JPH0714602B2 - Method for manufacturing ceramic substrate for electronic component - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a method for manufacturing a ceramic substrate for electronic components such as chip resistors.

[Prior art]

As shown in FIGS. 5 and 6, a small electronic component such as a chip resistor has a plurality of columns and a plurality of rows divided by a grid-like slit having vertical slits a and horizontal slits b of a predetermined depth. A flat rectangular ceramic substrate c having a region for unit parts is used, and element structures such as an electromagnetic coating d and a resistance coating e are formed on the surface of the ceramic substrate c by a thick film printing method, and a large number of pieces are formed on one ceramic substrate. The manufacturing method is adopted in which the electronic components of (1) are manufactured in a batch and then divided by the above-mentioned lattice slit to obtain each unit electronic component. The above-mentioned ceramic substrate is generally manufactured as follows. A semi-dry intermediate product called a rectangular plate-shaped green sheet is created from a mixture of a raw material consisting of alumina fine powder and a sintering aid, a solvent, and a binder material to form a suspension. At this point, the above-mentioned lattice slits are formed. Then, this is sintered and solidified in the heating furnace.

[Problems to be Solved by the Invention]

More specifically, the green sheet is in the form of a semi-dry strip by pulling out the raw material suspension from a slit having a predetermined thickness onto a conveyor that moves at a constant speed and removing part of the solvent by forced heating. It is created by press-forming the above-mentioned lattice-like slits on the surface and punching into a rectangular shape. However, in order to make the suspension half dry in a short time, 100 ℃
Due to the forced heating to some extent, not all of the solvent in the raw material is blown away, but rather the solvent remains unevenly in the thickness direction, which causes the following problems. It was That is, after forming the grid-like slits, the green sheet which has been die-cut into a rectangular shape is then subjected to a step of removing chips generated during die-cutting, a secondary drying step, before firing in a heating furnace. Several steps are waiting, such as the step of applying fine alumina powder called grain sand coating, to prevent the adhesion of green sheets that are stacked in the furnace during firing. The solvent remaining in the green sheet gradually escapes, which causes shrinkage of the green sheet between the die cutting and the firing. This shrinkage depends on the extent to which the solvent remains,
Alternatively, there are many variations due to subtle differences in the raw material composition in the longitudinal direction before stripping, which makes it difficult to control this, and as a result, thick film printing after firing into a ceramic substrate Print misalignment in the process leads to a problem that defective products are generated and the yield is reduced.
That is, in the conventional method of manufacturing a ceramic substrate, the dimensional variation of the finished ceramic substrate was large. Therefore, it is an object of the present invention to provide a method for manufacturing a ceramic substrate for electronic parts, which can manufacture a ceramic substrate with less dimensional variation.

[Means for Solving the Problems]

In order to solve the above problems, the method of the present invention takes the following technical means. That is, the method for producing a ceramic substrate for an electronic component of the present invention is such that a suspension containing a raw material, a solvent, and a binder material is continuously drawn from a certain gap and is forcibly heated to produce a semi-dry strip green.・ Step of forming a sheet, winding the above strip-shaped green sheet into a roll and
A step of storing for 10 days or more in a room temperature dry atmosphere of 25 ° C. to 35 ° C., a step of obtaining a substrate semi-finished product in which a lattice-like slit is formed on the surface and die-cut into a predetermined shape from the band-shaped green sheet, And a step of baking and solidifying the substrate semi-finished product in a heating furnace. The binder has a boiling point of 250 ° C to 3
The one having a temperature of 00 ° C. is preferably adopted (Claim 2).

[Operation of the invention]

For example, forced heating in an atmosphere of about 100 ° C that forms a band-shaped green sheet does not remove all the solvent in the suspension, and in particular, the solvent remains unevenly in the thickness direction of the green sheet. . In the present invention, a semi-finished substrate is not immediately obtained from the strip-shaped green sheet, but an aging step of inserting the strip-shaped green sheet into a dry atmosphere at room temperature is inserted. In this aging step, since the drying is performed at room temperature for a long time, the solvent that remains unevenly in the green sheet forming step is almost completely removed. However, even at this point in time, since the binder material still remains in the belt-shaped green sheet,
It is semi-dry. Since this binder material is preferably one having a boiling point of 250 ° C to 300 ° C, in the above-mentioned forced heating step in an atmosphere of about 100 ° C and the storage step for 10 days or more, It is not removed but is removed only in the firing process.

【The invention's effect】

Therefore, according to the method for manufacturing a ceramic substrate for an electronic component of the present invention, after the residual solvent is almost completely removed (even in this state, the green sheet is semi-dried due to the binder material), the grid Since a substrate semi-finished product before baking is obtained by forming the slits and die-cutting into a predetermined shape, shrinkage due to evaporation of residual solvent in the subsequent steps is suppressed to a minimum, and as a result, baking is completed. The dimensional variation of the ceramic substrate is significantly reduced. In the first place, since the chip type electronic component is intended for miniaturization, high precision is required for thick film printing on the substrate, but the ceramic substrate obtained by the method of the present invention has variations in its dimensions. Is extremely small, there is little occurrence of inconvenience due to printing misalignment even in element formation by the above-mentioned thick film printing method, and it greatly contributes to improvement in product yield.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 shows a process of forming a strip-shaped green sheet. About 95% of alumina fine powder, about 4% of baking aid consisting of silica and calcium oxide, and a substrate raw material consisting of a mixture of some additives, and a binder agent consisting of polyvinyl butyral, dibutyl phthalate, etc., in an appropriate solvent. Due to the clearance between the roller 2 and the doctor blade 4 which is opposed to the roller 2 with a predetermined gap, the suspension 1 having a relatively viscous state, which is dispersed, has a constant speed according to the rotation of the roller 2. While being carried on the running resin film 3, the resin film 3 is continuously drawn onto this. Behind the doctor blade 4, a liquid reservoir 6 is formed by the doctor blade 4, a part of the peripheral surface of the roller 2 and a wall 5 contacting the peripheral surface of the roller 2, and the liquid reservoir 6 is formed. The suspension 1 is continuously supplied to 6. The roller 2 and the doctor blade 4 have a constant lateral length, so that the suspension drawn onto the running resin film 3 has a strip shape having a predetermined thickness and a predetermined width. The resin film 3 moves in an atmosphere of about 100 ° C. as it is, during which part of the solvent in the suspension is forcibly vaporized and diffused, and the suspension has a cake-like shape with some flexibility. It becomes a band-shaped solid. However, since the lower surface of the suspension is supported by the resin film, the solvent has to evaporate from the surface side, and in the forced drying at this time, not all the solvent is necessarily removed, and, The residual solvent in the strip-shaped green sheet is not always uniform in each part. The strip-shaped solid matter is separated from the resin film 3 by peeling off the resin film 3 with a peeling roller 7, and then, by a plurality of rotary slitters 8, as shown in FIG. It is separated into a number of strips with a certain width. Then, each band is wound into a roll. The strip-shaped green sheet thus wound into a roll is stored for 10 days or more in a normal temperature dry atmosphere at 25 ° C to 35 ° C. During this time, the solvent remaining unevenly in the strip-shaped green sheet is removed almost completely over time. Thus, the strip-shaped green sheet from which the residual solvent has been almost completely removed is still in a semi-dried state due to the presence of the binder. This is because a binder having a boiling point of 250 ° C. to 300 ° C. is usually adopted and does not easily vaporize in a dry atmosphere at room temperature. Then, as shown in FIG. 3, the strip-shaped green sheet 9 is press-formed with a lattice-shaped slit 10 consisting of vertical slits 10a and horizontal slits 10b having a predetermined depth on the surface thereof, and a rectangular plate. The semi-finished substrate as shown in FIG. Substrate semi-finished products are then subjected to an intermediate drying step in which a part of the binder material is evaporated, and the solid content ratio is increased to reduce flexibility, and then the chips that are inevitably generated during the above-mentioned cut molding. Is carried out. And, in addition, in order to prevent solidification while adhering to each other when a plurality of substrate products are stacked in a sintering furnace,
A process of sprinkling fine alumina powder is performed. Subsequently, the semi-finished substrate product is sintered and solidified in a sintering furnace. As described above, before obtaining a substrate semi-finished product having a lattice slit from a strip-shaped green sheet, the strip-shaped green sheet is stored for 10 days or more in a dry atmosphere at room temperature. According to the method for manufacturing a ceramic substrate, as in the conventional case, there is an unacceptable variation in the dimensions of the ceramic substrate after firing due to the temporal evaporation of the solvent that remains unevenly inside the semi-finished substrate. The problem of occurrence is solved, problems such as printing misalignment do not occur during thick film printing of elements, the yield of ceramic substrates is improved, and the product quality of electronic components is also constant. Of course, the scope of the present invention is not limited to the above embodiments. For example, the target is not limited to the chip-type resistor, but can be applied to a ceramic substrate used for manufacturing all electronic components using a manufacturing method in which elements are collectively manufactured in each region divided by a lattice slit.

[Brief description of drawings]

Fig. 1 is the manufacturing process diagram of the green sheet, and Fig. 2 is the first
II-II line enlarged arrow view of the figure, FIG. 3 is a plan view showing a state in which grid-like slits are formed in the green sheet, FIG.
FIG. 5 is a plan view of a semi-finished substrate, FIG. 5 is a plan view of a ceramic substrate, and FIG. 6 is a partially enlarged detailed view of FIG. 1 ... Suspension, 9 ... Green sheet, 10 ... Semi-finished substrate, a ... Vertical slit, b ... Horizontal slit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhito Sakai, 21, Saiin Mizozaki-cho, Ukyo-ku, Kyoto City, Kyoto Prefecture Rome (72) Inventor, Shigeru Kambara 21, Mizozaki-cho, Saiin-ku, Kyoto, Kyoto Prefecture Mu Co., Ltd. (56) Reference JP-A-63-102910 (JP, A)

Claims (2)

[Claims] 1. A step of forming a semi-dry band-shaped green sheet by continuously pulling out a suspension containing a raw material, a solvent and a binder material from a certain gap and forcibly heating this, said band-shaped green・ Rewind the sheet into a roll and
A step of storing for 10 days or more in a room temperature dry atmosphere of 25 ° C. to 35 ° C., a step of obtaining a substrate semi-finished product in which a lattice-like slit is formed on the surface and die-cut into a predetermined shape from the band-shaped green sheet, A method of manufacturing a ceramic substrate for electronic parts, comprising the steps of firing and solidifying the above-mentioned semi-finished substrate in a heating furnace. 2. The binder material has a boiling point of 150 ° C. to 3 °
The method for producing a ceramic substrate for electronic parts according to claim 1, which is at 00 ° C.