JP2009123731A - Manufacturing method of ceramic multilayer substrate - Google Patents

Abstract

A method for manufacturing a ceramic multilayer substrate with improved reliability is provided.
A step of drawing a liquid pattern on a green sheet GS by discharging a dispersion system of conductive fine particles Is containing a dispersion aid Ib as droplets onto the green sheet GS, and evaporating the dispersion medium from the liquid pattern. Forming a pressure-bonded body by stacking and compressing the green sheet GS having the dry pattern PD and the step of forming the dry pattern PD
A step of forming an LTCC multilayer substrate by firing the pressure-bonded body, and a dispersion aid Ib
And a cleaning liquid 31 that does not dissolve the conductive fine particles Is.
Before laminating S, the dry pattern PD is washed.
[Selection] Figure 6

Description

  The present invention relates to a method for manufacturing a ceramic multilayer substrate.

Low temperature co-fired ceramics (LTCC) technology enables the simultaneous firing of a green sheet and a metal, so that an element-embedded substrate incorporating various passive elements between ceramic layers can be realized. In the system-on-package (SOP) mounting technology, this element-embedded substrate (hereinafter simply referred to as an LTCC multilayer substrate) is used in order to reduce the parasitic effects that occur in the combination of electronic components and surface-mounted components. The manufacturing method involved has been intensively developed.

In the manufacturing method of the LTCC multilayer substrate, a drawing step of drawing a pattern of passive elements, wirings, etc. on each of a plurality of green sheets, a crimping step of laminating and crimping a plurality of green sheets having the pattern, and a crimped body And a firing step of collectively firing. In the drawing process of drawing a pattern on a green sheet, a so-called inkjet method is proposed in which conductive ink is discharged as fine droplets in order to increase the density of the pattern (for example, Patent Document 1). . Since the ink jet method uses droplets of several picoliters to several tens of picoliters, the pattern can be made finer and the pitch can be reduced by changing the droplet discharge position.

In the ink jet method, the gas-liquid interface (meniscus) of the conductive ink stored in the nozzle is forcibly vibrated in order to discharge minute droplets. The meniscus formed on the nozzle continuously evaporates the dispersion medium contained in the conductive ink when the nozzle is in a standby state for a long period of time. I will come. On the other hand, when the viscosity of the droplet landed on the green sheet is too low, the droplet spreads wet along the surface of the green sheet, which hinders pattern miniaturization and narrow pitch. Therefore, for conductive ink, conventionally, drying suppression inside the nozzle,
In order to promote drying on the surface of the green sheet, various dispersion aids added to the dispersion medium have been proposed.

For example, sugar alcohols that exhibit solids at room temperature, such as xylitol and arabinitol, can suppress drying of the aqueous dispersion medium by the interaction between the sugar alcohol and water, such as hydrogen bonds or van der Waals bonds. Further, the interaction between the sugar alcohol and the conductive fine particles, for example, coordinate bond, promotes the redispersion of the conductive fine particles once aggregated or precipitated. And
Since sugar alcohols that exhibit solids at room temperature quickly precipitate as the dispersion medium volatilizes,
Excessive wetting and spreading of droplets can be suppressed. For this reason, sugar alcohols that are solid at room temperature are expected as dispersion aids in aqueous conductive inks.
JP 2005-57139 A

However, when a dispersion aid that exhibits a solid at room temperature is used, the dispersion aid is deposited on the surface of the pattern after drying, leading to deterioration of the adhesion between the pattern and the green sheet. Peeling and migration between the ceramic substrate and the ceramic substrate.

The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing a ceramic multilayer substrate with improved reliability.

The method for producing a ceramic multilayer substrate of the present invention includes a step of drawing a liquid pattern on each green sheet by discharging a dispersion system of conductive fine particles containing a dispersion aid into each of a plurality of green sheets as a droplet. Forming a dry pattern on each of the green sheets by evaporating the dispersion medium from the liquid pattern; and laminating and pressing the green sheets having the dry pattern to form a pressure-bonded body; Forming the ceramic multilayer substrate by firing a body, dissolving the dispersion aid, and
The dry pattern is cleaned before laminating the green sheets using a cleaning solution that does not dissolve the conductive fine particles.

The method for producing a ceramic multilayer substrate of the present invention can improve the adhesion between the pattern and the green sheet because the dispersion aid deposited on the dry pattern is washed with the washing liquid. Therefore, the method for manufacturing a ceramic multilayer substrate according to the present invention can suppress the peeling of the ceramic substrate, the migration in the internal wiring, and the like, and thus can improve the reliability of the ceramic multilayer substrate.

In this method for producing a ceramic multilayer substrate, the conductive fine particles are silver fine particles, the dispersion medium is a dispersion medium containing water as a main component, the dispersion aid is a sugar alcohol, and the cleaning liquid is mainly water. It may be a cleaning liquid as a component.

In this method of manufacturing a ceramic multilayer substrate, even if silver particles having low migration resistance are used, the precipitated sugar alcohol is washed with an aqueous cleaning solution, so that the pattern is refined and the migration resistance is improved. As a result, the reliability of the ceramic multilayer substrate can be improved.

This method for producing a ceramic multilayer substrate preferably has a configuration in which an adhesion layer that provides adhesion is formed between the surface of the green sheet and the conductive fine particles before discharging the droplets.
In the method for manufacturing the ceramic multilayer substrate, preferably, the adhesion layer is formed by applying a coupling agent to the surface of the green sheet before discharging the droplets.

According to the method for producing a ceramic multilayer substrate, since the adhesion layer provides adhesion between the green sheet and the conductive fine particles, peeling and erosion of the dry pattern can be suppressed when the dry pattern is washed. Therefore, according to this method for manufacturing a ceramic multilayer substrate, the reliability of the ceramic multilayer substrate can be improved more reliably.

In this method for manufacturing a ceramic multilayer substrate, the conductive fine particles contained in the liquid pattern may be fused to each other by heating the liquid pattern before washing the dry pattern.

According to this method for manufacturing a ceramic multilayer substrate, the conductive fine particles contained in the dry pattern are fused to each other, so that the dry pattern can be more reliably prevented from peeling or eroding when the dry pattern is washed. Therefore, according to this method for manufacturing a ceramic multilayer substrate, the reliability can be improved more reliably.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a circuit module having a ceramic multilayer substrate manufactured by using the manufacturing method of the present invention.

In FIG. 1, a circuit module 10 includes a low temperature co-fired ceramics (LTCC) multilayer substrate 11 as a ceramic multilayer substrate, and a semiconductor chip 12 connected to the LTCC multilayer substrate 11. Each LTCC substrate 13 of the LTCC multilayer substrate 11 is a sintered body of a green sheet, and has a thickness of several tens to several hundreds of μm. Between the layers of each LTCC substrate 13, various internal elements 14 such as a resistance element, a capacitive element, and a coil element, and an internal wiring 15 electrically connected to each internal element 14 are incorporated. Are formed with via wirings 16 each having a stacked via structure or a thermal via structure. Each of the internal element 14, the internal wiring 15, and the via wiring 16 is a sintered body of conductive fine particles, and is formed by an ink jet method using a conductive ink.

Next, a method for manufacturing the LTCC multilayer substrate 11 will be described with reference to FIGS. 2 shows L
It is a flowchart which shows the manufacturing method of the TCC multilayer substrate 11, and FIG. 3 is a time chart which shows the temperature of the green sheet in each process. 4 to 7 are process diagrams showing a method for manufacturing the LTCC multilayer substrate 11.

In FIG. 2, in the manufacturing method of the LTCC multilayer substrate 11, the drawing process (step S11) which draws a liquid pattern on the green sheet which is the precursor of the LTCC substrate 13, and the drying process (step S12) which dries the liquid pattern; Are executed in order. Moreover, in the manufacturing method of the LTCC multilayer board | substrate 11, the washing | cleaning process (step S13) which wash | cleans the dried pattern, the crimping | compression-bonding process (step S14) which laminates | stacks and crimps | bonds a some green sheet, and baked the crimped green sheet. A baking process (step S15) is performed in order.

In FIG. 3, the temperature of the green sheet in the drawing process and the drying process is set as the drawing temperature Tp and the drying temperature Td, respectively, and the temperature of the green sheet in the cleaning process, the pressure bonding process, and the baking process is set as the cleaning temperature Tw, It is referred to as a pressure bonding temperature Tc and a firing temperature Ta.
In the present embodiment, the drawing temperature Tp, the drying temperature Td, the cleaning temperature Tw, the pressure bonding temperature Tc, and the firing temperature Ta are all higher than room temperature (20 ° C.).

In FIG. 4, in the drawing process, a laminated sheet TS composed of a carrier film BS and a green sheet GS applied to the carrier film BS, and a droplet discharge device 22 are used.

The carrier film BS is a green sheet GS in the drawing process, drying process and cleaning process.
For example, a plastic film excellent in peelability from the green sheet GS and mechanical resistance in each process can be used. Carrier film B
For S, for example, a polyethylene terephthalate film, a polyethylene naphthalate film, a polyethylene film, or a polypropylene film can be used.

The green sheet GS is a layer made of a glass ceramic composition containing glass ceramic powder, a binder, and the like. The film thickness of the green sheet GS is several tens of μm when a capacitor element is formed as the internal element 14, and the other layer is formed with a thickness of 100 μm to 200 μm.

An adhesion layer GSa made of a coupling agent having a thiol group or an amino group is applied and formed on the surface of the green sheet GS. The adhesion layer GSa is a layer that exhibits adhesion with the conductive fine particles Is, and suppresses peeling of the pattern made of the conductive fine particles Is.

The glass ceramic powder is a powder having an average particle diameter of 0.1 μm to 5.0 μm. For example, a glass composite ceramic obtained by mixing borosilicate glass with ceramic powder such as alumina or forsterite can be used. As the glass ceramic powder, ZnO
A crystallized glass ceramic using a MgO—Al ₂ O ₃ —SiO ₂ type crystallized glass, B
aO—Al ₂ O ₃ —SiO ₂ ceramic powder and Al ₂ O ₃ —CaO—SiO ₂ —MgO
Non-glass ceramics using -B ₂ O ₃ ceramic powder or the like may be used.

The binder is an organic polymer that has a function as a binder of the glass ceramic powder and can be easily removed by decomposition in the firing process. As the binder, for example, a binder resin such as butyral, acrylic or cellulose can be used. As the 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.

A circular hole having a predetermined hole diameter (hereinafter simply referred to as a positioning hole H) is provided at the edge of the laminated sheet TS.
) Is formed by punching. In each positioning hole H, positioning pins 21P of the mounting plate 21 are inserted, and each position of the adhesion layer GSa is positioned with respect to the droplet discharge device 22.

In the green sheet GS, a circular hole or a conical hole (hereinafter simply referred to as a via hole VH) having a hole diameter of several tens μm to several hundreds μm is formed by penetrating and laser processing. The via hole VH is filled with a conductive material such as silver, gold, copper, or palladium in the previous step by a squeegee method using a conductive paste or an inkjet method using a conductive ink.

The droplet discharge device 22 includes a placement plate 21 for placing the laminated sheet TS, an ink tank 23 that stores the conductive ink Ik, and a liquid that discharges the conductive ink Ik of the ink tank 23 to the adhesion layer GSa. And a droplet discharge head 24.

The mounting plate 21 is a plate made of a rigid material having substantially the same size as the laminated sheet TS, and includes positioning pins 21P for positioning the laminated sheet TS and a heater 21H for heating the laminated sheet TS. When the laminated sheet TS is placed on the placement plate 21, the positioning pins 21 </ b> P are inserted through the positioning holes H, and the adhesion layer GSa is positioned and fixed on the placement plate 21. Further, when the laminated sheet TS is placed on the placement plate 21, the placement plate 21 drives the heater 21H, and the laminated sheet TS is heated to the drawing temperature Tp.

The conductive ink Ik is a dispersion system of conductive fine particles Is in which conductive fine particles Is are dispersed in a dispersion medium Ia, and includes a dispersion aid Ib for uniformly dispersing the conductive fine particles Is in the dispersion medium Ia.

The conductive fine particle Is is a fine particle having a particle size of several nm to several tens of nm. For example, gold, silver, copper, platinum, palladium, rhodium, osmium, ruthenium, iridium, iron, tin, cobalt, nickel, chromium Further, metals such as titanium, tantalum, tungsten, and indium, or alloys thereof can be used.

Any dispersion medium Ia may be used as long as it uniformly disperses the conductive fine particles Is in a system containing the dispersion aid Ib, and water or an aqueous solution containing water as a main component can be used. The dispersion medium Ia is
In order to adjust the viscosity of the conductive ink Ik, a water-soluble organic solvent may be included as necessary. Examples of the water-soluble organic solvent include ethanol, methanol, butanol, propanol,
Alkyl alcohols such as isopropanol, ethylene glycol monomethyl ether,
Examples include glycol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and propylene glycol monoethyl ether, and these may be used in combination.

The dispersion aid Ib dissolves easily in the dispersion medium Ia and coordinates with the conductive fine particles Is to stabilize the colloidal state of the conductive fine particles. The dispersion aid Ib includes a hydroxy acid or a hydroxy acid salt having a carboxyl group and a hydroxyl group as functional groups. Examples of the hydroxy acid include citric acid, malic acid, tartaric acid, and the like, and these may be used in combination. Examples of the hydroxy acid salt include sodium citrate, potassium citrate, lithium citrate, sodium malate, sodium tartrate and the like, and these may be used in combination.

The dispersion aid Ib is a polyhydric alcohol having an alcohol valence of 3 to 6, and is in a standard state (
The polyhydric alcohol which shows a solid under 25 degreeC and 1 atmosphere state) is contained. Examples of the polyhydric alcohol include sugar alcohols obtained by reducing carbonyl groups of monosaccharides, disaccharides, oligosaccharides and polysaccharides, 2- (hydroxymethyl) -1,3-propanediol, 1,2,3-hexanetriol, 1 2,3-heptanetriol and the like can be used. Examples of sugar alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, erythritol, threitol, ribitol, arabinitol, xylitol, allitol, mannitol, dolitol, iditol, glycol, inositol, maltitol, lactitol, etc. A mixture of these may be used.

The concentration of the polyhydric alcohol is 5% to 20% by weight, preferably 10% by weight or more, based on the total mass of the conductive ink Ik. When the concentration of the polyhydric alcohol is lower than 5% by weight, the moisturizing effect of the dispersion medium Ia due to the polyhydric alcohol is reduced, and drying suppression inside the nozzle 26 becomes insufficient. On the other hand, when the concentration of the polyhydric alcohol is higher than 20% by weight, dispersion of the conductive fine particles Is becomes unstable.

When the conductive ink Ik is stored in a predetermined storage chamber, the interaction between the dispersion aid Ib and water, for example, hydrogen bonding or van der Waals bonding, suppresses evaporation of the dispersion medium Ia. In addition, the interaction between the dispersion aid Ib and the conductive fine particles Is, for example, coordinate bond, causes the conductive fine particles Is once aggregated or precipitated to be dispersed again in the dispersion medium Ia, that is, redispersed.

When the conductive ink Ik is ejected as droplets and lands on the object, the re-dispersion of the conductive fine particles Is makes the dry state of the conductive ink Ik uniform, thereby suppressing cracks caused by differences in the dry state. Let Then, from the conductive ink Ik landed on the object, the dispersion medium I
When a continues to evaporate or evaporate, the dispersion aid Ib sequentially deposits on the surface of the conductive ink Ik, and the dispersion aid Ib deposited on the object suppresses the wetting and spreading of the conductive ink Ik.

The droplet discharge head 24 includes a cavity 25 communicating with the ink tank 23 and a cavity 2.
5 and a pressure generating element 27 connected to the cavity 25.
The cavity 25 receives the conductive ink Ik from the ink tank 23 and supplies the conductive ink Ik to the nozzle 26. The nozzle 26 accommodates the conductive ink Ik from the ink tank 23 and forms a gas-liquid interface, that is, a meniscus. The pressure generating element 27 is connected to the cavity 2
5 is a piezoelectric element or a capacitance element that changes the volume of 5 or a resistance heating element that changes the temperature of the cavity 25, and generates a predetermined pressure inside the cavity 25. Pressure generating element 27
When the nozzle 26 is driven, the nozzle 26 vibrates the meniscus of the conductive ink Ik, and discharges the conductive ink Ik into droplets D of several picoliters to several tens of picoliters.

In FIG. 4, in the drawing process, the laminated sheet TS and the droplet discharge head 24 are adhered to the adhesion layer GSa.
A plurality of liquid droplets D that are relatively moved along the surface direction and land on the adhesion layer GSa to form a liquid pattern PL that is continuous in a predetermined direction. Since the temperature of the green sheet GS is heated to the drawing temperature Tp, the liquid pattern PL formed on the adhesion layer GSa is wetted by receiving the amount of heat from the green sheet GS and sequentially depositing the dispersion aid Ib. Spreading can be suppressed.

When the drawing temperature Tp becomes excessively high, the carrier film BS and the green sheet GS
Causes thermal deformation, and the landing accuracy of the droplet D is impaired. Therefore, the drawing temperature Tp is, for example, 40 ° C. to 80 ° C., and may be a lower limit temperature at which a part of the dispersion medium Ia can be evaporated on the surface of the liquid pattern PL. A configuration that is appropriately selected according to the composition of the laminated sheet TS and the composition of the conductive ink Ik is preferable.

In FIG. 5, in the drying process, the laminated sheet TS after the drawing process is carried into a drying apparatus such as a drying furnace, and the green sheet GS having the liquid pattern PL is heated to the drying temperature Td.
The drying temperature Td is a temperature for substantially removing the dispersion medium Ia from the liquid pattern PL. The state in which the dispersion medium Ia is substantially removed is different from the state in which the dispersion medium Ia is completely removed (the state without the dispersion medium Ia) in terms of the frequency of pattern peeling and the degree of pattern deformation. It is in a state of not playing. Note that when the drying temperature Td is excessively high, the carrier film BS and the green sheet GS are thermally deformed, and the positional accuracy during the pressure bonding process is impaired. Therefore, the drying temperature Td is, for example, 40 ° C. to 80 ° C., and a configuration that is appropriately selected according to the composition of the laminated sheet TS and the composition of the conductive ink Ik so as to ensure the positional accuracy during the crimping process. preferable.

When the green sheet GS is heated to the drying temperature Td, the dispersion medium Ia contained in the liquid pattern PL is substantially removed. As a result, a dry pattern PD comprising an aggregate made of the conductive fine particles Is and the dispersion aid Ib deposited on the surface of the aggregate is formed on the adhesion layer GSa. The dry pattern PD formed on the adhesion layer GSa is fixed to the adhesion layer GSa by the bonding force between the adhesion layer GSa and the conductive fine particles Is and the cohesive force of the conductive fine particles Is.

In FIG. 6, in the cleaning process, the laminated sheet TS after the drying process is carried into the cleaning apparatus, and the cleaning liquid 31 is supplied toward the green sheet GS having the drying pattern PD. Cleaning solution 3
As a supply method 1, the green sheet GS may be immersed in a cleaning tank in which the cleaning liquid 31 circulates, or the cleaning liquid 31 may be sprayed constantly from the cleaning nozzle toward the adhesion layer GSa.

The cleaning liquid 31 only needs to dissolve the dispersion aid Ib and not dissolve the conductive fine particles Is. As the cleaning liquid 31, water or an aqueous solution containing water as a main component can be used. The cleaning liquid 31 may contain a water-soluble organic solvent as necessary in order to adjust the solubility of the dispersion aid Ib. Examples of the water-soluble organic solvent include alkyl alcohols such as ethanol, methanol, butanol, propanol, and isopropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether. And glycol ethers such as propylene glycol monoethyl ether and the like, and these may be used in combination. Further, the cleaning liquid 31 may be configured to include a surfactant such as Surfynol (registered trademark) in order to improve the permeability to the dry pattern PD or the cleaning performance of the dry pattern PD. When an organic solvent-based ink is used as the conductive ink Ik, the dispersion aid Ib is dissolved and the conductive fine particles I are dissolved.
An organic solvent that does not dissolve s may be used as the cleaning liquid 31.

When the cleaning liquid 31 is supplied to the green sheet GS, the dispersion aid Ib deposited on the dry pattern PD is eluted into the cleaning liquid 31 and is substantially removed from the dry pattern PD. As a result, a dry pattern PD made of the conductive fine particles Is is formed on the adhesion layer GSa. At this time, the dry pattern PD is fixed to the adhesion layer GSa by the bonding force between the adhesion layer GSa and the conductive fine particles Is and the cohesive force of the conductive fine particles Is. Therefore, the shape can be sufficiently maintained. Note that the state in which the dispersion aid Ib is substantially removed means that the frequency of pattern peeling or pattern deformation is smaller than the state in which the dispersion aid Ib is completely removed (the state in which there is no dispersion aid Ib). This is a state in which there is no fluctuation with respect to the degree or the like.

In the cleaning process, when the dispersion aid Ib is removed from the dry pattern PD, the laminated sheet TS
Is carried into a drying apparatus such as a drying furnace, and the green sheet GS having the drying pattern PD is heated to the cleaning temperature Tw. The cleaning temperature Tw is a temperature for evaporating and removing the cleaning liquid 31 from the green sheet GS.

When the green sheet GS is heated to the cleaning temperature Tw, the cleaning liquid 31 attached to the green sheet GS and the dry pattern PD evaporates and is removed from the green sheet GS and the dry pattern PD.

In FIG. 7, in the crimping process, a base plate 32 for stacking a plurality of green sheets GS, a cover plate 33 for pressing the plurality of green sheets GS, and a vacuum packaging for vacuum packaging the plurality of green sheets GS. A bag 35 is used.

The base plate 32 has positioning pins 32P for positioning a plurality of green sheets GS.
The green sheets GS are positioned on the base plate 32 by inserting the positioning pins 32P into the positioning holes H of the green sheets GS. The cover plate 33 has a plurality of insertion holes 33h through which the positioning pins 32P can be inserted, and the positioning pin 32P is inserted into the insertion holes 33h of the cover plate 33, whereby a laminated body composed of a plurality of green sheets GS. 34 is sandwiched between the base plate 32 and the cover plate 33.

The vacuum packaging bag 35 is a packaging bag having flexibility that can enclose the base plate 32, the cover plate 33, and the laminated body 34. The base plate 32 and the cover plate 33 are accommodated in a vacuum packaging bag 35 with the laminate 34 sandwiched therebetween, and are vacuum-sealed inside the vacuum packaging bag 35 by suction using a sealer or the like. The laminated body 34 that has been vacuum-sealed is carried into a predetermined hydrostatic press, and is subjected to hydrostatic pressure while being heated to the pressure bonding temperature Tc. Since the laminated body 34 that receives the hydrostatic pressure presses substantially the entire dry pattern PD isotropically, the green sheets GS are pressure-bonded between the green sheets GS while maintaining the shape of the dry pattern PD. A crimped body is formed.

In the firing step, the crimped body obtained in the crimping step is taken out from the base plate 32, carried into a predetermined firing furnace, and fired. The firing temperature Ta is, for example, 800 ° C. to 1000 ° C., and is appropriately changed according to the composition of the green sheet GS. When using Cu as the dry pattern PD, it is preferable to fire in a reducing atmosphere to prevent oxidation. Silver, gold, platinum,
When palladium or the like is used, it may be fired in the air.

Next, the effect of 1st embodiment comprised as mentioned above is described below.
(1) In the first embodiment, the dry pattern PD is cleaned before laminating the green sheets GS by using the cleaning liquid 31 that dissolves the dispersion aid Ib and does not dissolve the conductive fine particles Is. Therefore, since the dispersion aid Ib deposited on the dry pattern PD can be removed, it is possible to improve the adhesion between the dry pattern PD and the laminated green sheet GS. As a result,
It is possible to suppress peeling of the LTCC substrate 13 and migration of the internal wiring 15.
The reliability of the TCC multilayer substrate 11 can be improved.

(2) In the first embodiment, an adhesion layer GSa that provides adhesion between the green sheet GS and the conductive fine particles Is is formed by applying a coupling agent to the surface of the green sheet GS. Therefore, since the adhesion layer GSa provides adhesion between the green sheet GS and the conductive fine particles Is, peeling and erosion of the dry pattern PD can be suppressed when the dry pattern PD is washed. As a result, the reliability of the LTCC multilayer substrate 11 can be improved more reliably.

(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the process is changed between the drying process and the cleaning process in the first embodiment. Therefore, in the following, the changes will be described in detail.

In FIG. 8, in the manufacturing method of the LTCC multilayer substrate 11, between the drying process and the crimping process,
A temporary baking process (step 12a) is performed. In the present embodiment, the temperature of the green sheet GS in the temporary baking step is referred to as a temporary baking temperature Tx (see FIG. 9).

In the temporary baking step, the laminated sheet TS after the drying step is carried into a temporary baking apparatus such as a temporary baking furnace,
It is heated to the pre-baking temperature Tx in the state having the dry pattern PD. The temporary firing temperature Tx is a temperature at which the conductive fine particles Is are fused, and is a temperature lower than the decomposition temperature of the binder contained in the green sheet GS.

When the green sheet GS is heated to the temporary firing temperature Tx, a part of the conductive fine particles Is included in the dry pattern PD starts to be fused. As a result, since the bonding force between the conductive fine particles Is and the adhesion force between the dry pattern PD and the adhesion layer GSa increase, peeling and erosion of the dry pattern PD can be more reliably suppressed.

If the pre-baking temperature Tx becomes excessively high, the carrier film BS and the green sheet G
S has undergone thermal deformation, and the positional accuracy with other laminated sheets TS during the crimping process is impaired,
Further, the binder included in the green sheet GS starts to be decomposed. Therefore, the temporary firing temperature Tx is, for example, 80 ° C. to 100 ° C.
A configuration that is appropriately selected according to the composition of the laminated sheet TS and the elements of the conductive fine particles Is is preferable so that the adhesion between S can be secured.

In addition, you may change the said embodiment as follows.
In the above embodiment, the dispersion medium Ia of the conductive ink Ik is embodied as an aqueous dispersion medium.
Not limited to this, the dispersion medium Ia of the conductive ink Ik may be embodied as an organic solvent-based dispersion medium. That is, the present invention only needs to use a conductive ink Ik that precipitates the dispersion aid Ib as the dispersion medium Ia evaporates, and the dispersion aid Ib deposited on the dry pattern PD is washed with a cleaning liquid.

The firing process of the above embodiment is a configuration in which the oxidized conductive pattern is reduced by dissociating and scattering the binder under an oxygen atmosphere and then firing the dry pattern PD under a hydrogen reducing atmosphere. May be. That is, the present invention is not limited to the temperature, time, atmosphere, etc. of the firing step.

Sectional drawing which shows a circuit module. The flowchart which shows the manufacturing method of a ceramic multilayer substrate. The figure which shows the temperature of the green sheet in each manufacturing process. Process drawing which shows the manufacturing method of a ceramic multilayer substrate. Process drawing which shows the manufacturing method of a ceramic multilayer substrate. Process drawing which shows the manufacturing method of a ceramic multilayer substrate. Process drawing which shows the manufacturing method of a ceramic multilayer substrate. The flowchart which shows the manufacturing method of 2nd embodiment. The figure which shows the temperature of the green sheet in each manufacturing process of 2nd embodiment.

Explanation of symbols

D ... droplet, GS ... green sheet, Ia ... dispersion medium, Ib ... dispersion aid, Ik ... conductive ink, Is ... conductive fine particle, PD ... dry pattern, PL ... liquid pattern, 11 ... as a ceramic multilayer substrate LTCC multilayer substrate, 23 ... green sheet, 31 ... cleaning liquid.

Claims (5)

A method for producing a ceramic multilayer substrate, comprising:
Drawing a liquid pattern on each green sheet by discharging a dispersion system of conductive fine particles containing a dispersion aid into each of a plurality of green sheets as droplets;
Forming a dry pattern on each green sheet by evaporating a dispersion medium from the liquid pattern;
Forming the pressure-bonded body by laminating and pressure-bonding the green sheets having the dry pattern, and forming the ceramic multilayer substrate by firing the pressure-bonded body,
A method for producing a ceramic multilayer substrate, comprising: washing the dry pattern before laminating the green sheets using a washing liquid that dissolves the dispersion aid and does not dissolve the conductive fine particles. A method for producing a ceramic multilayer substrate according to claim 1,
The conductive fine particles are silver fine particles,
The dispersion medium is a dispersion medium mainly composed of water,
The dispersion aid is a sugar alcohol;
The method for producing a ceramic multilayer substrate, wherein the cleaning liquid is a cleaning liquid containing water as a main component. A method for producing a ceramic multilayer substrate according to claim 1 or 2,
A method for producing a ceramic multilayer substrate, comprising: forming an adhesion layer that provides adhesion between a surface of the green sheet and the conductive fine particles before discharging the droplets. A method for producing a ceramic multilayer substrate according to claim 3,
A method for producing a ceramic multilayer substrate, wherein the adhesion layer is formed by applying a coupling agent to the surface of the green sheet before discharging the droplets. A method for producing a ceramic multilayer substrate according to any one of claims 1 to 4,
A method for producing a ceramic multilayer substrate, wherein the conductive fine particles contained in the liquid pattern are fused to each other by heating the liquid pattern before washing the dry pattern.

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