JPH02294091A - Baking method of ceramic device - Google Patents

Abstract

PURPOSE:To prevent fusion welding and enable correcting warpage by arranging a mesh of high melting point metal on a ceramic body at the time of baking multilayer ceramic bodies which are not yet baked. CONSTITUTION:On a substrate 1 made of alumina or the like, a plurality of multilayer ceramic bodies 2... which have not yet been baked and turned into a ceramic package are set. On the multilayer ceramic bodies 2... which have not yet been baked, a mesh 3 composed of high melting point metal like Mo is arranged and baked. Since the high melting point metal like Mo is used as the weight 3 for reforming, the strength is superior at a high temperature, and reforming capability is not lost by deformation. Further, since the weight 3 is formed in a mesh type, the weight per unit area is small. Thereby fusion welding is not caused, and warpage after baking can be reformed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for firing ceramic devices such as ceramic multilayer wiring boards and ceramic packages.

(Prior art) Ceramic multilayer wiring board or I
A ceramic package enclosing a C-chip is manufactured by setting an unfired multilayer ceramic body obtained by a green sheet lamination method or a printing lamination method on a base plate and firing it. By the way, an unfired multilayer ceramic body has metal layers formed between each layer or on the surface of each layer that have a firing shrinkage rate different from that of the ceramic, and the temperature inside the furnace may be uneven, and the shrinkage rate of each ceramic layer may vary. They often differ, and warping is likely to occur after firing. Conventionally, as shown in FIG. 7, an unfired multilayer ceramic body 101 is set on a bottom plate 100 and fired at 1500 to 1600°C, and then the ceramic body 101 is placed on top of the ceramic body 101 as shown in FIG. For example, a plate 102 made of alumina (AJZ203) is placed as a weight and fired again at 1350-1400°C to correct the warpage. (Problems to be Solved by the Invention) As described above, when re-firing is carried out by placing the plate 102 such as alumina as a weight, the melting point of the material constituting the plate is low or the weight of the plate is excessive. If the plate is light, the plate and the ceramic body tend to be fused together.If the plate is light, it lacks rigidity and warpage cannot be corrected sufficiently, resulting in dimensional errors of 50 μm/inch or more, making it difficult to meet the accuracy required for the product. This is not satisfactory and may damage the W or MO metallized surface applied to the surface of the ceramic layer.

Furthermore, in order to prevent oxidation of the metallized surface, re-firing must be performed in a reducing atmosphere, which increases the cost of nitrogen and hydrogen gas introduced.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method for placing a mesh of high melting point metal such as Mo (molybdenum) on the ceramic body when firing the green multilayer ceramic body. I made it.

(Function) The high melting point metal net placed on the unfired multilayer ceramic body has a higher melting point and is lighter than the conventional plate used as a weight, so it does not fuse with metallized parts, etc. By doing so, the rigidity is higher than that of a plate of the same weight, and warping after firing can be corrected. (Example) Examples of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a cross-sectional view showing a state in which a ceramic package is fired by the method of the present invention. In the figure, 1 is an alumina base plate, and on this base plate 1 is placed an unfired multilayer ceramic body 2 that will become a ceramic package. (approximately 15 to 20 in the case of a ceramic package, approximately 4 to 5 in the case of a ceramic multilayer wiring board), and placed on top of these unfired multilayer ceramic bodies 2 as shown in Fig. 2. A net 3 made of a high melting point metal such as MO (molybdenum) is placed thereon.

Here, the unfired multilayer ceramic body 2 is formed by forming unfired ceramic layers 2 by a green sheet lamination method or a printing lamination method.
The net 3 is made by laminating a metal layer and a metal layer, and the net 3 may be a knitted one as shown in Fig. 2, a punched one as shown in Figs. 3 (A) and (B), or a porous one. The material may be any material, as long as it has a high melting point, is light, and has rigidity. In addition, it is preferable that the load per unit area of the net 3 on the unfired multilayer ceramic body 2 is 1.0 g/cm' or less from the viewpoint of preventing fusion.

FIG. 4 shows a cross section of the ceramic package obtained by immersing the package in a furnace with the net 3 placed thereon and firing it at 1500 to 1600 DEG C. as described above. Although the ceramic package 2 after firing has some warpage due to the difference in firing shrinkage rate, non-uniformity of austral temperature, etc., the maximum error t is 30 pm/inch or less.

(Effects of the Invention) The following table compares the conventional method using an alumina plate and the method of the present invention.

Regarding the ceramic package with data (■) in the table, as shown in Fig. 5 (A) and (13), one piece is placed on the alumina base plate 1 with dimensions of 30.48 mm x 15.2 mm.
A total of 18 unfired multilayer ceramic bodies 2 that form a 4 mm x 2.03 mm ceramic package are arranged in 3 vertical rows and 6 horizontal rows.
Place it on the soil and its dimensions are 130ma + x 130
mm, weight 32.3g (0.191g/cm”)
, and fired by covering with MO mesh 3 having a mesh size of 24 mesh. As a result, the warpage was 30μ as shown in Figure 5A (C).
m or less/30.48 mm, and the warpage was 30 to 120 μm/730.48 mm in the case where the net 3 was not used, so it can be seen that the warpage was significantly reduced. Also, the shrinkage rate change is 0.2 compared to when no mesh is used! l
i became smaller, but there was no deformation.

Regarding the ceramic multilayer wiring board of data (1), as shown in FIGS. 6(A) and (B), one board with dimensions of 78.6mm
Four unfired ceramic bodies 2 to be used as ceramic multilayer wiring boards having an Ix of 2.14 IIlm were placed, and the same MO mesh 3 as used for data (2) was placed thereon and fired.

As a result, the average warpage was 23μm778.6arm,
When net 3 is not used, the average is 80 μm/78. fuam
It can be seen that the warpage was significantly reduced. Also, the shrinkage rate change is 0.2% compared to when no mesh is used.
Although it became smaller, there was no deformation.

Data ■ is a 1.5mm thick MO board (1.53g/
ca+') was used for firing. As a result, the MO board and the product were fused together. Furthermore, data ■ and ■ are each 0.5 mm.
Thickness (0.18g/cm2) and IIIlm thickness (0.38
The firing was performed using an alumina plate of g/cm'). As a result, with a thickness of 0.5a+m, the strength at high temperatures is weak and deforms, and there is no straightening ability, and fusion occurs in the l. With a thickness of 0 mm, there was a correction ability, but fusion occurred.

(Left below) As described above, according to the present invention, since a high melting point metal such as MO is used as the weight for straightening, it has excellent strength even at high temperatures.
Modification 1, (The correction ability is not lost due to any damage, and the weight is made into a net shape, so the weight per unit is smaller.
No fusion.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the state in which an unfired multilayer ceramic body is fired by the method of the present invention, FIG. 2 is a plan view of the mesh, and FIG.
Figures (A) and (B) are a plan view and a side view showing another embodiment of the mesh, Figure 4 is a sectional view of a ceramic package fired by the method of the present invention, and Figure 5 (A). (B) is a diagram showing the arrangement state of the unfired multilayer ceramic body, Figure 5 (C) is a diagram showing the warpage of the multilayer ceramic body after firing, and Figure 6 (A)
．． (B) is a diagram showing another arrangement state of an unfired multilayer ceramic body, and FIGS. 7 and 8 are diagrams showing conventional examples. In the drawings, 1 is a bottom plate, 2 is an unfired multilayer ceramic body, and 3 is a bottom plate.
is a net. Fig. 5 t<3~m 2-30.48 mm Fig. 1 Fig. 2 Fig. 3! ≠−=− (B)

Claims (2)

[Claims] (1) An unfired multilayer ceramic body was set on a base plate, a net made of a high melting point metal was placed on the upper surface of the set green multilayer ceramic body, and the green multilayer ceramic body was fired in this state. A method for firing a ceramic device characterized by: (2) The weight per unit area of the net is 1.0 g/cm^
2. The method for firing a ceramic device according to claim 1, wherein the firing rate is 2 or less.