JPS6145877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves laminating a predetermined number of unfired ceramic substrates, so-called green sheets, on which a circuit pattern of conductor paste is printed, and integrating the laminate of unfired ceramic substrates and the conductor paste. The present invention relates to a method for manufacturing a ceramic multilayer circuit board using a firing method, and specifically to a method for constructing a ceramic laminate before firing.

This type of ceramic multilayer circuit board has two types: one has a recess in which a semiconductor chip such as an integrated circuit element is housed, and the other has a flat surface where semiconductor elements and/or other electronic components are mounted as necessary. There is something. In either case, the unfired ceramic sheets to be laminated, that is, the raw ceramic sheets, are coated with the following steps to provide interlayer conduction between the circuit patterns of each layer.
If necessary, circular through holes are formed at desired locations, and these holes are filled with conductive paste when printing the surface circuit pattern. In the case of a package type multilayer circuit board, in addition to the through-holes described above, accommodation holes for accommodating semiconductor chips are also made in the green sheet. This receiving hole is significantly larger than the through hole and is generally square in shape depending on the shape of the semiconductor chip. In any case, when stacking raw sheets, each sheet must be aligned with high precision.

The so-called lamination method for providing a conventional green sheet laminate is to integrate aligned and stacked unfired ceramic substrate groups by hot pressing.

Specifically, if we take as an example a ceramic multilayer circuit board having a concave portion on its surface, it is laminated in the arrangement shown in FIGS. 1a and 2a. Both figures show ceramic circuit boards of different constructions.
In the figure, 1 is an unfired ceramic substrate, a so-called green sheet, and 10 is a receiving hole formed in the green sheet by punching. Through holes are formed as necessary, but illustration is omitted. Each green sheet has a stage pattern 21 for fixing a semiconductor chip as required.
Metal patterns such as a wiring lead pattern 22, a sealing cap fixing frame pattern 23, and the like are printed with conductive paste. After aligning and stacking these raw sheet groups, a core 5 that matches the contour of the stack is set in the stack, and in this state the stack is heated at a temperature of 40 to 120 [°C] for 100℃. ~300
Hot pressed at a pressure of [Kg/cm ² ].

Figures 1b and 2b respectively show the laminates obtained by this hot pressing. This laminate is
After firing at 1400 to 1600 [°C], a semiconductor chip 2 is housed in this as shown in FIG. 1c and FIG. After the lead wires are connected, the lid 3 fixed by the frame pattern 23 is hermetically sealed. In the example shown in FIG. 1, the semiconductor chip is mounted on a stage 4 with a bottom plate, but in the example shown in FIG.
It will be installed on 1. In this way, a ceramic multilayer circuit board having recesses on its surface is obtained. By the way, the above-mentioned core 5 is an elastic body made of rubber, and due to its presence, the contour of the complex stack of raw sheets can be maintained to a predetermined size, and the whole can be hot-pressed. If the core were not present, the laminate obtained by hot pressing would have a desired shape and sheet alignment that would be disrupted since it is pressure molded.

However, in the hot press method, the elastic core is deformed by pressure and heating, and the green sheet itself and the conductor pattern are accordingly deformed. As a result, yield improvement is hindered. This type of deformation may be unacceptable due to the complexity of the green sheet geometry and the density of the circuit pattern.

Therefore, a plasticizer or binder is applied to both the upper and lower surfaces of the green sheets, the sheets are aligned, stacked, and left as is under static pressure, that is, without hot pressing, to provide an integrated laminate. A method is proposed. Although this method certainly avoids the disadvantages caused by the core, since the adhesive is applied to each green sheet, there is no flexibility in the mutual positioning of the stacked green sheets. That is, since the green sheets are in a state where they are easily joined to each other, it becomes difficult to adjust the green sheets by relatively moving them for alignment. On the other hand, if there is no hole for accommodating the semiconductor chip, that is, a recess, the core as described above is not used. However, hot pressing is performed with an elastic sheet interposed.

Therefore, even in the case of a ceramic multilayer circuit board with a flat surface, the deformation of the surface of the green sheet and the deformation of the circuit pattern during the lamination process will cause deformation of the elastic sheet, similar to the multilayer circuit board with surface recesses as described above. This is likely to occur due to deformation.

Therefore, an object of the present invention is to realize a novel lamination method that solves the above problems.

According to the present invention, after forming a desired circuit pattern on a plurality of unfired ceramic substrates each having a predetermined shape using a conductive paste, the unfired ceramic substrates are stacked one on top of the other, and then joined together, and the resulting laminated layers are stacked together. In a method for producing a ceramic multilayer circuit body, which includes a step of firing the ceramic circuit body, the unfired ceramic substrates are sequentially stacked, and then the stacked body is treated with a solvent capable of dissolving the organic binder contained in the green ceramic substrates. There is provided a method for manufacturing a ceramic multilayer circuit board, which comprises the step of bonding together a group of stacked unfired ceramic substrates by leaving them in an atmosphere of .

3 and 4 are process explanatory diagrams showing the lamination and integration method according to the present invention, and FIGS. 3A and 3B show stacked green sheets according to the structure of FIGS. 1 and 2, respectively. It shows.

In the present invention, a green sheet 1 that has been punched and printed with a metal pattern with a necessary conductive paste is aligned and formed into a polyester film 6.
(Fig. 3 A, B). In this case, the green sheet is not coated with an adhesive such as a plasticizer or binder as described above. The obtained stacks A and B are housed in a desiccator box 7 that is integrated with a support film 6. A solvent 8 for dissolving the binder in the ceramic green sheet, such as an alcohol or ketone solvent for a butyral resin binder, is stored in advance in this box to create a solvent atmosphere inside the box. 1 to 5 stacks are in this box.
It is left to stand for a period of time, ie under static pressure, and then removed and dried in a thermostatic oven. As a result, multiple layers of green sheets are integrated, and a dried laminate is obtained. The support film 6 is peeled off after drying. This laminate is then transferred to a firing step and fired in the same manner as conventional products.

In summary, the method of the present invention is such that an unfired ceramic substrate, a so-called green sheet, is formed from a slurry containing ceramic powder, a sintering aid, an organic binder, a dispersant, and a plasticizer, and that the organic binder is contained inside and on the surface. By focusing on the fact that the binder is contained in the binder, the sheets are bonded together by permeating the sheets from the atmosphere with a solvent that dissolves the binder.

Therefore, according to the present invention, since hot pressing is omitted, there are no disadvantages that occur when using elastic cores and elastic sheets as described above, and when multilayering, plasticizers and Since there is no need to apply a binder, it is easy to align a plurality of green sheets with each other. Moreover,
Since the multi-layered green sheets are joined under static pressure, they are essentially free from deformation of the green sheets themselves or of the metal pattern due to pressure.

It goes without saying that the method of the present invention can be advantageously applied not only to a ceramic multilayer circuit board having a concave surface as in the illustrated embodiment, but also to a process for forming a ceramic multilayer circuit board having a flat surface.

[Brief explanation of the drawing]

Figure 1 a, b, c and Figure 2 a, b, c are process diagrams showing the conventional method of manufacturing two types of ceramic multilayer circuit boards, Figure 3 A, B, and Figure 4 are the same as Figure 1. FIG. 3 is an explanatory diagram showing a lamination process according to the present invention when manufacturing a ceramic multilayer circuit board of the type shown in FIG. 2; In the figure, 1 is an unfired ceramic substrate, and 2 is an unfired ceramic substrate.
IC chip, 3 is the lid, 4 is the stage with bottom plate, 1
0 is a chip receiving hole, 21, 22, 23 are metal patterns, 5 is a core, 6 is a support film, 7 is a desiccator box, and 8 is a solvent.

Claims (1)

[Claims] 1. After forming a desired circuit pattern on a plurality of unfired ceramic substrates each having a predetermined shape using a conductive paste, stacking the unfired ceramic substrates and then joining them together; and firing the obtained laminate. In the method for manufacturing a ceramic multilayer circuit body, the unfired ceramic substrates are stacked one after another, and then the stacked body is left standing in an atmosphere of a solvent capable of dissolving the organic binder contained in the green ceramic substrates. 1. A method for manufacturing a ceramic multilayer circuit board, comprising the step of: placing a stack of unfired ceramic substrates together;