KR102543291B1 - Composition for forming conductor, conductor and manufacturing method thereof, and chip resistor - Google Patents

Abstract

In the firing process using a belt furnace, bonding between the dry film and other members such as a belt does not occur even without using a jig, and a composition for forming a conductor that enables fine-line formation of a conductor pattern, and manufacture thereof provision of methods. A composition for forming a conductor containing a conductive powder, an inorganic powder other than the conductive powder, a glass frit, and an organic vehicle, wherein the inorganic powder has an average particle diameter of 0.3 μm or more and 5.0 μm or less based on SEM measurement, and the conductive powder It has a higher sintering start temperature and is based on the composition for conductor formation etc. which contains 10 mass parts or more and 45 mass parts or less with respect to 100 mass parts of conductive powders.

Description

Composition for forming conductor, conductor and manufacturing method thereof, and chip resistor

The present invention relates to a composition for forming a conductor, a conductor and a method for producing the same, and a chip resistor.

A conductor for forming an electrode or circuit of an electronic component or the like is formed using, for example, a composition for forming a conductor formed by dispersing a conductive powder having high conductivity together with a glass frit or the like in an organic vehicle. The conductor is, for example, coated with a composition for forming a conductor on a ceramic substrate such as an alumina substrate in a required shape by a screen printing method or the like, dried at 120°C to 150°C, and then fired at 600°C to 900°C. is formed

Conventionally, in the case of forming a conductor on the outer surface of a chip component such as a multilayer ceramic capacitor (hereinafter also referred to as "MLCC"), a composition for forming a conductor is applied to the outer surface of the chip component, dried to obtain a dry film, In the process of firing together with chip components, there was a problem that adjacent chip components were bonded to each other or bonded to shelf boards such as ceramics on which chip components were placed. In order to prevent these bonding, a method such as applying alumina or the like powder has been performed in a step after applying the conductor-forming composition, but a step of removing the alumina or the like powder after firing is required, which takes time. Therefore, several proposals have been made to prevent bonding of external electrodes of multilayer ceramic capacitors with other members.

For example, in Patent Literature 1, it is described that metal powder having multiple types of particle shapes, for example, two types of large and small spherical powder and scaly metal powder are used for an electrically conductive paste. . Further, Patent Literature 2 describes a conductive paste containing 1 to 10 wt% of a metal additive having a higher melting point than that of the metal powder as a conductive paste containing metal powder and glass frit. In these conductive pastes, sintering of the metal powder is suppressed during firing, the metal components do not shrink densely, and gaps are formed between the metal components, thereby preventing the glass component that causes bonding from seeping through to the surface of the conductor layer. What can be done is listed.

Further, in Patent Literature 3, it is described that an inorganic powder having an average particle diameter of 0.1 mm or less is used. A method for preventing seizing between MLCC chips or ceramic clusters in which MLCC chips are installed in an MLCC firing step by exposing the inorganic powder on the surface of the conductor layer is described. Further, Patent Literature 4 describes a conductive paste in which the composition of the glass powder is limited in order to control the flowability of the glass and prevent it from exuding to the surface of the conductor layer.

The above problems occur also when manufacturing chip resistors. A chip resistor consists of a pair of conductors (surface electrode and back electrode) formed on the front and back surfaces of a substrate, a resistor formed between the pair of surface electrodes, an insulating protective layer covering the resistor, and an end face of the substrate. and a pair of end face electrodes which conduct the surface electrode and the back electrode. Further, the back electrode formed on the chip resistor is for electrically bonding the chip resistor and the circuit board when the chip resistor is mounted on the circuit board.

A chip resistor is manufactured, for example, by the following method. First, a board|substrate (slit board|substrate) in which slits were put into desired dimensions according to chip size in advance is prepared, and on this board|substrate, the composition for conductor formation is printed so that it may span a slit, and after drying and baking, the surface of the board|substrate A plurality of pairs of conductors (surface electrode and back electrode) are formed on the and back surfaces, respectively. Next, after forming a resistor on the surface of the substrate so that each pair of surface electrodes are disposed on both ends thereof, a glass layer called a precoat is formed on the resistor, and further as a protective layer thereon, for example, form a resin layer. Next, the substrate is divided into strips along the slit to form single-sided electrodes, and after plating, the strip-shaped substrate is further divided to obtain chipped resistors.

For the conductor (surface electrode and back electrode), for example, a composition for forming a conductor obtained by dispersing a conductive powder having high conductivity and a glass frit in an organic vehicle is applied onto a substrate in a required shape by a screen printing method or the like, and 120 After drying at about °C to 150 °C, it is formed by firing at about 600 °C to 900 °C. In the case of forming conductors (surface electrodes and back electrodes) on both sides of a substrate, conventionally, a composition for forming a conductor is printed on one side of a substrate, followed by drying and firing to form a conductor (for example, back electrodes). ) is formed, and thereafter, printing, drying and firing are performed on the other side of the substrate in the same way to form a conductor (for example, a surface electrode).

In recent years, in response to requests for cost reduction and energy saving, simplification of processes from drying to firing has been implemented. For example, in a chip resistor, in the process of forming a conductor (surface electrode and back electrode), a composition for forming a conductor is printed on one surface of a substrate, dried, and dried as a film (for example, a dried film on the back). After forming, and before firing, the composition for forming a conductor is printed on the other side of the substrate and dried to form a dried film (eg, surface dried film). Further, by simultaneously firing the dried films on both surfaces of the substrate, the firing step can be omitted once. However, in such a manufacturing method, for example, when the dry film is fired in a belt furnace, the dry film is always present on the surface facing the belt, and the dry film formed on the surface facing the belt burns the belt during firing. There have been cases where the belt and the conductor are joined by contact with the belt portion of the furnace, and the pattern of the conductor is missing, or the conductor is attached to the belt, and the belt furnace is unusable. In order to prevent such bonding between the belt and the conductor, when the dry film formed on both sides of the substrate is fired, a jig that prevents the dry film from touching other members is required.

On the other hand, in recent years, miniaturization and high density of electrode patterns have been progressing due to requests for miniaturization and large capacity of electronic parts, and a composition for forming conductors capable of forming electrode patterns with finer line widths has been demanded.

Japanese Unexamined Patent Publication No. 8-306580 Japanese Unexamined Patent Publication No. 10-12481 Japanese Unexamined Patent Publication No. 9-129480 Japanese Unexamined Patent Publication No. 2001-297628

However, in the techniques described in Patent Literatures 1 to 4, the following problems were encountered when forming the conductors (surface electrode and back electrode) of the resistor. That is, in the conductive pastes described in Patent Literature 1 and Patent Literature 2, since a gap is formed between the metal components when forming the conductor, the sintering of the conductive powder becomes insufficient, the electrical resistivity of the conductor tends to increase, and a low-resistance conductor It cannot adapt to electrodes of electronic components such as resistors that are required. In addition, in these conductive pastes, since the conductor is easily brittle, the bonding strength between parts through the conductor is easily insufficient, and the surface of the conductor is likely to be rough, so when electrolytic plating is applied on the conductor, acidic There was a problem that the plating solution tended to infiltrate the inside, and the glass component dissolved in the plating solution easily caused a decrease in strength or the like.

Further, in the conductive paste of Patent Document 3, inorganic particles having an average particle diameter of 0.05 mm to 0.2 mm are used in the examples, and the conductive paste containing such large particles is used as a slit substrate for manufacturing chip resistors. In the case of printing on the substrate, inorganic particles ooze through the slits, or when the slit substrate is divided, the inorganic particles drop out, forming holes in the electrode, or the dropped inorganic particles cause contamination, which causes problems in the manufacturing process. may occur. In addition, it is generally considered undesirable to manufacture electronic components so that non-conductive inorganic powder is exposed on the surface, which causes connection failure when mounted on a circuit board and increases the defect rate. .

In addition, in the conductive paste described in Patent Literature 4, an alkali metal oxide is contained in the glass powder, and, for example, when combining a conductor and other members such as a resistor in a chip resistor, the alkali component easily enters the other member. , it may affect the properties of the member. In addition, the composition of the glass powder used in this conductive paste makes it difficult to obtain adhesion strength to the base material when the conductor layer is formed on ceramic, as it is described that it is difficult to wet the ceramic body.

On the other hand, when firing for forming resistor conductors (surface electrodes and back electrodes) as described above using a conventional conductor-forming composition is carried out in a belt furnace, a drying film and other members such as a belt are used. A process to prevent contact with the material is required, which has become an obstacle to process simplification.

In view of the above circumstances, the present invention, for example, in the firing process using a belt furnace, does not cause bonding between the dry film and other members such as a belt even without using a jig, and furthermore, the conductor pattern An object of the present invention is to provide a composition for forming a conductor capable of forming a fine line and a method for producing the same.

In the first aspect of the present invention, a composition for forming a conductor containing a conductive powder, an inorganic powder other than the conductive powder, a glass frit, and an organic vehicle, wherein the inorganic powder has an average particle diameter of 0.3 µm based on SEM measurement A composition for forming a conductor, which is not less than 5.0 μm and has a sintering start temperature higher than that of the conductive powder, and is contained in an amount of 10 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the conductive powder.

In addition, the inorganic powder preferably contains at least one of a metal powder, a metal oxide powder, and a metal powder having an oxide film. Moreover, it is preferable that inorganic substance powder contains at least 1 of copper powder, copper oxide powder, and the copper powder which has an oxide film. Moreover, it is preferable that the organic vehicle contains a binder resin and a solvent, and the binder resin is contained at 1% by mass or more and 10% by mass or less with respect to the composition for forming a conductor. Also, the conductive powder preferably contains at least one of Au, Ag, Pd, and Pt. In addition, when the composition for forming a conductor is placed on a belt using a belt furnace and fired, the amount of the inorganic powder is present on the surface of the conductor rather than inside the conductor, so that the conductive powder for the belt member It is desirable to be able to prevent aging. Moreover, it is preferable to use for formation of at least one of the surface electrode and the back electrode of a chip resistor.

In the second aspect of the present invention, the composition for forming a conductor is applied to at least one surface of a substrate, and the substrate coated with the composition for forming a conductor is dried to remove at least a part of the solvent contained in the composition for forming a conductor. Thus, a dry film is formed on the substrate, the substrate on which the dried film is formed is fired, and the conductive powder contained in the conductor-forming composition is sintered so that more inorganic powder is formed on the surface opposite to the surface in contact with the substrate than inside. A method of making a conductor is provided, comprising forming an existing conductor.

Further, in the method for producing a conductor, the composition for forming the conductor contains a metal powder as an inorganic powder, and the metal powder reacts with oxygen in the air during firing to form a metal oxide powder or a metal powder having an oxide film. can do. Moreover, it is preferable that a metal powder is a copper powder.

In the third aspect of the present invention, as a conductor formed on a substrate using the above conductor-forming composition, the inorganic powder is disposed biasedly on the surface opposite to the surface in contact with the substrate in the conductor. Is provided.

In a fourth aspect of the present invention, an electronic component having a conductor formed using the above composition for forming a conductor is provided.

In a fifth aspect of the present invention, there is provided a chip resistor comprising at least a substrate, a conductor, and a resistor, wherein the conductor is formed using the above conductor-forming composition.

The composition for conductor formation of the present invention can suppress a phenomenon in which a dried film obtained in a conductor manufacturing process is bonded to other members such as a belt in a belt during a firing process. Moreover, the conductor pattern obtained using the composition for conductor formation of this invention can be fine-lined. In addition, the conductor manufacturing method of the present invention can produce a fine-lined conductor pattern simply and efficiently. In addition, even when a conductor obtained by using the above conductor-forming composition is obtained by being placed on a belt in a belt and fired, bonding of the conductor component to the belt is suppressed and can have a low resistance value.

Fig. 1(A) is a cross-sectional view schematically showing an example of a conductor formed on a substrate portion, and Fig. 1(B) is a cross-sectional view in which a part of the conductor is enlarged.
Fig. 2(A) is a cross-sectional view schematically showing an example of a state in which a substrate portion on which a conductor is formed is placed on a belt by a belt, and Fig. 2(B) is a cross-sectional view in which a part of the conductor is enlarged. (C) is a diagram schematically showing a dried film (or conductor).
3 is a flow chart showing an example of a method for producing a conductor.
4 is a schematic diagram showing an example of a chip resistor.
Fig. 5 is a SEM photograph showing the contact portion of the conductor of Example 1 with the belt.
Fig. 6 is a SEM photograph showing the contact portion of the conductor of Comparative Example 1 with the belt.

Hereinafter, an example of each embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4 . In addition, in the drawings, in order to make each configuration easy to understand, some parts are emphasized or some parts are simplified, and the actual structure, shape, scale, etc. may differ.

The composition for forming a conductor of the present embodiment contains conductive powder, inorganic powder other than the conductive powder, glass frit, and an organic vehicle. The composition for forming a conductor can suppress bonding of the obtained conductor to other members by containing the inorganic powder. Hereinafter, with reference to Figs. 1 and 2, a dried film obtained using the composition for forming a conductor of the present embodiment and a formed conductor will be described.

1(A) is a schematic diagram showing an example of a conductor of the present embodiment formed on a substrate portion. The conductor 10 is formed in layers on one or both surfaces of the substrate portion 20 . The conductor 10 is formed by applying a composition for forming a conductor to the substrate 20, drying it, and then firing it. The substrate portion 20 is, for example, a substrate portion (region) forming one chip component among slit substrates. The substrate portion 20 is not particularly limited, and a known substrate can be used. For example, an alumina substrate containing alumina as a main component can be used. In addition, the conductor 10 may be formed on one surface (surface or back surface) of the substrate portion 20, or may be formed on both surfaces (front surface and rear surface).

Fig. 1(B) is an enlarged view showing the portion of the conductor 10 surrounded by the broken line in Fig. 1(A). As shown in Fig. 1(B), the conductor 10 includes an inorganic powder 1 and a conductor portion 2 formed by sintering the conductive powder. The conductor portion 2 contains a metal derived from conductive powder and glass derived from a glass frit. In addition, components derived from the organic vehicle contained in the composition for forming a conductor are removed in the steps of drying and firing.

The inorganic powder 1 is disposed so that more is present on the surface of the conductor 10, at least on the surface opposite to the surface where the conductor 10 and the substrate portion 20 come into contact, than inside. Since the inorganic powder 1 is disposed so as to be biased toward the surface of the conductor 10, the metal component contained in the conductor 10 and other members in contact with the conductor 10 (for example, a belt to a belt) member) can be reduced, and bonding between other members and metal components can be suppressed. When the conductor 10 is used as a conductor of a resistor (at least one of a surface electrode and a back electrode), the thickness of the conductor 10 can be 2 μm or more and 10 μm or less, and is 3 μm or more and 8 μm or less. desirable. In addition, the thickness of a conductor can be measured with a stylus-type surface roughness meter.

2(A) to 2(C) are diagrams schematically showing a dried film or a conductor. The dried film 11 can be obtained by applying the composition for forming a conductor of the present embodiment onto the substrate portion 20 and drying it. The obtained dry film 11 is mounted on the belt member 25 of a belt, for example, as shown in FIG. 2(A). The belt member 25 is in contact with at least a part of the surface of the dry film 11 formed on the substrate portion 20 . Fig. 2(B) is a schematic diagram showing a contact portion between the dry film 11 and the belt member 25 in an enlarged manner. The inorganic powder 1 is substantially uniformly dispersed in the dry film 11, as shown in FIG. 2(B).

Fig. 2(C) is a schematic view showing the dried film 11 or the layered conductor 10 in the step of forming the conductor 10 by firing the dried film 11. As shown in FIG. 2(C), in the firing step, the inorganic powder 1 moves toward the surface of the dry film 11 or the conductor portion 2 (conductor 10), gradually from the inside. There are many on the surface. Although this reason is not particularly limited, since the sintering start temperature of the inorganic powder 1 is higher than the sintering start temperature of the conductive powder, in the firing step, when the conductive powder is sintered, the inorganic powder 1 is a dry film. It is conceivable to move so as to be extruded to the outside (surface) of (11). And in the conductor 10 obtained after baking, the inorganic powder 1 exists more on the surface of the conductor 10 than inside.

In addition, the inorganic powder 1 only needs to be present at least on the surface opposite to the surface in contact with the substrate portion 20, rather than inside the conductor 10, and for example, also on the surface in contact with the substrate portion 20. may exist In addition, the inorganic powder 1 is, for example, reacted with the substrate on the surface in contact with the substrate portion 20 to be alloyed, so that in the conductor obtained, it is biased toward the surface opposite to the surface in contact with the substrate portion 20. It can be. Hereinafter, the inorganic powder 1 will be described in detail.

[Inorganic powder]

In the composition for forming a conductor, the inorganic powder 1 has an average particle diameter (SEM average particle diameter) based on scanning electron microscope (SEM) measurement of 0.3 μm or more and 5.0 μm or less. When the SEM average particle diameter is within the above range, the obtained conductor has a low resistance value, can have excellent conductivity, and can suppress bonding of the conductor to other members. In addition, when the SEM average particle size is within the above range, it can be particularly preferably used for fine-lined electronic parts.

On the other hand, when the SEM average particle size is less than 0.3 μm, the inorganic powder 1 may be embedded in the conductor, and the effect of preventing bonding may be insufficient. In addition, when the SEM average particle diameter exceeds 5.0 μm, the resistivity of the obtained conductor may increase. In addition, the SEM average particle diameter of the inorganic powder (1) was observed using a scanning electron microscope (SEM), photographed at a magnification that can confirm 300 or more particles in which the entire particle shape is visible in the photograph, and observed. The diameter of each particle was calculated from the average value of the longest diameter and the shortest diameter of each particle, and the average value of the diameters of the obtained inorganic powders (sum of calculated diameters of each particle / number of measured particles, number average) was determined. In addition, in other parts of this specification, the SEM average particle diameter has the same meaning. The magnification when observing by SEM can be set arbitrarily as long as 300 or more can be confirmed as described above, but in the case of the inorganic powder used in the present invention, it is preferable to observe in the range of 1,000 to 20,000 times.

As the inorganic powder 1, a powder composed of particles that are not sintered when the conductor-forming composition is fired at a temperature at which the conductive powder can be sintered, can be used. That is, the inorganic powder 1 has a higher sintering start temperature than the conductive powder, and particles that are not sintered when fired (heat treated) at 120°C or more and 900°C or less in an air atmosphere can be used. In the case of using such particles, as described above, when the dried film formed from the conductor-forming composition is fired, the inorganic powder 1 can be distributed biasedly to the surface of the conductor.

The inorganic powder 1 is not particularly limited as long as it is a powder having the above characteristics, and a known powder material used in a composition for forming a conductor can be used. For the inorganic powder 1, for example, ceramic powder or the like can be used, but preferably, at least one of metal powder, metal oxide powder, and metal powder having an oxide film can be used, more preferably , at least one of copper powder, copper oxide powder, and copper powder having an oxide film can be used. When a copper-containing powder is used as the inorganic powder (1), most of the powder is biased toward the side opposite to the surface in contact with the substrate, but the powder remaining on the substrate side also has an effect of improving adhesion to the substrate. desirable.

In addition, as the inorganic powder 1, insulating particles can be used, for example, powder made of the same material as the substrate 11 (for example, alumina powder) can be used.

The inorganic powder (1) is preferably contained in an amount of 10 parts by mass or more and 45 parts by mass or less, and more preferably 15 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the conductive powder. When the content of the inorganic powder (1) is less than 10 parts by mass, the bonding preventing effect may become insufficient. When the content of the inorganic powder 1 is more than 45 parts by mass, the powder tends to be transferred to other adjacent members, or the resistivity of the obtained conductor may increase.

The composition for forming a conductor of the present embodiment contains, in addition to the inorganic powder (1), a conductive powder, a glass frit, and an organic vehicle. These components are not particularly limited, and known powder materials used in compositions for forming conductors can be used. Hereinafter, an example of each component constituting the conductor-forming composition will be described.

[Conductive Powder]

The conductive powder is not particularly limited, and a known conductive powder used in a composition for forming a conductor can be used. The conductive powder may contain, for example, at least one of Au, Ag, Pd, and Pt. Also, the conductive powder may be contained in an amount of 30% by mass or more and 60% by mass or less with respect to the entire composition for forming a conductor.

[Glass Frit]

The glass frit is not particularly limited, and a known glass frit used in a composition for forming a conductor may be used. As the glass frit, for example, a glass frit having an average particle diameter of 0.5 μm or more and 5 μm or less and a softening point of 500° C. or more and 700° C. or less may be used. As the glass frit, it is preferable to use a lead-free glass frit, and specifically, a glass frit containing substantially no alkali metal such as borosilicate glass (SiO ₂ -B ₂ O ₃ type) can be used. The glass frit may contain CaO, BaO, ZnO, TiO ₂ , V ₂ O ₅ or the like as a glass component for the purpose of improving the wettability between the glass and the substrate, the adhesion between the substrate and the conductor, and the oxidation resistance of the conductor. do. Further, the glass frit may be contained in a range of 0.1% by mass or more and 5% by mass or less with respect to the entire composition for forming a conductor.

[Organic vehicle]

The organic vehicle is obtained by dissolving a binder resin in a solvent. The binder resin is not particularly limited, and the same resin as in the prior art can be used, and for example, ethyl cellulose, methacrylate and the like can be used. It is preferable that the binder resin is contained within the range of 1% by mass or more and 10% by mass or less with respect to the composition for forming a conductor. When the content of the binder resin is less than 1% by mass, the handleability of the composition for forming a conductor is poor, and the viscosity characteristics as a paste necessary for forming a conductor may not be obtained. On the other hand, when the content of the binder resin exceeds 10% by mass, the binder resin easily overflows to the surface of the resulting dry film, and the overflowing binder resin covers the inorganic powder 1 and adheres to another member adjacent to the conductor obtained. and other members may be joined.

The solvent is not particularly limited, and known solvents can be used. For example, organic solvents such as terpineol and butylcarbitol can be used.

[Solvent for viscosity adjustment]

The composition for conductor formation of the present embodiment may further contain a solvent for adjusting the viscosity when the paste is produced. The solvent for viscosity adjustment is not particularly limited, and known solvents can be used. For example, organic solvents such as terpineol and butylcarbitol can be used. In addition, the solvent for adjusting the viscosity may be the same as or different from the solvent contained in the above organic vehicle. In addition, the content of the solvent in the entire composition for forming a conductor can be appropriately adjusted, and for example, it can be set within the range of 20% by mass or more and 60% by mass or less with respect to the entire composition for forming a conductor.

The method for producing the conductor-forming composition of the present embodiment is not particularly limited, and a conventionally known production method can be used. For example, the above conductive powder, inorganic powder (1), glass frit, and organic vehicle It can be manufactured by mixing a material containing the with a 3-roll mill or the like.

Fig. 3 is a flow chart showing an example of a method for producing a conductor of the present embodiment produced using the above conductor-forming composition. Hereinafter, with reference to FIG. 3, the manufacturing method of the conductor of this embodiment is demonstrated.

First, the composition for forming a conductor is applied to at least one surface of a substrate (step S1). For application, for example, screen printing or the like can be used. As the substrate, for example, a slit substrate having a slit can be used. The slit substrate is divided along the slit in a subsequent step to form individual chip components. In the case of using a slit substrate, the substrate portion 20 shown in FIGS. 1 and 2 is a substrate portion corresponding to one chip portion in a chip component (eg, chip resistor).

Next, the substrate coated with the composition for forming a conductor is dried to form a dried film on the substrate (step S2). Drying conditions are not particularly limited, as long as at least a part of the solvent contained in the conductor-forming composition can be removed. The drying temperature is, for example, 80°C or higher and 150°C or lower. Drying time is 1 minute or more and 15 minutes or less, for example.

When the composition for forming conductors is applied to both surfaces (front and back surfaces) of a substrate, the composition for forming conductors is applied to one surface of the substrate by screen printing or the like, dried, and then applied to the other surface of the substrate in the same manner. Apply and dry. By this step, as shown in FIG. 2(A), for example, a pair of dried films 11 facing each other with a predetermined gap between the back surface and the front surface of the substrate section 20 can be obtained. .

Next, the substrate on which the dried film is formed is fired (step S3). In the firing step (step S3), the conductive powder contained in the conductor-forming composition is sintered to form a conductor portion 2 as shown in FIG. 1(B). In addition, as the firing progresses, the inorganic powder 1 is more present on the surface than the inside on the opposite side to the surface in contact with the substrate. The sintering conditions are not particularly limited, and conditions in which the conductive powder is sintered can be used, but it is preferable to carry out the sintering in an air atmosphere. The firing temperature is, for example, 600°C or higher and 900°C or lower. In the case of firing using a belt furnace, the peak temperature set at 600 ° C. or more and 900 ° C. or less is set to be maintained for a predetermined time, for example, 1 minute or more and 15 minutes or less, taking into account the conveyance speed.

When the conductor-forming composition contains a metal powder as the inorganic powder 1, the metal powder reacts with oxygen in the air during firing to form a metal oxide powder or a metal powder having an oxide film. When the inorganic powder 1 is a copper powder, the copper powder reacts with oxygen in the atmosphere during firing to form a copper oxide powder or a copper powder having an oxide film. When copper powder is used as the inorganic powder 1, it is preferable because it is also excellent in adhesion to the substrate. In addition, as the inorganic powder 1 used in the composition for forming a conductor, copper oxide powder or copper powder having an oxide film may be directly used.

4 is a schematic diagram showing an example of the resistor of the present embodiment. The resistor 100 includes at least a substrate 20, a conductor 10, and a resistor 30. Moreover, the resistor 100 has a protective layer 40, such as a glass layer or a resin layer, on the resistor 30.

As shown in Fig. 4, the conductor 10 constituting the resistor 100 includes a front electrode 10a and a back electrode 10b. The surface electrode 10a and/or the back electrode 10b are formed using the above composition for forming a conductor. In addition, conductor 10 includes end face electrode 10c. Since the conductor 10 obtained using the above conductor-forming composition has a low resistance value and excellent conductivity, it can be suitably used for fine-lined electronic parts.

Example

Hereinafter, the present invention will be further explained by examples, but the scope of the present invention is not limited by the examples. Hereinafter, details of each Example and Comparative Example will be described.

(Example 1)

[Preparation of Composition for Forming Conductor (Conductive Paste)]

An organic vehicle containing 15% by mass of ethyl cellulose as a binder resin in the organic vehicle and 85% by mass of terpineol as a solvent in the organic vehicle was prepared in advance.

Next, as the conductive powder, 50 parts by mass of Ag powder with respect to the entire conductive paste, 20 parts by mass of Cu powder having an SEM average particle diameter of 1.0 μm with respect to 100 parts by mass of the conductive powder, 3.0 mass% of glass frit with respect to the entire conductive paste, An organic vehicle was added in an amount of 3.0% by mass of ethyl cellulose with respect to the entire conductive paste, mixed using a 3-roll mill (SDY-300 manufactured by Beuler Co., Ltd.), and finally a solvent for adjusting the viscosity was added to prepare a paste-like composition for forming a conductor (conductive paste).

[Production of dry film and conductor]

The obtained conductive paste was printed on a 96% alumina substrate in a predetermined pattern (width 20 mm × length 20 mm) using a screen printing machine, and dried at 150 ° C. for 5 minutes using a belt-type drying furnace to form a dry film (film thickness 15 μm) was formed. Next, the dried film was installed so as to contact the belt in a belt furnace, and fired at a peak temperature of 850°C for 9 minutes for a total of 50 minutes to form a conductor.

[Evaluation of joining with belt]

The formed conductor was evaluated by observing the contact portion with the belt visually or under an optical microscope, and visually observing the presence or absence of bonding and the presence or absence of transfer (adhesion of inorganic powder) to the belt. Table 1 shows the evaluation results. Moreover, the observation result by the optical microscope of the conductor (conductive film) is shown in FIG. A portion indicated by an arrow corresponds to a contact portion (joint portion) with the belt.

[Measurement of thickness of conductor and resistance value]

The thickness of the obtained conductor was measured using a stylus type surface roughness meter (SURFCOM 480A, manufactured by Tokyo Precision Co., Ltd.). Next, the resistance value of the conductor pattern having a width of 0.5 mm and a length of 50 mm was measured using a digital multimeter (manufactured by ADVANTEST Co., Ltd., R6871E), and the resistance value of the previously measured film thickness was converted into a film thickness of 5 μm. The resistance value at the time was calculated. Table 1 shows the measurement results.

(Example 2)

A conductive paste was produced under the same conditions as in Example 1, except that the SEM average particle diameter of the Cu powder was changed to 4.0 µm. Table 1 shows the measurement results.

(Example 3)

A paste was prepared in the same manner as in Example 1, except that the content of Cu powder was changed to 40 parts by mass with respect to 100 parts by mass of the conductive powder. Table 1 shows the measurement results.

(Example 4)

A conductive paste was prepared under the same conditions as in Example 1 except that the Cu powder (inorganic powder) was changed to CuO powder. Table 1 shows the measurement results.

(Example 5)

A conductive paste was prepared under the same conditions as in Example 1 except that the Cu powder (inorganic powder) was changed to an alumina powder. Table 1 shows the measurement results.

(Comparative Example 1)

A paste was produced in the same manner as in Example 1, except that the SEM average particle diameter of the Cu powder was changed to 0.1 µm. Table 1 shows the measurement results.

(Comparative Example 2)

A paste was prepared in the same manner as in Example 1, except that the SEM average particle diameter of the Cu powder was changed to 10.0 µm. Table 1 shows the measurement results.

(Comparative Example 3)

A paste was produced in the same manner as in Example 1, except that the content of Cu powder was changed to 2.0 parts by mass with respect to 100 parts by mass of the conductive powder. Table 1 shows the measurement results.

(Comparative Example 4)

A paste was produced in the same manner as in Example 1, except that the content of Cu powder was changed to 50 parts by mass with respect to 100 parts by mass of the conductive powder.

(Evaluation results)

The conductors obtained in Examples had a film thickness of about 7 μm to 9 μm, and a resistance value in terms of 5 μm was 20 mΩ or more and 40 mΩ or less. Further, the resistance value in terms of 5 μm could be 25 mΩ or less depending on conditions. In addition, as a result of visual and SEM observation of the surface of these conductors, bonding with the belt and transfer to the belt were not confirmed. In FIG. 5, the photograph which observed the part of the belt which mounted the conductor formed using the composition of Example 1 by SEM is shown. Although the part of the belt on which the conductor was placed was confirmed, the constituent components of the conductor and adhesion of the Cu powder were not confirmed.

On the other hand, for the conductor formed using the composition of Comparative Example 1, inorganic powder having an SEM average particle diameter of 0.1 µm was used, and it was visually confirmed that the surface of the portion placed on the belt was deformed. In FIG. 6, the photograph which observed the part of the belt which mounted the conductor part formed using the composition of the comparative example 1 by SEM is shown. As shown in Fig. 6, it was confirmed that the surface of the conductor (film) was peeled off, joined to the belt, and transferred to the conductor formed using the composition of Comparative Example 1.

The conductor formed using the composition of Comparative Example 2 used inorganic powder having an SEM average particle diameter of 10 µm, and exhibited a high resistance value of 51.2 mΩ in terms of 5 µm. In addition, no traces of bonding with the belt were observed on the surface of the conductor, and no adhesion of constituents of the conductor and Cu powder was observed on the part in contact with the conductor in the belt as well.

In the conductor formed using the composition of Comparative Example 3, the inorganic powder content was less than 10 parts by mass, and it was visually confirmed that the surface of the part mounted on the belt was deformed. As a result of SEM observation, it was confirmed that the surface of the conductor was peeled off, bonded to the belt, and transferred.

The conductor formed using the composition of Comparative Example 4 had an inorganic powder content of more than 45 parts by mass and exhibited a resistance value as high as 65.7 mΩ in terms of 5 µm. As a result of visual and SEM observation of the surface of the conductor, bonding with the belt was not confirmed. On the other hand, as a result of confirming the part in contact with the conductor film of the belt, it was confirmed that a part of the Cu powder was transferred.

In addition, the technical scope of this invention is not limited to the said embodiment. For example, one or more of the requirements described in the above embodiments may be omitted. In addition, the requirements described in the above embodiments can be appropriately combined. In addition, as far as permitted by laws and regulations, the contents of all documents cited in Japanese Patent Application No. 2017-104658 and the above-described embodiments are used as part of the description of the text.

1: Inorganic Powder
2: conductor part
10: conductor
10a: surface electrode
10b: back electrode
10c: single-sided electrode
11: dry film
20: board part
25: belt member
30: resistor
40: protective layer
100: resistor

Claims (13)

A composition for forming a conductor containing a conductive powder, an inorganic powder other than the conductive powder, a glass frit, and an organic vehicle,
The inorganic powder has an average particle size of 0.3 μm or more and 5.0 μm or less based on SEM measurement, has a higher sintering start temperature than the conductive powder, and contains 10 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the conductive powder ,
A composition for forming a conductor used for forming at least one of the surface electrode and the back electrode of a chip resistor. According to claim 1,
The inorganic powder contains at least one of a metal powder, a metal oxide powder, and a metal powder having an oxide film, the composition for forming a conductor. According to claim 2,
Wherein the inorganic powder contains at least one of copper powder, copper oxide powder, and copper powder having an oxide film. According to claim 1,
The composition for forming a conductor, wherein the organic vehicle contains a binder resin and a solvent, and the binder resin is contained in an amount of 1% by mass or more and 10% by mass or less with respect to the composition for forming a conductor. According to claim 1,
The composition for forming a conductor, wherein the conductive powder contains at least one of Au, Ag, Pd, and Pt. According to claim 1,
When the composition for forming the conductor is brought into contact with the belt member and calcined using a belt furnace, since the inorganic powder is more present on the surface than the inside of the conductor, it is possible to prevent the conductive powder from saging on the belt member. A composition for forming a conductor. delete Applying the composition for forming a conductor according to any one of claims 1 to 6 on at least one surface of a substrate;
drying the substrate coated with the composition for forming a conductor, removing at least a part of the solvent contained in the composition for forming a conductor, and forming a dried film on the substrate;
The substrate on which the dry film is formed is fired, and the conductive powder contained in the conductor-forming composition is sintered to form a conductor in which the inorganic powder is more present on the surface opposite to the surface in contact with the substrate than inside. A method for producing a conductor comprising: According to claim 8,
The composition for forming a conductor contains a metal powder as the inorganic powder, and the metal powder reacts with oxygen in the air during firing to form a metal oxide powder or a metal powder having an oxide film. According to claim 9,
A method for producing a conductor, wherein the inorganic powder is copper powder. A conductor formed on a substrate using the composition for forming a conductor according to any one of claims 1 to 6, wherein the inorganic powder is biased toward a surface opposite to a surface in contact with the substrate in the conductor. becoming, conductor. An electronic component having a conductor formed using the composition for forming a conductor according to any one of claims 1 to 6. A chip resistor comprising at least a substrate, a conductor, and a resistor, wherein the conductor was formed using the composition for forming a conductor according to any one of claims 1 to 6.

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