JPH04106998A - Manufacture of ceramic multi-layer board - Google Patents

Abstract

PURPOSE:To prevent the uneven deformation of green sheet laminates and to increase the size accuracy of ceramic multi-layer boards, by laminating green sheets rotating the position of every sheet by nearly 90 degrees. CONSTITUTION:After adding proper quantities of, for example, a sintering assistant, and an organic binder to ceramic powder and making it pastelike, the ceramic paste is molded into sheets by a doctor blade method, a roll molding method, etc. These green sheets 1-4 are laminated rotating the position of every sheet by 80-100 degrees to the direction of lamination (vertical direction). Namely adjacent green sheets are put in directions perpendicular to each other, and every other sheet is put in the opposite direction (in a state of being rotated by 180 degrees), constituting one cycle by four green sheets. This diminishes the uneven elongations of the sheets owing to the directions mutually produced in time of molding the green sheets, and makes it possible to increase the uniformity as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a ceramic multilayer substrate in which green sheets are laminated and co-fired.

(Prior Art) Hybrid ICs have been developed in a way that utilizes the surface of a substrate two-dimensionally. However, there is a strong trend toward increasing the density of ICs, and a three-dimensional circuit configuration by multilayering the board is being adopted as a mounting form to achieve higher circuit density per unit area.

Such a multilayer board is one in which ceramic layers and conductive layers are alternately laminated. For example, tungsten is layered on an unfired ceramic sheet (hereinafter referred to as a green sheet) in which through holes for conduction are provided in advance. Alternatively, a conductive paste containing molybdenum as the main component is printed, the required number of green sheets are stacked together, thermocompression bonded using uniaxial pressure in the vertical direction, and then simultaneously fired, or the pressure is applied at high temperatures. Therefore, it is manufactured by a hot press method in which compression bonding and firing are performed at the same time.

(Problem to be Solved by the Invention) Recently, the number of layers in multilayer boards has increased due to the increase in the density of LSIs, and it has been necessary to press with higher pressure in order to press these laminates together. .

However, with the above-mentioned uniaxial pressing method, if high pressure is applied, the green sheet shrinks in the thickness direction and expands in the surface direction due to unidirectional pressing, resulting in dimensional defects and There was a problem that it caused distortion of the circuit pattern.

In addition, increasing the pressure inevitably increases the size of the press, which increases costs, and there is a limit to increasing the pressure using uniaxial pressing due to the strength of the bunches, etc.

Furthermore, if the parallelism accuracy of the upper and lower surfaces of the press is not constant, the pressure on the green sheet will be uneven, and the shrinkage rate after firing will be different in each three-dimensional direction, leading to problems such as warping and dimensional defects. Ta.

Furthermore, as circuit patterns become finer due to the higher density of LSIs, the through holes used to conduct the upper and lower circuit patterns on multilayer boards are becoming finer, and even slight distortion of the board can cause disconnections between layers. It became.

The present invention has been made to address such problems, and provides a method for manufacturing a ceramic multilayer substrate that can prevent uneven stretching of green sheets during lamination and improve dimensional accuracy. With the goal.

[Structure of the Invention] (Means for Solving the Problems) The present invention involves stretching a raw material paste in a certain direction to form a ceramic green sheet, laminating the ceramic green sheets to produce a laminate, and then A method for manufacturing a ceramic multilayer substrate to be fired, characterized in that the ceramic green sheets are arranged in a stacked manner with their forming direction rotated by 80 degrees to 100 degrees with respect to the lamination direction. be.

The ceramics used in the present invention are not particularly limited, and various ceramics can be used, such as oxide ceramics such as alumina and zirconia, and non-oxide ceramics such as aluminum nitride and silicon nitride.

Then, an appropriate amount of, for example, a sintering aid or an organic binder is added to these ceramic powders to form a paste, and then a ceramic belt is formed into a belt shape by a doctor blade method, a roll forming method, or the like. In such a forming method, the raw material paste is stretched in a certain direction, so the green sheet after forming has a certain directionality.

In the present invention, the green sheets are stacked and arranged so that the orientation of the green sheets is rotated by 80 degrees to 100 degrees with respect to the stacking direction (vertical direction). In other words, in one cycle of four green sheets, adjacent green sheets have directionality that is orthogonal to each other, and when you look at every other green sheet, the directionality is reversed (rotated 180 degrees).

As a result, nonuniform elongation of the sheet due to directionality that occurs during green sheet molding is mutually alleviated, and uniformity as a whole can be improved.

The rotation angle of the green sheet with respect to the stacking direction is in the range of 80 degrees to 100 degrees for the purpose of alleviating uneven elongation of the green sheets, preferably 85 degrees to 95 degrees, that is, in approximately 90 degree increments. It's an angle.

(Function) According to the method for manufacturing a ceramic multilayer substrate of the present invention, the individual green sheets are arranged in a direction that is alternately perpendicular to the molding direction and -
Because every other green sheet is stacked in opposite directions, the directionality of the green sheets themselves is dispersed, and the deformation of individual green sheets is not amplified by stacking, improving the dimensional accuracy of the laminate as a whole. I can do it.

(Example) Next, embodiments of the present invention will be described using the drawings.

Example First, aluminum nitride powder was used as the ceramic powder, and a predetermined amount of a sintering aid and an organic binder were mixed to prepare a raw material slurry.

Then, using this raw material slurry, an aluminum nitride green sheet with a thickness of 0.3 cm was formed by the doctor blade method.

The difference in thickness of the obtained sheet in the forming direction was 0.2951 at one end and 0.3051 at the other end.

Using this sheet, as shown in FIG.
, Sheet 3 and Sheet 4 were sequentially laminated. The arrow illustrated on each sheet indicates the molding direction.

A marker was printed on the surface of the top layer to determine the elongation M of the sheet before and after lamination.

When the elongation of the sheet after lamination was measured, the average value of elongation was 0.019°, and the standard deviation was 0.004%.

Thereafter, the green sheet was fired according to a conventional method to obtain a ceramic multilayer substrate.

Comparative Example Using aluminum nitride green sheets produced under the same conditions as in the example, a laminate was produced in the stacking direction as shown in FIG.

That is, the forming directions of every other sheet 21, 22, 23, and 24 are made to intersect with each other.

Furthermore, markers were printed on the surface of the uppermost layer of this laminate in order to measure the elongation of the sheets before and after lamination, as in the example.

When the elongation of the sheet after lamination was measured, the average value of elongation was 01% and the standard deviation was 0.05%.

As is clear from these results, in the multilayer substrate produced by the manufacturing method of the example, uneven elongation of the ceramic green sheet was prevented, and the dimensional accuracy was able to be greatly improved.

Furthermore, by improving dimensional accuracy, it was possible to prevent misalignment and disconnection of the multilayer wiring, thereby improving reliability.

[Effects of the Invention] As explained above, according to the method for manufacturing a ceramic multilayer substrate of the present invention, the stacked green sheets can be stacked by rotating the stacking direction of each green sheet by approximately 90 degrees. It is possible to prevent uneven deformation of the ceramic multilayer substrate and improve the dimensional accuracy of the ceramic multilayer substrate.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the lamination direction of ceramic green sheets according to an embodiment of the present invention, and FIG. 2 is a diagram showing the lamination direction of conventional ceramic green sheets. 1.2.3.4... Green sheet 21.22.23.24... Green sheet applicant
Toshiba Corporation

Claims (1)

[Claims] (1) A method for manufacturing a ceramic multilayer substrate, in which a raw material paste is stretched in a certain direction to form a ceramic green sheet, the ceramic green sheets are laminated to produce a laminate, and then fired, the ceramic green sheet is A method for manufacturing a ceramic multilayer substrate, characterized in that the forming direction thereof is rotated by 80 degrees to 100 degrees with respect to the lamination direction and stacked.