JPS6318114B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for manufacturing an alumina substrate for a hybrid integrated circuit, and more particularly to a method for firing a green sheet.

(b) Background of technology As hybrid integrated circuits become smaller and more dense, various patterns formed on substrates become finer, and processes such as forming various patterns, mounting various parts, and testing are becoming automated. Warpage and waviness of substrates used in hybrid integrated circuits have become a major factor influencing the quality and yield of hybrid integrated circuits. For example, the allowable warpage for a board of 95 mm x 114 mm and 0.65 mm thickness is limited to 0.2 to 0.3 mm, and sometimes even stricter dimensions are required.

(c) Prior art and problems Figure 1 shows the conventional manufacturing method. A die-cut green sheet 1 is placed on a base plate 2, and placed in a high-temperature firing furnace and fired at a high temperature. Green sheets shrink by about 18% during the firing process, causing warping and waviness. The size of the warpage can be as large as several millimeters for a board of the above-mentioned size, and from among these, boards that fall within the above-mentioned allowable dimensions are selected and used. Further, for substrates that do not fit within the above-mentioned allowable dimensions, warpage is corrected by applying pressure from above the substrate and leaving it in a high temperature environment.

However, when pressure is applied from above the substrate, there are many cases where the substrate cracks or the surface is scratched, making it impossible to use it as a substrate.

(d) Purpose of the Invention The purpose of the present invention is to provide a method for manufacturing an alumina substrate that can minimize warping and waviness that occur during the firing process of a green sheet.

(e) Structure of the invention And this purpose is to place a green sheet on the base plate,
A frame that presses the periphery of the green sheet and a plate that acts as a weight to press the periphery of the green sheet through the frame are stacked and fired, and after firing, the area pressed by the frame is This is achieved by removing the alumina substrate.

(f) Embodiments of the invention Examples of the invention will be described below with reference to the accompanying drawings.
FIG. 2 shows an embodiment of the present invention, and the same objects as in FIG. 1 are denoted by the same symbols.

In the figure, a green sheet 3 is cut out on a base plate 2, a frame 5 that holds the peripheral part 4 of the green sheet 3, and the green sheet 3 is placed through the frame 5.
A plate 6 serving as a weight for pressurizing the peripheral portion 4 of the plate is stacked, and this is placed in a high-temperature firing furnace and fired at a high temperature. The green sheet 3 contracts during the firing process, but since the peripheral part 4 is pressed down, the green sheet 3 itself becomes taut, minimizing warping and waviness (for example, the size of warping is 0.1 for a board of the size mentioned above). (less than mm).

However, the peripheral part 4 of the green sheet 3 that is pressed against the base plate 2 by the frame 5 may be scratched on the surface when pressed against the base plate 2 by the frame 5, or the green sheet 3 may shrink. When doing so, it may be dragged and the surface may be scratched. Therefore, in order to obtain a high quality alumina substrate, it is desirable to remove the peripheral portion 4 of the green sheet 3 after firing. Removal of the green sheet peripheral area 4 is as follows:
It is also possible to scratch the surface of the alumina substrate after firing and break off the peripheral portion 4 along the scratches.
Since it is difficult to process the alumina substrate after firing, in this example, we used a green sheet that is easy to process.
A groove 7 is provided to facilitate removal of the peripheral portion 4 after firing.

In addition, in order to prevent the surface of the substrate from being contaminated by impurities during firing and to prevent distortion from being applied to the substrate due to differences in thermal expansion coefficients, a frame 5 for holding the peripheral portion 4 of the green sheet 3; The plate 6 serving as a weight for applying pressure to the peripheral portion 4 of the green sheet 3 via the frame 5 is preferably a plate made of a green sheet made of the same material as the green sheet. Therefore, in this example, we used a green sheet that was processed into the desired shape and fired.
It is used as a frame 5 and a board 6 serving as a weight.

(g) Effects of the Invention As described above, according to the present invention, it is possible to provide a method for manufacturing an alumina substrate in which warping and waviness that occur during the firing process of a green sheet can be suppressed to a minimum.

[Brief explanation of the drawing]

FIG. 1 shows a conventional manufacturing method, and FIG. 2 shows an embodiment of the present invention. In the figure, 1 and 3 are green sheets, 2 is a base plate, 4 is a peripheral part of green sheet 3, 5 is a frame, 6 is a plate serving as a weight, and 7 is a groove that facilitates the removal of the peripheral part 4 after firing. shows.

Claims (1)

[Claims] 1. In the process of placing a die-cut green sheet on a base plate and firing it at a high temperature to form an alumina substrate, the green sheet is placed on the base plate, a frame is placed on the base plate to hold down the peripheral part of the green sheet, and A method for producing an alumina substrate, which comprises stacking plates serving as weights to pressurize the peripheral portion of a green sheet, firing the sheets, and removing the alumina substrate in the portions held down by the frame after firing.