JPS63152197A - Method of baking ceramic substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a ceramic substrate, particularly a ceramic multilayer substrate or a ceramic substrate with a smooth surface and no waviness or warpage, which is precisely adjusted according to design values. The purpose is to obtain.

(Prior art) With the recent increase in the degree of integration of conductor integrated circuit devices, there is a strong trend toward larger devices, an increase in the number of Vt terminals connected to the outside, and miniaturization. Also, the use of ceramic multi-N substrates has become popular.

This ceramic multilayer board was manufactured by stacking a large number of raw ceramic sheets (ceramic molded bodies before sintering) that had been subjected to via hole processing and wiring formation by screen printing, and sintering them all at once.

(Problems to be Solved by the Invention) Although such a ceramic board can have a higher mounting density than a printed circuit board using resin, the shrinkage due to Vε bonding is large, so the surface flatness is insufficient. There is a large variation in the precision dimensions of the board, and it is common for warpage to occur during the manufacturing process, so the warp or waviness is corrected by surface polishing, or a load is applied to the board using a flat surface polished refractory plate and re-fired. This often required complicated corrections.

(Means for solving the problems) The present invention was made as a result of intensive studies to solve the above problems, and its outline is as follows: porosity is 5 to 20%,
Smooth-surface carbon plates with a thickness of 21 to 31 mm and ceramic-formed substrates of the same thickness or slightly thinner are stacked alternately and heated at approximately 1500°C (approximately 1
This is a method for manufacturing a ceramic substrate in which firing is performed at a temperature of 480 to 1560°C. The most preferable ceramic forming substrate is formed by the doctor blade method.
It is obtained by baking the resin-removed product in the atmosphere at 200° C. for 10 hours to 20 hours.

(Function) The carbon plate used in the present invention has very little frictional resistance, and the surface can be easily processed to obtain smoothness. This is a great advantage compared to ceramics and metals, which have high frictional resistance and cannot be easily processed to have a smooth surface.

In other words, regarding the method of forming green ceramic sheets, it is manufactured by mixing raw materials, a dispersant, and a solvent, and after pulverizing, adding a plasticizer and a binder, mixing, pulverizing, forming into a sheet, and drying. , it was difficult to process it smoothly and uniformly. However, in the present invention, a carbon plate is also used, and the smoothness and low frictional resistance of the carbon plate are utilized.

It should be noted that the ceramic body molded substrate is coated with resin (
Binder) is removed in the atmosphere at 200°C and 211r, but the resin is not completely removed, so by stacking it on a carbon plate with low porosity and firing it, it is reduced by the carbon and carbon is deposited in the substrate. However, since the carbon plate used in the present invention has a porosity of about 5 to 20%, it can be fired so that fewer carbon molecules remain. That is, carbon plates with a porosity of less than 5% are difficult to manufacture, and carbon plates with a porosity of more than 20% are undesirable because they have low strength and are inconvenient for repeated use.

In addition, the low friction caused by the combined use of carbon plates means that when the substrate is fired, it shrinks relatively easily, which has little effect on the dimensions of the fired product, ensuring dimensions with the required tolerance. be able to.

In the present invention, the thickness of the carbon plate is 2 to 3 mm,
The reason for this is that an unnecessarily large load would affect the shrinkage of the ceramic substrate, resulting in poor dimensional accuracy, so the above thickness was used and the load was controlled. The reason why the thickness of the carbon plate is made thicker than that of the ceramic molded substrate is to prevent the carbon plate from breaking during handling and to increase the number of times of use.

(Example) The following three types of substrates were prepared as ceramic substrates.

A: Alumina content 95%, -Substrate with surface roughness 0.3-0.5 μRa baked in the atmosphere for thick shell films B: Alumina content 97%, - Read out for thick shell films and thin films. Substrate C with a surface roughness of 0.2 to 0.4 μRa: alumina containing ff 199.5%, a substrate with a surface roughness of O, OS ~ 0.08 μRa read out for thin films. As shown, it was placed on a ceramic refractory center 6 whose surface had been polished with diamond, and fired in the air at a temperature of 1480° C. for No. 8, 1500° C. for No. 150 C, and 1520° C. for No. C. At this time, each board has 3
Spherical grain sand 7 of approximately 0 μm to 50 μm was uniformly applied, and five of each substrate was stacked and fired. The ceramic plugging plates are designated la, 2a, 3a, 4a, and 5a from the top. Board size is 55mm x 65+wm x Q
, 8mff1, and the measurement results of warpage and waviness are as follows.

On the other hand, according to the method of the present invention, carbon plates 8 with a porosity of 18% are arranged on the upper and lower surfaces and in the middle using the above-mentioned materials A, B, and C, as shown in FIG.

Δ is 1450℃ and B is 1490℃ in 40% mixed gas
, C was fired at 1500°C. Carbon plate size is 6
0III11×7011II*×311IIn, and the size of the ceramic substrate is 55mmX65mmX0.
8mm Teal m Also, the ceramic substrate is lb from the top,
Shown as 2b, 3b, 4b and 5b. The measurement results of warpage and waviness are as follows.

In addition, since slightly black carbon molecules were attached to the above substrate, bisque firing was performed in the air at 1000℃, and the electrical properties and surface roughness were measured. As a result, the electrical properties were no different from those fired in the air. .

Note 2: The above warpage and waviness are defined as below.

(1) Warpage: As shown in Figure 3, the distance between the edges of the board from the center of each stage (ms) (2) Waviness: As shown in Figure 4, 30III Amount of deviation per length (μm) Next, the electrical properties and surface roughness of the laminated substrate according to the present invention and the laminated substrate according to the comparative example were measured, and the results shown in the table below were obtained.

(Effects of the Invention) According to the present invention, a substrate with a smooth surface with extremely little waviness or warpage can be obtained, and there is no need to correct the waviness or warp by surface polishing, which was conventionally done.
There is no longer a need to flatten a refractory flat plate, apply a load to the refractory, and re-fire it.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of the structure of a conventional ceramic substrate firing set, FIG. 2 is a vertical cross-sectional view showing a structural example of a ceramic substrate firing set according to the present invention, and FIG. 4M is an explanatory diagram showing a method of measuring waviness; FIG. lb, 2b, 3b, 4b, 5b: ceramic substrate, 8
：Carbon plate

Claims (2)

[Claims] (1) Carbon plates with a flat surface with a porosity of 5 to 20% and a thickness of 2 mm to 3 mm and ceramic substrates that are the same or slightly thinner are stacked alternately and heated at approximately 1500°C in an H_2 or N_2 atmosphere. A method for firing a ceramic substrate, characterized by firing. (2) The ceramic molded substrate is a ceramic according to claim 1, which is formed by a doctor blade method, and the resin removal is performed by baking at 200°C in the atmosphere for 10 to 20 hours. Method of firing the substrate.