JP3150784B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to through holes and conductors.
The present invention relates to a method for manufacturing a ceramic wiring board having a circuit pattern , and more particularly to a method for drying a formed green sheet.

[0002]

2. Description of the Related Art Conventionally, when manufacturing this type of wiring board, a raw material slurry containing ceramic powder, a solvent and the like is first prepared, and a green sheet is formed from the slurry according to, for example, a doctor blade method. A plurality of through-hole forming holes are punched at predetermined coordinates of such a green sheet, and the through-hole forming holes are filled with a conductive metal paste for forming a conductive circuit. Further, after the green sheets are laminated and laminated as necessary, the green sheets are subjected to degreasing / temporary firing and main firing.

When a green sheet is continuously formed according to the doctor blade method, a solvent, a plasticizer, and the like remain in the green sheet immediately after the green sheet is obtained. Therefore, conventionally, volatile components such as a solvent are removed from the green sheet by sufficiently drying after punching the through-hole forming hole.

[0004]

However, if a green sheet containing a large amount of a solvent or a plasticizer is left as it is, it evaporates as time passes and the green sheet shrinks.

Therefore, even if the hole 12 for forming a through hole can be formed at a predetermined coordinate (a position shown by a two-dot chain line in FIG. 2A), the position will be changed to the green sheet 1 later.
1, which is an undesirable result of being slightly shifted in the center direction. If the relative position of the through-hole forming holes 12 is misaligned in a relatively early step, it is extremely difficult to completely repair the through-hole in a later step. As a result, a wiring board having excellent dimensional accuracy cannot be obtained.

In addition, such a through hole forming hole 1
The second misalignment problem also causes another problem as follows. In other words, in order to fill the paste P into all the through hole forming holes 12 in the next step, it is necessary to use FIG.
As shown in (b), a metal mask M having a large diameter of the hole Ma must be used. When such a mask M is used, the diameter of the land L is inevitably increased, so that it is difficult to form a fine conductor circuit pattern.

Furthermore, since the undried green sheet 11 has a certain degree of plasticity, it is easily deformed if handled carelessly. This has been one of the causes of deteriorating the dimensional accuracy of the wiring board.

[0008] The present invention has been made in view of the above circumstances, an object of the dimensional accuracy of the wiring board can be reliably improved, and reliably formed can Rousset la mix wiring more fine conductor circuit pattern An object of the present invention is to provide a method for manufacturing a substrate.

[0009]

According to the present invention, there is provided a through hole (hereinafter abbreviated as TH).
Facilities Succoth firing the green sheets for forming hole is formed
The method for manufacturing a ceramic wiring board having a TH and a conductive circuit pattern according to the method described above , wherein a volatile component in the green sheet is reduced before forming a hole for forming a TH in the green sheet. 1% by weight to solid content
Drying is performed until it becomes 3% by weight.

In this case, in the drying step, the green sheet is desirably dried at 80 ° C. to 120 ° C. for 3 hours to 7 hours. Further, it is desirable that the volatile components contained in the green sheet be removed by 85% to 97% before forming the TH forming hole.

[0011]

According to this method, since the dimensional change (shrinkage) of the green sheet does not occur with time, the amount of displacement of the TH forming hole is extremely small. Also, with this method,
After the plasticity is lost by drying, various steps after the step of forming the hole for forming TH are performed, so that the risk of deformation of the green sheet during handling is small.

Accordingly, the dimensional accuracy of the wiring board can be reliably improved, and a fine conductor circuit pattern can be reliably formed. Hereinafter, a method of manufacturing a ceramics circuit board of the present invention in order of steps in detail.

The ceramic material forming the green sheet includes aluminum nitride, alumina, silicon carbide,
Powder such as silicon nitride is used. Among them, it is desirable to select, as a material, aluminum nitride powder which is particularly excellent in electric insulation and thermal conductivity. A predetermined amount of a binder, a sintering aid, a plasticizer, a dispersant, a solvent and the like are then added to the ceramic powder selected from these. By kneading this mixture uniformly,
A raw material slurry for producing a green sheet is obtained.

Next, green sheets are continuously formed from the raw material slurry by, for example, a doctor blade method. In order to form a green sheet by the above method, a sheet forming machine equipped with a doctor blade, a film, and a drying oven is used. In this case, the raw material slurry is drawn to a predetermined thickness on the film by a doctor blade, and then continuously transferred to a drying furnace.
Then, the sheet-shaped raw material slurry dried for a predetermined time is wound around a cylindrical body after being separated from the film.

However, if the green sheet is excessively dried at this stage, cracks, pores, and the like are generated in the green sheet. Therefore, in this case, drying is performed to such an extent that the raw material slurry loses fluidity and can maintain the sheet shape (to the extent that the volatile components in the green sheet are removed by about 75% to 85%). Therefore, the green sheet at this time contains 3% by weight to 10% by weight based on the solid content.
The green sheet still contains plasticity because it contains a certain amount of volatile components. In this case, if the content of the volatile component is less than 3% by weight, it becomes difficult to shape the green sheet. On the other hand, if the content of the volatile component exceeds 10% by weight, the plasticity becomes too large and it becomes difficult to handle.

The drying performed at this stage is hereinafter referred to as primary drying. Hereinafter, the term “green sheet” refers to a sheet-shaped ceramic molded body that has been subjected to primary drying.

Furthermore, the resulting green sheet is dried again after being cut to a predetermined <br/> OUTLINE. Drying at this stage needs to be performed to such an extent that the laminability of the green sheet is not deteriorated. In addition, the plasticity of the green sheet is almost lost by this drying, and the handling becomes easier than the green sheet in the previous stage. Hereinafter, the drying performed at this stage is referred to as secondary drying.

In the secondary drying step, the green sheet is desirably dried at 80 ° C. to 120 ° C. for 3 hours to 7 hours. If the drying temperature is lower than 80 ° C., the drying time will be longer because the temperature is lower than the temperature at which the solvent and the plasticizer can volatilize. On the other hand, when the drying temperature is higher than 120 ° C., the binder starts to soften, and the laminability of the green sheet deteriorates.

On the other hand, if the drying time is shorter than 3 hours, the green sheet cannot be dried sufficiently, and the probability of uneven drying and deformation increases. On the other hand, if the drying time is longer than 7 hours, the volatile components evaporate more than necessary, and the laminating property deteriorates.

Further, the volatile components contained in the green sheet are subjected to the above-mentioned primary and secondary drying to obtain T
It is desirable that the H-forming hole be removed to a level of 85% to 97% before the hole is formed. At this time, the amount of the volatile component in the green sheet is 1 to the solid content of the green sheet.
It must be in the range of 3% by weight to 3% by weight.

The reason is that if the volatile component is less than 1% by weight, the laminating property is deteriorated. Conversely, if the content of the volatile component exceeds 3% by weight, shrinkage after the formation of the TH forming hole increases, and the dimensional accuracy deteriorates.

A hole for forming a TH is formed in the dried green sheet, and a paste containing a conductive metal as a main component is printed on the green sheet. The paste forms a conductive circuit in the TH and on the surface of the green sheet. As the conductive metal, for example, tungsten, molybdenum, tantalum, niobium or the like is used.

Thereafter, the green sheet is dried again. As a result, the solvent and the like in the paste are removed from the green sheet (hereinafter, this is referred to as tertiary drying). In addition,
Volatile components in the green sheet are hardly removed by the third drying. Further, the obtained green sheets are laminated and laminated as required. And
The green sheet undergoes a final drying step (quaternary drying) for almost completely removing volatile components from the green sheet, and is then degreased, temporarily baked, and finally baked. As a result, a ceramic wiring board having a desired TH is manufactured.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in which the present invention is embodied in a method of manufacturing a multilayer wiring board made of aluminum nitride (AlN) having TH will be described in detail with reference to FIG.

In Example 1, the average particle diameter of A was 1.5 μm.
330 g of acrylic binder is added to 1500 g of 1N powder.
g, 75 g of Y ₂ O ₃ as a sintering aid, 470 g of toluene and ethanol as solvents, and predetermined amounts of a plasticizer and a dispersant were added. Then, the mixture is uniformly kneaded with a ball mill to form a green sheet 1.
A raw material slurry for preparation was prepared.

Next, a green sheet 1 having a thickness of 0.3 mm was continuously formed from the raw material slurry by a doctor blade method. At this time, about 80% of the volatile components in the green sheet 1 are removed by primary drying performed in a drying furnace of a sheet forming machine (not shown). This value is a value when the weight of the volatile component contained in the raw slurry is 100%. At this time, the ratio of the volatile component to the solid content was 4% by weight.

Further, the obtained green sheet 1 was
After the outer shape was cut into a mm square, the green sheet 1 was charged into a dryer D and subjected to secondary drying at 100 ° C. for 1 hour (see FIG. 1A). By this secondary drying, about 85% of the volatile components in the green sheet 1 were removed.

Subsequently, a plurality of TH forming holes 2 were formed by punching predetermined coordinates on the green sheet 1 by punching (see FIG. 1B). In the first embodiment, T
The diameter of the H forming hole 2 was 0.2 mm, and the pitch thereof was 1.27 mm.

Here, the green sheet 1 was set on a screen printing machine, and a metal mask M having a plurality of holes Ma was arranged close to the upper surface of the green sheet 1. Then, a tungsten paste P produced by a conventionally known method is printed on the green sheet 1 and T
A conductor circuit 3a made of the paste P was formed in the H forming hole 2 (see FIG. 1 (c)). Also, by the same procedure,
A conductive circuit (conductor)
Circuit pattern) 3b was formed.

Thereafter, the green sheet 1 was subjected to tertiary drying at 80 ° C. for 6 hours to remove mainly the solvent and the like in the paste P. Next, the obtained green sheets 1 were laminated, and the green sheets 1 were laminated together by a laminating apparatus (see FIG. 1 (d)). And
After the laminating step, quaternary drying was further performed at 120 ° C. for 24 hours to remove the volatile components from the green sheet laminate 4 almost completely.

Thereafter, the green sheet laminate 4 is subjected to degreasing, preliminary baking and main baking in an inert atmosphere to obtain a desired A
1N multilayer wiring board. In Examples 2 to 4, a green sheet 1 was produced in the same procedure as in Example 1 above.
The outer shape was cut into the same shape as in Example 1. It should be noted that the primary drying at the time of sheet molding caused
Volatile components have been removed to the same extent. Next, secondary drying was performed under conditions different from those in Example 1. That is, as shown in Table 1 below, in Example 2, the secondary drying was performed at 100 ° C.
3 hours, 100 ° C., 5 hours in Example 3, and 100 ° C., 7 hours in Example 4. Thereafter, an AlN multilayer wiring board was manufactured according to the procedure of Example 1.

Further, in Comparative Examples 1 and 2, similarly, only the conditions for the secondary drying were changed, and AlN multilayer wiring boards were produced. That is, as shown in Table 1 below, in Comparative Example 2, the secondary drying was performed at 100 ° C. for 9 hours. In Comparative Example 1, a conventional manufacturing method in which secondary drying was not performed was followed.

Next, in order to judge the quality of the dimensional accuracy of the obtained AlN multilayer wiring board, a ratio (%) at which a position shift of 20 μm or more occurs in TH and a maximum position shift amount (μm) of TH are investigated. did. The results are shown in Table 1 below.

Further, in the process of manufacturing each AlN multilayer wiring board, the punching property of TH, the laminating property of the green sheet 1 and the amount of the volatile component in the green sheet 1 at the time of the secondary drying with respect to the solid content. The ratio (% by weight) was also investigated. The results are shown in Table 1 below.

[0035]

[Table 1]

Investigation of the rate of occurrence of a displacement of 20 μm or more in TH revealed that Comparative Example 1 was the largest. The ratios of Examples 3 and 4 and Comparative Example 2 were considerably smaller than those of Comparative Example 1, and Examples 1 and 2 were intermediate values between them. In addition, the tendency about the maximum displacement of TH was almost the same as the investigation result, and the displacements of Examples 2 to 4 and Comparative Example 2 were particularly small.

From the results described above and above, the secondary drying can eliminate the drying shrinkage of the green sheet 1 over time,
It can be seen that the dimensional accuracy of the multilayer wiring board is improved. Further, by performing the secondary drying, the green sheet 1 loses plasticity at the same time, so that deformation during handling hardly occurs.

Regarding the punching property of TH, Comparative Example 2
All were good except for. In Comparative Example 2, which was slightly good, cracks sometimes occurred in the green sheet 1 when the TH forming holes 2 were formed.

As a result of examining the laminating property of the green sheet 1, Comparative Example 1 and Examples 1 to 4 were good. On the other hand, Comparative Example 2 in which the lamination property was slightly good
Then delamination was confirmed in some of them.

Comparing the above results, the results of Examples 1 to 4 were generally superior to Comparative Examples 1 and 2, indicating that the production method of the present invention was superior to the conventional method. Reach a valid conclusion. In particular, Examples 2 to 4 in which secondary drying is performed for 3 hours to 7 hours, and Example 4 in which secondary drying is performed for 7 hours are more preferable.

Further, according to the manufacturing method of the present invention, as described above, the problem relating to the positional deviation of the TH forming hole 2 is surely solved. As a result, unlike the prior art, the hole M
There is no need to use a metal mask M having a large diameter a. For this reason, the land L diameter of the TH can be reduced, and a finer conductive circuit pattern can be easily formed than before.

The present invention is not limited to the above embodiments but can be modified as follows. For example, (a) the green sheet 1 does not have to be a sheet molded product as in each of the above embodiments, but may be, for example, a press molded product.

(B) Further, the present invention is not limited to the multilayer wiring board as in each of the above embodiments, but may be applied to a single green sheet 1.
Of course, it is also possible to embody a single-sided plate or a double-sided plate by firing.

[0044]

As described in detail above, according to the method for manufacturing a ceramic wiring board having through-holes and conductive circuit patterns of the present invention, the dimensional accuracy of the wiring board can be reliably improved, and the fineness of the wiring board can be improved. An excellent effect that a reliable conductor circuit pattern can be reliably formed.

[Brief description of the drawings]

1 (a) to 1 (d) show a through hole according to the present invention and FIG.
It is a partial schematic front view for explaining the manufacturing process of the ceramic wiring board which has a conductor circuit pattern .

FIG. 2 (a) is a schematic plan view showing a part of a green sheet obtained by a conventional manufacturing method, and FIG. 2 (b) is a partial schematic front view when the conductive sheet is filled in the green sheet. FIG.

[Explanation of symbols]

1 green sheet, 2 holes for forming through holes , 3a
Conductor circuit (inside through hole), 3b conductor times
Road pattern .

Claims (3)

(57) [Claims] The method according to claim 1] facilities Succoth fired green through hole forming holes (2) formed sheet (1), through
A method of manufacturing a ceramic circuit board having a hole and a conductor circuit patterns, before forming the through-hole forming holes (2) on the green sheet (1), the volatile component in the green sheet (1) is the same 1% by weight to 3% based on the solid content of the green sheet (1)
Features and to Rousset Rami'<br/> box wiring substrate manufacturing method of that for drying until the weight%. 2. A said drying step, the manufacturing method of the green sheet (1) is ceramics circuit board according to claim 1, characterized in that it is dried for 3 hours to 7 hours at 80 ° C. to 120 ° C. . 3. The method according to claim 1, wherein the volatile component contained in the green sheet is removed by 85% to 97% before forming the through hole forming hole.
Or ceramics wiring board manufacturing method according to.