JP2009152350A - Manufacturing method of wiring substrate, ink for forming conductor pattern, conductor pattern, and wiring substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a wiring substrate equipped with a conductor pattern having high reliability, and to provide conductor pattern forming ink capable of forming the conductor pattern having stability in discharging droplets and excellent reliability. <P>SOLUTION: This manufacturing method of the wiring substrate includes a process to give ink containing an aqueous dispersion medium, metal particles, and sugar-alcohol onto a ceramic molded body containing ceramic particles and binder by a droplet discharge method, a process to form a laminated body by pressure-bonding and laminating a plurality of ceramic molded bodies on which a pattern is formed, and a process to form the wiring substrate having a ceramic substrate and a conductor pattern by sintering the laminated body. The melting point of sugar alcohol is higher than the glass transition temperature of the binder contained in the ceramic molded body, and the temperature of the ceramic molding in the press-bonding process is higher than the glass transition temperature of the binder and lower than the melting point of sugar alcohol. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a wiring board, a conductive pattern forming ink, a conductive pattern, and a wiring board.

  As a circuit board (wiring board) on which electronic components are mounted, a ceramic circuit board in which wiring made of a metal material is formed on a board made of ceramics (ceramic board) is widely used. In such a ceramic circuit board, since the board (ceramic board) itself is made of a multifunctional material, it is advantageous in terms of formation of interior parts by multi-layering, dimensional stability, and the like.

  Such a ceramic circuit board is provided with a composition containing metal particles in a pattern corresponding to a wiring (conductor pattern) to be formed on a ceramic molded body made of a material containing ceramic particles and a binder. Thereafter, the ceramic molded body to which the composition is applied is manufactured by degreasing and sintering. Moreover, such a ceramic circuit board is generally manufactured as a laminate in which a plurality of ceramic substrates and a plurality of conductor patterns are alternately laminated for the purpose of improving the wiring density.

By the way, a screen printing method is widely used as a method for forming a pattern on a ceramic molded body. On the other hand, in recent years, miniaturization of wiring (for example, wiring with a line width of 60 μm or less) and high density circuit boards by narrowing the pitch have been demanded. It is disadvantageous for pitching and it is difficult to meet the above requirements.
Therefore, in recent years, a so-called ink jet method has been proposed as a method for forming a pattern on a ceramic molded body, in which a liquid material containing metal particles (ink for forming a conductor pattern) is ejected in droplets from a liquid ejection head. (For example, refer to Patent Document 1).

  However, with the conventional conductor pattern forming ink, the dispersion medium of the conductor pattern forming ink is in the vicinity of the droplet ejection portion of the droplet ejection head (inkjet head) during ejection standby or when ejected continuously for a long time. There has been a problem that conductive fine particles are precipitated by volatilization of the liquid. When conductive fine particles are deposited in the vicinity of the droplet ejection portion in this way, the trajectory of the ejected droplet changes (so-called flight bending occurs), making it impossible to land the droplet on the target site. In some cases, the droplet discharge amount may become unstable. In such a case, it is difficult for the pattern formed on the substrate with the conventional conductor pattern forming ink to have a sufficiently uniform thickness and width.

  Further, conventionally, when a ceramic molded body is laminated from the pattern formed on the ceramic molded body or when the pattern is sintered, cracks are easily generated in the pattern, and as a result, the formed conductor Some patterns were easily broken. In particular, the occurrence of such a problem has been remarkable with the recent increase in the density of circuit boards due to the miniaturization of wiring and the reduction in pitch.

JP 2007-84387 A

  An object of the present invention is to provide a method of manufacturing a wiring board provided with a highly reliable conductor pattern, and to provide a conductor pattern forming ink capable of forming a highly reliable conductor pattern with excellent droplet ejection stability. Another object is to provide a highly reliable conductor pattern and to provide a highly reliable wiring board having such a conductor pattern.

Such an object is achieved by the present invention described below.
The method for manufacturing a wiring board according to the present invention includes an aqueous dispersion medium, a conductive pattern forming ink containing metal particles and sugar alcohol dispersed in an aqueous dispersion medium by a droplet discharge method, and a material containing ceramic particles and a binder. An ink application step of applying a predetermined pattern on the formed ceramic molded body;
A laminated body forming step of forming a laminated body by laminating the ceramic formed body on which the pattern is formed by press bonding a plurality of sheets under heating;
A sintering step of forming a wiring board having a ceramic substrate and a conductor pattern by sintering the laminate;
The melting point of the sugar alcohol is higher than the glass transition temperature of the binder contained in the ceramic molded body,
The temperature of the ceramic molded body in the laminate forming step is higher than the glass transition temperature of the binder and lower than the melting point of the sugar alcohol.
Thereby, the manufacturing method of the wiring board provided with the highly reliable conductor pattern can be provided.

In the method for manufacturing a wiring board according to the present invention, it is preferable that the laminated body forming step is to press-bond a plurality of the ceramic molded bodies by an isostatic pressing method.
Thereby, the manufacturing method of the wiring board provided with the highly reliable conductor pattern can be provided.
In the method for manufacturing a wiring board according to the present invention, it is preferable that the ink application step heats the ceramic molded body to 40 to 80 ° C.
Thereby, a finer pattern can be formed easily and a more reliable conductor pattern can be manufactured.

The conductive pattern forming ink of the present invention is a conductive pattern forming ink used for forming a conductive pattern, which is applied to a ceramic molded body made of a material containing ceramic particles and a binder by a droplet discharge method. And
The ceramic molded body is laminated and sintered in a state where a conductive pattern forming ink is applied,
An aqueous dispersion medium, metal particles dispersed in the aqueous dispersion medium, and a sugar alcohol,
The melting point of the sugar alcohol is higher than the glass transition temperature of the binder contained in the ceramic molded body.
As a result, it is possible to provide a conductive pattern forming ink that can form a highly reliable conductive pattern with excellent droplet ejection stability.

In the conductive pattern forming ink of the present invention, it is preferable that the sugar alcohol contains at least two kinds of components.
This makes it possible to more reliably prevent the sugar alcohol from precipitating as crystals while making the ink for forming the conductor pattern particularly excellent, and more reliably prevent disconnection and cracks from forming in the conductor pattern. can do.

In the conductive pattern forming ink of the present invention, it is preferable that the sugar alcohol contains a sugar alcohol derived from a monosaccharide.
Thereby, the discharge stability of the droplet can be made particularly excellent, and the reliability of the formed conductor pattern can be made particularly high.
In the conductive pattern forming ink of the present invention, it is preferable that the sugar alcohol contains a sugar alcohol derived from a disaccharide.
Thereby, it can prevent more reliably that sugar alcohol precipitates as a crystal | crystallization, and can prevent more reliably the generation | occurrence | production of a disconnection and a crack in the conductor pattern to form.

In the conductive pattern forming ink of the present invention, the sugar alcohol preferably has a melting point of 90 to 200 ° C.
Thereby, it can prevent more reliably that sugar alcohol precipitates as a crystal | crystallization, and can prevent more reliably the generation | occurrence | production of a disconnection and a crack in the conductor pattern to form.
In the conductive pattern forming ink of the present invention, the conductive pattern forming ink preferably contains a polyglycerin compound.
Thereby, it can prevent more reliably that sugar alcohol precipitates as a crystal | crystallization, and can prevent more reliably the generation | occurrence | production of a disconnection and a crack in the conductor pattern to form.

In the conductive pattern forming ink of the present invention, the binder preferably has a glass transition temperature of 25 to 95 ° C.
Thereby, it can prevent more reliably that sugar alcohol precipitates as a crystal | crystallization, and can prevent more reliably the generation | occurrence | production of a disconnection and a crack in the conductor pattern to form.
In the ink for forming a conductor pattern of the present invention, the binder of the ceramic molded body preferably contains polyvinyl butyral.
Polyvinyl butyral has a moderate affinity with the conductor pattern forming ink of the present invention, so that a pattern having a desired shape can be formed more accurately, and the formed conductor pattern has a particularly high reliability. Become.

The conductor pattern of the present invention is formed by the conductor pattern forming ink of the present invention.
Thereby, a highly reliable conductor pattern can be provided.
The wiring board of the present invention is provided with the conductor pattern of the present invention.
Thereby, a highly reliable wiring board can be provided.
The wiring board of the present invention is manufactured by the method for manufacturing a wiring board of the present invention.
Thereby, a highly reliable wiring board can be provided.

Hereinafter, preferred embodiments of the present invention will be described in detail.
First, prior to the method for manufacturing a wiring board of the present invention, a conductor pattern forming ink and a method for manufacturing the conductor pattern forming ink used for manufacturing the wiring board will be described.
<Conductor pattern forming ink>
The ink for forming a conductor pattern of the present invention is an ink used for forming a conductor pattern on a ceramic substrate, in particular, an ink used for forming a conductor pattern by a droplet discharge method. In the present embodiment, the description will be made assuming that the ink for forming a conductor pattern is applied to a sheet-like ceramic formed body (ceramic green sheet) made of a material containing ceramics and a binder. The ceramic molded body and the ink pattern (precursor) applied to the ceramic molded body are sintered as described later to become a ceramic substrate and a conductor pattern, respectively.

Hereinafter, preferred embodiments of the conductor pattern forming ink will be described. In this embodiment, a case where a dispersion liquid in which silver particles are dispersed is used as a dispersion liquid in which metal particles are dispersed in an aqueous dispersion medium.
The conductive pattern forming ink (hereinafter also simply referred to as ink) contains an aqueous dispersion medium, silver particles dispersed in the aqueous dispersion medium, and a sugar alcohol.

Hereinafter, each component of the conductor pattern forming ink will be described in detail.
[Aqueous dispersion medium]
First, the aqueous dispersion medium will be described.
In the present invention, the “aqueous dispersion medium” refers to a liquid composed of water and / or a liquid having excellent compatibility with water (for example, a liquid having a solubility in 100 g of water at 25 ° C. of 30 g or more). As described above, the aqueous dispersion medium is composed of water and / or a liquid having excellent compatibility with water, but is preferably composed mainly of water. It is preferably 70 wt% or more, more preferably 90 wt% or more.

Specific examples of the aqueous dispersion medium include, for example, water, methanol, ethanol, butanol, propanol, isopropanol and other alcohol solvents, 1,4-dioxane, tetrahydrofuran (THF) and other ether solvents, pyridine, pyrazine, pyrrole and the like. Aromatic heterocyclic compound solvents, amide solvents such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA), nitrile solvents such as acetonitrile, and aldehyde solvents such as acetaldehyde. Of these, one or a combination of two or more can be used.
In addition, the content of the aqueous dispersion medium in the conductor pattern forming ink is preferably 25 to 60 wt%, and more preferably 30 to 50 wt%. Thereby, while making the viscosity of an ink suitable, the change of the viscosity by volatilization of a dispersion medium can be made small.

[Silver particles]
Next, silver particles (metal particles) will be described.
Silver particles are the main component of the conductor pattern to be formed, and are components that impart conductivity to the conductor pattern.
The silver particles are dispersed in the ink.

The average particle diameter of the silver particles is preferably 1 to 100 nm, and more preferably 10 to 30 nm. Thereby, it is possible to make the ink ejection property higher, and it is possible to easily form a fine conductor pattern.
In addition, the content of silver particles (silver particles in which the dispersant is not adsorbed on the surface) contained in the ink is preferably 0.5 to 60 wt%, and more preferably 10 to 45 wt%. Thereby, disconnection of a conductor pattern can be prevented more effectively, and a more reliable conductor pattern can be provided.
The silver particles (metal particles) are preferably dispersed in an aqueous dispersion medium as silver colloid particles (metal colloid particles) having a dispersant attached to the surface thereof. Thereby, the dispersibility of the silver particles in the aqueous dispersion medium is particularly excellent, and the ink droplet discharge property is particularly excellent.

  The dispersant is not particularly limited, but may contain a hydroxy acid or a salt thereof having three or more COOH groups and OH groups in total and having the same or more COOH groups as the OH groups. preferable. These dispersants adsorb on the surface of silver particles to form colloidal particles, and the colloidal liquid is stabilized by uniformly dispersing silver colloidal particles in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Has the function of As described above, since the silver colloid particles are stably present in the ink, a fine conductor pattern can be more easily formed. Further, the silver particles are uniformly distributed in the pattern (precursor) formed by the ink, and cracks, disconnections, and the like are less likely to occur. On the other hand, if the number of COOH groups and OH groups in the dispersant is less than 3 or the number of COOH groups is less than the number of OH groups, the dispersibility of the silver colloid particles cannot be sufficiently obtained. There is a case.

Such dispersants include, for example, citric acid, malic acid, trisodium citrate, tripotassium citrate, trilithium citrate, triammonium citrate, disodium malate, tannic acid, gallotannic acid, pentaploid tannin and the like. 1 type or 2 types or more of them can be used in combination.
Further, the dispersant may contain mercapto acid or a salt thereof having two or more COOH groups and SH groups. In these dispersants, mercapto groups are adsorbed on the surface of silver fine particles to form colloidal particles, and colloidal particles are uniformly dispersed in an aqueous solution by the electric repulsive force of COOH groups present in the dispersant. Has the function of stabilizing As described above, since the silver colloid particles are stably present in the ink, a fine conductor pattern can be more easily formed. Further, the silver particles are uniformly distributed in the pattern (precursor) formed by the ink, and cracks, disconnections, and the like are less likely to occur. On the other hand, when the number of COOH groups and SH groups in the dispersant is less than 2, that is, only one, the dispersibility of the silver colloidal particles may not be sufficiently obtained.

  Examples of such a dispersant include mercaptoacetic acid, mercaptopropionic acid, thiodipropionic acid, mercaptosuccinic acid, thioacetic acid, sodium mercaptoacetate, sodium mercaptopropionate, sodium thiodipropionate, disodium mercaptosuccinate, Examples include potassium mercaptoacetate, potassium mercaptopropionate, potassium thiodipropionate, dipotassium mercaptosuccinate, and the like, and one or more of these can be used in combination.

  The content of the silver colloid particles in the ink is preferably about 1 to 60 wt%, and more preferably about 10 to 50 wt%. When the content of the silver colloidal particles is less than the lower limit, the silver content is small, and when a conductive pattern is formed, it is necessary to apply a plurality of times when a relatively thick film is formed. On the other hand, when the content of the silver colloidal particles exceeds the upper limit, the silver content increases and the dispersibility decreases. To prevent this, the frequency of stirring increases.

The heat loss up to 500 ° C. in the thermogravimetric analysis of the silver colloidal particles is preferably about 1 to 25 wt%. When the colloidal particles (solid content) are heated to 500 ° C., the dispersant adhering to the surface, the reducing agent (residual reducing agent) described later, etc. are oxidatively decomposed, and most of them are gasified and disappear. Since the amount of the residual reducing agent is considered to be small, the weight loss due to heating up to 500 ° C. is considered to substantially correspond to the amount of the dispersant in the silver colloid particles. When the loss on heating is less than 1 wt%, the amount of the dispersant for the silver particles is small, and the sufficient dispersibility of the silver particles is lowered. On the other hand, when it exceeds 25 wt%, the amount of the residual dispersant with respect to the silver particles increases, and the specific resistance of the conductor pattern increases. However, the specific resistance can be improved to some extent by heating and sintering after formation of the conductor pattern to decompose and disappear organic components. Therefore, it is effective for a ceramic substrate that is sintered at a higher temperature.
The formation of silver colloid particles will be described in detail later.

[Sugar alcohol]
The conductive pattern forming ink of the present invention contains sugar alcohol.
Sugar alcohol is obtained by reducing aldehyde groups and ketone groups of sugars.
By the way, when a pattern is formed using the conventional ink for forming a conductor pattern, the aqueous dispersion medium tends to volatilize in the vicinity of the discharge portion, and the discharge of the droplet becomes unstable. For this reason, it is difficult to form a pattern having a uniform film thickness and line width. As a result, cracks or the like were generated from thin portions of the pattern when the ceramic molded body was laminated or sintered, and the formed conductor pattern had many cracks, disconnections, etc., and was inferior in reliability.

  In contrast, the conductor pattern forming ink of the present invention contains sugar alcohol. Sugar alcohol is generally a component excellent in moisture retention, and can contribute to preventing volatilization of the dispersion medium of the conductor pattern forming ink. For this reason, the sugar alcohol is contained in the conductor pattern forming ink, whereby the aqueous dispersion medium can be prevented from volatilizing in the vicinity of the discharge portion of the ink jet apparatus, and the increase in the viscosity of the ink and the drying can be suppressed. As a result, the ejection stability of the ink droplets is excellent. That is, variation in the weight of ink droplets is small, and clogging, flight bending, and the like are small. In particular, even when the ink jet device is in a standby state without being operated for a long time (for example, 5 days) after the ink for forming the conductor pattern is filled in the ink jet device, the conductor pattern forming ink of the present invention is used. The ink can be ejected with a uniform amount to a target position with high accuracy.

  In addition, in the pattern (precursor) formed by the conductor pattern forming ink, the aqueous dispersion medium volatilizes and the sugar alcohol concentration increases when dried (dehydrated dispersion medium). As a result, the viscosity of the conductor pattern precursor is increased, so that the ink constituting the precursor can be more reliably prevented from flowing to an unintended portion. As a result, the formed conductor pattern can be formed into a desired shape with higher accuracy.

  In addition, since the droplet of the conductive pattern forming ink applied on the ceramic molded body contains sugar alcohol, it is prevented from being completely dried in the step of applying the ink. Thereby, even if it is a case where the droplet of an ink is further provided on the droplet, droplets can be mixed and adhered suitably. For this reason, a pattern having a desired shape can be formed with a uniform film thickness and width, and a highly reliable conductor pattern can be formed. In addition, a conductive pattern having a relatively large thickness can be formed by applying ink droplets to the same location a plurality of times.

As described above, a pattern having a uniform thickness and width can be easily formed with ink, and the obtained conductor pattern has a uniform thickness and width.
In addition, since sugar alcohol has a large number of oxygen per molecular weight, it is easily decomposed and removed when the atmosphere reaches the decomposition temperature of sugar alcohol. For this reason, when forming a conductor pattern, sugar alcohol can be reliably removed (oxidative decomposition) from within the conductor pattern by setting the temperature of the pattern higher than the decomposition temperature of the sugar alcohol.

By the way, a plurality of ceramic molded bodies on which a pattern is formed are laminated and sintered. When laminating ceramic molded bodies, generally, the ceramic molded bodies are pressure-bonded to each other while being heated to a sufficiently high temperature. The present inventors have found that when the conductive alcohol is simply included in the conductive pattern forming ink, the formed conductive pattern is disconnected.
For this reason, as a result of intensive studies to solve the above problems, the present inventors have found that the sugar alcohol is melted at the time of pressure bonding, and the sugar alcohol is converted into crystals in the ceramic molded body cooled until the subsequent process. Further, it was found that the precipitated crystal was damaged to the precursor.

  Therefore, the present inventors have reached the present invention. That is, by making the melting point of the sugar alcohol contained in the conductor pattern forming ink higher than the glass transition temperature of the binder contained in the ceramic molded body, it is possible to prevent disconnection from occurring in the formed conductor pattern. I found. This is considered as follows. At the time of pressure bonding, the ceramic molded body is heated to a temperature equal to or higher than the glass transition temperature of the contained binder. At this time, since the melting point of each component of the sugar alcohol is higher than the glass transition temperature of the binder, each component of the sugar alcohol is maintained in a state of being dispersed in the conductor pattern without melting. For this reason, sugar alcohol is prevented from precipitating as crystals even when the laminate of ceramic molded bodies is cooled. As a result, in the laminate of the ceramic molded body, the pattern (precursor) is preferably prevented from being damaged by the sugar alcohol crystals, and thus the formed conductor pattern is prevented from being disconnected or the like. It will be highly reliable.

  On the other hand, when the melting point of the sugar alcohol contained in the conductor pattern forming ink is equal to or lower than the glass transition temperature of the binder contained in the ceramic molded body, the sugar alcohol exceeds the melting point during lamination and pressure bonding of the ceramic molded body. It will be heated. As a result, the sugar alcohol in the pattern melts and precipitates as crystals when the ceramic molded body is cooled. As a result, the formed conductor pattern has many disconnections and damages and is inferior in reliability.

  Moreover, the melting point of the sugar alcohol of the conductor pattern forming ink is not limited as long as it is higher than the glass transition temperature of the binder of the ceramic molded body, but preferably 3 ° C. higher than the glass transition temperature of the binder of the ceramic molded body. More preferably, it is 5 ° C higher. Thereby, it is possible to prevent the sugar alcohol crystals from being more reliably precipitated, and the formed conductor pattern is particularly reliable.

As will be described later, the temperature at the time of lamination of the ceramic molded body can be lower than the melting point of the sugar alcohol and higher than the glass transition temperature of the binder.
Moreover, in this specification, melting | fusing point of sugar alcohol can be measured based on JISK0064, for example. Moreover, in this specification, the glass transition temperature of components, such as a binder, can be measured based on JISK7121.

  The sugar alcohol that can be used in the conductive pattern forming ink is not particularly limited as long as it is higher than the glass transition temperature of the binder. For example, threitol, erythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, arabitol. , Ribitol, xylitol, sorbitol, mannitol, threitol, glycol, tallitol, galactitol, allitol, altitol, dolcitol, idiitol, glycerin (glycerol), inositol, maltitol, isomaltitol, lactitol, tunitol, etc. 1 type or 2 types or more can be used in combination.

Among the above-mentioned, it is preferable to include a sugar alcohol derived from a monosaccharide as the sugar alcohol. A sugar alcohol derived from a monosaccharide is particularly excellent in moisture retention, and the discharge stability of the conductor pattern forming ink can be particularly improved.
Among the above, the sugar alcohol preferably contains one or more selected from erythritol, xylitol, sorbitol, mannitol, galactitol, and inositol as a sugar alcohol derived from a monosaccharide. These sugar alcohols are particularly excellent in moisture retention in the ink, and can make the discharge stability of the conductor pattern forming ink particularly excellent.

  Moreover, among the above-mentioned, it is preferable that the sugar alcohol derived from a disaccharide is included as sugar alcohol. A sugar alcohol derived from a disaccharide is a sugar alcohol that has a relatively high melting point and is difficult to crystallize. In addition, when a plurality of types of components as sugar alcohols are contained in the conductor pattern forming ink, the sugar alcohol derived from disaccharide can reliably prevent other sugar alcohols from being precipitated as crystals. From the above, it is possible to prevent sugar alcohol crystals from depositing more reliably and damaging the pattern before and after lamination of the ceramic molded bodies.

  Moreover, among the above-mentioned, it is preferable that sugar alcohol contains 1 type, or 2 or more selected from maltitol and lactitol as sugar alcohol derived from a disaccharide. These sugar alcohols are sugar alcohols that are particularly difficult to crystallize. Further, when a plurality of types of components as sugar alcohols are contained in the conductor pattern forming ink, it is possible to more reliably prevent other sugar alcohol components from being precipitated as crystals. Thereby, the formed conductor pattern has particularly high reliability.

Further, the conductor pattern forming ink preferably contains at least two kinds of components as sugar alcohol. As described above, by mixing a plurality of types of components as the sugar alcohol, the components interfere with each other and crystallization of the components can be prevented more reliably. Thereby, the formed conductor pattern has particularly high reliability.
In particular, when the conductor pattern forming ink contains sugar alcohols derived from monosaccharides and sugar alcohols derived from disaccharides as sugar alcohols, the water retention is particularly excellent, and sugar alcohols are particularly crystallized. It becomes difficult to precipitate. As a result, the conductor pattern forming ink has particularly excellent droplet ejection stability, and can form a pattern with uniform film pressure and line width. In addition, the formed conductor pattern is highly reliable in that crack disconnection and the like are more reliably prevented.

  In such a case, when the content of the monosaccharide-derived sugar alcohol in the conductive pattern forming ink is A [wt%] and the content of the disaccharide-derived sugar alcohol is B [wt%], 1 It is preferable to satisfy the relationship of ≦ A / B ≦ 12, and it is more preferable to satisfy the relationship of 3 ≦ A / B ≦ 9. Thereby, the ink for forming a conductor pattern can more reliably prevent the sugar alcohol from being precipitated as crystals while making the water retention particularly excellent.

  Although it will not specifically limit if melting | fusing point of sugar alcohol is higher than the glass transition temperature of a binder, It is preferable that it is 90-200 degreeC, and it is more preferable that it is 90-180 degreeC. Thereby, sugar alcohol can be more reliably removed during sintering while preventing crystallization of sugar alcohol more reliably. For this reason, sugar alcohol is prevented from remaining in the conductor pattern after sintering and lowering the resistance value and the like. That is, the formed conductor pattern has a particularly high reliability.

When a plurality of types of sugar alcohols are included, the melting point of the sugar alcohol as described above can be the melting point of the sugar alcohol having the lowest melting point among the plurality of types of sugar alcohols.
In addition, the sugar alcohol content in the conductor pattern forming ink is preferably 3 to 20 wt%, and more preferably 5 to 15 wt%. Thereby, volatilization of the aqueous dispersion medium of the conductor pattern forming ink can be more reliably suppressed, and the conductor pattern forming ink has particularly excellent droplet discharge stability over a longer period of time. On the other hand, if the content of the sugar alcohol contained in the ink is less than the lower limit, the moisture retention of the ink may not be sufficiently increased depending on the composition of the ink. On the other hand, if the upper limit is exceeded, the amount of sugar alcohol with respect to the silver particles becomes too large and tends to remain during sintering. As a result, the specific resistance of the conductor pattern is increased. However, the specific resistance can be improved to some extent by controlling the sintering time and the sintering environment.

[Organic binder]
The conductive pattern forming ink may contain an organic binder. The organic binder prevents aggregation of silver particles in a pattern formed by the conductor pattern forming ink. That is, in the formed pattern, the organic binder is present between the silver particles, so that the silver particles can be prevented from agglomerating and a crack (crack) can be prevented from being generated in a part of the pattern. Further, at the time of sintering, the organic binder can be decomposed and removed, and silver particles in the pattern are bonded to form a conductor pattern. As described above, when a conductor pattern forming ink containing an organic binder is used, it is possible to easily form a conductor pattern having a desired shape while more reliably preventing the occurrence of cracks and disconnections.

  Although it does not specifically limit as an organic binder, For example, polyethyleneglycol # 200 (weight average molecular weight 200), polyethyleneglycol # 300 (weight average molecular weight 300), polyethyleneglycol # 400 (average molecular weight 400), polyethyleneglycol # 600 ( Weight average molecular weight 600), polyethylene glycol # 1000 (weight average molecular weight 1000), polyethylene glycol # 1500 (weight average molecular weight 1500), polyethylene glycol # 1540 (weight average molecular weight 1540), polyethylene glycol # 2000 (weight average molecular weight 2000), etc. Polyethylene glycol, polyvinyl alcohol # 200 (weight average molecular weight: 200), polyvinyl alcohol # 300 (weight average molecular weight: 300), polyvinyl alcohol # 400 (average molecular weight: 400), polyvinyl alcohol # 600 (weight average molecular weight: 600), polyvinyl alcohol # 1000 (weight average molecular weight: 1000), polyvinyl alcohol # 1500 (weight average molecular weight: 1500), polyvinyl alcohol # 1540 (weight average molecular weight: 1540), polyvinyl alcohol such as polyvinyl alcohol # 2000 (weight average molecular weight: 2000), polyglycerol compounds having a polyglycerol skeleton such as polyglycerol, polyglycerol ester, etc. Alternatively, two or more kinds can be used in combination. Examples of the polyglycerol ester include polyglycerol monostearate, tristearate, tetrastearate, monooleate, pentaoleate, monolaurate, monocaprylate, polycinnolate, sesquistearate, decaoleate, and sesquioleate. Etc.

Among these, when a polyglycerin compound is used as the organic binder, the following effects can be obtained.
The polyglycerin compound particularly suitably prevents the pattern from cracking when a pattern (a conductor pattern precursor, which will be described in detail later) formed by the conductor pattern forming ink is dried (dedispersion medium). be able to. This is considered as follows. When the polyglycerin compound is contained in the conductive pattern forming ink, a polymer chain exists between the silver particles (metal particles), and the polyglycerin compound can keep the distance between the silver particles. Furthermore, since the polyglycerin compound has a relatively high boiling point, it is not removed when the aqueous dispersion medium is removed, and adheres around the silver particles. As described above, at the time of removing the aqueous dispersion medium, the polyglycerin compound continuously encapsulates the silver particles, and as a result, rapid volume shrinkage due to volatilization of the aqueous dispersion medium is avoided and silver grain growth (aggregation) is hindered. It is considered that the occurrence of cracks in the pattern is suppressed.

  Further, the polyglycerin compound can more reliably prevent disconnection from occurring during sintering when forming the conductor pattern. This is considered as follows. Polyglycerin compounds have a relatively high boiling point or decomposition temperature. For this reason, in the process of forming the conductor pattern from the conductor pattern forming ink, it can exist in the pattern formed of the ink even at a relatively high temperature.

Further, until the polyglycerin compound evaporates or is thermally (oxidized) decomposed, the polyglycerin compound is present around the silver particles, and the approach and aggregation of the silver particles can be suppressed, and the polyglycerin compound is decomposed. Later, the silver particles can be joined more uniformly.
Furthermore, a polymer chain (polyglycerin compound) exists between silver particles (metal particles) in the pattern during sintering, and the polyglycerin compound can keep the distance between the silver particles. Moreover, this polyglycerin compound has moderate fluidity | liquidity. For this reason, by including a polyglycerin compound, the precursor of the conductor pattern has excellent followability to expansion / contraction due to temperature change of the ceramic molded body.

From the above, it is considered that disconnection of the formed conductor pattern can be more reliably prevented.
Furthermore, the polyglycerol compound and the sugar alcohol have high affinity. For this reason, when the organic binder contains a polyglycerin compound, the sugar alcohol is more reliably prevented from crystallizing during the lamination of the ceramic molded body.

Moreover, by including such a polyglycerin compound, the viscosity of the ink can be made more appropriate, and the ejection stability from the ink jet head can be improved more effectively. In addition, film formability can be improved.
In addition, since the polyglycerol compound contains a relatively large amount of oxygen atoms in the molecule, it is easily and reliably decomposed and removed from the pattern by placing it in an atmosphere at a decomposition temperature or higher during sintering. .

  Among the above-mentioned polyglycerin compounds, polyglycerin is preferably used. Since polyglycerin has a particularly high affinity with sugar alcohol, the fluidity in ink is sufficiently high. For this reason, the pattern formed with the ink can have sufficiently high fluidity during drying and sintering. Moreover, it can prevent more reliably that sugar alcohol crystallizes. As a result, the conductor pattern formed is more reliably prevented from being broken or cracked. Furthermore, since polyglycerin has high solubility in an aqueous dispersion medium, it can be suitably used.

  Moreover, as an organic binder, it is preferable to use the thing whose weight average molecular weight is 300-3000, It is more preferable to use what is 400-1000, It is still more preferable to use what is 400-600. Thereby, when the pattern formed with the conductor pattern forming ink is dried, the occurrence of cracks can be more reliably prevented. In addition, the affinity between the organic binder and the sugar alcohol is sufficiently high, and the pattern formed by the ink during sintering can maintain the fluidity for a longer period of time due to the temperature change of the ceramic molded body. The followability to shrinkage and expansion is particularly excellent. On the other hand, when the weight average molecular weight of the organic binder is less than the lower limit, depending on the composition of the organic binder, the organic binder tends to be decomposed when removing the aqueous dispersion medium, thereby preventing the occurrence of cracks. The effect is reduced. When the weight average molecular weight of the organic binder exceeds the upper limit, the solubility and dispersibility in the ink may be reduced depending on the composition of the organic binder due to the excluded volume effect or the like.

  In addition, the content of the organic binder in the ink is preferably 1 to 40 wt%, and more preferably 5 to 20 wt%. This makes it possible to more effectively prevent the occurrence of cracks and disconnections while making the ink ejection stability particularly excellent. On the other hand, when the content of the organic binder is less than the lower limit, the effect of preventing the occurrence of cracks may be reduced depending on the composition of the organic binder. If the content of the organic binder exceeds the upper limit, it may be difficult to make the viscosity of the ink sufficiently low depending on the composition of the organic binder.

  Further, when the content of the sugar alcohol having crystallinity in the conductive pattern forming ink is X [wt%] and the content of the organic binder is Y [wt%], 0.5 ≦ X / Y ≦ It is preferable that the relationship of 20 is satisfied, and it is more preferable that the relationship of 1.0 ≦ X / Y ≦ 10 is satisfied. As a result, it is possible to ensure sufficient fluidity of the pattern while reliably preventing the formed pattern from absorbing moisture, and the formed conductor pattern is more reliably prevented from being broken or cracked. It will be. Further, the ink ejection stability can be made particularly excellent.

[Other ingredients]
In addition to the above components, the conductive pattern forming ink may contain an acetylene glycol compound. The acetylene glycol-based compound has a function of adjusting the contact angle between the conductor pattern forming ink and the ceramic molded body within a predetermined range. Further, the contact angle between the conductor pattern forming ink and the ceramic molded body can be adjusted within a predetermined range with a small amount of the acetylene glycol compound. Further, even when bubbles are mixed in the discharged droplets, the bubbles can be quickly removed.

Thus, a finer conductor pattern can be formed by adjusting the contact angle between the conductor pattern forming ink and the ceramic molded body within a predetermined range.
Specifically, the compound has a function of adjusting the contact angle between the conductor pattern forming ink and the ceramic molded body to 40 to 90 ° (more preferably 50 to 80 °). If the contact angle is too small, it may be difficult to form a conductor pattern with a fine line width. On the other hand, if the contact angle is too large, it may be difficult to form a conductor pattern with a uniform line width depending on the discharge conditions and the like. In addition, the contact area between the landed droplet and the ceramic molded body may be too small, and the landed droplet may be displaced from the landing position.

  Examples of the acetylene glycol compounds include Surfinol 104 series (104E, 104H, 104PG-50, 104PA, etc.), Surfynol 400 series (420, 465, 485, etc.), Olphine series (EXP4036, EXP4001, E1010, etc.). ("Surfinol" and "Orphine" are trade names of Nissin Chemical Industry Co., Ltd.) and the like, and one or more of these can be used in combination.

The ink preferably contains two or more acetylene glycol compounds having different HLB values. The contact angle between the conductor pattern forming ink and the ceramic molded body can be easily adjusted within a predetermined range.
In particular, the difference between the HLB value of the acetylene glycol compound having the highest HLB value and the HLB value of the acetylene glycol compound having the lowest HLB value among the two or more acetylene glycol compounds contained in the ink is 4 It is preferably -12, and more preferably 5-10. Accordingly, the contact angle between the conductor pattern forming ink and the ceramic molded body can be easily adjusted within a predetermined range with a smaller amount of the acetylene glycol compound.

When the ink containing two or more acetylene glycol compounds is used, the HLB value of the acetylene glycol compound having the highest HLB value is preferably 8 to 16, more preferably 9 to 14. .
Moreover, when using what contains 2 or more types of acetylene glycol type compounds in an ink, it is preferable that the HLB value of the acetylene glycol type compound with the lowest HLB value is 2-7, and it is 3-5. More preferred.

The content of the acetylene glycol compound contained in the ink is preferably 0.001 to 1 wt%, and more preferably 0.01 to 0.5 wt%. As a result, the contact angle between the conductor pattern forming ink and the ceramic molded body can be more effectively adjusted to a predetermined range.
Further, the conductor pattern forming ink may contain 1,3-propanediol in addition to the above components. As a result, volatilization of the aqueous dispersion medium in the vicinity of the ejection portion of the inkjet head can be more effectively suppressed, the viscosity of the ink can be made more appropriate, and ejection stability is further improved.

When 1,3-propanediol is contained in the ink, the content thereof is preferably 0.5 to 20 wt%, and more preferably 2 to 10 wt%. Thereby, the ejection stability of ink can be improved more effectively.
The constituent components of the conductor pattern forming ink are not limited to the above components, and may include components other than those described above.
For example, the conductive pattern forming ink may contain a polyhydric alcohol such as ethylene glycol, 1,3-butylene glycol, or propylene glycol.

<< Method for producing conductive pattern forming ink >>
Next, an example of a method for producing the above-described conductor pattern forming ink will be described.
In this embodiment, the conductor pattern forming ink will be described as a colloidal liquid in which silver colloidal particles are dispersed in an aqueous dispersion medium.
When manufacturing the ink of this embodiment, first, an aqueous solution in which the dispersant and the reducing agent are dissolved is prepared.

As a blending amount of the dispersing agent, it is preferable to blend so that a molar ratio of silver and the dispersing agent in a silver salt such as silver nitrate as a starting material is about 1: 1 to 1: 100. When the molar ratio of the dispersant to the silver salt is increased, the particle size of the silver particles is reduced and the contact points between the particles after the formation of the conductor pattern is increased, so that a film having a low volume resistance value can be obtained.
The reducing agent has a function of generating silver particles by reducing Ag ⁺ ions in a silver salt such as silver nitrate (Ag ⁺ NO ³⁻ ) which is a starting material.

  The reducing agent is not particularly limited, and examples thereof include amines such as hydrazine, dimethylaminoethanol, methyldiethanolamine, and triethanolamine; hydrogen compounds such as sodium borohydride, hydrogen gas, and hydrogen iodide; carbon monoxide, Oxide systems such as sulfurous acid hypophosphorous acid, low valent metal salt systems such as Fe (II) compounds and Sn (II) compounds, saccharides such as D-glucose, organic compound systems such as formaldehyde, or the above dispersions Examples include hydroxy acids citric acid and malic acid, and hydroxy acid salts such as trisodium citrate, tripotassium citrate, trilithium citrate, triammonium citrate, disodium malate and tannic acid. It is done. Among them, tannic acid and hydroxy acid can be suitably used because they function as a reducing agent and at the same time exert an effect as a dispersant. Alternatively, mercaptoacetic acid, mercaptopropionic acid, thiodipropionic acid, mercaptosuccinic acid, mercaptosuccinic acid, mercaptoacetate sodium that is thioacetic acid or mercaptoate, listed above as a dispersant that forms a stable bond on the metal surface, Sodium mercaptopropionate, sodium thiodipropionate, sodium mercaptosuccinate, potassium mercaptoacetate, potassium mercaptopropionate, potassium thiodipropionate, potassium mercaptosuccinate and the like can be suitably used. These dispersants and reducing agents may be used alone or in combination of two or more. When these compounds are used, the reduction reaction may be promoted by applying light or heat.

In addition, the amount of the reducing agent is required to be an amount that can completely reduce the silver salt that is the starting material. However, the excessive reducing agent remains as impurities in the silver colloidal solution, and the film is formed after film formation. The necessary minimum amount is preferable because it causes deterioration of conductivity. Specifically, the molar ratio of the silver salt to the reducing agent is about 1: 1 to 1: 3.
In this embodiment, it is preferable to adjust the pH of the aqueous solution to 6 to 12 after dissolving the dispersant and the reducing agent to prepare the aqueous solution.

This is due to the following reasons. For example, when trisodium citrate, which is a dispersant, and ferrous sulfate, which is a reducing agent, are mixed, the pH is about 4 to 5 and lower than the above pH 6, although it depends on the overall concentration. The hydrogen ions present at this time move the equilibrium of the reaction represented by the following reaction formula (1) to the right side, and the amount of COOH increases. Therefore, thereafter, the electric repulsive force on the surface of the silver particles obtained by dropping the silver salt solution decreases, and the dispersibility of the silver particles (colloid particles) decreases.
−COO ⁻ + H ⁺ → −COOH (1)

Therefore, after dissolving the dispersant and the reducing agent to prepare an aqueous solution, an alkaline compound is added to the aqueous solution to reduce the hydrogen ion concentration.
It does not specifically limit as an alkaline compound to add, For example, sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia water etc. can be used. In these, sodium hydroxide which can adjust pH easily with a small amount is preferable.
In addition, when there is too much addition amount of an alkaline compound and pH exceeds 12, precipitation of the hydroxide of the ion of the remaining reducing agent like iron ion will occur easily.

Next, in the ink manufacturing process of this embodiment, an aqueous solution containing a silver salt is dropped into an aqueous solution in which the prepared dispersant and reducing agent are dissolved.
The silver salt is not particularly limited, and for example, silver acetate, silver carbonate, silver oxide, silver sulfate, silver nitrite, silver chlorate, silver sulfide, silver chromate, silver nitrate, silver dichromate and the like can be used. . Among these, silver nitrate having a high solubility in water is preferable.

The amount of the silver salt is determined in consideration of the content of the desired colloidal particles and the ratio reduced by the reducing agent. For example, in the case of silver nitrate, 15 to 70 parts per 100 parts by weight of the aqueous solution. The amount is preferably about parts by weight.
The silver salt aqueous solution is prepared by dissolving the silver salt in pure water, and the prepared silver salt aqueous solution is gradually dropped into the aqueous solution in which the dispersing agent and reducing agent described above are dissolved.

In this step, the silver salt is reduced to silver particles by a reducing agent, and the dispersant is adsorbed on the surface of the silver particles to form silver colloidal particles. As a result, an aqueous solution in which silver colloidal particles are colloidally dispersed in the aqueous solution is obtained.
In the obtained solution, in addition to the colloidal particles, a reducing agent residue and a dispersing agent are present, and the ion concentration of the whole liquid is high. The liquid in such a state is likely to coagulate and precipitate easily. Therefore, it is desirable to perform cleaning in order to remove excess ions in such an aqueous solution and lower the ion concentration.

As a washing method, for example, the aqueous solution containing the obtained colloidal particles is allowed to stand for a certain period, and the resulting supernatant liquid is removed, and then pure water is added and stirred again, and further left to stand for a certain period. In addition, a method of repeating the step of removing the supernatant liquid several times, a method of performing centrifugation instead of the above-mentioned standing, a method of removing ions by ultrafiltration, and the like can be mentioned.
Alternatively, cleaning may be performed by the following method. After the solution is prepared, the pH of the solution is adjusted to an acidic region of 5 or less, and the electric repulsive force on the surface of the silver particles is reduced by moving the equilibrium of the reaction of the above reaction formula (1) to the right side. It is possible to remove salts and solvents by washing in a state where metal colloidal particles are aggregated. In the case of a metal colloid particle having a low molecular weight sulfur compound such as mercapto acid on the particle surface as a dispersant, a stable bond is formed on the metal surface. Therefore, the aggregated metal colloid particle has an alkaline pH of 6 or more. By re-adjusting to this region, it is possible to obtain a metal colloid liquid that is easily redispersed and excellent in dispersion stability.

In the ink production process of the present embodiment, it is preferable to adjust the final pH to 6 to 11 by adding an aqueous alkali metal hydroxide solution to an aqueous solution in which silver colloidal particles are dispersed as necessary after the above step.
This is because the concentration of sodium, which is an electrolyte ion, may be decreased because washing is performed after reduction. In the solution in such a state, the equilibrium of the reaction represented by the following reaction formula (2) moves to the right side. To do. If this is the case, the electrical repulsive force of the silver colloid is reduced and the dispersibility of the silver particles is lowered. Therefore, by adding an appropriate amount of alkali hydroxide, the equilibrium of the reaction formula (2) is shifted to the left side, and silver It stabilizes the colloid.
—COO ^— Na ⁺ + H ₂ O → —COOH + Na ⁺ + OH ⁻ (2)

As said alkali metal hydroxide used at this time, the compound similar to the compound used when adjusting pH first can be mentioned, for example.
If the pH is less than 6, the equilibrium of the reaction formula (2) shifts to the right side, so that the colloidal particles become unstable. On the other hand, if the pH exceeds 11, hydroxides of remaining ions such as iron ions This is not preferable because precipitation of selenium tends to occur. However, if iron ions or the like are removed in advance, there is no major problem even if the pH exceeds 11.
Cations such as sodium ions are preferably added in the form of hydroxides. This is because the self-protolysis of water can be used, so that cations such as sodium ions can be added to the aqueous solution most effectively.

By adding other components such as sugar alcohol as described above to the aqueous solution in which the colloidal silver particles obtained as described above are dispersed, the conductive pattern forming ink (the conductive pattern forming ink of the present invention) is obtained. obtain.
In addition, the addition time of other components, such as sugar alcohol, is not specifically limited, As long as it is after formation of a silver colloid particle, it may be sufficient.

<< Method for Manufacturing Wiring Board and Method for Forming Conductor Pattern >>
Next, the manufacturing method of the wiring board (ceramic circuit board) of this invention and the formation method of a conductor pattern are demonstrated.
FIG. 1 is an explanatory diagram showing a schematic process of a method for manufacturing a wiring board (ceramic circuit board) of the present invention, FIG. 2 is an explanatory diagram of a manufacturing process of the wiring board (ceramic circuit board) of the present invention, and FIG. FIG. 5 is a schematic diagram for explaining a schematic configuration of an inkjet head (droplet ejection head).

  The method for manufacturing a wiring board according to the present invention includes an ink application step of applying a conductive pattern forming ink as described above to a ceramic molded body in a predetermined pattern by a droplet discharge method, and a ceramic molded body on which the pattern is formed. A laminated body forming step of forming a laminated body by laminating a plurality of sheets by pressure bonding under heating, and a sintering step of forming a wiring board having a ceramic substrate and a conductor pattern by sintering the laminated body And have. Moreover, in this embodiment, the manufacturing method of a wiring board further has the ceramic molded body preparation process which prepares a ceramic molded body, and the drying process which removes an aqueous dispersion medium from the pattern formed on the ceramic molded body. .

Hereinafter, each step will be described in detail.
[Ceramic compact body preparation process]
First, a ceramic molded body is prepared.
The raw material powder is made of ceramic powder made of alumina (Al ₂ O ₃ ) or titanium oxide (TiO ₂ ) having an average particle diameter of about 1 to 2 μm, and borosilicate glass having an average particle diameter of about 1 to 2 μm. Glass powder is prepared, and these are mixed at an appropriate mixing ratio, for example, a weight ratio of 1: 1.

Next, a suitable binder (binder), a plasticizer, an organic solvent (dispersant), etc. are added to the obtained mixed powder, and a slurry is obtained by mixing and stirring.
The binder is not particularly limited as long as it has a glass transition temperature lower than the melting point of the sugar alcohol as described above. For example, a binder resin such as polyvinyl butyral, acrylic, or cellulose can be used.
Although not preferred, it preferably contains polyvinyl butyral. Since polyvinyl butyral has an appropriate affinity with the conductor pattern forming ink of the present invention, a pattern having a desired shape can be formed more accurately. Polyvinyl butyral is insoluble in water and easily dissolved or swelled in a so-called oil-based organic solvent.

  As an acrylic binder resin, for example, a homopolymer of a (meth) acrylate compound such as alkyl (meth) acrylate, alkoxyalkyl (meth) acrylate, polyalkylene glycol (meth) acrylate, cycloalkyl (meth) acrylate, or the like is used. Can do. Moreover, as an acrylic binder resin, it can be obtained from a copolymer obtained from two or more of the (meth) acrylate compounds or from other copolymerizable monomers such as (meth) acrylate compounds and unsaturated carboxylic acids. Can be used.

The binder may contain a plasticizer such as an adipate ester plasticizer, dioctyl phthalate (DOP), dibutyl phthalate (DBP) phthalate ester plasticizer, or a glycol ester plasticizer.
Moreover, although the glass transition temperature of a binder should just be lower than melting | fusing point of sugar alcohol as mentioned above, it is preferable that it is 25-95 degreeC, and it is more preferable that it is 30-85 degreeC. As a result, it is possible to reliably prevent the ceramic molded body from being carelessly deformed and damaging the conductor pattern, or poor conduction between the plurality of conductor patterns. Further, the binder can be more reliably decomposed and removed during sintering.

Next, the obtained slurry is formed into a sheet on a PET film using a doctor blade, reverse coater, etc., and formed into a sheet having a thickness of several μm to several hundred μm depending on the production conditions of the product. Take up on a roll.
Subsequently, the sheet is cut according to the use of the product, and further cut into a sheet having a predetermined size. In this embodiment, for example, it is cut into a square shape having a side length of 200 mm.

Next, a through hole is formed at a predetermined position by drilling with a CO ₂ laser, a YAG laser, a mechanical punch or the like as required. Then, by filling this through hole with a thick film conductive paste in which metal particles are dispersed, a portion to be the contact 6 as shown in FIG. 2A is formed. Further, a terminal portion (not shown) is formed at a predetermined position by screen printing of the thick film conductive paste. Thus, the ceramic green sheet (ceramic molded body) 7 is obtained by forming the contact 6 and the terminal portion. As the thick film conductive paste, the conductor pattern forming ink of the present invention can be used.

[Ink application process]
On the surface of one side of the ceramic green sheet 7 obtained as described above, the precursor of the circuit 5 to be a conductor pattern in the present invention is formed in a continuous state with the contact 6 (ink application step). That is, as shown in FIG. 2A, a conductive pattern forming ink (hereinafter also simply referred to as ink) 10 as described above is applied onto the ceramic green sheet 7 by a droplet discharge (inkjet) method, and the circuit 5 A precursor 11 is formed.

The ink for forming the conductor pattern can be discharged by using, for example, an ink jet device (droplet discharge device) 50 shown in FIG. 3 and an ink jet head (droplet discharge head) 70 shown in FIG. Hereinafter, the inkjet device 50 and the inkjet head 70 will be described.
FIG. 3 is a perspective view of the inkjet device 50. In FIG. 3, the X direction is the left-right direction of the base 52, the Y direction is the front-rear direction, and the Z direction is the up-down direction.

The ink jet apparatus 50 includes an ink jet head (hereinafter simply referred to as a head) 70 and a table 46 on which a substrate S (ceramic green sheet 7) is placed. The operation of the ink jet device 50 is controlled by the control device 53.
The table 46 on which the substrate S is placed can be moved and positioned in the Y direction by the first moving means 54, and can be swung and positioned in the θz direction by the motor 44.

  On the other hand, the head 70 can be moved and positioned in the X direction by a second moving means (not shown), and can be moved and positioned in the Z direction by a linear motor 62. The head 70 can be swung and positioned in the α, β, and γ directions by motors 64, 66, and 68, respectively. Based on such a configuration, the ink jet apparatus 50 can accurately control the relative position and posture of the ink discharge surface 70P of the head 70 and the substrate S on the table 46.

A rubber heater (not shown) is disposed on the back surface of the table 46. The entire upper surface of the ceramic green sheet 7 placed on the table 46 is heated to a predetermined temperature by a rubber heater.
At least a part of the aqueous dispersion medium evaporates from the surface side of the ink 10 that has landed on the ceramic green sheet 7. At this time, since the ceramic green sheet 7 is heated, evaporation of the aqueous dispersion medium is promoted. The ink 10 that has landed on the ceramic green sheet 7 thickens from the outer edge of the surface as it dries. That is, the solid content (particle) concentration in the outer peripheral portion is faster than the central portion and reaches the saturation concentration. Thicken from the outer edge. The thickened ink 10 at the outer edge stops its own wetting and spreading along the surface direction of the ceramic green sheet 7, so that it is particularly easy to control the line width with respect to the landing diameter.

  Although this heating temperature is not specifically limited, Specifically, it is preferable that it is 40-80 degreeC, and it is preferable that it is 50-70 degreeC. Accordingly, it is possible to more reliably prevent the ink 10 from spreading and to control the landing diameter and the line width more reliably. Further, when the conventional conductive pattern forming ink is used, in the state where the ceramic green sheet is heated in this way, the ink near the nozzle 91 described later is easily dried, clogged, and the droplet discharge amount is unstable. Etc. were likely to occur. However, since the conductive pattern forming ink of the present invention contains sugar alcohol, volatilization of the aqueous dispersion medium in the vicinity of the nozzle 91 is suitably prevented, and the ink is stably ejected over a long period of time.

As shown in FIG. 4, the head 70 ejects the ink 10 from a nozzle (ejection unit) 91 by an inkjet method (droplet ejection method).
Various known techniques such as a piezo system that ejects ink using a piezoelectric element as a piezoelectric element and a system that ejects ink by bubbles generated by heating the ink are applied as the droplet ejection method. can do. Of these, the piezo method has the advantage that it does not affect the composition of the material because it does not apply heat to the ink. Therefore, the above-described piezo method is adopted for the head 70 shown in FIG.

A head body 90 of the head 70 is formed with a reservoir 95 and a plurality of ink chambers 93 branched from the reservoir 95. The reservoir 95 is a flow path for supplying the ink 10 to each ink chamber 93.
A nozzle plate (not shown) that constitutes an ink ejection surface is attached to the lower end surface of the head main body 90. In this nozzle plate, a plurality of nozzles 91 for discharging the ink 10 are opened corresponding to the respective ink chambers 93. An ink flow path is formed from each ink chamber 93 toward the corresponding nozzle 91. On the other hand, a diaphragm 94 is attached to the upper end surface of the head main body 90. The diaphragm 94 constitutes a wall surface of each ink chamber 93. Piezo elements 92 are provided outside the diaphragm 94 so as to correspond to the ink chambers 93. The piezo element 92 is obtained by sandwiching a piezoelectric material such as quartz with a pair of electrodes (not shown). The pair of electrodes is connected to the drive circuit 99.

The nozzle plate 96 is provided so as to cover the base material made of stainless steel and the base, and is provided so as to cover the silica film mainly made of the silica compound and the silica film. And a liquid repellent film containing a compound.
As described above, since the surface of the nozzle plate 96 has the liquid repellent film containing the fluoroalkylsilane compound, the affinity between the ink and the nozzle plate 96 can be made moderate. The contact angle can be more easily as described above. As a result, the ink is more easily liable to run out of the ejection portion 91, and the ink droplet amount is particularly easy to adjust. Further, by having such a liquid repellent film, the nozzle plate 96 is particularly excellent in wear resistance and weather resistance.

Further, the silica film has a function of closely attaching the liquid repellent film and the stainless steel base material, and also has a function of protecting the stainless steel base material.
As described above, the ink jet apparatus using such a nozzle plate 96 has particularly stable ink droplet discharge properties over a long period of time.
When an electric signal is input from the drive circuit 99 to the piezo element 92, the piezo element 92 is expanded or contracted. When the piezo element 92 contracts and deforms, the pressure in the ink chamber 93 decreases, and the ink 10 flows from the reservoir 95 into the ink chamber 93. Further, when the piezo element 92 expands and deforms, the pressure in the ink chamber 93 increases and the ink 10 is ejected from the nozzle 91. Note that the amount of deformation of the piezo element 92 can be controlled by changing the applied voltage. Further, the deformation speed of the piezo element 92 can be controlled by changing the frequency of the applied voltage. That is, by controlling the voltage applied to the piezo element 92, the ejection conditions of the ink 10 can be controlled.

  Therefore, by using the ink jet apparatus 50 including such a head 70, the ink 10 can be discharged and arranged with a desired amount and accuracy in a desired place on the ceramic green sheet 7. By the way, a droplet discharge device (industrial use) used for forming a conductor pattern is completely different from that applied to a printer (consumer use). For example, a large number of droplets are long for mass production. It is required to discharge over time. In addition, the droplet discharge device (industrial use) used for forming the conductor pattern generally has a higher viscosity than the ink used in printers (consumer use), so that the liquid runs out during discharge. The ink tends to remain in the discharge part (nozzle) of the inkjet head. In addition, solid portions such as agglomerated metal particles tend to clog the discharge part of the droplet discharge head, and the flight of the droplets frequently occurs. As described above, when droplets cannot be stably discharged, there is a problem that it is difficult to form a fine conductor pattern using ink. However, since the ink 10 is the conductor pattern forming ink of the present invention, the above-described effects can be obtained and droplets can be stably discharged. Therefore, the precursor 11 can be easily formed with high accuracy.

Further, when forming the conductor pattern, by repeating the process of applying the ink and then preheating to evaporate the aqueous dispersion medium and applying the ink again on the preheated film, A thick film conductor pattern can also be formed.
In particular, the conductive pattern forming ink of the present invention contains a sugar alcohol. For this reason, even when the ceramic green sheet is heated as described above, the aqueous dispersion medium is prevented from being completely removed in the precursor 11, and the aqueous dispersion medium is appropriately retained. .

  In particular, when the polyether compound as described above is contained in the conductor pattern forming ink, the ink after the aqueous dispersion medium is evaporated contains the polyether compound and silver colloid particles as described above. This polyether compound remains, and since the viscosity of the polyether compound is relatively high, there is no possibility that the film will be washed away even when the formed film is not completely dried. Therefore, it is possible to apply the ink once, dry it, leave it for a long time, and then apply the ink again.

  In addition, since the sugar alcohol and the polyether compound as described above have a relatively high boiling point, there is no possibility that the ink will be deteriorated even if the ink is applied and dried and then left for a long time, and the ink can be applied again. And a homogeneous film can be formed. Thereby, there is no possibility that the conductor pattern itself has a multilayer structure, and there is no possibility that the specific resistance between the layers increases and the specific resistance of the entire conductor pattern increases.

  The conductor pattern formed through the above steps can be formed thicker than a conductor pattern formed with a conventional ink. More specifically, a film having a thickness of 5 μm or more can be formed. Since such a conductor pattern is formed with the above-mentioned ink, even if it is formed in a thick film of 5 μm or more, the occurrence of cracks is small, and a conductor pattern having a low specific resistance can be formed. The upper limit of the thickness is not particularly required, but if it is excessively thick, it may be difficult to remove the dispersion medium or the polyether compound and the specific resistance may be increased.

[Drying process]
Next, the aqueous dispersion medium is removed from the precursor 11 formed on the ceramic green sheet.
As drying conditions, it is preferable to carry out at 40-80 degreeC, for example, and it is more preferable to carry out at 50-70 degreeC. By setting it as such conditions, when it dries, it can prevent more effectively that a crack generate | occur | produces.

[Laminated body forming step]
After the precursor 11 is formed in this way, the required number of ceramic green sheets 7 on which the precursor 11 is formed, for example, about 10 to 20 are produced by the same process.
Next, the PET film is peeled off from these ceramic green sheets, and these are laminated as shown in FIG. At this time, the ceramic green sheets 7 to be laminated are arranged so that the precursors 11 are connected via the contacts 6 as necessary between the ceramic green sheets 7 stacked one above the other.

Thereafter, the ceramic green sheets 7 stacked on each other are heated and the ceramic green sheets 7 are pressed together. Thereby, the laminated body 12 is obtained.
By the way, in this process, the temperature of the ceramic green sheet (ceramic molded body) at the time of lamination is higher than the glass transition temperature of the binder and lower than the melting point of the sugar alcohol contained in the ink. Thereby, the plurality of ceramic green sheets 7 can be firmly adhered to each other while preventing the sugar alcohol from melting and crystallizing after lamination. That is, the binder contained in the ceramic green sheet 7 is slightly softened by being heated higher than the glass transition temperature, and is bonded to the binder contained in the adjacent ceramic green sheet 7. On the other hand, since the sugar alcohol contained in the pattern is heated to a temperature lower than the melting point, it can maintain a dispersed state in the precursor 11 and does not melt and further crystallize. For this reason, it is prevented that the precursor 11 is damaged between the ceramic green sheets 7 to be laminated.
On the other hand, when the temperature of the ceramic green sheets 7 at the time of lamination is equal to or lower than the glass transition temperature of the binder, the ceramic green sheets 7 cannot be in close contact with each other. As a result, peeling or the like between the ceramic green sheets 7 is likely to occur, and accordingly, the formed conductor pattern is easily disconnected.

On the other hand, when the temperature of the ceramic green sheet 7 at the time of lamination is higher than the melting point of the sugar alcohol, the sugar alcohol is melted and crystallized, and the precursor 11 is easily damaged. As a result, the conductor pattern to be formed has many disconnections.
When the glass transition temperature of the binder of the ceramic green sheet 7 is T _G [° C.], the melting point of the sugar alcohol is T _S [° C.], and the temperature of the ceramic green sheet 7 at the time of lamination is T _P [° C.] the wiring substrate manufacturing method of the _invention, T _{G <as} long as it satisfies the relation of T P _{<T S,} but it is preferable to satisfy the relation _{T G +2 <T P <T} S -2, T _G +4 can obtain the effects as described above more preferably more pronounced to satisfy the relation of _<T P <T S _-4.

In this step, it is preferable that the plurality of ceramic green sheets 7 are pressed by a hydrostatic press method in which the plurality of ceramic green sheets 7 are heated and pressurized in still water. Thereby, pressure is uniformly applied to the plurality of stacked ceramic green sheets 7, and the distortion of each ceramic green sheet 7 and the distortion of the obtained laminate 12 are surely prevented. Moreover, by heating simultaneously with pressurization in still water, heat can be more uniformly transmitted to the stacked ceramic green sheets 7. Thereby, the heating temperature in each part of the precursor 11 can be made more uniform, and the heating temperature of the precursor 11 can be controlled more strictly. Thereby, heat can be transmitted to a part of the precursor 11 excessively, and sugar alcohol can be reliably prevented from melting and crystallizing.
In such a case, the hydrostatic pressure at the time of pressure bonding is preferably 250 to 400 kgf / m ² .

[Sintering process]
When the laminated body 12 is formed in this way, for example, it is heated and sintered by a belt furnace or the like. As a result, each ceramic green sheet 7 is fired to form a ceramic substrate 2 (wiring substrate of the present invention) as shown in FIG. 2B, and the precursor 11 is composed of silver colloid particles constituting the ceramic substrate 2. Sinters into a circuit (conductor pattern) 5 composed of a wiring pattern or an electrode pattern. And the laminated body 12 becomes the laminated substrate 3 shown in FIG. 5 mentioned later by heat-processing the laminated body 12 in this way.

  Here, the heating temperature of the laminated body 12 is preferably not less than the softening point of the glass contained in the ceramic green sheet 7, and specifically, not less than 600 ° C and not more than 900 ° C. As heating conditions, the temperature is raised and lowered at an appropriate rate, and the maximum heating temperature, that is, the temperature of 600 ° C. to 900 ° C. is maintained for an appropriate time according to the temperature. To do.

  Thus, the glass component of the obtained ceramic substrate 2 can be softened by raising the heating temperature to a temperature equal to or higher than the softening point of the glass, that is, the temperature range. Therefore, after cooling to room temperature and curing the glass component, the ceramic substrate 2 constituting the laminated substrate 3 and the circuit (conductor pattern) 5 are more firmly fixed.

Further, by heating in such a temperature range, the obtained ceramic substrate 2 becomes a low-temperature fired ceramic (LTCC) formed by firing at a temperature of 900 ° C. or less.
Here, the metals in the ink 10 disposed on the ceramic green sheet 7 are fused to each other by heat treatment and become conductive by being continuous.
By such heat treatment, the circuit 5 is directly connected to the contact 6 in the ceramic substrate 2 and is made conductive. Here, if the circuit 5 is merely placed on the ceramic substrate 2, the mechanical connection strength to the ceramic substrate 2 is not ensured, and therefore there is a possibility that the circuit 5 may be damaged by an impact or the like. However, in the present embodiment, as described above, the circuit 5 is firmly fixed to the ceramic substrate 2 by once softening the glass in the ceramic green sheet 7 and then curing it. Therefore, the formed circuit 5 has a high mechanical strength.

Note that, by such heat treatment, the circuit 4 can be formed simultaneously with the circuit 5, whereby the ceramic circuit board 1 can be obtained.
In such a method of manufacturing the ceramic circuit board 1, the ink 10 (the ink for forming a conductor pattern of the present invention) as described above is applied to the ceramic green sheet particularly when the ceramic substrates 2 constituting the multilayer substrate 3 are manufactured. Since the conductor pattern forming ink 10 can be satisfactorily arranged in a desired pattern on the ceramic green sheet 7, a highly accurate conductor pattern (circuit) 5 is formed. be able to.

≪Conductor pattern≫
The conductor pattern of the present invention is a thin-film conductor pattern formed using the above-described conductor pattern forming ink, wherein silver particles are bonded to each other, and at least on the surface of the conductor pattern, the silver particles are bonded to each other. Are bonded without a gap, and the specific resistance is less than 20 μΩcm.

In particular, the conductor pattern is formed by discharging the conductor pattern forming ink of the present invention by the droplet discharge method, and is formed by the method for manufacturing the wiring board of the present invention as described above. It has high adhesion, particularly high reliability, and a finer pattern.
The specific resistance of the conductor pattern is preferably less than 20 μΩcm, and more preferably 15 μΩcm or less. When the specific resistance is 20 μΩcm or more, it becomes difficult to use it for applications requiring electrical conductivity, that is, for electrodes formed on a circuit board.

≪Wiring board≫
Next, the wiring board of the present invention obtained by the method as described above will be described.
FIG. 5 is a longitudinal sectional view showing an example of the wiring board (ceramic circuit board) of the present invention.
As shown in FIG. 5, a ceramic circuit board (wiring board) 1 includes a laminated board 3 in which a large number (for example, about 10 to 20) of ceramic boards 2 are laminated, and an outermost layer of the laminated board 3, that is, one of them. Alternatively, it is formed with a circuit 4 made of fine wiring or the like formed on the surfaces on both sides.

The laminated substrate 3 includes a circuit (conductor pattern) 5 formed between the laminated ceramic substrates 2 and 2 using the conductor pattern forming ink of the present invention.
In addition, these circuits 5 have contacts (vias) 6 connected thereto. With this configuration, the circuit 5 is electrically connected by the contact 6 between the circuits 5 and 5 arranged above and below. The circuit 4 is also formed by the conductor pattern forming ink of the present invention, like the circuit 5.

The wiring board according to the present invention is an electronic component used in various electronic devices. A circuit pattern composed of various wirings, electrodes, etc., a multilayer ceramic capacitor, a multilayer inductor, an LC filter, a composite high-frequency component, etc. are formed on the substrate. It is made.
In addition, such a wiring board is a high-frequency module of a mobile telephone device such as a mobile phone or a PDA, an interposer, a MEMS (Micro Electro Mechanical Systems), an acceleration sensor, a surface acoustic wave device, a deformed electrode such as an antenna or a comb electrode. Further, it can be applied to electronic parts such as various measuring devices.

Moreover, since such a wiring board is manufactured using the conductive pattern forming ink of the present invention, the conductive pattern in the wiring board can be reliably conducted between any desired parts, and the conductor Excellent pattern reliability. Moreover, even when a fine conductor pattern is provided on the wiring board, it has excellent reliability.
As mentioned above, although this invention was demonstrated based on suitable embodiment, this invention is not limited to these.
In the above-described embodiment, the case where the colloid liquid is used as the dispersion liquid in which the metal particles are dispersed in the solvent has been described. However, the colloid liquid may not be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
[1] Preparation of conductive pattern forming ink Conductive pattern forming inks (inks) 1 to 15 were produced as follows.
17 mL of trisodium citrate dihydrate and 0.36 g of tannic acid were dissolved in 50 mL of water made alkaline by adding 3 mL of 10N-NaOH aqueous solution. To the obtained solution, 3 mL of 3.87 mol / L silver nitrate aqueous solution was added and stirred for 2 hours to obtain a silver colloid solution. The obtained silver colloid solution was desalted by dialysis until the electrical conductivity was 30 μS / cm or less. After dialysis, the coarse metal colloid particles were removed by centrifugation at 3000 rpm for 10 minutes.

  To this silver colloid liquid, sugar alcohol shown in Table 1, an organic binder, Surfynol 104PG50 (manufactured by Nissin Chemical Industry) and Olphine EXP4036 (manufactured by Nissin Chemical Industry) as acetylene glycol compounds, 3-Propanediol was added. When the pH of the silver colloid solution at this time was not in the range of 6 to 11, the pH of the silver colloid solution was adjusted to 6 to 11 using a 1N-NaOH aqueous solution. Furthermore, it was adjusted by adding ion exchange water for concentration adjustment to obtain a conductor pattern forming ink.

The conductor pattern forming ink 16 was manufactured as follows.
Silver nitrate aqueous solution having a concentration of 50 mmol / L: While stirring 1000 ml, mercaptoacetic acid: 3.0 g was added as a low molecular weight sulfur compound, and then the pH of the aqueous solution was adjusted to 10.0 with aqueous ammonia (26 wt%). . At room temperature, a sodium borohydride aqueous solution having a concentration of 400 mmol / L as a reducing agent was rapidly added to this aqueous solution: 50 ml, and a reduction reaction was performed to produce silver colloidal particles having mercaptoacetic acid on the particle surface in the solution. .

The colloidal solution thus obtained was adjusted to pH 3.0 with nitric acid (20 wt%) to precipitate silver colloid particles, and then filtered off with a vacuum filter. The electric conductivity of the filtrate was 10.0 μS. This was washed with water until it became less than / cm, to obtain a wet cake of silver colloid particles.
The wet cake of silver colloidal particles is added to water to a concentration of 10%, adjusted to pH 9.0 with ammonia water (26 wt%) with stirring, redispersed, and further concentrated. A silver colloid solution was obtained.

Thereafter, a conductor pattern forming ink was prepared in the same manner as the conductor pattern forming ink 1.
[2] Evaluation of Droplet Discharge Stability The conductive pattern forming inks 1 to 16 obtained as described above were put into an ink jet apparatus as shown in FIGS. First, drawing was performed using the above-described inkjet device equipped with the above-described conductor pattern forming ink, and it was confirmed that the ink was stably ejected. Next, the inkjet apparatus was left in a clean room environment of room temperature 25 ° C., relative humidity 50%, class 100 for 7 days in a standby state where the inkjet head was removed from the drawing position. Next, the inkjet apparatus was turned on, and a solid pattern was drawn on the 20 ceramic green sheets obtained as described above. When the ejection of ink became unstable, a predetermined cleaning function mounted on the ink jet apparatus was used to return to a stable ejection state. The above operation was performed and the ejection stability was evaluated according to the following evaluation criteria.

A: No nozzle clogging occurs during drawing, and ink is stably ejected. (Discharge stability is good.)
B: Clogging occurs during drawing, and cleaning operations within two times are required until ink ejection is stabilized. (There is no practical problem.)
C: Clogging occurs during drawing, and three or more cleaning operations are required until ink ejection is stabilized. (Practical possible.)
D: Clogging occurs during drawing and does not recover even by a cleaning operation. (Not practical.)

Further, the same operation as described above was performed with the period of the standby state being 30 days, and the same evaluation as above was performed.
Table 1 shows the composition of each conductor pattern forming ink and the results of the ejection stability evaluation. In the table, the content of each material indicates the content in the conductive pattern forming ink. In the table, “polyglycerin” is polyglycerin # 500 (average weight molecular weight: 462), “polyethylene glycol” "Used polyethylene glycol # 500 (average weight molecular weight: 500). In the table, “PVB” indicates polyvinyl butyral, and the glass transition temperature of each polyvinyl butyral was adjusted to the temperature shown in the table by adding a plasticizer to polyvinyl butyral. In the table, “G-41H” indicates an acrylic binder resin (manufactured by Nisshin Kasei Co., Ltd.). Moreover, melting | fusing point of sugar alcohol was measured based on JISK0064 using EXSTAR6000DSC (made by SII nanotechnology company) in the table | surface. The glass transition temperature of the binder was measured according to EXSTAR6000 DSC (manufactured by SII Nano Technology) JIS K7121.

[3] Fabrication and evaluation of ceramic circuit board (Example 1)
First, a ceramic green sheet (ceramic molded body) was prepared as follows (ceramic molded body preparation step).
1 ceramic powder composed of alumina (Al ₂ O ₃ ) and titanium oxide (TiO ₂ ) having an average particle diameter of about 1 to 2 μm, and glass powder composed of borosilicate glass and the like having an average particle diameter of about 1 to 2 μm. The mixture was mixed at a weight ratio of 1: polyvinyl butyral (PVB) as a binder (binder), dibutyl phthalate as a plasticizer, mixed and stirred, and a slurry was obtained on a PET film with a doctor blade. What was formed was a ceramic green sheet, and one that was cut into a square shape with a side length of 200 mm was used.

Next, the conductor pattern forming ink 1 obtained as described above was put into an ink jet apparatus as shown in FIGS.
Next, the ceramic green sheet was heated to 60 ° C. and held. Drops of 15 ng per droplet were sequentially discharged from each discharge nozzle, and 20 lines (precursors) having a line width of 50 μm, a thickness of 15 μm, and a length of 10.0 cm were drawn (ink application step). The distance between each line was 5 mm.

And the ceramic green sheet in which this line was formed was put into the drying furnace, and it heated and dried at 60 degreeC for 30 minutes (drying process).
The ceramic green sheet on which the line was formed as described above was used as the first ceramic green sheet. 20 sheets of this first ceramic green sheet were prepared for each ink. Each sheet was checked for cracks. The results are shown in Table 2. Table 2 shows the number of non-defective products having no cracks in the line among the first ceramic green sheets.

Next, a conductive pattern forming ink in which through holes having a diameter of 100 μm were formed in a total of 40 locations by punching another ceramic green sheet with mechanical punches or the like at both ends of the above metal wiring, thereby forming lines. The contact (via) was formed by filling Further, a 2 mm square pattern was formed on the contact (via), and a terminal portion was formed using the above-described droplet discharge device using the conductive pattern forming ink 1.
The ceramic green sheet on which this terminal portion was formed was used as the second ceramic green sheet.

Next, the first ceramic green sheet was laminated under the second ceramic green sheet, and two unprocessed ceramic green sheets were laminated as reinforcing layers to obtain a raw laminate. This raw laminate was prepared for each of the 20 first ceramic green sheets for each ink, and 20 blocks were prepared for each ink.
Next, the raw laminate was pressed for 30 seconds at a pressure of 350 kg / cm ² under hot water at 90 ° C. by a hydrostatic pressure pressing method to obtain a laminate (laminate formation step). That is, at this time, each ceramic green sheet in the raw laminate was pressure-bonded in an environment of 90 ° C.

Next, in the atmosphere, the temperature is increased continuously at a temperature rising rate of 66 ° C./hour for about 6 hours, a temperature rising rate of 10 ° C./hour for about 5 hours, and a temperature rising rate of 85 ° C./hour for about 4 hours. Through a temperature process, sintering was performed according to a sintering profile of holding at a maximum temperature of 890 ° C. for 30 minutes to obtain a ceramic circuit board (wiring board) (sintering process).
After cooling, for each ceramic circuit board, a tester was applied between the terminal portions formed on the 20 conductor patterns to confirm the presence or absence of conduction, and those with a conductivity of 100% were regarded as non-defective products. The conductivity was obtained by dividing the number of conductive patterns in each ceramic circuit board by the number of formed conductive patterns (20).

(Examples 2 to 20)
The ceramic used in the same manner as in Example 1 except that the ink and binder used as shown in Table 2, the temperature of the ceramic green sheet in the ink application process, and the temperature of the ceramic green sheet when forming the laminate are shown in Table 2. A circuit board (wiring board) was obtained.
(Comparative Examples 1 and 2)
The ceramic used in the same manner as in Example 1 except that the ink and binder used as shown in Table 2, the temperature of the ceramic green sheet in the ink application process, and the temperature of the ceramic green sheet when forming the laminate are shown in Table 2. A circuit board (wiring board) was obtained.
These results and are shown in Table 2.

As shown in Tables 1 and 2, all of the conductor pattern forming inks (conductor pattern forming inks 1 to 10 and 12 to 16) used in each example were excellent in ejection stability.
Moreover, as shown in Table 2, in each Example, the disconnection etc. were prevented and the conductor pattern with a high electrical conductivity was obtained. That is, a highly reliable wiring board was obtained.
On the other hand, in each comparative example, a satisfactory result was not obtained.
Further, when the content of the silver colloid particles in the ink was changed to 20 wt% and 30 wt%, the same result as above was obtained.

It is explanatory drawing which shows the process of the outline of the manufacturing method of a wiring board. (A)-(b) is manufacturing process explanatory drawing of the wiring board of FIG. It is a perspective view which shows schematic structure of an inkjet apparatus. It is a schematic diagram for demonstrating schematic structure of an inkjet head. It is a sectional side view which shows schematic structure of a wiring board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wiring board (ceramic circuit board) 2 ... Ceramic board 3 ... Laminated board 4, 5 ... Circuit (conductor pattern) 6 ... Contact 7 ... Ceramics green sheet 10 ... Ink (ink) for conductor pattern formation 11 ... Precursor 12 ... Laminated body 44 ... motor 46 ... table 50 ... inkjet device (droplet ejection device) 52 ... base 53 ... control device 54 ... first moving means 62 ... linear motors 64, 66, 68 ... motor 70 ... inkjet head (droplet ejection) 70P: Ink ejection surface 90 ... Head body 91 ... Nozzle (ejection part) 92 ... Piezo element 93 ... Ink chamber 94 ... Vibration plate 95 ... Reservoir 96 ... Nozzle plate 99 ... Drive circuit S ... Substrate

Claims (14)

By a droplet discharge method, an ink for forming a conductor pattern containing an aqueous dispersion medium, metal particles dispersed in the aqueous dispersion medium, and sugar alcohol is applied on a ceramic molded body made of a material containing ceramic particles and a binder. An ink application step of applying the pattern of
A laminated body forming step of forming a laminated body by laminating the ceramic formed body on which the pattern is formed by press bonding a plurality of sheets under heating;
A sintering step of forming a wiring board having a ceramic substrate and a conductor pattern by sintering the laminate;
The melting point of the sugar alcohol is higher than the glass transition temperature of the binder contained in the ceramic molded body,
The method of manufacturing a wiring board, wherein the temperature of the ceramic formed body in the laminate forming step is higher than a glass transition temperature of the binder and lower than a melting point of the sugar alcohol.   The method for manufacturing a wiring board according to claim 1, wherein the laminated body forming step is to press-bond a plurality of the ceramic formed bodies by an isostatic pressing method.   The method for manufacturing a wiring board according to claim 1 or 2, wherein the ink application step is to heat the ceramic molded body to 40 to 80 ° C. A conductive pattern forming ink that is applied to a ceramic molded body composed of a material containing ceramic particles and a binder by a droplet discharge method, and is used to form a conductive pattern,
The ceramic molded body is laminated and sintered in a state where a conductive pattern forming ink is applied,
An aqueous dispersion medium, metal particles dispersed in the aqueous dispersion medium, and a sugar alcohol,
The ink for forming a conductor pattern, wherein the melting point of the sugar alcohol is higher than the glass transition temperature of the binder contained in the ceramic molded body.   The conductive pattern forming ink according to claim 4, wherein the sugar alcohol contains at least two kinds of components.   The ink for forming a conductor pattern according to claim 4 or 5, wherein the sugar alcohol contains a sugar alcohol derived from a monosaccharide.   7. The conductive pattern forming ink according to claim 4, wherein the sugar alcohol contains a sugar alcohol derived from disaccharide.   The ink for forming a conductor pattern according to any one of claims 4 to 7, wherein the sugar alcohol has a melting point of 90 to 200 ° C.   The ink for forming a conductor pattern according to any one of claims 4 to 8, wherein the ink for forming a conductor pattern contains a polyglycerin compound.   10. The conductive pattern forming ink according to claim 4, wherein the binder has a glass transition temperature of 25 to 95 ° C. 10.   The ink for forming a conductor pattern according to any one of claims 4 to 10, wherein the binder of the ceramic formed body contains polyvinyl butyral.   A conductor pattern formed with the conductor pattern forming ink according to claim 4.   A wiring board comprising the conductor pattern according to claim 12.   A wiring board manufactured by the method for manufacturing a wiring board according to claim 1.

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