JP2001212489A - Coating device - Google Patents

Abstract

(57) [Problem] To provide a coating apparatus capable of making a surface of a slurry to be applied uniform when applying a slurry containing ceramic powder on a coating medium. I do. A coating head (10) includes a front edge (1) and a rear edge (2) which are divided into front and rear portions in a moving direction thereof via a slit (3). The portion 2 has an inclined surface 2a and a lower surface 2b formed substantially parallel to the application medium surface 50, and the lower surface 1b
The lower surface 2b is formed closer to the application medium 50 than the lower surface 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus for laminating ceramic green sheets while applying a slurry such as a ceramic slurry, and more particularly to a coating head for continuously pressing a slurry.

[0002]

2. Description of the Related Art A multilayer ceramic circuit board is indispensable for miniaturization and high-density mounting of a circuit. Its structure is such that a wiring pattern such as an internal wiring is formed between a plurality of laminated ceramic insulating layers. In addition, after a predetermined wiring pattern is formed on the surface, various electronic components such as chip resistors, chip capacitors, various types of surface mountable electrons, and IC bare chips bonded to the surface wiring are mounted. Have been.

Here, since a relatively large voltage is applied to a multilayer ceramic circuit board for a power amplifier module used in, for example, a portable telephone terminal, a conductor wiring pattern formed in the circuit is as large as possible. Low conductor resistance is required.

Therefore, in general, in order to reduce the conductor resistance value of the inner wiring pattern, a method of increasing the printed film thickness of the wiring pattern is used. That is, when the thickness of the dielectric layer is 10 to 50 μm, attempts have been made to reduce the thickness of the internal electrode to about 10 to 30 μm, which is close to the thickness of the dielectric layer.

However, as compared with a method of laminating a plurality of dielectric layers 5a on which a wiring pattern 6 having a normal thickness is formed as shown in FIG.
When the thickness of the wiring layer 6 is simply increased, the thickness of the wiring pattern 6 cannot be ignored with respect to the thickness of the dielectric layer 5a.
There has been a problem that a separation phenomenon occurs between the layers, which causes delamination d.

Therefore, as shown in FIG.
A dielectric slurry 5 is applied thereon by a printing method or a doctor blade method, dried, printed and formed with a wiring pattern 6, and further, the slurry 5 is further formed thereon to obtain a laminate. Thereafter, a method has been proposed in which the laminate is separated from the glass base plate 7 to form a laminate. As a result, the slurry 5 enters the non-formed portions V of the wiring pattern 6, so that the adhesion between the laminations is improved, and a ceramic circuit board having excellent reliability such as heat resistance can be obtained.

[0007]

However, in the above-mentioned coating apparatus, the slurry 5 is merely applied on the glass base plate 7 by a printing method or a doctor blade method. Due to the presence of agglomerated particles of ceramic powder and the fact that, in the binder removal step at the time of firing, the portion where the ceramic solvent has disappeared after drying becomes porous, the porcelain density of the dielectric layer 5a is low and the moisture resistance is low. There was a problem of getting worse.

When the dielectric layer applied on the wiring pattern 6 is dried, the surface of the laminated body rises where the wiring pattern 6 exists, depending on the presence or absence of the wiring pattern 6 on the dielectric layer 5a. Since the surface of the laminate is uneven, for example, where the surface of the laminate is not present, the thickness of the wiring pattern 6 printed on the dielectric layer 5a becomes non-uniform, and the electrical characteristics are reduced. Variation,
In addition, there is a problem that a difference occurs in the shrinkage rate when integrally firing, and defects such as delamination are easily generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to apply a slurry containing ceramic powder onto a coating medium and to uniformly coat the surface of the slurry. It is an object of the present invention to provide a coating device capable of performing the coating.

[0010]

In order to solve the above problems, a coating apparatus of the present invention moves on a coating medium while continuously extruding a slurry containing ceramic powder from a pocket section through a slit section. In the coating apparatus having a coating head for performing coating, the coating head has a front edge portion and a rear edge portion which are provided separately in front and behind the moving direction through the slit portion, A front edge side lower surface facing the coating medium at an edge portion, an inclined surface formed from a slurry extruding portion side of the slit portion at the rear edge portion, and a continuous surface from the inclined surface, and the coating medium surface And a lower surface on the rear edge side formed substantially in parallel with the coating medium, and the lower surface on the rear edge side is formed closer to the coating medium than the lower surface on the front edge side.

According to the structure of the present invention, since the lower surface on the rear edge side is formed closer to the coating medium than the lower surface on the front edge side, the slurry continuously extruded from the slit portion moves in accordance with the movement of the coating head. Then, the slurry is pushed from the inclined surface, and then the slurry is applied while the slurry is moved while the lower surface on the rear edge side of the rear edge portion presses the slurry.

As described above, since the slurry is applied while being pressed on the lower surface on the rear edge side, a shear stress is applied between the surface of the slurry and the lower surface on the rear edge side and / or between the coating medium and the slurry, and particularly, agglomerated particles on the surface of the slurry are pulverized. It is possible to planarize while applying, even if the surface of the coating medium is uneven due to an internal wiring pattern or the like,
The surface can be flattened while the slurry enters the recess. As a result, the packing density of the ceramic powder can be improved, the number of porous portions inside the laminate after firing decreases, and a laminate having improved structural defects and variations in quality of various characteristics can be formed.

[0013] Further, by forming the inclined width of the inclined surface of the coating head in the range of 0.1 to 0.7 mm and the distance of the lower surface on the rear edge side to the range of 1 to 8 mm, the molded body due to lack of slurry is formed. It is possible to prevent a decrease in the density and generation of streaks on the application surface, and it is possible to sufficiently crush the aggregated particles of the ceramic powder.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coating apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of a coating head 10 in a coating apparatus X according to the present invention, and FIG.
FIG. 3 is a cross-sectional view illustrating the operation and effect of the front edge portion 1 and the rear edge portion 2 of FIG.

In FIG. 1, a coating head 10 has a pocket 4 to which a slurry 5 is supplied, a slit 3 connected to the pocket 4 and continuously pushing out the slurry 5, and a sheet-like shape through the slit 3. A front edge portion 1 and a rear edge portion 2 provided respectively on the front and rear sides in the medium transport direction.
And

An external liquid receiving tank and a discharge pump (not shown) are connected to the pocket portion 4 of the coating head 10, and slurry 5 is supplied from the liquid receiving tank to the pocket portion 4 by the discharge pump. The slurry 5 is extruded from the slit 3, and the tip end surface of the coating head 10 runs on the coating medium 50, so that the coating film 50 having a uniform thickness is formed.
a is formed.

Here, the front edge portion 1 is formed with a front edge side lower surface 1b facing the coating medium 50 and an inclined surface 1a so as to communicate with the front side of the front edge portion. Further, the rear edge surface of the rear edge portion 2 has an inclined surface 2a continuous from the slit portion 3 and a rear edge side lower surface 2b continuous with the inclined surface 2a and formed substantially parallel to the coating medium 50.
And a notch portion 2c formed continuously from the rear edge side lower surface 2b, and a part of the rear surface of the rear edge portion is cut out, and the front edge side lower surface 1b of the front edge portion 1 is formed.
Thus, the rear edge side lower surface 1b of the rear edge surface 2 is closer to the application medium 50 side.

The slurry 5 includes a predetermined amount of a ceramic powder and a plasticizer made of a dielectric material such as barium titanate, magnesium titanate, strontium titanate or a low temperature fired glass ceramic material in a solvent such as water, alcohol or toluene. In addition, it consists of a muddy one.

The slurry 5 has a viscosity of 300
When a slurry 5 having a cP (centipoise) or less is used,
A sufficient shear stress cannot be applied, and the coating film 50a
Density cannot be increased. If the viscosity of the slurry 5 is greater than 1200 cP, it becomes difficult to obtain a coating film 50a having a uniform thickness. Therefore, it is desirable that the viscosity of the slurry 5 be in the range of 300 to 1200 cP (centipoise) or less.

In the present invention, the coating film 50a can be formed by increasing the density of the ceramic powder of the slurry 5, and the mechanism will be described below. (1) First, since the viscosity of the slurry 5 is high,
As shown in FIG. 2, the pressure P2 of the portion where the slurry 5 (not shown) is extruded from the slit portion 3 has a predetermined height, and from this portion toward the end of the upstream edge. , A gentle gradient is drawn such that the pressure P1 becomes smaller. Here, since the inclined surface 2a and the rear edge side lower surface 2c of the rear edge portion 2 are formed closer to the coating medium 50 side than the front edge side lower surface 1b of the front edge portion 1, the rear edge portion Pressure (P3
To P4) are even higher. (2) Next, as shown in FIG. 3, the lower surface 1b of the front edge 1 is moved from the lower surface 1b of the front edge 1 to the lower surface 2 of the rear edge 2.
c protrudes toward the application medium 50, the slit 3
First, the slurry 5 extruded from the surface tends to spread to the front edge portion 1 side. Here, since the coating head 10 moves to the front edge portion 1 side, the slurry 5 is relatively pushed back to the rear edge portion 2 side. At this time, the rear edge side lower surface 2c of the rear edge portion 2 is
Because the distance between the coating surface and the side is formed shorter than the side
The slurry 5 on the side facing the rear edge side lower surface 2c is leveled while being compressed. (3) When filling the agglomerated particles contained in the slurry 5, it is possible to pulverize the agglomerated particles in the slurry by moving in the horizontal direction, rather than simply pressing down from the top, thereby more effectively. Coating film 50a of slurry 5
The ceramic powder can be uniformly filled therein.
That is, since a shear stress acts on the surface of the coating film 50a, the aggregated particles on the surface move while physically pulverizing, so that the pulverized particles are uniformly filled in the coating film 50a.

Here, as shown in FIG. 4, due to the frictional force between the agglomerated particles and the front edge 1, the rear edge 2, and the surface of the slurry 5, the agglomeration after application close to the front edge 1 and the rear edge 2. The particles move in the traveling direction of the coating head 10 (C1, C
Agglomerated particles near the application surface tend to move in the direction (C2, C4) opposite to the traveling direction of the application head 1. Therefore, a shear stress acts between the surface of the slurry 5 and the lower surface on the rear edge side or between the coating medium 50 and the slurry 5 so that the aggregated particles can be pulverized and flattened, whereby the coating film 50a of the slurry 5 can be more effectively formed. Can be filled with the agglomerated particles.

From these facts, it is possible to obtain a ceramic circuit board in which the density of the dielectric is improved and the particles are dense. In addition, when forming the irregularities of the wiring pattern on the application medium 50 applied and dried on the glass substrate, and when the slurry 5 is applied thereon, the slurry 5 enters the recesses of the wiring pattern, and A smooth coating surface can be obtained without being affected by the formed convex portions, and structural defects and variations in quality of various characteristics can be improved.

The inclination width La of the inclined surface is 0.1 to
It is preferably in the range of 0.7 mm, preferably in the range of 0.2 to 0.5 mm. If the inclination width of the inclined surface is shorter than 0.1 mm, the slurry 5 does not easily flow into the lower surface 2b on the rear edge side, and if it exceeds 0.7 mm, it is difficult to apply pressure to the coating film 50a, and the density of the molded body is undesirably low.

The distance Lb of the rear edge side lower surface 2c is in the range of 1 to 8 mm, more preferably 3 to 7 mm. If the distance Lb of the rear edge side lower surface 2c is shorter than 1 mm, sufficient shear stress does not act on the coating film 50a to increase the density of the molded body. If the distance Lb exceeds 8 mm, the slurry 5 will be formed before the coating is completed. Is excessively advanced, so that friction occurs between the surface of the coating film 50a and the lower surface 2c on the rear edge side, and streaks are formed, which is not preferable.

Thus, according to the structure of the present invention, it is possible to prevent a decrease in the density of the molded body due to the shortage of the slurry 5 and the occurrence of streaks on the application surface. In addition, the step stress can be sufficiently generated.

Here, in FIG. 1, the coating head X is provided by providing an inclined surface 1a on the upstream side of the front edge portion 1.
This has the effect of smoothly flowing the slurry 5 that has protruded into the front surface of the coating head when it again enters the lower side of the coating head. Further, by providing the cutout portion 2c on the downstream side of the rear surface edge portion 2, the effect that the edge moves smoothly can be obtained.

Various changes and improvements may be made without departing from the spirit of the present invention. For example, in addition to circuit components, the present invention can be widely applied to multilayer ceramic capacitors and multilayer filters as multilayer components.

[0028]

Next, in order to confirm the operation and effect of the present invention,
The following experiment was performed. In the description, a method of manufacturing a multilayer ceramic circuit board in which internal electrodes are formed between dielectric layers will be described. * Coating base material: glass Size: width 200 x length 200 x thickness 8 mm * Dielectric slurry composition 100 parts by weight Barium titanate 55 parts by weight Organic solvent 35 parts by weight Binder resin content 7 parts by weight Powder and plasticizer 3 parts by weight Part * Slurry viscosity 491 cps (Brookfield viscometer measurement) * Coating speed 80 mm / sec * Coating width 180 mm * Dielectric thickness 10 μm While changing the size of the inclined surface 2 a and the size of the lower surface 2 b on the rear edge side, Apply dielectric slurry 5 /
After drying, the wiring pattern 6 was alternately repeated by screen printing / drying to form a laminate composed of a dielectric layer. Then, evaluation of the molding density and the application surface was performed. Here, since the molding density, that is, the density of the dielectric portion not including the wiring pattern affects the porcelain density of the fired laminate, 3.7 (g / cm ² ) or more was determined to be OK. The evaluation of the coated surface was performed by using a microscope (10 times), providing a light source on the side surface, and observing the state of streaks. The results are shown in Tables 1 and 2. The appearance inspection results were as follows: な し: no streaks ○: 1 to 5 streaks / coated surface △: 6 to 10 streaks / coated surface ×: 11 or more streaks / coated surface .

[0029]

[Table 1]

From the results shown in Table 1, the inclination width Lb is 0.1 to
When the density is 0.7 mm, the density of the molded body and the appearance inspection of the coated surface are good, but when the inclination width La is less than 0.1 mm, the slurry 5 becomes difficult to flow into the coating head 10, and the stripe 5 is insufficient due to the shortage of the slurry 5. Occurs. At the same time, there is a problem that the compact density is low. When the inclination width La exceeds 0.7 mm, pressure is hardly applied to the application surface, and the density of the molded body is low.

[0031]

[Table 2]

From the results shown in Table 2, when the distance Lb is 1 to 8 mm, the density of the molded product and the results of the appearance inspection of the coated surface are good, but when the distance Lb is 1 mm or less, sufficient shear stress is applied to the slurry. And the density of the compact cannot be increased. Also, the leveling of the coated surface is insufficient. When the thickness exceeds 8 mm, drying of the slurry proceeds too much before the coating is completed, so that friction is generated between the coated surface and the head, and there is a problem that streaks are generated.

[0033]

[Table 3]

As shown in Table 3, the inclined surface 2a has an inclination angle α of 1
It is considered that the slurry 5 flows most easily at 20 to 150 degrees. If it exceeds 150 degrees or less than 120 degrees, a decrease in the density of the molded body and generation of streaks on the coated surface are observed. In particular, at 180 degrees and 90 degrees, the slurry 5 hardly flows into the application surface, and a streak occurs due to the shortage of the slurry 5. The same tendency can be seen at 165 degrees and 105 degrees,
At the same time, since the compression effect of the inclined surface 2a is low, it can be seen that the density of the compact does not increase.

[0035]

As described above, according to the coating apparatus of the present invention, the packing density of the ceramic powder is improved, and the formation of porous portions after firing is reduced, so that the moisture resistance can be improved. . In addition, when applied on a coating medium having irregularities, a smooth coated surface can be obtained, and structural defects and variations in quality of various characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a coating head in a coating apparatus according to the present invention.

FIG. 2 is a view for explaining the function and effect of a front edge portion and a rear edge portion in the coating head of the present invention.

FIG. 3 is a diagram for explaining the function and effect of a front edge portion and a rear edge portion in the coating head of the present invention.

FIG. 4 is a view for explaining the function and effect of a front edge portion and a rear edge portion in the coating head of the present invention.

FIG. 5 is an explanatory diagram showing a problem when the thickness of an internal electrode is made larger than the thickness of a conventional ceramic green sheet. (A) is an explanatory diagram when the internal electrode thickness is small, and (b) is an explanatory diagram when the internal electrode thickness is large.

FIG. 6 is a cross-sectional view illustrating a conventional coating apparatus.

[Explanation of symbols]

 Reference Signs List 10 coating head 1 front edge 1a inclined surface 1b front lower surface 2b rear edge 2a inclined surface 2b lower edge lower surface 2c: Notch 3: Slit 4: Pocket 5: Slurry 50a: Coating film 6: Wiring pattern 7: Glass base plate

Claims (3)

[Claims] 1. A coating apparatus having a coating head for moving and applying a slurry containing ceramic powder from a pocket portion through a slit portion on a coating medium while continuously extruding the slurry, the coating head comprising: A front edge portion and a rear edge portion provided separately in the front and rear of the moving direction, a front edge side lower surface facing the coating medium on the front edge portion, and a rear edge portion. An inclined surface formed from the slurry extruding portion side of the slit portion, and a rear edge side lower surface continuous from the inclined surface and formed substantially parallel to the coating medium surface; A coating apparatus, wherein a lower surface on a rear edge side is formed closer to the coating medium than a lower surface on a side. 2. The method according to claim 1, wherein the inclination width of the inclined surface of the coating head is 0.5.
2. The coating apparatus according to claim 1, wherein the distance is 1 to 0.7 mm and a distance between the lower surface on the rear edge side is 1 to 8 mm. 3. 3. The viscosity of the slurry is 100 to 1200.
The coating device according to claim 1, wherein the coating device is in a range of cP (centipoise).