JPH0358525B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing laminated ceramic electronic components, and in particular to a method for manufacturing laminated ceramic electronic components, which is used to manufacture electronic components such as a laminated capacitor by laminating ceramic green sheets. Concerning a method for manufacturing parts.

(Prior Art) FIG. 10 is a diagram showing a multilayer capacitor as an example of a multilayer ceramic electronic component which is the background of the present invention. The multilayer capacitor 1 has a plurality of internal electrodes (not shown) formed inside a ceramic 2, and external electrodes 3 electrically connected to the internal electrodes at both ends thereof.

Conventionally, as a method for manufacturing such a multilayer capacitor 1, a plurality of rectangular electrodes are formed on a ceramic green sheet, a plurality of green sheets on which such a plurality of electrodes are formed are laminated, and then the green sheets are stacked. Crimp with a rigid press. In the crimping process using a rigid press, the stacked green sheets are put into the lower die of the mold, and the upper die is pressurized, thereby crimping each green sheet and the internal electrode without any gaps within the layers. In this case, if there is a gap, delamination will occur during cutting or firing, so it is necessary to press with high pressure.

After crimping, the green sheet is cut into rectangular parallelepiped chips, which are fired and then external electrodes are formed on both sides.

(Problem to be Solved by the Invention) Since there is a difference in the thickness of the sheet between the part where the internal electrodes are formed and the part where the internal electrodes are not formed, the method of crimping the rigid body using a press makes it difficult to form the internal electrodes. There is a problem in that the molding density does not increase in the areas where it is not coated, and layer peeling is likely to occur in these areas. In particular, as the number of stacked green sheets increases, the difference in density during pressure bonding becomes more pronounced, so the effect is greater. For this reason, when manufacturing a multilayer multilayer capacitor, there is a problem that defective products are likely to occur due to poor crimping, and the yield will be significantly reduced.

In addition, in the crimping method using a rigid press, the mold is distorted when pressure is applied, so the way the force is applied differs depending on the working position of the upper and lower molds, which tends to cause uneven pressing force. This also causes layer peeling.

Furthermore, when the chip is crimped with a rigid press, the chip becomes an almost perfect rectangular parallelepiped after firing, so when an external electrode is formed on this chip, it protrudes from the rectangular parallelepiped by the thickness of the external electrode, making it easier to mount it on the board. There are also problems that reduce the

Therefore, the main object of the present invention is to provide a method for manufacturing laminated ceramic electronic components that can improve the yield of products by uniformly pressing laminated ceramic green sheets without causing layer peeling. That's true.

(Means for Solving the Problems) In the present invention, when ceramic green sheets provided with electrodes are laminated and pressure bonded, the laminate of ceramic green sheets is placed in a frame and vacuum packaged, and then the ceramic green sheets are vacuum-packed. This is a manufacturing method including a step of crimping by hydrostatic pressing.

(Effects of the Invention) According to this invention, since the laminated ceramic green sheets are placed in a frame and pressed together using a hydrostatic press, there is no pressure difference between the electrode portion and other portions due to the difference in molding density. This eliminates uniformity and prevents layer peeling, and since the pressure applied to the peripheral edge of the ceramic green sheet is suppressed by the frame and is not applied directly to the ceramic green sheet, shrinkage can be prevented from occurring at the peripheral edge. , it is possible to eliminate irregularities in chip shape caused by shrinkage. As a result, the yield of products can be significantly improved.

Furthermore, since the pressure can be made uniform regardless of the number of laminated layers, multilayer laminated electronic components can be manufactured with high yield. Furthermore, as a result, the parts of the internal electrodes with fewer layers are pressurized to be thinner than the parts with more layers, so if the external electrodes are formed on these parts,
Undesirable protrusions caused by external electrodes are not formed, and it is possible to improve mounting performance on a board and stability of storage during packaging.

The above objects and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Example) Figure 1A, Figure 1B, Figure 2, Figure 3, Figure 4
5 and 6 are diagrams showing the manufacturing process of a multilayer capacitor as an embodiment of the present invention. Particularly, FIG. 1A is a perspective view of the process of forming a laminate of ceramic green sheets, and FIG. The figure is a sectional view thereof.

First, as shown in FIGS. 1A and 1B,
A laminate 10 in which a plurality of ceramic green sheets 14 on which internal electrodes 12a to 12c are formed are laminated.
is prepared, and this laminate 10 is held in a frame 15. That is, the laminate 10 includes a plurality of internal electrodes 121 on one green sheet 141.
, green sheets 142 and 143 on which a plurality of electrodes 122 and 123 are similarly formed are stacked so that the internal electrodes 121, 122, and 123 are alternately shifted slightly, and green sheets 144
It is made by laminating. In addition, in the illustration, there are three layers of internal electrodes (121, 122, 123) and four layers of green sheets (141 to 144, collectively referred to as 14), and the horizontal direction of one stacked laminate 10 is 3 groups of internal electrodes 12
A case where a, 12b, and 12c are formed is shown. However, these numbers are arbitrary.

The thus produced laminate 10 is placed in the frame 15 and held by the frame 15. This frame 1
5 has an internal space approximately the same size as the planar shape of the laminate 10, and a thickness thereof is selected to be approximately the same as the thickness of the laminate 10.

The reason why the frame 15 is used to hold the laminate 10 in this way is as follows. That is, if frame 1
If 5 is not used, when the laminate 10 is hydrostatically pressed, the pressure applied to the vertical and horizontal side edges of the laminate 10 will cause the frame-shaped peripheral portion of the laminate 10 to shrink. When the laminate 10 is cut out and made into chips, the shrinkage at the circumferential end portion causes irregularities in chip size and shape. However, the capacitance of a multilayer ceramic capacitor is determined by the area S and thickness t.
Since it is proportional to S/t, the capacitance of the shrunk chip decreases in proportion to the shrunk area, and this includes chips that cannot be manufactured with the designed capacity, and these are considered defective products. As a result, the yield becomes worse. Therefore, if hydrostatic pressing is performed as shown in FIG. 3, which will be described later, while holding the laminate 10 using the frame 15 as in this embodiment, the laminate 10
Pressure is applied only from the top and bottom directions of the laminate 10, and the pressure applied to the side surfaces is suppressed by the frame 15.
This is because since it is not directly applied to the chip, it is possible to prevent shrinkage from occurring at the peripheral end portion, thereby making it possible to eliminate irregularities in chip size and shape.

In the above description, the method of holding the laminate 10 in the frame 15 was described in which the stacked bodies 10 are placed in the frame 15 as they are, as shown in FIG. 1B, but there are other methods as follows. may be applied.
That is, the frame 15 may be placed on a stand first, and green sheets provided with electrodes may be stacked and placed into the frame 15. In this way, the frame 15 becomes a jig for positioning the green sheets and the internal electrodes, and there is an advantage that the stacking and positioning of these can be easily performed.

Thereafter, the laminate 10 held by the frame 15 is wrapped (ie, vacuum packed) with a flexible material 16 such as rubber while applying a vacuum to the area surrounded by the frame, as shown in FIG. 2A. The flexible material 16 may be made of any material such as rubber or vinyl, as long as it has excellent water resistance and is compatible with the shape of the object to be pressed. In this vacuum packaged state, due to the influence of the negative pressure, the parts of the internal electrodes 121 to 123 that overlap more or less overlap are slightly depressed compared to the parts that overlap more.

Note that the vacuum packaging method involves wrapping both sides of the laminate 10 and the frame 15 with a flexible material 16, as shown in FIG. 2B.
Alternatively, the frame 15 and the flexible material 16 may be covered with a bolt, and then the frame 15 and the flexible material 16 are tightened with bolts and then degassed.

Next, the laminate 10 vacuum-packed with the flexible material 16
is placed in water or oil 20 stored in a high-pressure molding container 18, as shown in FIG. Then, the hydrostatic pressure within the high-pressure molded container 18 is increased.
Therefore, uniform pressure is applied to the outer circumference of the laminate 10 from above the flexible material 16 by water pressure. In other words, the laminate 10 has green sheets 14 regardless of whether the internal electrodes have no overlap, a small overlap, or a large overlap.
Since the entire surface of the laminate 10 is uniformly pressed and bonded, there is no variation in the molding density of the laminate 10. After crimping until a predetermined molding density is achieved, the pressure is reduced.

The laminate 10 is taken out from the high-pressure molding container 18, and after the flexible material 16 is peeled off, it is taken out from the frame 15. The laminate 10 after this pressure bonding is shown in FIG. The laminated body 10 after being crimped is cut into chips at the portions indicated by arrows in FIG. 4, that is, at both ends of the internal electrodes which are alternately shifted.

The chips are then fired at high temperatures. This fired chip 24 is shown in FIG. As is clear from FIG. 5, the chip 24 is
Internal electrodes 121 and 123 are exposed at one end 241 thereof, and internal electrode 122 is exposed from the other end 242. Both ends 241, 2 of this chip 24
42 is a constricted portion 24 compared to the portion where the internal electrodes 121 to 123 overlap.
It becomes 3.

External electrodes 26 are formed on both ends 241 and 242 of the chip 24 and around the constricted portion 243 by applying and baking an electrode paste, for example.
a, 26b are formed. The external electrode 26a is electrically connected to the internal electrodes 121 and 123, and the external electrode 26b is electrically connected to the internal electrode 122.

Multilayer capacitor 28 made in this way
Since the thickness of the external electrodes 26a and 26b can be made almost the same as that of the chip 24, when mounted on the board 30 as shown in FIG. will improve.

In addition, the multilayer capacitor 2 made as described above
8 is packaged, it is placed in a magazine 32 as shown in FIG. 8 or in a tape body 34 as shown in FIG. When a plurality of multilayer capacitors 1 manufactured by a conventional rigid press shown in FIG.
When it hits the inner wall, the alignment may be misaligned and it may not be possible to remove it properly. However, in the multilayer capacitor 28 according to this embodiment, since the thickness of the ceramic and the thickness of the external electrode can be made almost equal, there is an advantage that even if a plurality of multilayer capacitors are stacked and placed in the magazine 32, the arrangement will not be misaligned and it can be taken out easily. .

Furthermore, by inserting the multilayer capacitor 28 into the hole of the tape body 34 shown in FIG.
When packaging the multilayer capacitor 1 shown in FIG. 10, only the external electrode 3 is attached to the adhesive tape 36 and is likely to peel off or shift during transportation. In the multilayer capacitor 28 manufactured according to the example, not only the external electrodes 26a and 26b but also the chip 24 can be sufficiently attached to the adhesive tape 36, so that they will not come off during transportation.

In the above embodiment, a case where a large number of multilayer capacitors are manufactured at the same time has been described, but it is naturally possible to manufacture them individually, and the electronic components are not limited to multilayer capacitors.

[Brief explanation of drawings]

1A, 1B, 2A, 2B, 3, 4, 5, and 6 are diagrams showing the manufacturing process of an embodiment of the present invention.
The figure shows a perspective view of the step of forming a laminate of ceramic green sheets, FIG. 1B shows a sectional view thereof, FIGS. 2A and 2B show a sectional view of the step of vacuum packaging the laminate, 3 shows the hydrostatic pressing process, FIG. 4 shows a cross-sectional view of the laminate after pressure bonding, FIG. 5 shows the chip after firing, and FIG. 6 shows the multilayer capacitor after electrode formation. FIG. 7 is a sectional view showing a multilayer capacitor manufactured according to this embodiment mounted on a substrate. FIGS. 8 and 9 are diagrams showing the state in which the multilayer capacitor manufactured according to this embodiment is packaged. FIG. 10 is a diagram showing a multilayer capacitor as an example of a multilayer ceramic electronic component which is the background of the present invention. In the figure, 10 is a laminate, 121 to 123 are internal electrodes, 14 is a ceramic green sheet, 1
5 is a frame, 16 is a flexible material for vacuum packaging, 18 is a high-pressure molded container, 20 is water or oil, and 28 is a laminated capacitor.

Claims (1)

[Claims] 1. A step of holding stacked ceramic green sheets, each of which has an electrode, in a frame. While vacuuming the ceramic green sheets held by the frame, the area surrounded by the frame is removed. A method for producing a laminated ceramic electronic component, comprising: covering with a flexible sheet; hydrostatically pressing the ceramic green sheet covered with the flexible sheet; and taking out the hydrostatically pressed ceramic green sheet. .