JPH04149072A - Production of ceramics base plate - Google Patents

Abstract

PURPOSE:To produce a ceramics base body which is small in a warpage and free from generation of an unevenness and to enhance treating efficiency by pinching a green sheet of ceramics between the heat resistant mesh sheets of a jig for burning and thereafter burning the green sheet to remove a binder. CONSTITUTION:A jig 1 for burning is obtained by arranging two sheets of ceramic green sheets 6 on the mesh sheet 5 having mesh size No.30-100 in a mesh panel 2 of one side and thereafter overlapping a mesh panel 3 of the other side thereon and pinching the sheets 6 between the sheets 5 and fixing them by the jig fixing fittings 7. Then, after a jig 1 is superposed and vertically overlapped in the part of a reinforcing casing 4, this jig 1 is introduced into a hot air circulation type oven furnace 9 equipped with a blower 8 and burned at about 1900 deg.C for about 5 hours in the atmosphere to remove a binder. Then the obtained sintered base plate is normally burned at about 1900 deg.C for about 5 hours in the N2 atmosphere to produce a ceramics base plate 10 which is free from a sintering unevenness and is small (<=80mum/inch) in a warpage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a ceramic substrate (brane substrate). Specifically, the present invention relates to a method for burning off binder from green sheets of ceramic substrates.

[Background Art] FIG. 7 shows a conventional method for debinding and firing an aluminum nitride substrate (blank substrate).

That is, conventionally, as shown in FIG. 7(a), a green sheet 52 of aluminum nitride was placed on an alumina box 51.
5 to 20 sheets were stacked, and boxes 51 carrying green sheets 52 were further stacked in multiple stages and fired in a batch furnace 53.

However, in the method of performing binder removal firing with the green sheets 52 stacked in this manner, the binder removal is insufficient in the portions where the green sheets 52 are in contact with each other, so uneven sintering tends to occur. In particular, the batch furnace 53 did not provide a good binder removal process because the binder removal atmosphere that escaped from the green sheets 52 was likely to remain in the furnace. Therefore, when the box 51 is taken out from the batch furnace 53, as shown in FIG. 7(b), the sintered substrate 5
4, 200 lessons/more than 1 nch of warpage has occurred,
Moreover, sintering unevenness 55 was generated on each sintered substrate 54, as shown in FIG. 7(C).

Further, FIG. 8 shows another conventional example. This is done in a hot air circulation oven 6 in order to perform a uniform debinding process.
1, as shown in FIG. 8(a), the oven furnace 61
In this method, aluminum nitride green sheets 62 are placed one by one in a furnace, and the binder is removed from the green sheets 62 while the inside of the furnace is ventilated by an air blower 63. According to such a binder removal firing method, as shown in FIG.
As shown in FIG. 8(b) and (c), sintering unevenness no longer occurs on the sintered substrate 64 and a uniform sintered substrate 64 can be obtained, but as shown in FIGS. 8(b) and 8(c), Warping occurred during firing due to thermal stress during binder firing, and the sintered substrate 64 was warped at a rate of about 200 mm/1 nch. Furthermore, since the green sheets θ2 were laid flat one by one, it was not possible to fire a large number of green sheets at the same time, resulting in poor space efficiency within the furnace.

[Problems to be Solved by the Invention] The present invention has been made in view of the drawbacks of the conventional example of slanting. The objective is to eliminate uneven sintering of the substrate and further reduce the warpage of the sintered substrate.

[Means for Solving the Problems] Therefore, in the method for manufacturing a ceramic substrate of the present invention, a ceramic green sheet is sandwiched between the mesh sheets of a firing jig equipped with at least two heat-resistant mesh sheets. A feature of this method is that the green sheet is binder-removed and fired while being held by a jig.

[Function] In the present invention, the green sheet is sandwiched between the mesh sheets of the firing jig, and the binder is removed and fired in this state.

Therefore, during binder removal firing, the combustion gas of the binder extracted from the green sheet passes through the mesh sheets and is discharged to the outside of the firing jig, so that there is no shortage of binder removal in the green sheet.

In particular, even if binder removal firing is performed with multiple firing jigs holding green sheets stacked one on top of the other, gaps are formed between the green sheets due to the mesh sheets of the firing jigs, so the binder combustion gas is Exhaust air is vented outside without being trapped between the seats. Therefore, even if the green sheets are stacked, there will be no shortage of binder removal between the green sheets.

Furthermore, since each green sheet is sandwiched between the mesh sheets of the firing jig, warping due to thermal stress is corrected, and warping during firing can be prevented.

[Example] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a firing jig 1 according to the present invention. The firing jig 1 is composed of a pair of mesh panels 2 and 3, each of which has a heat-resistant mesh sheet 5 stretched inside a square-shaped reinforced frame 4 made of fired metal or ceramics. It's free. The material of the heat-resistant mesh sheet 5 is stainless steel (SUS), nickel, etc., and the mesh size is #
30-100 is preferable. Moreover, inside this baking jig 1, two green sheets θ can be sandwiched apart, and the dimensions of each mesh panel 2.3 are as follows.
For example, in the case of a type of sandwiching two green sheets 6 with vertical and horizontal dimensions of X Cll1m], the vertical dimension is L-(2x+21)C], and the width is W-(x+16).
Cmm], and the width and thickness of the reinforced frame 4 are 3 mm and 1.5 mm. Also, this mesh panel 2
As shown in Fig. 2, the three-piece frame can be assembled together using lip-shaped jig fixing fittings 7, and the reinforcing picture frame 4 is sandwiched by the spring force of the jig fixing fittings 7. , the firing jig 1 can be easily assembled and disassembled.

As shown in FIG. 1, first, two ceramic green sheets 6 are placed side by side on the mesh sheet 5 of one mesh panel 2, and then the other mesh panel 3 is stacked on top of the mesh sheet 5, and the mesh sheets 1-5 of the pair of mesh sheets 1-5 are stacked on top of each other. The green sheet 6 is sandwiched between the two mesh panels 2 and 3, and appropriate parts (for example, the parts on both sides of the green sheet 6) of the reinforcing frame 4 of both mesh panels 2 and 3 are sandwiched between the jig fixing metal fittings 7, and the The firing jig 1 is integrated with a jig fixing fitting 7. The mesh sheet 5 is stretched flat by the reinforcing frame 4 and is prevented from deforming due to heat. Therefore, by sandwiching the green sheet 6 between the mesh sheets 5 stretched over the bottle, it is possible to correct the warpage that occurs in the green sheet 6 during firing.

Each baking jig 1 with the green sheet 6 sandwiched in this way
are stacked one above the other at the reinforced frame 4, as shown in FIG. As shown in FIG. 6(a), the baking jigs 1 stacked in multiple stages are placed in a hot air circulation type oven 9 having a blower 8, and the binder is removed and baked in the oven 9. . In this binder removal firing step, the binder combustion gas combusted and evaporated in each green sheet 6 is extracted to the outside of the firing jig 1 through the mesh sheets 5, and further between the firing jig 1. Escape to the outside through the gap. In particular, since the hot air in the oven furnace 9 is circulated by the blower 8, the combustion gas of the binder does not become trapped between the green sheets 6, thereby preventing debinding from the green sheets 6. Therefore, even if the green sheets 6 sandwiched between the sintering jigs 1 are piled up, uneven sintering will not occur in the sintered substrate 10 that has been subjected to binder removal and sintering. Furthermore, since the sintered substrate 10 is sandwiched between the mesh sheets 5, the warpage caused by thermal stress is corrected, and the warpage that occurs during binder removal firing is also reduced (less than 80X+/1nch), as shown in FIG. 6(b). It is possible to obtain a good sintered substrate 10 as shown in FIG.

An attempt was also made to prevent the sintered substrate 10 from warping by pressing the green sheets 6 placed flat one by one with a loading jig, but the parts of the green sheets 6 that were in contact with the loading jig were Uneven sintering occurred due to insufficient binder removal, and a good nitrided ceramic substrate could not be obtained. On the other hand, according to the method using a mesh sheet, good results were obtained in terms of both warpage and sintering unevenness as described above.

Next, a comparison result between a sintered substrate fired by the binder removal firing method of the present invention and a sintered substrate fired by the conventional binder removal firing method will be described.

First, an aluminum nitride material containing 3.0 wt% of Y2O3 as a sintering aid, 10 wt% of a binder (butyral resin), and 3.0 wt% of other additives was formed into a sheet by the doctor blade method. After that, cut it to 100 u each in length and width.

An aluminum nitride green sheet with a thickness of 0.8 mm was produced.

Ten green sheets thus produced were fired by the binder removal firing method of the present invention.

That is, this green sheet is placed in the above-mentioned baking jig.
Place the sheets in a hot air circulation oven for 5 hours at 1900'C (temperature increase rate 5°).
C/m1n) and the binder was removed by firing. Furthermore, the sintered substrate that had been subjected to binder removal firing was heated at 1900"C for 5 hours (temperature increase rate 5°C) in a nitrogen atmosphere.
/m1n) Main firing was performed to obtain an aluminum nitride substrate A.

In addition, 10 of the same green sheets were fired using the conventional binder removal firing method shown in FIG.

That is, 10 green sheets were stacked on top of a box, placed in a batch furnace, and heated for 1900 minutes in the atmosphere.
Baked at 'C for 5 hours (heating speed 5°C/m1n),
Binder removal firing was performed. Furthermore, the sintered substrate that had been subjected to binder removal firing was heated to 1900°C in a nitrogen atmosphere.
Main firing was performed for 5 hours (temperature increase rate: 5'C/m1n) to obtain an aluminum nitride substrate B.

In addition, 10 of the same green sheets were fired using another conventional binder-removal firing method shown in FIG. That is, 10 green sheets were placed flat in a hot air circulation type oven and fired in the atmosphere at 1900°C for 5 hours (temperature increase rate 5°C/m1n) to remove the binder. Furthermore, the sintered substrate that has been fired to remove the binder,
Main firing was performed at 1900'C in a nitrogen atmosphere for 5 hours (temperature increase rate 5'C/m1n) to obtain an aluminum nitride substrate C.

Each aluminum nitride substrate A, B obtained as above
, C, the presence or absence of firing unevenness (visually checked after the penetration test) and the size of warpage were measured.

As a result, in the binder removal treatment method of the present invention, no uneven firing occurred on any of the aluminum nitride substrates A. In addition, the amount of warpage is the average value x - 45 inches/1nch,
The maximum Rr value Max was 75 grn/1 nch, and the minimum value Min was 201 trr+/1 nch.

On the other hand, in the conventional method using a batch furnace, uneven firing occurred in 10 aluminum nitride substrates B. In addition, the amount of warpage is the average value X = 350 pn/1n
ch, maximum value Max = 530 gn/1 nch, minimum value Min = 230 ufrl/1 nch, and the warp was the largest.

Further, in the conventional method using a hot air circulation type oven, no uneven firing was observed in the aluminum nitride substrate C.

However, the amount of warpage was as follows: average value x=150 groups/1nch, maximum value Max=240 urr+/1nch, minimum value Min=100 tlfn/1nch, and considerably larger warpage occurred compared to the method of the present invention.

From the above experimental results, according to the present invention, an aluminum nitride substrate (
It was confirmed that a sintered substrate) could be obtained.

Although the above embodiments have been described with respect to aluminum nitride substrates, it is clear that the present invention can be implemented on ceramic substrates other than aluminum nitride.

The present invention is also effective for binder removal firing of large ceramic substrates of 8 inches square or more.

[Effects of the Invention] According to the present invention, since the binder is removed and fired while the green sheet is sandwiched between the firing jigs, warpage caused by thermal stress during firing can be corrected by the sintering jig. This makes it possible to reduce the warpage of the sintered substrate.

Moreover, since the green sheet is sandwiched between the mesh sheets of the firing jig, the combustion gas of the binder that has escaped from the green sheet is discharged through the mesh sheets, thereby preventing uneven sintering. In particular, even if the green sheets held in the baking jig are stacked,
The green sheets do not stick to each other, and the combustion gas of the binder can be discharged through the gap between the mesh sheet and the green sheet, resulting in insufficient removal of the binder between the green sheets. Warpage of the junction board can also be reduced. Therefore, it is possible to remove the binder from a large number of green sheets at the same time.
Processing efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of an open firing jig according to an embodiment of the present invention, FIG. 2 is a perspective view showing a jig fixing fitting for fixing the same firing jig, and FIG. Figures 4 and 4 are a perspective view and a sectional view of a firing jig with green sheets sandwiched between them, Figure 5 is a sectional view showing a stacked state of multiple firing jigs, and Figures 6 (a) (b) 7(a), 7(b), and 7(c) are explanatory diagrams showing the conventional binder removing firing process, and FIG. a), (b), and (c) are explanatory diagrams showing another conventional example. 1... Firing jig 5... Mesh sheet 6... Green sheet Patent applicant Murata Manufacturing Co., Ltd. Representative Patent attorney Masafusa Nakano Figure 1 Figure 3 Figure 6

Claims (1)

[Claims] (1) A ceramic green sheet is sandwiched between the mesh sheets of a firing jig equipped with at least two heat-resistant mesh sheets, and the green sheet is binder-removed and fired while being held by the firing jig. Features: A method for manufacturing ceramic substrates.