical and has no rectangular shape, it cannot be used for a high-density mounting substrate or the like, which requires a high pattern shape and accuracy.

In Japanese Patent Application Laid-Open No. 6-204645 (Patent Document 3), in order to obtain a good pattern shape, a conductor paste for a thick film is not printed in a pattern but is printed on an area larger than the pattern or on the entire surface of a substrate (solid printing). A method has also been proposed in which a resist pattern is formed on the surface of the conductor film after the conductor film is fired, and an unnecessary conductor portion is removed by etching to obtain a required pattern.

However, even with this method, the etching resistance of the glass component blended in the conductor paste is strong, and a part of the glass component remains even after normal etching, so that the insulating property between the patterns is lowered and fine patterns are formed. Is unsuitable. Due to such circumstances, the thick film method has not been realized in the wiring board for application to high-performance applications requiring fine patterns.

Japanese Patent Application Laid-Open No. 6-99199 (Claim 1, Example) JP-A-2008-226771 (Claim 1, paragraph [0059]) JP-A-6-204645 (Claims)

Therefore, an object of the present invention is to provide a metallized substrate in which a high-performance conductor pattern is formed on an insulating substrate with high productivity and a method for manufacturing the same.

Another object of the present invention is to provide a metallized substrate on which a surface conductor layer is formed with high adhesion and a method for producing the same.

Still another object of the present invention is to provide a metallized substrate having high heat resistance, heat impact resistance and reliability, and a method for producing the same.

Another object of the present invention is to provide a metallized substrate having excellent etching suitability and capable of forming a fine pattern, and a method for producing the same.

As a result of diligent studies to achieve the above problems, the present inventors have obtained an insulating substrate, a bonding layer laminated on at least a part of the surface of the insulating substrate, and containing an active metal layer, and this bonding. The present invention has been completed by finding that a high-performance conductor pattern can be formed on an insulating substrate with high productivity by combining with a surface conductor layer including a conductor which is laminated on the layer and has a porous structure.

That is, the metallized substrate of the present invention is laminated on an insulating substrate, a bonding layer that is laminated on at least a part of the surface of the insulating substrate and contains an active metal layer, and is laminated on the bonding layer and includes a conductor. , And includes a surface conductor layer having a porous structure. The active metal layer may contain at least one active metal selected from the group consisting of Ti, Zr, Hf, Nb, Ta, Cr, Mn and Al, or an alloy containing the active metal. The bonding layer may further include a non-permeable layer. The non-permeable layer may contain at least one barrier metal selected from the group consisting of Mo, W, Ni, Pd and Pt, or an alloy containing the barrier metal. The non-permeable layer may be interposed between the active metal layer and the surface conductor layer. The bonding layer may further include an affinity layer. This affinity layer may contain the same metal as the metal contained in the surface conductor layer or a metal that can be alloyed. The affinity layer may be in contact with the surface conductor layer. The conductor contained in the surface conductor layer may contain at least one conductive metal selected from the group consisting of Ni, Pt, Cu, Ag, Au and Al, or an alloy containing the conductive metal. The porosity of the surface conductor layer is about 5 to 30% by volume. The surface conductor layer may not contain a glass component. The average thickness of the surface conductor layer is about 5 to 1000 times the average thickness of the bonding layer. The insulating substrate may be a ceramic substrate. In the metallized substrate of the present invention, a plating layer (particularly a wet plating layer) may be further laminated on the surface conductor layer. Further, the metallized substrate of the present invention may be an electronic substrate.

In the present invention, there is a step of forming a bonding layer in which a bonding layer containing an active metal layer is laminated on the surface of an insulating substrate, and a conductor in which a conductor paste for a surface conductor layer containing metal particles and an organic vehicle is applied on the bonding layer. The metallized substrate including a coating step, a conductor firing step of heating the coated metal particles contained in the conductor paste to a temperature equal to or higher than the sintering temperature to fire the conductor paste to form a surface conductor layer containing a conductor having a porous structure. The manufacturing method of is also included. In the bonding layer forming step, after forming the active metal layer, a non-permeable layer and / or an affinity layer may be further laminated on the active metal layer. In the bonding layer forming step, the bonding layer may be formed by a physical vapor deposition method. In the conductor coating step, before coating the conductor paste, the melting point of the metal having a melting point of 400 ° C. or higher and the lowest melting point among all the metal species constituting the bonding layer in an inert gas atmosphere, and the bonding layer The bonding layer may be annealed by heating the bonding layer at a temperature equal to or lower than the melting point of the alloy constituting the above. In the production method of the present invention, after forming a resist pattern on the surface conductor layer obtained in the conductor firing step, the surface conductor layer and the bonding layer in the exposed region where the resist pattern is not formed are removed, and further, the resist pattern is formed. May further include a first etching step of removing. Further, the manufacturing method of the present invention is a bonding layer in which the conductor paste for the surface conductor layer is pattern-printed in the conductor coating process, and the bonding layer exposed from the surface conductor layer (pattern) is removed as a subsequent step in the conductor firing process. It may further include a removal step. In the bonding layer forming step, the bonding layer including the active metal layer may be formed in a pattern (the target pattern in the surface conductor layer) on the surface of the insulating substrate. The production method of the present invention may further include a plating step of forming a plating layer on the surface of the surface conductor layer obtained in the conductor firing step. Further, in the production method of the present invention, after forming a resist pattern on the surface conductor layer obtained in the conductor firing step, a plating layer containing a noble metal is formed on the surface of the surface conductor layer in the exposed region where the resist pattern is not formed. May further include a second etching step of forming the resist pattern to remove the surface conductor layer and the bonding layer in the exposed region where the plating layer is not formed.

In the present invention, an insulating substrate, a bonding layer laminated on at least a part of the surface of the insulating substrate and containing an active metal layer, and a conductor laminated on the bonding layer and having a porous structure are provided. Since it is combined with the including surface conductor layer, a high-performance conductor pattern can be formed on the insulating substrate with high productivity. In addition, the surface conductor layer can be formed with high adhesion. In particular, when the bonding layer contains a specific active metal, heat resistance and reliability can be highly improved. Further, since the surface conductor layer is a porous body, the thermal stress caused by the difference in the coefficient of thermal expansion between the surface conductor layer and the insulating substrate can be alleviated, and the thermal impact resistance can be improved. In addition, since the surface conductor layer does not contain additives such as glass components that are difficult to etch, it has excellent etching suitability, and when the surface conductor layer is etched to form a pattern, insulation reliability is high and right angle (rectangularity) is achieved. It is possible to form an excellent fine pattern.

[Metallized board]
The metallized substrate of the present invention has an insulating substrate, a bonding layer laminated on at least a part of the surface of the insulating substrate and containing an active metal layer, and a porous structure laminated on the bonding layer. Includes a surface conductor layer that includes the conductor to have.

(Insulating substrate)
The material constituting the insulating substrate is required to have heat resistance because it undergoes a firing process, and may be an organic material such as engineering plastic, but is usually an inorganic material (inorganic material).

Examples of the inorganic material include ceramics {metal oxides (quartz, alumina or aluminum oxide, zirconia, sapphire, ferrite, titania or titanium oxide, zinc oxide, niobium oxide, mullite, berylia, etc.), silicon oxide (silicon dioxide, etc.). , Metal nitride (aluminum nitride, titanium nitride, etc.), silicon nitride, boron nitride, carbon nitride, metal carbide (titanium carbide, tungsten carbide, etc.), silicon carbide, boron carbide, metal boride (titanate borate, zirconium booxide, etc.) , Etc.), Metal composite oxide [Metallic acid titanate (barium titanate, strontium titanate, lead titanate, niobium titanate, calcium titanate, magnesium titanate, etc.), metal dilcone acid salt (barium zirconate, zirconic acid, etc.) Calcium, lead zirconate, etc.)], etc.}, Glasses (soda glass, borosilicate glass, crown glass, barium-containing glass, strontium-containing glass, boron-containing glass, low-alkali glass, non-alkali glass, crystallized transparent glass, etc. Silica glass, quartz glass, heat-resistant glass, etc.), silicon (semiconductor silicon, etc.) and the like can be mentioned. The inorganic material may be a composite material (for example, enamel) of these inorganic materials and a metal.

The insulating substrate may be, for example, a heat-resistant substrate such as a ceramic substrate, a glass substrate, a silicon substrate, or an enamel substrate. Among these heat-resistant substrates, ceramic substrates such as alumina substrates, aluminum nitride substrates, and silicon nitride substrates are preferable.

The insulating substrate usually has a smooth surface shape. The surface of such an insulating substrate is subjected to oxidation treatment [surface oxidation treatment, for example, discharge treatment (corona discharge treatment, glow discharge, etc.), acid treatment (chromic acid treatment, etc.), ultraviolet irradiation treatment, flame treatment, etc.], surface treatment. Surface treatment such as uneven treatment (solvent treatment, sandblast treatment, etc.) may be performed.

The average thickness of the insulating substrate may be appropriately selected depending on the application, for example, 0.01 to 10 mm, preferably 0.05 to 5 mm, more preferably 0.1 to 1 mm (particularly 0.2 to 0.8 mm). ) May be the case.

(Active metal layer)
The bonding layer is a thin film laminated on at least a part of the surface of the insulating substrate, and usually has a shape corresponding to the pattern shape of the surface conductor layer. By including the active metal layer (reaction layer with the insulating substrate) as an essential layer, the bonding layer reacts with the constituent components of the insulating substrate or forms a compound to form a compound with the insulating substrate. The adhesion with the surface conductor layer is improved.

The active metal layer includes an active metal or an alloy containing the active metal. The active metal may be a metal that reacts with the constituents of the insulating substrate or a metal that can form a compound with the constituents and is different from the metal that constitutes the surface conductor layer. For example, Ti, Zr, Hf, and the like. Examples thereof include Nb, Ta, Cr, Mn and Al. These active metals can be used alone or in combination of two or more, and may be an alloy in which two or more are combined.

Among these active metals, active metals containing Ti, Zr, and Cr are preferable, and these active metals alone are usually widely used.

Further, the active metal has both the electrical characteristics of the surface conductor layer and the adhesion between the surface conductor layer and the insulating base material, even if it has a simple film structure (particularly, without forming a non-permeable layer). From the point of view, it may be an alloy with a barrier metal (particularly Mo or W) constituting the non-permeable layer described later. In the alloy of the active metal and the barrier metal, the ratio of the barrier metal is 200 parts by mass or less with respect to 100 parts by mass of the active metal, for example, 1 to 150 parts by mass, preferably 5 to 150 parts by mass, more preferably. Is about 10 to 100 parts by mass. If the proportion of the barrier metal is too large, the adhesion between the insulating substrate and the active metal layer may decrease.

The active metal layer may contain an active metal and may be, for example, an active metal compound, but is usually a simple substance of the active metal, an alloy of the active metals, or an alloy of the active metal and the barrier metal. As the active metal compound, a compound (for example, TiH ₂ , ZrH _2, etc.) in which an active metal is easily produced by heating is preferable.

The average thickness of the active metal layer may be 0.005 μm or more, for example 0.005 to 1.0 μm, preferably 0.01 to 0.5 μm, and more preferably 0.05 to 0.3 μm (particularly 0. It is about 08 to 0.2 μm). If the thickness of the active metal layer is too thin, the adhesion between the surface conductor layer and the insulating substrate may decrease. On the other hand, if the thickness of the active metal layer is too thick, the conductivity of the surface conductor layer may be impaired, which is disadvantageous in terms of cost.

(Non-transparent layer)
The bonding layer may be formed of the active metal layer alone, but the active metal layer can be highly improved in terms of the electrical characteristics of the surface conductor layer and the adhesion between the surface conductor layer and the insulating base material. A non-permeable layer may be further interposed between the surface conductor layer and the surface conductor layer. When the bonding layer is formed of the active metal layer alone, it has high electrical characteristics and adhesion to the conventional metallized substrate, but as a phenomenon that occurs between the active metal layer and the surface conductor layer. If the active metal layer diffuses into the surface conductor layer, the electrical characteristics of the surface conductor layer may be slightly deteriorated. On the other hand, when the metal constituting the surface conductor layer diffuses into the active metal layer and is further alloyed, the adhesion to the insulating substrate is slightly lowered (the active metal film is peeled off from the insulating substrate due to diffusion and alloying). There is also a risk. Therefore, in order to further improve the effect of the present invention, if a non-permeable layer is interposed between the active metal layer and the surface conductor layer, the non-permeable layer becomes a barrier, and the active metal layer and the surface conductor layer are formed during high-temperature firing. It is possible to prevent the constituent metals from diffusing each other. Further, when the active metal layer is exposed to air after being formed, the active metal is easily oxidized, and the function as a bonding layer may be deteriorated. On the other hand, by coating a metal that is relatively difficult to oxidize as a non-permeable layer (barrier layer), oxidation of the active metal can be suppressed.

The non-permeable layer contains a barrier metal or an alloy containing the barrier metal. The barrier metal is not particularly limited as long as it has the above-mentioned barrier property and is different from the metal constituting the surface conductor layer, and examples thereof include Mo, W, Ni, Pd, and Pt. These barrier metals can be used alone or in combination of two or more, and may be an alloy in which two or more are combined.

Among these barrier metals, Pd, Pt, and Ni are preferable from the viewpoints of conductivity, stability, adhesion to the surface conductor layer, and barrier properties, and these barrier metals alone are usually widely used.

The non-permeable layer may contain a barrier metal and may be, for example, a barrier metal compound, but is usually a barrier metal simple substance or an alloy of barrier metals.

The average thickness of the non-permeable layer may be 0.01 μm or more, for example, 0.01 to 1.0 μm, preferably 0.05 to 0.5 μm, and more preferably about 0.1 to 0.3 μm. If the thickness of the non-transmissive layer is too thin, the effect of the active metal layer may be reduced, or the adhesion between the surface conductor layer and the insulating substrate may be reduced. If the thickness of the non-transmissive layer is too thick, it is disadvantageous in terms of cost.

(Affinity layer)
The bonding layer may include an affinity layer (a layer that enhances the affinity with the surface conductor layer) on the outermost surface in contact with the surface conductor layer in order to further improve the adhesion between the surface conductor layer and the insulating substrate. .. The affinity layer may be in contact with the surface conductor layer, may be laminated on the active metal layer, or may be formed on the non-permeable layer. By bringing the affinity layer into contact with the surface conductor layer, the affinity (wetting property) with the surface conductor layer is enhanced, and the surface conductor layer and the insulating substrate (specifically, the active metal layer or the non-permeable layer) are satisfactorily bonded. can. When the metal of the non-permeable layer is a metal having the property of an affinity layer, the non-permeable layer can also serve as an affinity layer.

The affinity layer is a metal different from the metal forming the layer (impermeable layer or active metal layer) in contact with the affinity layer, and is the same as or alloyable with the metal contained in the surface conductor layer (metal for affinity). including. Examples of the affinity metal include Ni, Pd, Pt, Cu, Ag, Au, Al and the like. These affinity metals can be used alone or in combination of two or more, and may be an alloy in which two or more are combined.

Among these affinity metals, the same metal as the metal contained in the surface conductor layer is preferable. The preferred affinity metal may be, for example, a metal containing Ni, Cu, Ag, Au, Al, and these metals alone are usually used in general. These affinity metals are highly conductive metals that are usually used as a surface conductor layer, and in particular, when they are the same as the metal contained in the surface conductor layer, wettability and adhesion can be improved, and thus an insulating substrate. Can be adhered more firmly.

The affinity layer may contain an affinity metal, and may be, for example, an affinity metal compound, but is usually a simple substance of the affinity metal or an alloy of the affinity metals.

The average thickness of the affinity layer may be 0.01 μm or more, for example, 0.01 to 0.5 μm, preferably 0.1 to 0.3 μm, and more preferably about 0.1 to 0.25 μm. If the thickness of the affinity layer is too thin, the effect of forming the affinity layer may be reduced.

The average thickness of the bonding layer may be 0.05 μm or more, for example, 0.1 to 1 μm, preferably 0.2 to 0.8 μm, and more preferably about 0.3 to 0.5 μm.

(Surface conductor layer)
The surface conductor layer (or surface conductor film) is laminated on the bonding layer, contains a conductor (particularly a sintered conductor), and has a porous structure, so that high conductivity can be realized as a metallized substrate. The surface conductor layer may be laminated on the insulating substrate with a bonding layer interposed therebetween in at least a part of the region, and there is a region in which the surface conductor layer is directly laminated on the insulating substrate without interposing the bonding layer. You may. For example, in order to improve economic efficiency, a bonding layer is interposed in a region where high adhesion and pattern accuracy are required (usually the front surface), and a bonding layer is interposed in a region where high adhesion and pattern accuracy are not required (usually the back surface). You do not have to let it. From the viewpoint of the performance of the metallized substrate, it is preferable that all the surface conductor layers are laminated on the insulating substrate with the bonding layer interposed therebetween.

The conductor contained in the surface conductor layer is not particularly limited as long as it has conductivity, but is usually a conductive metal or an alloy containing the conductive metal. Examples of the conductive metal include Ni, Pt, Cu, Ag, Au, Al and the like. These metals can be used alone or in combination of two or more, and may be an alloy in which two or more are combined. Of these, Cu or Ag is preferable from the viewpoints of conductivity, reliability, economy and the like. The conductor may be a sintered conductor.

The surface conductor layer may be a non-conductor such as a semiconductor or an insulator (for example, a filler such as ceramic, an organic vehicle remaining after firing, an inorganic binder such as a glass component, etc.) as long as the effect of the present invention is not impaired. It may be included. The proportion of the conductor in the surface conductor layer may be 50% by mass or more, for example, 90% by mass, preferably 95% by mass or more, more preferably 99% by mass or more, and particularly 100% by mass (formed by the conductor alone). ) May be. As described above, the surface conductor layer can improve the adhesion to the insulating substrate even if it does not contain an inorganic binder such as a glass component by interposing a bonding layer. Therefore, the surface conductor layer does not have to substantially contain an inorganic binder (particularly a glass component), and preferably does not contain a glass component. The ratio of the inorganic binder (particularly the glass component) is 1 part by mass or less (particularly 0.1 part by mass or less) with respect to 100 parts by mass of the conductor, and if the ratio of the glass component is too large, the adhesiveness and electrical characteristics deteriorate. There is a risk of

Further, since the surface conductor layer is a porous body having a porous structure, the elastic modulus of the surface conductor layer is low, and the thermal stress caused by the difference in the coefficient of thermal expansion between the surface conductor layer and the insulating substrate is relaxed. Thermal impact resistance can be improved. The porous structure of the porous body is not particularly limited, and may be any of a communicative pore structure, an independent pore structure, and a mixed structure of both. An independent pore structure is preferable because of the airtightness of the surface conductor layer and the barrier property against the plating solution. In particular, the surface conductor layer obtained by using the conductor paste (metal paste or conductive paste) may be a porous body (sintered body) produced by firing. The average pore size of the porous body is, for example, 0.01 to 5 μm, preferably 0.05 to 3 μm, and more preferably about 0.1 to 2 μm. The porosity of the porous body is, for example, 1 to 40% by volume, preferably 5 to 30% by volume, and more preferably about 10 to 20% by volume. If the porosity is too large, the conductivity may decrease, and if it is too small, the thermal impact resistance may decrease.

The average pore size of the porous body can be measured based on observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Further, the porosity of the porous body can be measured based on the volume fraction of the organic component and the firing shrinkage ratio contained in the conductor paste, and can be measured in detail by the method described in Examples described later.

Further, the surface conductor layer is a thicker film than the thin film bonding layer, and in forming the surface conductor layer, the formation of the bonding layer by the thin film method and the formation of the surface conductor layer by the thick film method are combined. A conductor pattern can be formed. Therefore, due to the bonding layer, the surface conductor layer can realize high adhesion to the insulating substrate without using a glass component. In the present invention, in addition to the above-mentioned features, the features can be exhibited in all aspects such as adhesion, reliability, conductivity (corresponding to a large current), pattern accuracy, and cost.

The film thickness of the surface conductor layer may be set according to the required amount of current, and since the surface conductor layer is a porous body in the present invention, a thick film, for example, 200 μm, which was difficult to form by the conventional method. Even with the above, it is possible to form an ultra-thick film having high reliability. The average thickness of the surface conductor layer may be 0.5 μm or more, for example, 1 to 1000 μm, preferably 2 to 600 μm (for example, 3 to 500 μm), and more preferably 4 to 300 μm (particularly 5 to 200 μm). If the thickness of the surface conductor layer is too thin, the electrical characteristics and plating resistance may deteriorate. If the surface conductor layer is too thick, it is disadvantageous in terms of cost.

The surface conductor layer is thicker than the bonding layer, and the average thickness of the surface conductor layer can be selected from a range of about 3 to 5000 times the average thickness of the bonding layer, for example, 5 to 3000 times (for example, 5 to 5). It is about 1000 times), preferably 8 to 2000 times (for example, 10 to 1500 times), and more preferably 10 to 1000 times (particularly 15 to 500 times). If the thickness ratio of the surface conductor layer is too small, the electrical characteristics may deteriorate, and conversely, if it is too thick, it is disadvantageous in terms of cost.

(Plating layer)
In the metallized substrate of the present invention, a plating layer may be further laminated on the surface conductor layer. The metal type is not particularly limited as the plating layer, and examples thereof include copper plating, nickel plating, silver plating, nickel gold plating, nickel palladium gold plating, tin plating, and solder plating. Of these, a plating layer containing a noble metal such as gold, silver, palladium, or platinum is preferable, and is particularly effective when a pattern is formed by a lift-off method as a second etching step.

The plating layer may be a dry plating layer, but a wet plating layer whose film thickness can be easily adjusted is preferable. Examples of wet plating include electroplating and electroless plating. Further, as the plating method, electroplating is particularly preferable because a wide range of plating metal types and plating film thicknesses can be selected.

The average thickness of the plating layers (total thickness when a plurality of plating layers are laminated) is, for example, about 0.5 to 30 μm, preferably 1 to 10 μm, and more preferably 1.5 to 5 μm (particularly 2 to 4 μm). ..

[Manufacturing method of metallized substrate]
The metallized substrate of the present invention has a bonding layer forming step of forming a bonding layer including an active metal layer on the surface of an insulating substrate, and a conductor paste for a surface conductor layer containing metal particles and an organic vehicle is applied on the bonding layer. The conductor coating step is performed, and the conductor coating step is performed by heating the metal particles contained in the coated conductor paste to a temperature equal to or higher than the sintering temperature to fire the conductor paste to form a surface conductor layer containing a conductor and having a porous structure. You may get it through.

(Joint layer forming process)
In the bonding layer forming step, a bonding layer containing an active metal layer may be laminated on the surface of the insulating substrate. After forming the active metal layer, a non-permeable layer and / or an affinity layer is further formed on the active metal layer. May be laminated.

Further, the bonding layer may be formed on the entire surface of the insulating substrate or may be formed in a pattern shape on the surface of the insulating substrate. As a method for forming the pattern, a conventional method can be used, for example, a method using a mask, a method of forming a photoresist pattern on the surface of a substrate and then forming a bonding layer on an exposed portion, a method of forming a bonding layer on the entire surface of the substrate, and a bonding layer on the entire surface of the substrate. After forming the pattern, a method of forming a pattern by photolithography and etching can be mentioned.

As a method for forming the bonding layer, a physical vapor deposition method (PVD method), a chemical vapor deposition method (CVD method), or the like can be used, but the physical vapor deposition method is preferable because a metal film can be easily formed. Examples of the physical vapor deposition method include a vacuum vapor deposition method, a flash vapor deposition method, an electron beam vapor deposition method, an ion beam vapor deposition method, a sputtering method, an ion plating method, a molecular beam epitaxy method, and a laser ablation method. Of these, the sputtering method, the vacuum vapor deposition method, and the ion plating method are preferable from the viewpoint of being able to stably process a large amount. Further, the sputtering method is particularly preferable because it has high physical energy and can improve the adhesion between the formed metal film and the insulating substrate. Sputtering methods can be used under conventional conditions.

(Conductor coating process)
In the conductor coating step, a conductor paste (metal paste or conductive paste) for a surface conductor layer containing metal particles and an organic vehicle is coated on the bonding layer.

The conductor paste contains metal particles formed of the conductive metal. The average particle size (center particle size) of the metal particles is about 100 μm or less (particularly 50 μm or less), for example, 0.001 to 50 μm, preferably 0.01 to 20 μm, and more preferably about 0.1 to 10 μm. .. In particular, when the metal particles are Cu particles, the average particle size of the metal particles is, for example, 0.1 to 3 μm, preferably 0.2 to 2 μm, and more preferably about 0.3 to 1 μm. When the metal particles are Ag particles, the average particle size of the metal particles is, for example, 0.1 to 2 μm, preferably 0.1 to 1.5 μm, and more preferably about 0.1 to 1 μm. If the average particle size of the metal particles is too small, the viscosity of the conductor paste may increase and handleability may become difficult, and if it is too large, the effect of improving the denseness may decrease.

The metal particles have a particle size of less than 1 μm (for example, 1 nm or more and less than 1 μm) and a particle size of 1 to 50 μm from the viewpoint that the metal content in the paste can be improved and the density and conductivity of the surface conductor layer can be improved. May be combined with large metal particles of. The average particle size (center particle size) of the small metal particles can be selected from the range of about 0.01 to 0.9 μm (particularly 0.1 to 0.8 μm). The average particle size (center particle size) of the large metal particles can be selected from the range of about 1.5 to 30 μm (particularly 2 to 10 μm). The mixing ratio of the small metal particles to the large metal particles is, for example, as a volume ratio, for example, small metal particles / large metal particles = 10/90 to 50/50, preferably 20/80 to 40/60, and more preferably 25 /. It is about 75 to 35/65.

As a method for measuring the particle size of the metal particles, it can be measured with a laser diffraction / scattering type particle size distribution measuring device or a transmission electron microscope (TEM), and in detail, it can be measured by the method described in Examples described later.

The organic vehicle includes an organic binder, a dispersion medium (organic solvent), and the like. The protective colloid (carboxylic acid, polymer dispersant, etc.) contained in the above-mentioned metal colloid particles is also contained in the organic vehicle. The organic vehicle may be a combination of an organic binder and a dispersion medium.

Examples of the organic binder include thermoplastic resins (olefin resins, vinyl resins, acrylic resins, styrene resins, polyether resins, polyester resins, polyamide resins, cellulose derivatives, etc.) and thermosetting resins (cell curable resins). Thermosetting acrylic resin, epoxy resin, phenol resin, unsaturated polyester resin, polyurethane resin, etc.) and the like can be mentioned. These organic binders can be used alone or in combination of two or more. Among these organic binders, acrylic resins (polymethylmethacrylate, polybutylmethacrylate, etc.), cellulose derivatives (nitrocellulose, ethylcellulose, butylcellulose, cellulose acetate, etc.), polyethers (polyoxymethylene, etc.), polyvinyls (polyoxymethylene, etc.) Polybutadiene, polyisoprene, etc.) are widely used, and poly (meth) acrylate C _1-10 alkyl esters such as methyl poly (meth) acrylate and butyl poly (meth) acrylate are preferable from the viewpoint of thermodegradability. ..

Examples of the dispersion medium include aromatic hydrocarbons (paraxylene, etc.), esters (ethyl lactate, etc.), ketones (isophorone, etc.), amides (dimethylformamide, etc.), and aliphatic alcohols (octanol, decanol, diacetone, etc.). Alcohol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates (ethyl cellosolve acetate, butyl cellosolve acetate, etc.), carbitols (carbitol, methyl carbitol, ethyl carbitol, etc.), carbitol acetates (calcitol, methyl carbitol, ethyl carbitol, etc.) Ethyl carbitol acetate, butyl carbitol acetate, etc.), aliphatic polyhydric alcohols (ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, pentanediol, triethylene glycol, glycerin, etc.), alicyclic alcohols [for example, Cycloalkanols such as cyclohexanol; terpen alcohols such as terpineol and dihydroterpineol (monoterpene alcohol, etc.)], aromatic alcohols (metacresol, etc.), aromatic carboxylic acid esters (dibutylphthalate, dioctylphthalate, etc.) , Nitrogen-containing heterocyclic compounds (dimethylimidazole, dimethylimidazolidinone, etc.) and the like. These dispersion media can be used alone or in combination of two or more. Among these dispersion media, an aliphatic polyhydric alcohol such as pentanediol and an alicyclic alcohol such as terpineol are preferable from the viewpoint of the fluidity and coatability of the paste.

When the organic binder and the dispersion medium are combined, the ratio of the organic binder is, for example, 1 to 200 parts by mass, preferably 5 to 100 parts by mass, and more preferably about 10 to 50 parts by mass with respect to 100 parts by mass of the dispersion medium. be.

The ratio of the organic vehicle may be 50 parts by mass or less with respect to 100 parts by mass of the metal particles, for example, 1 to 50 parts by mass, preferably 3 to 40 parts by mass, and more preferably 5 to 30 parts by mass (particularly 10). ~ 20 parts by mass). If the proportion of the organic vehicle is too large, the shrinkage rate of the conductor paste due to drying or firing after coating becomes large, and there is a possibility that gaps may occur.

The conductor paste may further contain a filler or an inorganic binder for the purpose of adjusting the sintering behavior, the coefficient of thermal expansion, the adhesion, and the like. Examples of the filler include alumina powder and silica powder, and examples of the inorganic binder include glass powder having a low melting point.

As a method for applying the conductive paste, for example, screen printing, offset printing, inkjet printing, dispenser coating, roller coater coating, spin coating coating, spray coating, dip coating and the like can be used. The printing (coating) shape may be full surface coating (solid printing) or direct pattern printing. In direct pattern printing, the accuracy of the pattern shape may decrease, but the process is simple and the cost is low. When the bonding layer is formed into a pattern shape, the same shape as the pattern of the bonding layer may be printed on the pattern of the bonding layer by screen printing or the like.

In the conductor coating step, the insulating substrate provided with the bonding layer may be heated in an inert gas atmosphere for annealing before coating the conductor paste. Annealing treatment is not essential, but depending on the type of bonding layer, if the insulating substrate is fired at a high temperature for firing without annealing, the metal of the conductor paste and the bonding layer are alloyed during firing. Since the bonding layer is taken into the surface conductor layer and disappears, the adhesion between the surface conductor layer portion and the insulating substrate may decrease. On the other hand, by subjecting to the annealing treatment, the active metal of the bonding layer reacts preferentially with the surface of the insulating substrate rather than alloying the conductor paste with the metal, forming a strong bonding layer on the surface and adhering force. Along with the improvement, alloying of different metals in the bonding layer also occurs. As a result, the alloying of the metal component of the bonding layer and the metal of the conductor paste at the time of firing the conductor paste can be suppressed, and the adhesion can be improved.

The heating temperature in the annealing treatment is 400 ° C. or higher, and the melting point of the metal having the lowest melting point among all the metal species constituting the bonding layer and the melting point of the alloy constituting the bonding layer, whichever is lower. The temperature may be as follows, and can be selected according to the metal type. The specific heating temperature is, for example, 400 to 1500 ° C, preferably 500 to 1200 ° C, and more preferably 600 to 1100 ° C (particularly 700 to 1000 ° C). If the heating temperature is too low, the effect of improving the adhesion between the bonding layer and the insulating substrate may be reduced, and if it is too high, the metal components may melt and move, resulting in a decrease in the uniformity of the bonding layer or the substrate. There is a risk that part of the substrate will be exposed.

The heating time may be, for example, 1 minute or more, for example, 1 minute to 1 hour, preferably 3 to 30 minutes, and more preferably about 5 to 20 minutes. If the heating time is too short, the effect of improving the adhesion between the bonding layer and the substrate may be reduced.

The annealing treatment may be performed in an active gas atmosphere such as in air, but since the active metal does not oxidize and the bonding layer can be efficiently formed to improve the adhesion to the substrate, the annealing treatment can be performed in vacuum or in an inert gas. It is preferably carried out in an atmosphere (for example, nitrogen gas, argon gas, helium gas, etc.).

(Conductor firing process)
In the conductor firing step, the conductor paste is fired by heating it to a temperature equal to or higher than the sintering temperature of the metal particles contained in the applied conductor paste to form a surface conductor layer.

In the conductor firing step, the firing temperature may be equal to or higher than the sintering temperature of the metal particles in the conductive paste for the surface conductor layer. The firing temperature may be, for example, 500 ° C. or higher, for example, 500 to 1500 ° C., preferably 550 to 1200 ° C., and more preferably 600 to 1000 ° C. The firing time is, for example, 10 minutes to 3 hours, preferably 20 minutes to 3 hours, and more preferably about 30 minutes to 2 hours.

The firing atmosphere can be selected according to the type of metal particles, and is not particularly limited for noble metal particles such as Ag and may be in the air, but for metal particles such as Cu, an inert gas is usually used. In an atmosphere (for example, nitrogen gas, argon gas, helium gas, etc.) is preferable.

(Etching process)
When a pattern is not formed in the bonding layer forming step or the conductor coating step, the surface conductor layer obtained by firing is usually subjected to an etching step. In the etching process, a resist pattern is used to form a pattern on the surface conductor layer and the bonding layer. The etching step includes a first etching step of forming a resist pattern as a pattern of a surface conductor layer and a bonding layer, and a second etching step (lift-off) of forming a region other than the resist pattern as a pattern of a surface conductor layer and a bonding layer. Law) etc. are included.

Specifically, in the first etching step, after forming a resist pattern on the surface conductor layer obtained in the conductor firing step, the surface conductor layer and the bonding layer in the exposed region where the resist pattern is not formed are removed. Further, the resist pattern is removed. On the other hand, in the second etching step (lift-off method), after forming a resist pattern on the surface conductor layer obtained in the conductor firing step, a noble metal is formed on the surface of the surface conductor layer in the exposed region where the resist pattern is not formed. After forming the plating layer containing the above, the resist pattern is peeled off to remove the surface conductor layer and the bonding layer in the exposed region where the plating layer is not formed. By forming a resist pattern and performing an etching process, it is possible to form a fine pattern or a highly accurate pattern that cannot be handled by the direct printing method.

The method for forming the resist pattern is not particularly limited, and a conventional method can be used. For example, direct pattern printing of the resist, a lithography method, or the like can be used.

The method for removing the surface conductor layer and the bonding layer is not particularly limited, and a conventional method can be used, and examples thereof include wet etching, dry etching, blasting, and laser.

The method for removing the resist pattern is not particularly limited, and a conventional method can be used, and examples thereof include peeling removal.

In the second etching step, as a method for forming the plating layer containing a noble metal, the same method as the plating step described later can be used.

If the surface conductor layer and the bonding layer are formed by direct pattern printing instead of full surface coating (solid printing), the etching step is not required.

(Joint layer removal process)
When the conductor paste for the surface conductor layer is printed in a pattern in the conductor coating step, the bonding layer existing between the adjacent surface conductor layers and the surface conductor layers in the formed pattern is removed in the bonding layer removing step to remove the pattern. Achieves insulation between.

The method for removing the bonding layer is not particularly limited, and a conventional method can be used, and examples thereof include wet etching, dry etching, blasting, and laser.

(Plating process)
The obtained surface conductor layer is plated according to demands for further improvement of conductivity, oxidation prevention, solder wettability, etc., except when a plating layer is formed on the surface conductor layer by the lift-off method. .. The plating method is not particularly limited, and a conventional method can be used. For example, a chemical plating method such as an electroplating method or an electroless plating method can be used. The electroplating method is not particularly limited, and may be performed under the conditions recommended by the plating chemical manufacturer according to the plating type. The method of electroless plating is not particularly limited, and may be performed under conventional conditions depending on the type of plating.

The order of the etching process and the plating process may be reversed. In that case, after forming the resist film, the exposed portion is plated (in this case, the resist film is not an etching resist but a plating resist). After plating, the resist film is peeled off and removed, and the conductor film exposed by the peeling of the resist film is removed by etching. In this case, if the uppermost plating film is an etching resistant layer formed of Au or the like, the plating film itself functions as an etching resist.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The method for preparing the conductor paste used in Examples and Comparative Examples, and the measurement method for the evaluation test of the wiring board obtained in Examples and Comparative Examples are shown below.

[Preparation method of conductor paste]
(material)
Cu particles with a central particle size (D50) of 7 μm: manufactured by Mitsui Metal Mining Co., Ltd. Cu particles with a central particle size (D50) of 0.8 μm: Ag particles with a central particle size (D50) of 0.25 μm : Mitsui Metal Mining Co., Ltd. Glass particles: Zinc borosilicate glass powder with an average particle size of 3 μm, softening point 565 ° C
Organic vehicle: A mixture of an acrylic resin which is an organic binder and a mixed solvent (mass ratio 1: 1) of carbitol and terpineol which are organic solvents in a mass ratio of organic binder: organic solvent = 1: 3.

(Example of preparation of conductor paste)
Each raw material was weighed according to the compositions shown in Tables 1 and 2, mixed with a mixer, and then uniformly kneaded with three rolls to prepare a Cu paste for the surface conductor layer and an Ag paste for the surface conductor layer.

[Porosity of conductor]
It was calculated by the following formula based on the ratio (volume fraction) of the organic component contained in the conductor paste and the shrinkage ratio due to firing.

Porosity (v / v%) = (volume fraction of organic components in conductor paste-firing shrinkage) / (1-firing shrinkage) x 100
(In the formula, the firing shrinkage rate (v / v%) = [(film thickness after printing-film thickness after firing) / film thickness after printing] × 100).

In the present invention, since the paste for the surface conductor layer is formed on the active metal bonding layer, it is not necessary to add a glass component for adhering to the ceramic substrate. On the other hand, Cu paste B for the surface conductor layer contains a glass component so as to be in close contact with the substrate as a paste used in a comparative example in which an active metal bonding layer is not formed on the surface of the substrate.

[Average particle size of metal particles]
The average particle size of Cu particles and Ag particles was measured with a laser diffraction / scattering type particle size distribution measuring device.

[Thickness of metal film]
The average thickness of the active metal layer and the barrier layer was measured at 5 points by a fluorescent X-ray film thickness meter.

[Adhesion test (adhesion)]
^{A stud pin having a tip area of 1 mm 2} was vertically joined to a 2 × 2 mm square conductor pattern formed on the surface of the substrate by solder (63Sn / 37Pb) to obtain a test piece. When the test piece (fired substrate) is fixed, the stud pin is grasped by the chuck part of the tensile tester, and the test piece is pulled vertically upward at an ascending speed of 33 mm / min, and the conductor film (surface conductor layer) is peeled off from the insulating substrate. The breaking load was measured. Then, the adhesion strength was calculated from the obtained measured value of the fracture load and the fracture area of the conductor film using the following formula.

Adhesion strength (MPa) = breaking load (kgf) / breaking area (mm ² ) x 9.8 (N / kgf).

The measured value was the average of 6 points. The adhesion was evaluated based on the following criteria with respect to the calculated average value of the adhesion strength.

◯: 50 MPa or more ×: less than 50 MPa.

[Etching aptitude test (etchability)]
The pattern after etching was observed with a microscope of 60 times, the pattern shape and the removal state of the conductor were confirmed, and the evaluation was made according to the following criteria.

◯ (Pass): The pattern shape was rectangular, and the conductor film and the bonding layer were cleanly removed up to the hem of the pattern.

Hereinafter, the results of verifying the effects under various conditions will be described as Examples 1 to 23 and Comparative Examples 1 to 3. The results of the obtained heat resistance test, adhesion test and etching aptitude test are shown in Tables 3 and 4.

Example 1
A wiring board was produced by the method shown below.

(Formation process of bonding layer)
A Ti film with a thickness of 100 nm as an active metal layer and a Pd film with a thickness of 150 nm as a barrier layer are laminated in this order on the entire surface of one side of an AlN substrate (manufactured by MARUWA Co., Ltd.) having a thickness of 2 inches x 2 inches x 0.635 mm. And formed a bonding layer. The sputtering conditions were an introduction gas: argon, a sputtering pressure: 0.5 Pa, and a substrate heating temperature: 300 ° C.

(Step of forming the surface conductor layer (Cu))
Cu paste A (Cu-A) for the surface conductor layer shown in Table 1 was printed on one side of the substrate on which the bonding layer was formed on the entire surface using a 250 mesh stainless steel plate having a wire diameter of 30 μm, and then printed at 120 ° C., 20 ° C. Dry for minutes. The substrate was fired in a nitrogen atmosphere at a peak temperature of 700 ° C. and a peak holding time of 10 minutes to obtain a metallized substrate in which a surface conductor layer (Cu film) having a thickness of about 8 μm was baked on one side.

(Formation of etching resist pattern)
In order to remove the conductor film on the unnecessary part of the substrate surface and form the required pattern, the etching resist is pattern-printed so that the unnecessary part is exposed on the surface of the Cu film on one side of the substrate, and the temperature is 120 ° C. for 30 minutes. It was dried to form a resist film for etching. The resist film is formed so as to hide necessary parts such as a 2 mm × 2 mm pattern for evaluating the adhesion of the conductive film on the surface of the substrate.

(etching)
An etching solution capable of dissolving Cu / Pd / Ti in the exposed Cu film of the substrate on which the etching resist film is formed and the Ti / Pd film which is the underlying bonding layer thereof ("TCL-2 series" manufactured by Wako Pure Chemical Industries, Ltd. ”) And removed. Then, the etching resist film was peeled off to obtain a wiring board in which the required conductor pattern remained on the surface.

Although the formation of the wiring board was completed, a plating film was formed on the outermost surface of the conductor pattern for the purpose of preventing oxidation of the Cu film surface, improving solder wettability and wire bonding property.

(Ni / Au plating on the surface of Cu film)
A nickel-plated film and a gold-plated film were formed in this order on the Cu film on the surface of the substrate by electroplating. The nickel-plated film was electroplated using a watt bath at a current density of 2.0 A / dm ² and a temperature of 65 ° C. to form a nickel film having a thickness of 2 μm. The gold-plated film was formed using a pure gold bath at a current density of 0.5 A / dm ² and a temperature of 70 ° C. to form a gold film of 1 μm.

(evaluation)
When the wiring board obtained in the above step is patterned by an adhesion test for evaluating the adhesion between the surface conductor layer and the substrate and etching, the etchability of the conductor film is evaluated. rice field. As a result, good results were obtained in all the evaluation items.

Examples 2-3
A wiring board was produced by the same method as in Example 1 except that the printing plate of the Cu film for the surface conductor layer was changed and the fired Cu film thickness was changed to 5 μm and 12 μm, respectively. In both Cu thick films, there was no significant difference in heat resistance, adhesion, and etching property, and all were good. Therefore, in the present invention, the Cu film thickness can be adjusted inexpensively and easily as required.

Comparative Example 1
In the bonding layer forming step, a wiring board was produced by the same method as in Example 1 except that the active metal layer (Ti film) was not formed.

Comparative Example 2
In the bonding layer forming step, a wiring board was produced by the same method as in Example 1 except that the Ti film and the Pd film were not completely formed.

In Comparative Example 1, since the active metal layer that contributes to the adhesion to the substrate does not exist, the adhesion of the surface conductor layer is as low as 12 MPa, and some peeling occurs during etching. In Comparative Example 2, since neither the Ti film nor the Pd film was present, the Cu paste film hardly adhered to each other and was easily peeled off.

From these results, it was found that the Cu paste A for the surface conductor layer could not obtain the adhesion of the surface Cu film in Comparative Examples 1 and 2 in which the active metal layer that could react with the substrate and could be bonded did not exist.

Comparative Example 3
A wiring board was produced by the same method as in Comparative Example 2 except that Cu paste B for the surface conductor layer was used instead of Cu paste A for the surface conductor layer. Since the Cu paste B contains a glass component, a certain degree of adhesion to the substrate can be obtained even if the active metal layer does not exist. Further, in order to improve the adhesion of Cu paste B, the firing temperature was set to 900 ° C. As a result, the adhesion of the surface conductor layer to the substrate was 38 MPa, which was clearly lower than that of the example having the active metal bonding layer. In addition, a copper film residue was present on the surface of the substrate after etching. SEM-EDS analysis revealed that the etching residue was mainly the glass component in the copper paste, and the Cu component also remained in the residue. These residues may adversely affect the insulation reliability of the substrate.

Examples 4 and 5
A wiring board was produced by the same method as in Example 1 except that Cr and Zr were used instead of Ti as the active metal species. The adhesion was good enough, although it tended to be slightly lower.

Examples 6 and 7
In the bonding layer forming step, a wiring board was produced by the same method as in Example 1 except that Pt and Ni were used instead of Pd as the barrier metal. Good results were obtained for all items.

Example 8
In the bonding layer forming step, a film was formed in the order of Ti and Pd, and then 0.2 μm of Cu was formed as an affinity layer on the surface of the Pd film by a sputtering method, but the wiring board was formed by the same method as in Example 1. Was produced. As a result, the heat resistance and the etching property were almost the same as those of the other examples, but the adhesion was high. It can be presumed that the reason why the adhesion is improved is that the Cu film (affinity layer) produced by the sputtering method and the Cu paste serving as the surface conductor layer are integrated at the time of firing.

Example 9
Examples except that the substrate having the bonding layer was annealed in a nitrogen atmosphere at a peak temperature of 700 ° C. and a peak temperature holding time of 10 minutes after forming the bonding layer and before printing the Cu paste for the surface conductor layer. A wiring board was produced by the same method as in 1.

Example 10
Examples except that the substrate having the bonding layer was annealed in a nitrogen atmosphere at a peak temperature of 700 ° C. and a peak temperature holding time of 10 minutes after forming the bonding layer and before printing the Cu paste for the surface conductor layer. A wiring board was produced by the same method as in 8.

As a result, the adhesion of the conductor film was further improved to 82 MPa and 85 MPa in Examples 9 and 10, respectively, by the annealing treatment of the bonding layer. It can be presumed that the reason why the adhesion is improved is that the active metal preferentially reacts with the substrate by the annealing treatment. On the other hand, when the Cu paste for the surface conductor layer is printed and fired at the same time without annealing, a part of the metal components of the bonding layer containing the active metal diffuses and alloys with the Cu paste layer, and the active metal reacts with the substrate. It can be estimated that it will decrease.

Examples 11 and 12
The same method as in Example 1 except that the heat-resistant substrate was changed to an alumina substrate (“96% alumina” manufactured by Kyocera Corporation) and a silicon nitride substrate (manufactured by Toshiba Materials Co., Ltd.) instead of the AlN substrate, respectively. A wiring board was produced. Both types of wiring boards were good in all evaluation items.

Example 13
A wiring board was produced by the same method as in Example 1 except that a Pd metal film (barrier layer) was not formed in the process of forming the bonding layer. As a result, the adhesive force of the conductor film was reduced to 53 MPa as compared with Example 1, but the heat resistance and the etching property were good. Adhesion is also sufficient as a normal metallized film.

Example 14
In the bonding layer forming step, the same method as in Example 1 except that a Ti film (active metal layer) is formed and then a Cu film (surface layer) is formed by a sputtering method without forming a Pd film (barrier layer). The wiring board was manufactured in. As a result, all the evaluation items were good, but the adhesion was improved as compared with Example 13 without the Cu film by the sputtering method. The Cu thin film produced by the sputtering method on the Ti film has the effect of preventing oxidation of the Ti film when exposed to the air after forming the bonding layer and improving the wettability of the Cu paste for the surface conductor layer with respect to the Ti film. , It can be estimated that the adhesion is improved.

Examples 15-18
In the bonding layer forming step, a wiring board was produced by the same method as in Example 1 except that the thickness of the Ti film (active metal layer) was 0.2 μm, 0.15 μm, 0.05 μm and 0.02 μm, respectively. .. As a result, the film thicknesses of 0.15 μm and 0.2 μm were almost the same as those of Example 1 of 0.1 μm, but the adhesion decreased as the film thickness became thinner to 0.05 μm and 0.02 μm. There was a tendency to do. However, even when the film thickness is 0.02 μm, the adhesion is remarkably high as compared with Comparative Example 3 in which there is no active metal film.

Example 19
In the step of forming the surface conductor layer, the same method as in Example 1 except that the Ag paste for the surface conductor layer shown in Table 2 was used instead of the Cu paste A for the surface conductor layer and fired in the air at 600 ° C. for 60 minutes. The wiring board was manufactured in. Even if the paste for the surface conductor layer was changed from Cu to Ag, all the characteristics were good.

Example 20
In the bonding layer forming step of Example 1, after the bonding layer is formed by the sputtering method, in the surface conductor layer forming step, the Cu paste A for the surface conductor layer is printed on the surface of the bonding layer on one side of the substrate. , The pattern of the specified shape was printed directly using the screen plate instead of full-page printing. Then, it was dried at 120 ° C. for 20 minutes. The substrate was fired in a nitrogen atmosphere at a peak temperature of 700 ° C. and a peak holding time of 10 minutes to obtain a metallized substrate having a surface conductor layer (Cu film) having a film thickness of about 9 μm on one side. Then, the substrate was immersed in an etching solution to dissolve and remove the bonding layer existing between the Cu patterns. Since the etching resist was not applied, the Cu pattern film was also slightly dissolved, but the change in the Cu film was small because the etching solution with a higher etching rate for Ti and Pd than Cu was used and the thickness of the bonding layer was thin. rice field.

The subsequent plating step was carried out in the same manner as in Example 1 to obtain a wiring board. This method was also good in all characteristics. The pattern shape was semi-cylindrical, and the pattern shape of Example 1 was superior to the pattern shape of Example 20.

Example 21
A wiring board was obtained by the same method as in Example 1 except that a vacuum vapor deposition method was used instead of the sputtering method as a method for forming the bonding layer. Vacuum deposition was performed at a degree of vacuum of 2 × 10 ^-3 Pa and a substrate heating temperature of 300 ° C. The heat resistance, adhesion, and etching property were almost the same as those of the sputtering method, and all were good.

Example 22
In the same manner as in Example 1, a metallized substrate was obtained by baking a surface conductor layer (Cu film) having a thickness of about 8 μm on one side through a step of forming a bonding layer and a step of forming a surface conductor layer (Cu). A resist pattern for plating was formed on the surface of the Cu film of the obtained metallized substrate. In the plating resist pattern, contrary to the etching resist pattern, the Cu film held as wiring was exposed, and the Cu film in the region to be removed was covered with the resist. The exposed Cu film was plated with Ni / Au in the same manner as in Example 1. The resist film was peeled off from the substrate on which the Cu film was plated, and the Cu / Pd / Ti copper film in the unplated region was removed by etching. That is, at the time of etching, the Ni / Au film on the surface was made to function as a resist. The performance evaluation result of the obtained substrate was the same as that of Example 1.

Example 23
In the bonding layer forming step of Example 1, after the bonding layer was formed by the sputtering method, the etching resist pattern was formed as it was without performing the surface conductor layer forming step by printing Cu paste. After removing the exposed bonding layer by etching, the etching resist was peeled off and removed to obtain a conductor pattern composed of the bonding layer. A Cu film having the same shape as the bonding layer pattern was printed with Cu paste A for the surface conductor layer using a screen plate so as to be laminated on this conductor pattern. A substrate on which a Cu film is printed on a bonding layer is dried at 120 ° C. for 20 minutes, and then fired in a nitrogen atmosphere at a peak temperature of 700 ° C. and a peak holding time of 10 minutes to have a surface conductor (Cu film) pattern having a film thickness of about 9 μm. A metallized substrate was obtained. The obtained metallized substrate was subjected to a plating step in the same manner as in Example 1 to obtain a double-sided wiring board. This method was also good in all characteristics. The pattern shape was semi-cylindrical.

The metallized substrate of the present invention can be used as an electronic substrate such as a circuit board, an electronic component, or a substrate of a semiconductor package.

Claims (4)

An insulating substrate, a bonding layer laminated on at least a part of the surface of the insulating substrate, and containing an active metal layer , a non-permeable layer, and an affinity layer , and laminated on the bonding layer, containing a conductor, and A metallized substrate including a surface conductor layer having a porous structure.
The active metal layer contains at least one active metal selected from the group consisting of Ti, Zr and Cr, or an alloy containing the active metal.
The non-permeable layer contains at least one barrier metal selected from the group consisting of Pd and Pt or an alloy containing the barrier metal, has an average thickness of 0.01 to 0.3 μm, and is an active metal. Intervening between the layer and the surface conductor layer ,
The affinity layer, wherein comprises a metal identical with or capable of alloying metal in the surface conductor layer, and the affinity layer that has contact with the surface conductor layer metallized substrate. Conductors contained in the surface conductor layer, Ni, Pt, Cu, Ag , No placement claim 1 Symbol comprises at least one conductive metal or an alloy containing a conductive metal selected from the group consisting of Au and Al Metallized board. The metallized substrate according to claim 1 or 2, wherein the surface conductor layer has a porosity of 5 to 30% by volume. A bonding layer forming step in which a bonding layer including an active metal layer, a non-permeable layer and an affinity layer is laminated on the surface of an insulating substrate, and a conductor paste for a surface conductor layer containing metal particles and an organic vehicle is applied on the bonding layer. The conductor coating step is performed, and the conductor coating step is performed by heating the metal particles contained in the coated conductor paste to a temperature equal to or higher than the sintering temperature to fire the conductor paste to form a surface conductor layer containing a conductor and having a porous structure. The method for manufacturing a metallized substrate according to any one of claims 1 to 3, which includes the method.