JP4654572B2 - Green sheet and multilayer electronic component manufacturing method - Google Patents

Description

The present invention relates to a green sheet and multilayer electronic component manufacturing how.

  Multilayer electronic components such as multilayer ceramic capacitors, multilayer varistors, and chip inductors are usually manufactured through a sintering process after ceramic green sheets are laminated, pressure-bonded, heat-treated, cut into a predetermined size.

  For example, a multilayer ceramic capacitor is manufactured by the following method. First, a ceramic slurry obtained by dispersing and mixing ceramic powders such as titanium oxide, acrylic and butyral resin binders, plasticizers, organic solvents and the like as composition components is prepared.

  Next, this ceramic slurry is applied onto a carrier film (support) such as a PET film using a doctor blade method, a nozzle method, and the like, and this is heated and dried to form a coating film. Thereafter, an electrode paste (internal electrode) containing metal particles or the like is applied onto the formed coating film and dried to obtain a green sheet.

  Next, the green sheet is peeled off from the carrier film, and a plurality of the green sheets are laminated and pressure-bonded. These green chips are subjected to treatments such as firing and external electrode formation to obtain multilayer ceramic capacitors.

  The manufacturing process of the multilayer electronic component includes a step of applying a ceramic slurry and then an electrode paste on a support, and the sheet defect, adhesiveness, etc. of the green sheet formed in this way is a laminate (electronic component). This green sheet forming process is very important.

From this point of view, various methods have been developed for the green sheet forming process in order to reduce sheet defects and improve adhesion. For example, a method has been developed in which an electrode film is formed on a support, a first dielectric layer having a small particle size is formed thereon, and a second dielectric layer having a larger particle size is formed ( Patent Document 1). According to this method, since the amount of binder required at the time of heat transfer is small, it is easy to remove the binder, the occurrence of delamination can be suppressed, and a capacitor excellent in voltage resistance can be obtained.
JP-A-5-101970

  In recent years, in the multilayer electronic component as described above, sheet thickness reduction has been progressed in order to reduce the size and improve the performance. However, as the layer becomes thinner, peeling of the green sheet from the support becomes increasingly difficult, and thus the yield and reliability of the green sheet and the laminate using the same are reduced.

  Usually, in order to lighten peeling, the surface of a support such as a PET film is subjected to silicon treatment. Thereby, although the peeling becomes light, the sheet is liable to be wet, and the sheet is liable to cause a sheet defect such as slurry repelling or unevenness. This is more likely to occur with thinner layers. On the other hand, when a sheet is formed using a support having good wettability, the sheet is peeled off, and the sheet is cut or cannot be peeled at all at the time of peeling, so that lamination cannot be performed.

  In addition, in a sheet formed by a general one-time slurry application, as the sheet becomes thinner, the sheet defect at the time of application becomes a characteristic defect as it is. In this regard, according to the configuration in which the two layers as described above are applied, such a sheet defect of the first layer seems to be reduced to some extent by the second layer. However, when the sheet is thin, the badness of the first layer is also dragged by the second layer.

  In addition, the method described in Patent Document 1 is intended to suppress delamination, and does not enable easy sheet formation or improved adhesion between sheets. Further, when the electrode layer is directly formed on the support, the adhesion of the electrode portion is poor, the dielectric layer is not properly laminated by heat transfer, and the lamination is liable to occur.

  Thus, conventionally, with the progress of thinning, it has both good sheet characteristics with few sheet defects and good peelability, and high yield and reliability of green sheets and laminates using the same. There has been a demand for a method for manufacturing a green sheet and a multilayer electronic component capable of achieving the above.

In view of the above circumstances, the present invention aims at providing a less good sheet properties of the sheet defects, and good release properties, manufacturing how green sheet having both a.
The present invention also aims to provide good sheet properties and the green sheet having the peelability are laminated, yield and production how reliable multilayer electronic component.

In order to achieve the above object, a method for producing a green sheet according to the first aspect of the present invention includes:
Among ceramic powders, organic binders composed of at least one of butyral, acrylic and olefin resins, and aromatic hydrocarbons, ketones and alcohols which are good solvents for the organic binders An aromatic hydrocarbon, an alicyclic hydrocarbon, an aliphatic saturated hydrocarbon that is a poor solvent with respect to the organic binder and has a higher boiling point than the first solvent; And forming a first layer on a support using a first slurry containing a second solvent comprising at least one of mineral spirits ;
Using a second slurry containing the second solvent minor proportion than the first slurry, forming a second layer on said first layer,
With
In the first step of forming a layer, the second solvent of the first slurry, characterized in that the ratio of 35wt% ~45wt% of the total amount of organic solvent used.

  In the above method, the second slurry may be prepared from the same composition material as the first slurry.

  In the above method, a plurality of types of the first solvent may be used, and a solvent having a boiling point of 30 ° C. or higher with respect to the solvent having the lowest boiling point may be used for the second solvent.

In order to achieve the above object, a method for manufacturing a multilayer electronic component according to the second aspect of the present invention includes:
The method of manufacturing a green sheet in the first aspect, characterized in that it comprises a step of manufacturing a green sheet, a step of laminating the green sheet as prepared above.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a green sheet which has both the favorable sheet | seat characteristic with few sheet defects, and favorable peelability, and a green sheet using the same are provided.
In addition, according to the present invention, a method for manufacturing a multilayer electronic component having a high yield and reliability, and a multilayer electronic component using the same, which are formed by laminating green sheets having good sheet characteristics and peelability, are provided. Provided.

  A method for manufacturing a green sheet and a multilayer electronic component according to an embodiment of the present invention, and a green sheet and a multilayer electronic component using these will be described in detail below. In the following, a case where a multilayer ceramic capacitor using a ceramic green sheet is manufactured will be described as an example.

  The green sheet according to the present embodiment is manufactured using a slurry containing dielectric powder, an organic binder, an additive, an organic solvent, and other necessary additives as composition components.

  Ceramic powder can be used as the dielectric powder. The ceramic powder may be any material powder that is generally used for the production of multilayer ceramic electronic components. In addition to titanium oxide such as barium titanate, oxidation of aluminum, barium, lead, zirconium, silicon, yttrium, etc. Or mixtures thereof can be used. A dielectric powder having a predetermined particle size is used.

As the organic binder, a butyral resin, an acrylic resin, an olefin resin, or the like can be used.
The additive is composed of a plasticizer, a dispersant and the like. As the plasticizer, for example, a phthalate ester is used.

As an organic solvent, the 1st solvent which is a good solvent with respect to the organic binder to be used, and the 2nd solvent which is a poor solvent are used.
In this specification, claims, etc., “good solvent” means a solvent having a large ability to dissolve a predetermined organic resin , and “poor solvent” means that a predetermined organic resin is soluble. It means a solvent having a small ability to dissolve or a solvent that does not dissolve a predetermined organic resin at all.

  As the first solvent as the good solvent, a solvent having a high solubility of the organic binder is used. For example, a general organic solvent such as an aromatic hydrocarbon such as toluene, a ketone such as methyl ethyl ketone, and an alcohol such as ethyl alcohol can be used, depending on the organic binder used.

The second solvent as the poor solvent is a solvent having a low solubility of the organic binder to be used, and has a higher boiling point than the first solvent to be used. As described in detail below, the second solvent as a poor solvent uses the difference in volatilization amount of the first solvent to insolubilize and precipitate the organic binder in the applied slurry before the drying step. It is used to improve the peelability of the sheet.
The second solvent is preferably one having high compatibility with the first solvent, and one that can be removed in the drying step described later.

  Solvents that can be used as the second solvent include aromatic hydrocarbons such as xylene and toluene, alicyclic hydrocarbons such as cyclohexane and ethylcyclohexane, aliphatic saturated hydrocarbons such as n-hexane, and mineral spirits. In particular, those used as solvents can be used.

  Specifically, for example, when a butyral organic binder is used and ethanol is used as the first solvent (good solvent), the second solvent (poor solvent) has a higher boiling point than ethanol. Things are used. For example, as shown in Table 1, a solvent having a high boiling point of 30 ° C. or higher can be used as the second solvent. When the difference in boiling points is small, the insolubilizing effect of the organic binder described later is insufficient.

  Hereinafter, a method for producing a green sheet using the composition material will be described with reference to the drawings. FIGS. 1A to 1E are diagrams for explaining this manufacturing process.

  First, the above-described dielectric powder, organic binder, additive, organic solvent, and other necessary additives are mixed and dispersed together with, for example, a medium with a ball mill to form a slurry. The slurry is preferably filtered before coating to remove coarse particles, aggregates and the like.

Two types of slurries are prepared: a first slurry and a second slurry, which differ in the amount of organic solvent added. In the present embodiment, first, the first slurry is applied onto the support 11, then dried to remove the organic solvent, and the first layer 12 is formed as shown in FIG. Further, the second slurry is applied onto the first layer 12, and then dried to blow off the organic solvent, thereby forming the second layer 13 as shown in FIG.
As the support 11, for example, a polyethylene terephthalate (PET) film whose surface is silicon-treated is used.

  The composition of the first slurry is set to a good releasability with little repelling and unevenness when applied to the support 11. Thereby, even if it is a thin layer, the 1st layer 12 with few peels, nonuniformity, etc. and favorable peelability is formed on the support body 11. FIG.

  When a support having good wettability is used in order to obtain a sheet having a small number of sheet defects at the time of producing a thin sheet, generally the peelability of the formed sheet from the support is lowered. In this embodiment, the peelability is improved by adding a high-boiling poor solvent (second solvent) to the organic solvent at a relatively high predetermined ratio.

  Specifically, the organic solvent containing the second solvent in a predetermined ratio (poor solvent ratio) is used for the first slurry, so that the releasability and unevenness at the time of application to the support 11 are reduced and the releasability is reduced. Is enhanced as follows.

  As described above, when the first slurry is applied onto the support 11, the composition is set so that the first layer 12 with less unevenness and good peelability is formed. Thus, the uniform first layer 12 with less unevenness is formed.

  Thereafter, before the drying step, the organic solvent volatilizes naturally, but the second solvent has a higher boiling point than the first solvent, so the volatilization amount of the first solvent is large. For this reason, the ratio of the 2nd solvent which is a poor solvent increases in the apply | coated slurry. As the ratio of the poor solvent increases, a part of the organic binder becomes insoluble before or during the drying process. When the organic binder is insolubilized in the middle of drying, the adhesive force of the first layer 12 to the support 11 is lower than that in the case where the second solvent is not used. For this reason, the peelability between the first layer 12 and the support 11, that is, the peelability from the support 11 of the subsequent green sheet 15 is good.

  Therefore, even if a support having good wettability but low sheet releasability is used, by setting a predetermined ratio of the organic solvent as a poor solvent having a relatively high boiling point, there is little repelling, unevenness, etc. (less sheet defects) ) Light release from the support of the sheet is achieved while maintaining a uniform sheet.

  Here, the poor solvent ratio of the first slurry is determined by the type, amount, ratio, and the like of the organic binder used so that the organic binder is appropriately insolubilized before the drying step. However, in consideration of other requirements such as the support 11 to be used, for example, a ratio of 35 wt% to 45 wt% of the total amount of the organic solvent to be used (poor solvent ratio) is preferable.

  After forming the first layer 12 as described above, the second slurry is applied and dried on the first layer 12 to form the second layer 13 as shown in FIG. To do.

  Here, the 2nd slurry is set as the composition which can implement | achieve a favorable sheet | seat surface and favorable adhesiveness between sheets. As described above, the first layer 12 realizes reduced sheet defects and good peelability, but is optimal for good sheet surface formation such as surface roughness and adhesion between sheets. It has not been converted into one. Further, according to experiments, a sheet formed with a single layer of a slurry with an increased poor solvent ratio shows good peelability, but a laminated chip produced using this has a high defect rate.

  The second layer 13 formed on the first layer 12 is provided to compensate for such drawbacks of the first layer 12. For this reason, the 2nd slurry for forming the 2nd layer 13 is set as the composition which can form a favorable sheet | seat surface and can form a layer with favorable adhesiveness between sheets.

Specifically, the second slurry has the same composition as the first slurry. For example, using the same kind and amount of dielectric powder and organic binder, the second slurry has good sheet characteristics (sheet surface, sheet Optimized for adhesiveness etc.).
In addition, the second slurry does not contain the poor solvent (second solvent) at all, but contains a small amount of the poor solvent (second solvent) in a smaller proportion than that used for the first slurry.

  After forming the first layer 12 and the second layer 13 as described above, the second layer 13 includes a metal serving as an internal electrode such as palladium, silver-palladium, nickel, and an organic solvent. As shown in FIG. 1C, the electrode 14 having a predetermined pattern is printed using the electrode paste.

  Thereafter, the formed green sheet 15 is peeled off from the support 11 as shown in FIG. Next, as shown in FIG. 1E, a plurality of green sheets 15 are stacked and pressed in the thickness direction for pressure bonding. A peeling process and a lamination process can be performed with the same lamination machine, for example.

  In this peeling step, as described above, the green sheet 15 can be peeled lightly due to good peelability between the first layer 12 and the support 11, and breakage and the like during peeling are avoided. For this reason, lamination is possible with a sheet having few defects, and the yield of the green sheets 15 is improved.

  Subsequently, the pressure-bonded laminated body is cut so as to obtain a laminated body for obtaining individual ceramic capacitors, and the organic binder, plasticizer, and the like are removed by heat treatment or the like, and then fired to obtain a sintered body. . Finally, an external electrode that is electrically connected to the internal electrode 14 is baked to obtain a multilayer ceramic capacitor.

  The multilayer ceramic capacitor manufactured as described above has high reliability. That is, as described above, the green sheet 15 according to the present embodiment is a sheet with few sheet defects and a lightly peelable sheet from the support 11. Moreover, a layer having a good sheet surface is formed on the surface, and the sheet has good adhesion between sheets. For this reason, it becomes possible to manufacture a multilayer ceramic capacitor with high reliability and yield.

The present invention is not limited to the above example, and various modifications can be made.
In the above embodiment, the composition of the first slurry is determined first, and the composition of the second slurry is determined accordingly. However, conversely, the composition of the second slurry may be optimized with respect to adhesiveness, wettability, and the like, and the composition of the first slurry may be determined accordingly. For example, the optimized second slurry The first slurry may be formed by changing the poor solvent ratio.

  In the above embodiment, only one type of the first solvent which is a good solvent for the organic binder is used. However, a combination of a plurality of solvents may be used as the good solvent. In this case, for example, it is preferable to use a poor solvent having a predetermined high boiling point with respect to the good solvent having the lowest boiling point.

  In the above embodiment, the electrode 14 is formed after the first coating layer 12 and the second coating layer 13 are formed. However, as shown in FIGS. 2A to 2E, first the first coating layer 12 is formed (FIG. 2A), then the electrode 14 is formed (FIG. 2B), and then A second coating layer 13 may be formed (FIG. 2C), and further peeled from the support 11 (FIG. 2D) and laminated (FIG. 2E) may be performed.

  According to this method, the electrode 14 is not exposed on the surface of the green sheet 15 (adhesion surface at the time of lamination), and when the layers are laminated as shown in FIG. It is done.

  Further, when the electrode 14 is formed between the first coating layer 12 and the second coating layer 13 as described above, the electrodes 14 are laminated as shown in FIGS. 3 (a) to 3 (g). Further, the formation of the electrode 14 (FIG. 3D) and the second coating layer 13 (FIG. 3E) is further repeated on the support 11 (FIG. 3C). It may be peeled off (FIG. 3 (f)) and a predetermined number of them are laminated (FIG. 3 (g)). In this case, the peeling process of the support 11 can be omitted, and productivity can be improved, such as reduction of the number of processes.

  In the example shown in the figure, the process of forming the first coating layer 12, the electrode 14, and the second coating layer 13 is repeated twice. However, the number of repetitions, that is, the number of stacked green sheets 15 is not limited to this.

  In the above embodiment, a multilayer ceramic capacitor has been described as an example. However, of course, the present invention is not limited to the above example, and the present invention can also be applied to multilayer inductors, multilayer actuators, multilayer LC filters, and the like, or composite electronic components thereof.

Hereinafter, the present invention will be described in more detail with reference to specific examples of the present embodiment.
A ceramic green sheet according to the present embodiment and a multilayer ceramic capacitor using the same were produced, and the characteristics were examined.

  As a material for the green sheet, a dielectric material composed of a mixed powder of barium titanate and a small amount of several kinds of metal oxides, a binder, a solvent, and other additives suitable for the dielectric material were used. Examples 1 to 6 and Comparative Examples 1 to 3 according to the present embodiment were prepared by variously changing the composition, particularly the type of the organic solvent. Table 2 shows the compositions used for each, together with the experimental results.

  Green sheets are prepared by mixing materials with various compositions, mixing and dispersing with media using a ball mill disperser to form a slurry, applying this paint on a PET film by the doctor blade method, drying, and screen printing the electrodes. did. Here, in Examples 1 to 6 according to the embodiment, the coating and drying steps were repeated twice to form a green sheet. The PET film used was subjected to silicon treatment. Furthermore, this green sheet was peeled from the PET film with a laminating machine, laminated, press-bonded, and cut into a predetermined shape to produce a ceramic green chip.

In Examples 1 to 6, green sheets manufactured according to the present embodiment and laminated chips using the green sheets were examined. Moreover, in Examples 1-6, the addition amount of a poor solvent, its kind, etc. are changed. In Examples 1 to 6, the average particle size of the dielectric material used was constant at 0.31, and the thickness and density of the produced sheet were also substantially constant.
In addition, as a comparative example, a green sheet was formed from one coating layer and the amount of the poor solvent added was changed (Comparative Examples 1 to 3).

  As shown in Table 2, the characteristics of the produced green sheets according to the examples and comparative examples were examined with respect to the total sheet thickness, sheet density, peeling load and peeling from the support. I checked for defects.

    In Table 2, the peeling load refers to a load necessary for attaching a film having a width of 5 cm to the green sheet and peeling the film from the PET film. Further, the term “lamination” indicates whether or not the green sheet can be peeled and laminated in the laminating machine.

  Regarding the short circuit defect and the breakdown voltage defect, the defect rate was examined by a general evaluation method for a capacitor chip in which 100 layers of sheets were laminated. Moreover, about short circuit defect and pressure | voltage resistant defect, what put these numerical values together was shown as defect total.

First, a comparative example will be described. In Comparative Example 1, a green sheet is produced by applying one layer of a slurry to which xylene is added as a poor solvent at a poor solvent ratio of 15.0 wt%. Here, a poor solvent ratio is a ratio (wt%) which a poor solvent accounts among the whole usage-amount of a solvent.
As shown in Table 2, the viscosity of the slurry according to Comparative Example 1 was high (60 mPa · s), and the peelability of the sheet was low (peeling load 14.0 g).

In Comparative Examples 2 and 3, mineral spirits were added in various amounts while keeping the amount of solvent used substantially constant, and the poor solvent ratio was increased. The poor solvent ratio was 35.0 wt% in Comparative Example 2 and 45.0 wt% in Comparative Example 3.
From the results shown in Table 2, it can be seen that the peel load of the sheet decreases as the poor solvent ratio increases. However, on the other hand, it can be seen that the defect rate (total defect) is greatly deteriorated as the poor solvent ratio is increased.
This indicates that when the poor solvent ratio is increased, the peelability is improved, but the sheet surface is likely to be rough, and thus the defect rate is deteriorated. Therefore, a method of manufacturing a sheet by applying only one layer with an increased poor solvent ratio is not realistic.

  Hereinafter, examples according to the present embodiment will be described. Unlike the comparative example, in the example, a first slurry containing a poor solvent at a relatively high ratio is first applied on a PET film and dried to form a first layer, and then a lower ratio than the first slurry. Then, a second slurry containing a poor solvent is further applied and dried to form a second layer to produce a sheet.

First, in Example 1, in addition to a poor solvent (xylene, 8.4 wt%), a PET film using a slurry in which mineral spirit (12.4 wt%) was further added to make the poor solvent ratio 35.0 wt%. A first layer is formed thereon. The second layer on the first layer is formed using a slurry containing a poor solvent (xylene) at a lower ratio (15 wt%) than the first slurry.
As shown in the results, the sheet according to Example 1 shows better peelability (peeling load 6.0 g) than the comparative example, and also shows a good defect rate in the laminated chip. .

  In Example 2, the composition was almost the same as in Example 1, and the amount of mineral spirits was increased to increase the poor solvent ratio to 45 wt%. As shown in the results, the sheet according to Example 2 shows good peelability (peeling load 4.0 g), and a good defect rate as compared with the comparative example. However, compared with Example 1, although the peeling load is further improved by increasing the poor solvent ratio, the defect rate is slightly increased, and it is not preferable that the poor solvent ratio exceeds about 45 wt%. it is conceivable that.

In the reference example , a sheet is formed in substantially the same manner as in Example 1, but the second layer is increased to the same poor solvent ratio of 35.0 wt% as that of the first layer. The sheet according to the reference example also shows good peelability, and the defective rate of the sheet laminate is low. However, the defect rate is slightly increased as compared with Example 1, and it seems that the characteristics are not improved so much even if the poor solvent ratio of the second layer is increased.

In Example 4, a sheet is formed in substantially the same manner as in Example 1, but the second poor solvent ratio is reduced to 15.0 wt%.
As shown in the results, the sheet according to Example 4 exhibited good peelability similar to that of Example 1, and further reduced the good defect rate of Example 1 by half. This is considered to be due to the fact that the second layer of Example 4 was good by making the poor solvent ratio of the second layer slightly lower in Example 4 than in Example 1. .

Example 5 is almost the same as Example 4, except that xylene is not used, the amount of mineral spirits is reduced, and toluene is used as the main poor solvent, and the poor solvent ratio (35 wt%) is the same as in Example 4. ).
Moreover, Example 6 uses xylene as a main poor solvent in Example 5 instead of toluene.

  When Examples 4 to 6 are compared, it can be seen that even when any of mineral spirit, toluene, and xylene is used as the main poor solvent, it shows almost no change and shows a good sheet peelability and chip defect rate. From the above results, it can be seen that in order to obtain good sheet characteristics and chip characteristics, the ratio of the poor solvent in the slurry composition for forming the first layer only needs to be within a predetermined range and does not depend much on the type of the poor solvent.

It is a figure which shows the process of the manufacturing method of the green sheet concerning embodiment of this invention. It is a figure which shows the modification of the manufacturing method of the green sheet concerning embodiment of this invention. It is a figure which shows the modification of the manufacturing method of the green sheet concerning embodiment of this invention.

Explanation of symbols

11 Support 12 First Layer 13 Second Layer 14 Electrode 15 Green Sheet

Claims (4)

Among ceramic powders, organic binders composed of at least one of butyral, acrylic and olefin resins, and aromatic hydrocarbons, ketones and alcohols which are good solvents for the organic binders An aromatic hydrocarbon, an alicyclic hydrocarbon, an aliphatic saturated hydrocarbon which is a poor solvent for the organic binder and has a higher boiling point than the first solvent; And forming a first layer on a support using a first slurry containing a second solvent comprising at least one of mineral spirits ;
Using a second slurry containing the second solvent minor proportion than the first slurry, forming a second layer on said first layer,
With
In the step of forming the first layer, the second solvent of the first slurry is set to a ratio of 35 wt% to 45 wt% of the total amount of the organic solvent to be used. Method.   The method for producing a green sheet according to claim 1, wherein the second slurry is prepared from the same composition material as the first slurry.   3. The green sheet according to claim 1, wherein a plurality of types of the first solvent are used, and a solvent having a boiling point of 30 ° C. or higher with respect to the solvent having the lowest boiling point is used as the second solvent. Manufacturing method. A multilayer electronic component comprising: a step of producing a green sheet by the method for producing a green sheet according to any one of claims 1 to 3 ; and a step of laminating the produced green sheet. Manufacturing method.

Images