JP4431895B2 - Manufacturing method of laminated electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a laminated electronic component.

  As a multilayer electronic component, for example, a multilayer ceramic capacitor can be manufactured as follows. First, a green sheet laminate having a conductive layer inside is prepared. The green sheet laminate has a plurality of unfired green layers made of a ceramic material and a conductive layer appropriately interposed therebetween.

  Next, the green sheet laminate is cut to obtain a cuboid green chip having a predetermined size. Then, the first barrel polishing is performed and fired on the plurality of green chips, and the second barrel polishing is further performed. Thereafter, terminal electrodes are formed to obtain a multilayer ceramic capacitor.

  The first barrel polishing before firing described above is performed for the purpose of rounding the corners of a rectangular parallelepiped green chip in advance to prevent chipping or peeling of the green chip during the subsequent manufacturing process. On the other hand, the second barrel polishing after firing is performed for the purpose of reliably exposing the conductive layer on the end face of the green chip and further ensuring electrical connectivity with a terminal electrode to be formed later.

In addition, originally, the first barrel polishing is performed to prevent the occurrence of chipping or the like, but some green chips may have chipping in the first barrel polishing process. Therefore, in order to prevent this, it is also known to first perform a heat treatment for giving the green chip appropriate hardness before the first barrel polishing (see Patent Document 1). Patent Document 1 discloses that heat treatment is performed at 120 to 150 ° C. for 5 to 30 minutes.
JP 2003-332171 A

  However, as a result of investigation by the present inventors, in the heat treatment step before the first barrel polishing, the delamination of the green chip is caused to occur, depending on the heat treatment time and the heat treatment temperature. There is.

  Further, according to the study by the present inventors, the plasticizer among the constituent components of the green chip differs in degree of volatilization outside the green chip depending on the heat treatment time. For this reason, it is considered that it is difficult to consistently control the green chip to give a desired hardness.

  The present invention has been made in view of such problems, and provides a method for manufacturing a laminated electronic component that can perform a heat treatment that imparts a desired hardness to a green chip without having a heat treatment time as a direct element. The purpose is to provide.

  In order to solve the above-described problems, a method for manufacturing a laminated electronic component according to the present invention provides a green sheet laminate configured by interposing at least one conductive layer between a plurality of green sheets, and the green sheet Cutting the laminate into green chips of a predetermined size, subjecting the green chips to heat treatment, and barrel-polishing the green chips after the heat treatment, wherein the heat treatment includes heating and holding temperature and weight change of the green chips It carries out based on the heat processing conditions determined by correlation with these.

The heat treatment conditions are preferably
0 <Y ≦ A · exp (−Bt + C)
Given in.

The plasticizer content W [wt%] in the green chip before the heat treatment is
0.3 <W <6.5
Is preferable.

  According to the present invention described above, it is possible to perform a heat treatment that gives a desired hardness to the green chip without having a heat treatment time as a direct element.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  Hereinafter, an embodiment in which the method for manufacturing a multilayer electronic component according to the present invention is applied to the manufacture of a multilayer ceramic capacitor will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a cross-sectional view showing an example of a multilayer ceramic capacitor to which the manufacturing method according to the present embodiment is applied. In the illustrated multilayer ceramic capacitor 1, a plurality of internal electrodes (conductive layers) 5 and 7 are embedded in a dielectric substrate 3 made of ceramic. The dielectric substrate 3 is formed by laminating a plurality of green sheets as will be described later.

  Two internal electrodes 5, 7 adjacent to each other in the upper and lower directions in the figure are arranged so that their extending positions are alternated, and face each other through a dielectric layer constituting the dielectric substrate 3. The number of layers of the internal electrodes 5 and 7 is determined according to the required capacitance.

  Terminal electrodes 9 and 11 as external electrodes are provided on opposite side surfaces of the dielectric substrate 3. The internal electrode 5 is electrically connected to the terminal electrode 9, and the internal electrode 7 is electrically connected to the terminal electrode 11.

  Next, a method for manufacturing the multilayer ceramic capacitor according to the present embodiment will be described. As shown in FIG. 2, as step S1, a green sheet laminate is formed and prepared. Although it does not specifically limit as a formation aspect of a green sheet laminated body, The example is shown in FIG.

  First, a dielectric paste containing at least ceramic powder, a binder (butyral), a solvent, a plasticizer (DOP), and the like is applied to the upper surface of a flexible PET film, and then dried to obtain a thickness of 1 A green sheet of about 5 μm is formed. In applying the dielectric paste, for example, a doctor blade or an extrusion head can be used.

  Subsequently, a conductive paste for forming the internal electrodes 5 and 7 is disposed on the top surface of the dried green sheet separately in a plurality of portions. The conductive paste includes at least a conductive powder, a binder (ethyl cellulose), a solvent, and the like, and is printed by, for example, a screen printing method or a gravure printing method. Further, the printed conductive paste is dried to obtain the internal electrodes 5 and 7.

  Then, a plurality of green sheets having the internal electrodes 5 and 7 formed on the upper surface as described above are stacked. Such lamination is performed in such a manner that the positions of the internal electrodes 5 and 7 are alternately shifted. A protective layer in which a plurality of green sheets are stacked without including the internal electrodes 5 and 7 is provided at the uppermost and lowermost portions in the stack. In the present embodiment, the total number of stacked layers is 360 layers.

  In this way, a green sheet laminate is obtained in which at least one conductive layer is interposed between a plurality of green sheets. In addition, regarding the paste arrangement method described above, any of other methods such as coating, printing, and transfer, which are existing methods, may be used for each of the dielectric paste and the conductive paste.

  Further, the relationship between drying and lamination is not limited to the above example. In other words, as described above, a plurality of dried green sheets provided with the internal electrodes 5 and 7 are prepared, and these are laminated together. It may be a laminated form in which body paste or conductive paste is applied and dried repeatedly to form a green sheet laminate as a result. In short, the embodiment is not limited to a specific embodiment as long as a green sheet laminate is finally obtained in which at least one conductive layer is interposed between a plurality of green sheets.

  Next, as step S2, the green sheet laminate is cut into green chips having an appropriate size as a product. More specifically, the green sheet laminate obtained in step S1 is pressed and then cut to obtain a plurality of cuboid green chips from the green sheet laminate.

  Next, as step S3, heat treatment is performed on the plurality of cut green chips. This heat treatment is a solidification drying process for volatilizing the plasticizer component contained in the paste and giving the green chip appropriate hardness.

  In step S4, first barrel polishing is performed. The first barrel polishing is so-called wet barrel polishing, in which a polishing medium, a compound, a green chip, and the like are placed in a barrel rod and processed by causing relative movement between the green chip and the polishing medium by rotation, vibration, or the like. . As a result, the corners of the rectangular parallelepiped green chip are appropriately rounded in advance, and it is possible to prevent the chip from being chipped or peeled off during the subsequent manufacturing process.

  Next, as step S5, a binder removal process and a firing (sintering) process are performed. That is, the binder removal treatment is performed on the green chip, and the binder component is burned out from the green chip, followed by firing.

  Furthermore, 2nd barrel grinding | polishing is performed as step S6. Such barrel polishing is intended to ensure that the end portions of all the internal electrodes 5 and 7 are exposed to the end surface of the green chip, thereby further ensuring the connectivity between the terminal electrodes 9 and 11 and the internal electrodes 5 and 7. Done for. Furthermore, as step S7, terminal electrodes 9 and 11 are formed to obtain a multilayer ceramic capacitor.

  Here, when the present inventors investigated, in the heat treatment process of step S3, depending on the heat treatment time and the heat treatment temperature, the delamination in which the green chip layers are separated in the heat treatment process or the process after the first barrel polishing. May occur. In addition, among the constituents of the green chip, the plasticizer has a different degree of volatilization outside the green chip depending on the type of heat treatment time. That is, even when the heat treatment temperature profile is the same, the timing at which volatilization to the outside of the chip starts and the distribution of the volatilization amount differ depending on the plasticizer. For this reason, it is not easy to consistently control the green chip to give a desired hardness.

  Therefore, in the present invention, as step S3, heat treatment is performed based on the heat treatment condition determined by the correlation between the heating holding temperature and the weight change of the green chip. First, the meaning of such heat treatment conditions will be described.

  The present inventors examined the occurrence frequency of delamination using the heating holding temperature and the weight change rate of the green chip as parameters, and obtained the results shown in Table 1.

The vertical arrangement in Table 1 indicates the rate of change in weight of the green chip, where the weight of the green chip before heat treatment is W1, and the weight of the green chip after heat treatment is W2.
(W1-W2) / W1
The value given by. The change range of the weight change rate (weight decrease rate) is 0.2 to 6.5 [wt%].

  Moreover, the horizontal arrangement | sequence in Table 1 represents the heating holding temperature in heat processing. The temperature profile of the heat treatment includes a temperature rising gradient area, a top temperature holding area, and a temperature falling gradient area, and a constant temperature in the top temperature holding area is a heating holding temperature. The change range of the heating and holding temperature is 100 to 220 [° C.].

  Furthermore, the occurrence frequency [%] of the corresponding delamination is shown in the column where each weight change rate and each heating holding temperature intersect.

  As can be seen from Table 1, delamination occurs at all in the range of the weight change rate of 0.2 to 6.5 [wt%] when the heating and holding temperature is 100 [° C.] and 120 [° C.]. I did not. Under the condition of the heating and holding temperature of 130 [° C.], when the weight change rate reached 6.5 [wt%], the delamination occurrence frequency was 1 [%]. Thereafter, it can be seen that delamination occurs from a lower weight change rate as the heating and holding temperature increases.

FIG. 3 is a graph showing the results of Table 1. As a preferred example, an exponential function curve is obtained by obtaining a relationship connecting points having a delamination occurrence frequency of 1 [%] in order to obtain a condition that can keep a delamination occurrence frequency of 1 [%] or less. Obtained as
Y = A · exp (−Bt + C)
It becomes.
Here, the meaning of each symbol is
Y: Weight change rate of green chip t: Heat holding temperature [° C.]
A, B, C: constants.

Therefore, the heat treatment conditions that keep the delamination occurrence frequency at 1% or less are as follows:
0 <Y ≦ A · exp (−Bt + C)
It becomes.

  Regarding the lower limit condition 0 <Y, as long as heat treatment is performed on a green chip made of a paste containing a plasticizer, it is inevitable that the weight of the green chip is reduced, and this is a condition that clearly indicates that.

  In the present invention, by performing heat treatment based on such heat treatment conditions, first, the occurrence of delamination in the green chip can be reliably reduced to a desired ratio. In addition, since the heat treatment time is not a direct element of the treatment conditions, a constant heat treatment effect is always guaranteed by consistent heat treatment control regardless of the type of plasticizer.

  Next, a modified embodiment of the method for manufacturing a laminated electronic component according to the present invention will be described. In this embodiment, the plasticizer content in the green chip before the heat treatment is specified in the above-described embodiment. The inventors investigated the relationship between the plasticizer content, the sheet adhesion after lamination, and the mold separation property. The results are shown in Table 2.

  The upper part in Table 2 shows the content [wt%] of the plasticizer included in the green chip before the heat treatment. The middle part of Table 2 shows the adhesion between the stacked sheets. “◯” indicates good adhesion, and “x” indicates that the adhesion between the sheets is reduced. Furthermore, the lower part of Table 2 shows the separability of the green sheet laminate from the mold used to place the green sheet laminate. “◯” indicates a case where the green sheet laminate can be satisfactorily separated from the mold, and “X” indicates a case where adhesion to the mold occurs.

  As can be seen from the results in Table 2, when the content of the plasticizer included in the green chip before heat treatment is 0.3 [wt%] or less, adhesion between sheets may be reduced. . On the other hand, when the content of the plasticizer is 6.5 [wt%] or more, the green sheet laminate may adhere to the mold.

Therefore, in the modified embodiment, the plasticizer content W [wt%] in the green chip before heat treatment,
0.3 <W <6.5
It was.

  As described above, in the present embodiment, the weight change rate is determined while taking into account the condition of the plasticizer content in the green chip before the heat treatment, and the heat treatment conditions described above are carried out, whereby sheet adhesion and mold separation are performed. It is possible to obtain a certain heat treatment effect by consistent heat treatment control regardless of the type of plasticizer while maintaining good properties.

  Although the contents of the present invention have been specifically described above with reference to the preferred embodiments, those skilled in the art can take various modified modes based on the basic technical idea and teachings of the present invention. That is obvious.

  The multilayer electronic component to which the present invention is applied is not limited to the multilayer ceramic capacitor. That is, it can be widely applied as long as it is manufactured using a green sheet laminate in which at least one conductive layer is interposed between a plurality of green sheets. For example, inductors, LC filters, array components, etc. It can also be applied to.

It is sectional drawing of the multilayer ceramic capacitor to which the manufacturing method which concerns on embodiment of this invention is applied. It is a figure explaining the process of the manufacturing method which concerns on embodiment of this invention. It is a graph which shows the relationship between the heating holding temperature from which the occurrence frequency of delamination becomes 1% or less, and the weight change rate of a green chip.

Explanation of symbols

1 Multilayer ceramic capacitors (multilayer electronic components)
3 Dielectric substrate 5, 7 Internal electrode

Claims (3)

Preparing a green sheet laminate comprising at least one conductive layer interposed between a plurality of green sheets;
Cutting the green sheet laminate into green chips of a predetermined size,
Heat treating the green chip, and barrel-polishing the green chip after the heat treatment,
The heat treatment is performed based on a heat treatment condition determined by a correlation between a heating holding temperature and a weight change of the green chip, and the heating holding temperature is lowered as the weight change rate of the green chip increases. I,
When the weight change of the green chip before the heat treatment is W1, and the weight of the green chip after the heat treatment is W2,
(W1-W2) / W1
In the weight change rate given by the above, the change range is set to 0.2 to 6.5 [wt%]
The heating holding temperature is a constant temperature in the top temperature holding region in the temperature profile of the heat treatment including the temperature rising gradient region, the top temperature holding region, and the temperature falling gradient region, and the change range is set to 100 to 220 [° C.]. To be
A method for producing a monolithic ceramic capacitor. Preparing a green sheet laminate comprising at least one conductive layer interposed between a plurality of green sheets;
Cutting the green sheet laminate into green chips of a predetermined size,
Heat treating the green chip,
Barrel-polishing the green chip after heat treatment,
In the heat treatment, the occurrence frequency of delamination obtained by using the heating holding temperature and the weight change rate of the green chip as parameters, respectively,
The weight change rate is as follows. The weight of the green chip before the heat treatment is W1, and the weight of the green chip after the heat treatment is W2.
(W1-W2) / W1
The change range is set to 0.2 to 6.5 [wt%],
The heating holding temperature is a constant temperature in the top temperature holding region in the temperature profile of the heat treatment including the temperature rising gradient region, the top temperature holding region, and the temperature falling gradient region, and the change range is set to 100 to 220 [° C.]. And
The heat treatment is performed in a region that is determined by a correlation between the change range of the weight change rate and the change range of the heating and holding temperature and that can keep the occurrence frequency of delamination of 1% or less. ,
A method for producing a monolithic ceramic capacitor. The plasticizer content W [wt%] in the green chip before the heat treatment is:
0.3 <W <6.5
The method for producing a multilayer ceramic capacitor according to claim 1, wherein the method is a multilayer ceramic capacitor.

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