Patent Application
20090211687
The present invention relates to a method for manufacturing a multilayer electronic component; and more specifically the present invention relates to a method for manufacturing the multilayer electronic component of which a multilayer body can be easily removed from a press mold without breaking the multilayer body when removing a green sheet multilayer body which is applied with pressure from the press mold.
For example, the multilayer electronic component such as a multilayer ceramic capacitor is manufactured by going through the steps of stacking plurality of ceramic green sheets having an internal electrode pattern; and applying a pressure to this multilayer body by the press mold. However, when removing the multilayer body after applying the pressure to the multilayer body of the green sheet, the multilayer body sticks to the surface contacting with the press mold, and the multilayer body may break or deform if removed forcibly.
In order to prevent such problem, for example, in Japanese Unexamined Patent 7-101690 and Japanese Unexamined Patent 8-167538 has a separation sheet or a separation film (hereinafter separation sheet) between the press mold and the multilayer body. However, in such method having the separation sheet, these separation sheets must be prepared a part from the green sheet, thus the process becomes complicated.
Also, it is a waste of a material to prepare and discard the separation sheet every time applying a pressure to the multilayer body; and an effect to the environment is also concerned. Furthermore, it is necessary to have an automated replacement of the separation sheet, and thus a cost for the equipment increases.
The present invention is achieved reflecting such situation. The present invention aims to provide a method for manufacturing a multilayer electronic component capable to remove a multilayer body very easily from the press mold without breaking the multilayer body when removing a green sheet multilayer body applied with a pressure from the press mold, furthermore has no waste of material, contributes to the environment conservation, and also easy to automate.
In order to achieve the above mentioned aims, the method for manufacturing the multilayer electronic component according to the present invention comprises steps of
In the method for manufacturing the multilayer electronic component according to the present invention, the adhesive force of at least one of the first green sheet contacting with the press mold is weakened compared to that of the other second green sheet. Thus, while the adhesive force of each green sheet in the multilayer body, which has been pressured, is sufficient, the multilayer body can be removed from the press mold very easily without breaking the multilayer body when removing the multilayer body, which has been pressured, from the press mold.
Furthermore, the method of the present invention does not use the separation sheet, thus it does not waste the material and contributes to the environment conservation. Also, since there is no need for the replacement of the separation sheet, the automation for applying the pressure to the multilayer body of the green sheet is easy.
Preferably, the drying condition of said first green sheet is made different compared to that of said second green sheet. By making the drying condition different, the adhesive force of the first green sheet can be weakened compared to that of the second green sheet.
For example, said first green sheet is heated while contacting with said press mold and dried, then said second green sheet is stacked. Thereby the first green sheet is drier than the second green sheet, and thus the adhesive force of the first green sheet becomes relatively lower. Moreover, in such case, the first green sheet may be dried by simply contacting to the press mold, and can attain significant effect without largely modifying the conventional steps.
Also, said first green sheet and second green sheet can be dried at different condition before stacking on to said press mold to weaken the adhesive force of the first green sheet compared to the second green sheet.
Alternatively, the adhesive force of the first green sheet can be weakened compared to that of said second green sheet by making the thickness of said first green sheet thinner than that of said second green sheet.
Alternatively, the adhesive force of the first green sheet can be weakened compared to that of said second green sheet by making the amount of the plasticizer included in said first green sheet less than that of said second green sheet.
Alternatively, the adhesive force of the first green sheet can be weakened compared to that of said second green sheet by making a type of plasticizer included in said first green sheet different from that of said second green sheet.
Alternatively, the adhesive force of the first green sheet can be weakened compared to that of said second green sheet by making the amount of a resin included in said first green sheet less than that of said second green sheet.
Furthermore, the adhesive force of the first green sheet can also be weakened compared to that of said second green sheet by making the glass transitional temperature Tg of the resin included in said first green sheet higher than that of said second green sheet.
Hereinafter, the present invention will be explained based on the embodiment shown in the figures.
First, an over all constitution of a multilayer ceramic capacitor will be explained as an embodiment of a multilayer electronic component manufactured by the method according to the embodiment of the present invention.
As shown in
The capacitor element body 4 comprises outer dielectric layers 14 at the both end surfaces in the stacking direction thereof. One of the internal electrode layers 12 of which are stacked in alternating manner is electrically connected to the inside of the first terminal electrode 6 formed on the outside of the first terminal of the capacitor element body 4. Also, the other internal electrode layers 12 which are stacked in an alternating manner is electrically connected against the inside of the second terminal electrode 8 formed on the outside of the second terminal of the capacitor element body 4.
The material of these inner dielectric layers 10 and outer dielectric layers 14 are not particularly limited, and for example, it may be constituted by a dielectric material such as calcium titanate, strontium titanate and/or barium titanate. The thickness of each inner dielectric layer 10 is not particularly limited; however in general it is several μm to tens of μm. Also, the thickness of the outer layer part formed by the outer dielectric layer 14 is not particularly limited; however it is within the range of 10 to 200 μm.
The material for the terminal electrodes 6 and 8 are not particularly limited, however usually at least one from Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, and Ir or so, or an alloy thereof can be used. Usually, Cu, Cu alloy, Ni, Ni alloy, Ag, Ag—Pd alloy, or In—Ga alloy or so are used. The thickness of the terminal electrodes 6 and 8 are not particularly limited, however it is usually 10 to 50 μm or so. Note that, Ni plating and Sn plating may be performed to the terminal electrodes 6 and 8.
The shape and the size of the multilayer ceramic capacitor 2 can be determined according to the aim and use. In case the multilayer ceramic capacitor 2 is rectangular parallel shaped, usually the size is length (0.2 to 5.7 mm)×width (0.1 to 5.0 mm)×thickness (0.1 to 3.2 mm) or so.
Next, the method for manufacturing the multilayer ceramic capacitor 2 as an embodiment of the present invention will be explained.
First, the dielectric paste which forms the dielectric layers 10 and 14 shown in
Note that, the organic vehicle is obtained by dissolving a binder in the organic solvent. The binder used in the organic vehicle is not particularly limited, and it can suitably be selected from usual various binders such as ethyl cellulose and polyvinyl butyral or so.
Also, the internal electrode paste for forming the internal electrode layers 12 shown in
Next, by using the above dielectric paste, outer green sheets 14a1 to 14a4 and an inner green sheets 10a shown in
Note that, although in
On each surface of the inner green sheet 10a, an internal electrode pattern 12a is formed by a screen printing using the above-mentioned internal electrode paste. As shown in
In this embodiment, as shown in
In this condition, only the outer green sheet 14a1 is further dried. For example, if the lower mold 20 is a lower mold of the pre-press mold, when pressing, it is performed by heating at about 40° C.; therefore the lower mold 20 thereof is provided with heating device to heat at about 40° C. There, only the outer green sheet 14a1 is dried for example at about 40° C. for about 30 seconds using the heating device. Note that, the temperature and the time for drying only the outer green sheet 14a1 can be changed accordingly. As a result of this drying, the adhesive force of the outer green sheet 14a1 can be reduced significantly by 5 to 80% compared to that of others.
Next, as shown in
At any rate, another outer green sheet 14a2 and/or the inner green sheet 10a are stacked onto the outer green sheet 14a1 which is dried on the lower mold 20 as shown in
In case the lower mold 20 and the upper mold 24 are the pre-press mold, the pre-press treatment is performed for plurality of the green sheets, for example for every 8 to 9 sheets. At the pre-press, the pressure applied to the multilayer body from the upper mold 24 with respect to the lower mold 20 is not particularly limited, however for example it is 1 to 10 kgf/cm2 or so. In the pre-press, eventually 20 to several thousands of green sheets are stacked. The pre-pressed multilayer body of the green sheet is then pressed by the same press mold. Alternatively, as shown in
At the press mold 25a, the pressure preferably of 10 to 30 kgf/cm2 is applied to the multilayer body 4a at between the lower mold 20a and the upper mold 24a. The heating temperature at that time is not particularly limited, however for example it is about 70° C.
The multilayer body 4a finished with the press step is then cut to be a green chip. Then, the green chip is performed with a binder removal treatment and the firing treatment to be a sintered chip. The conditions for the binder removal treatment and firing treatment are not particularly limited, however, as for the firing temperature, for example, it is 1000 to 1400° C.
Then, the electrode paste, which becomes the first terminal electrode 6 and second terminal electrode 8 shown in
In the method according to the present embodiment, the adhesive forth of at least one of the outer green sheet 14a1 contacting the lower mold 20 or 20a of the press mold 25, 25a is made weaker compared to that of the other green sheets 14a2, 10a, 14a3, and 14a4. Therefore, even though the adhesive forth of each of the green sheet in the multilayer body 4a which has been applied with the pressure is sufficient, when removed the multilayer body 4a which has been applied with the pressure from the lower mold 20, 20a of the press mold 25, 25a, the multilayer body 4a can be removed significantly easily without damaging it.
Note that, in the present invention, the adhesive forth of the outer green sheet 14a4 contacting with the upper mold 24a in the multilayer body 4a shown in
Conventionally, the problem was that the outer green sheet 14a1 positioned at the lowest side in the staking direction adheres to the lower mold 20 or 20a. However, in the present embodiment, the adhesive force of at least one of the outer green sheet 14a1 contacting with the lower mold 20 or 20a is made weaker compared to that of the other green sheets 14a2, 10a, 14a3, and 14a4. Thus, the multilayer body 4a can be removed significantly easily without damaging.
Furthermore, the method of the present embodiment does not use the detachment sheet; hence no material is wasted and contributes to the environmental conservation. Also, since there is no need for changing the detachment sheet, the pressure to the multilayer body of the green sheet can be automated easily.
Moreover, the embodiment simply needs to dry the outer green sheet 14a1 positioned at the lowest side simply by contacting to the lower mold 20; thus significant effect can be obtained without making drastic change in the conventional steps.
In the second embodiment of the present invention, before stacking on to the press mold 25 which is shown in
Specifically, the outer green sheet 14a1 alone is dried in advance in a higher drying temperature and/or for a longer drying time compared to that of the other green sheets 14a2, 10a, 14a3, and 14a4. Further specifically, the dielectric paste is dried at about 90° C. for 5 seconds to form a green sheet. Other constitutions and effects are the same as in the above mentioned first embodiment.
In the third embodiment of the present invention, the thickness of the outer green sheet 14a1 which is stacked at the lowest side is made thinner compared to that of the other outer green sheet 14a2. Specifically, the thickness of the outer green sheet 14a1 is 20 to 80% or so thinner compared to that of the other outer green sheet 14a2. Further specifically, if the thickness of the outer green sheet 14a2 is 5 to 15 μm, then the thickness of the outer green sheet 14a1 is 1 to 12 μm. In order to form the sheet thin, the discharging amount of the doctor blade may be modified, or the moving speed of the film when pasting the dielectric paste may be made faster.
As such, for the same outer green sheet, the adhesive forth of the outer green sheets 14a1 can be made weaker compared to that of the other green sheets 14a2, 10a, 14a3, and 14a4 by making the thickness different. Other constitutions and effects are the same as in the above mentioned first embodiment. Also, since the sheet is thinner, it is easily dried and the adhesive forth can be controlled very easily.
In the forth embodiment of the present invention, before stacking the press mold 25 shown in
Specifically, the amount of the plasticizer included in the dielectric paste constituting the outer green sheet 14a1 is 30 to 95% less compared to that of the other outer green sheets 14a2, 14a3, and 14a4. As for the plasticizer, for example DOP (dioctyl phthalate), BBP (butyl benzyl phthalate), and DOA (dioctyl adipate) having the boiling point of about 384° C. may be mentioned as examples. Other constitutions and effects are the same as in the above mentioned first embodiment.
In the fifth embodiment of the present invention, before stacking the press mold 25 shown in
Specifically, the type of the plasticizer included in the dielectric paste which constitutes the outer green sheet 14a1 is BBP; and in accordance with that, the type of the plasticizer included in the dielectric paste which constitutes the other outer green sheets 14a2, 14a3, and 14a4 are DOP. Alternatively, the type of the plasticizer included in the dielectric paste which constitutes the outer green sheet 14a1 is DBP (dibutyl phthalate); and in accordance with that, the type of the plasticizer included in the dielectric paste which constitutes the other outer green sheets 14a2, 14a3, and 14a4 are DOP. Alternatively, the type of the plasticizer included in the dielectric paste which constitutes the outer green sheet 14a1 is DEP (diethyl phthalate); and in accordance with that, the type of the plasticizer included in the dielectric paste which constitutes the other outer green sheets 14a2, 14a3, and 14a4 are DOP. Other constitutions and effects are the same as in the above mentioned first embodiment.
In the sixth embodiment of the present invention, before stacking the press mold 25 shown in
Specifically, the amount of the binder resin included in the dielectric paste which constitutes the outer green sheet 14a1 is 50 to 95% less compared to that of the other outer green sheets 14a2, 14a3, and 14a4. As for the binder resin, for example, polyvinyl butyral resin, polyvinyl acetal resin, and acrylic resin may be mentioned. Other constitutions and effects are the same as in the above mentioned first embodiment.
In the seventh embodiment of the present invention, before stacking the press mold 25 shown in
Specifically, Tg of the binder resin included in the dielectric paste which constitutes the outer green sheet 14a1 is 40 to 100° C.; and in accordance with that, Tg of the binder resin included in the dielectric paste which constitutes the outer green sheets 14a2, 14a3, and 14a4 are higher by 1° C. or more than that of the outer green sheet 14a1. The main component of the resin may be same in the outside and inside. Other constitutions and effects are the same as in the above mentioned first embodiment. Note that, Tg of the binder resin can be controlled by the number of the butyral group or the degree of polymerization of the resin.
Note that, the present invention is not limited to the above mentioned embodiment, and it can be variously modified within the scope of the invention.
For example, the method of the present invention is not limited to the multilayer ceramic capacitor, and it can be applied to other electronic components.
Hereinafter the present invention will be explained based on the further detailed example.
This example 1 corresponds to the above mentioned first embodiment, and as shown in
As for the binder resin included in these green sheet 14a1 and 14a2, polyvinyl butyral resin was used, the glass transition temperature was 67° C. as shown in the following Table 1 and 2; and the amount of the resin was 5.5 parts by weight with respect to 100 parts by weight of ceramic powder. Also, as for the plasticizer included in the green sheet, DOP was used as shown in the following Table 1 and 2; and the added amount of the plasticizer was 45 parts by weight with respect to 100 parts by weight of the binder resin.
When the attachment of the mold to the multilayer body of the green sheet was checked against the surface 21 of the lower mold 20 which is shown in
As shown in Table 1, the multilayer body of the green sheet was obtained as same as Example 1 except for heating the green sheet 14a1 on the press mold 25 at 70° C. for 30 minutes. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was found. The results are shown in Table 1.
This example corresponds to the above mentioned second embodiment in which before stacking on to the mold 25 as shown in
After that, these green sheet 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. For other conditions, it is as same as Example 1. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
This example corresponds to the above mentioned third embodiment, and the thickness of the outer green sheet 14a1 which is staked at the lowest side was 4 μm which is thinner compared to that of the other outer green sheet 14a2 which was 7 μm. The drying condition of these green sheets is the same. Then, these green sheets 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. Other conditions were the same as example 1. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
This example corresponds to the above mentioned fourth embodiment, and the outer green sheet 14a1 which is stacked at the lowest side was formed in advance by the paste having less amount of the plasticizer compared to that of the other outer green sheet 14a2. Specifically, with respect to 100 parts by weight of the binder resin, the amount of the plasticizer of the outer green sheet 14a1 was 40 parts by weight which is less compared to the amount of plasticizer of 45 parts by weight of the other outer green sheet 14a2.
The drying condition of these green sheets 14a1 and 14a2 are the same. Then, these green sheet 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
This example corresponds to the above mentioned fifth embodiment in which the type of the plasticizer included in the dielectric paste constituting the outer green sheet 14a1 was BBP, and in accordance with that the type of the plasticizer included in the dielectric layer constituting the other similar outer green sheet 14a2 was DOP.
The drying condition of these green sheets 14a1 and 14a2 are the same. Then, these green sheet 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
This example corresponds to the above mentioned sixth embodiment, and the outer green sheet 14a1 which is stacked at the lowest side was formed in advance by the paste having less amount of the resin compared to that of the other outer green sheet 14a2. That is, with respect to 100 parts by weight of the ceramic powder, the content of the binder resin was 5.0 parts by weight, and that of the green sheet 14a2 was 5.5 parts by weight.
The drying condition of these green sheets 14a1 and 14a2 are the same. Then, these green sheet 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
This example corresponds to the above mentioned seventh embodiment, and the outer green sheet 14a1 which is stacked at the lowest side was formed in advance by the paste having higher Tg of the binder resin compared to that of the other outer green sheet 14a2. That is, Tg of the green sheet 14a1 was 71° C., and Tg of the green sheet 14a2 was 67° C.
The drying condition of these green sheets 14a1 and 14a2 are the same. Then, these green sheet 14a1 and 14a2 were stacked sequentially, and press treatment was performed to obtain the multilayer body of the green sheet. When the attachment of the mold to the multilayer body of the green sheet was checked, no attachment was confirmed. The results are shown in Table 1.
As same as example 1, the green sheet 14a1 and 14a2 was stacked on the mold 25 sequentially, and press treated to obtain the green sheet, except for the green sheet 14a1 was not heated in advance on the press mold 25. When the attachment of the mold to the multilayer body of the green sheet was checked, the attachment was confirmed. The results are shown in Table 1.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-043472 | Feb 2008 | JP | national |
