JPS6181693A - Manufacture of ceramic substrate and green sheet used therefor - 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 relates to a method of manufacturing a ceramic substrate and a green sheet used therein.

(Prior Art) This type of ceramic substrate is used as an insulating substrate or a ceramic package for a semiconductor device in the field of electronic equipment.

As shown in FIG. 6, the conventional method for manufacturing a ceramic package for a semiconductor device is to place a support film 2 in close contact with the back surface of a green sheet 1, and then insert through-holes 3 and guide holes for filling conductor paste. 4 is drilled, conductive paste is filled into the through holes 3 from the surface side of the green sheet 1 using a metal mask, and a wiring pattern of the conductive paste is printed on the surface of the green sheet 1 by screen printing or the like. A method for manufacturing a substrate is known (Japanese Patent Laid-Open No. 197796/1983).

According to this method, since the support film 2 is closely attached to the back surface of the green sheet 1 until the conductive paste is printed on the surface of the green sheet 1, the size of the green sheet 1 is prevented from shrinking, and the position of the guide hole 4 is prevented from shifting. can be prevented,
Through-hole drilling.

It has the advantage that conductor paste filling, conductor paste printing, and lamination adhesion can be performed with high precision. .

Ceramic I according to JP-A No. 59-101855
The method for manufacturing the C puff cage involves the following steps.

In other words, adhesive tape is pasted on the entire surface of the green sheet where the wiring pattern is printed or on the required specific surface, and when these are laminated and pressure bonded, only the adhesive tape on the top and bottom surfaces to be laminated is left, and the middle The laminated adhesive tape in the layers is peeled off and laminated and crimped, then cut and separated into multiple packages, followed by side printing and the final product.

The adhesive tape on the bottom surface is peeled off and fired.

According to this conventional example, green sheets are handled up to the lamination stage by pasting adhesive tape onto printed wiring patterns, peeling off the adhesive tape at the time of lamination, and cutting the green sheets into multiple packages after lamination. This has the advantage that cutting debris and the like do not adhere to the wiring pattern portion, and it is possible to prevent irregularities in electric resistance values and unevenness of the surface of the wiring portion.

(Problems to be Solved by the Invention) However, the above conventional method for manufacturing a ceramic substrate has the following problems.

That is, in the former manufacturing method, the support film 2 is closely attached to the back surface of the green sheet 1, and the wiring pattern of the conductive paste is printed.
The dimensional shrinkage of the green sheet 1 is eliminated, and the through holes 3 and guide holes 4 can be drilled in the green sheet 1 with high accuracy. However, filling the through hole 3 with conductive paste is
Since this is done by applying a metal mask to the surface of the green sheet 1 on the opposite side of the support film 2, even if the through holes 3 are drilled in the green sheet 1 with high precision, the metal mask is not attached to the green sheet. There is a high possibility that the mask will be misaligned, and in this case, the head of the filled conductive paste may be deviated as shown in Figure 7.
There is a problem that a short circuit occurs due to contact with the wiring pattern 5 of the stacked green sheets. In recent years, there has been a tendency for wiring patterns to become more and more dense, so there is a risk that the above-mentioned short-circuit accidents will occur more frequently.

Further, there is a possibility that the conductive paste may seep between the metal mask and the surface of the green sheet, and the above-mentioned short circuit may also occur due to the seepage.

Further, the support film 2 is tightly attached only to the front surface side of the green sheet 1, and the guide holes 4. The through hole 3 is drilled and filled with conductive paste, and during this time there is no cover on the surface side of the green sheet 1, so there is a problem that foreign matter may adhere to the surface side. If a conductor paste is printed using a blank screen, there is a risk that the pattern will bleed or be damaged.

On this point, in the latter conventional method, the wiring pattern of conductive paste is printed, the adhesive tape is pasted over the wiring pattern, and then the cutting process is performed, which eliminates the problem of adhesion of debris due to cutting. . However, this does not solve the above-mentioned problem of short-circuit failure due to bleeding etc. when filling the conductor paste, and there is a risk that foreign matter such as dust in the air may adhere to the surface of the green sheet until the wiring pattern is printed. In addition, since adhesive tape is pasted over the conductor paste after printing the conductor paste, depending on how the pressure is adjusted when pasting the adhesive tape, the adhesive force of the adhesive tape may be too strong. There is a risk that the conductor paste may peel off at the same time.

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide a method for manufacturing a ceramic substrate in which conductor paste can be easily and accurately filled, and a green sheet used in the method.

(Means for Solving the Problems) A method for manufacturing a ceramic substrate according to the present invention includes the following configuration in order to solve the above problems.

That is, a green sheet 10 with a protective film 11 adhered to one side is used. Then, with this protective film 11 in close contact, the necessary die-cutting process is performed.

A through hole 12 for filling the conductive paste is bored.

Next, leave the protective film 11 in close contact with the protective film 11.
The through hole 12 is filled with conductive paste from the side, then the protective film 11 is peeled off, and a wiring pattern of the conductive paste is printed on the surface of the green sheet 10 on the side to which the protective film 11 was in close contact.

In addition, a thin protective film 1 is placed on one side of the green sheet 10.
A green sheet is used in which a shape-retaining film 14, which is thicker than the protective film 11, is removably attached to the surface of the protective film 11. and through hole 12
Before drilling, only the shape-retaining film 14 is peeled off, and the same manufacturing process as described above is carried out with the protective film 11 still in close contact.

(Embodiments) Preferred embodiments of the present invention will be described in detail below based on the accompanying drawings.

Figure 1 shows a green sheet used in the method of the present invention, and a green sheet 10 formed by the doctor blade method.
A protective film 11 is adhered to one side of the. This protective film 11 is used as a carrier film during molding of the green sheet 10, and is closely attached to the surface side of the green sheet 10, which is the surface on which a conductive paste to be described later will be printed. The green sheet 10 with the protective film 11 tightly attached thereto is usually wound into a roll to prevent dust and the like from adhering to it.

The green sheet 10 wound into a roll is pulled out from an appropriate reel (not shown) with the protective film 11 in close contact with it, and is die-cut into a predetermined shape using a progressive die. Appropriate guide holes (not shown) and through holes 12 for filling conductor paste are bored. This through hole 12 is also bored in the protective film 11 at the same time. The thickness of the protective film 11 is 30 to 10
Although it is approximately 0 μm, a thinner one is preferable for the following reason.

In other words, if the protective film is thick, when the mold is cut from the protective film side, it will be pressed against the protective film,
The upper edge of the punched part of the green sheet will sag in a curved shape (see Figure 2), but if the protective film 11 is thin, the upper edge of the punched part will sag by adjusting the clearance of the punching die. congestion can be kept to a minimum. The protective film 11 also prevents punching debris and dust from adhering to the surface of the green sheet 10. Furthermore, since the protective film 11 is thin, it is possible to suppress the head of the filled conductive paste from protruding above the surface of the green sheet 10.

In this embodiment, the carrier film used when forming the green sheet 10 is used as the protective film 11, but another film other than the carrier film may be attached to the protective film 11 after forming the green sheet 10.

Next, the through holes 12 are filled with conductive paste. Filling with the conductor paste is performed from the protective film 11 side by applying a metal mask.

In this case, since the protective film 11 is in close contact with the green sheet 10, even if the conductive paste bleeds onto the surface of the protective film 11, it does not bleed onto the surface of the green sheet 10, and the surface of the green sheet 10 is not contaminated.

Furthermore, since the protective film 11 also serves as a mask, the opening of the metal mask can be enlarged to facilitate positioning of the through holes 12 of the green sheet 10 and the metal mask.

Alternatively, the through holes 12 can be filled with conductive paste by using the protective film 11 as a mask while keeping the protective film 11 in close contact with the protective film 11 .

It goes without saying that the through holes 12 may be filled with conductive paste by suction if necessary.

After filling the conductive paste, the protective film 11 is peeled off, and a wiring pattern using the conductive paste is printed on the surface of the green sheet 10 by screen printing. Protective film 1
When the green sheet 10 is peeled off, the head of the conductive paste filled in the through holes of the protective film 11 is slightly removed from the green sheet 10.
Although it may protrude on the surface (see Fig. 3), when the wiring pattern of the conductor paste is printed using the screen 13 as shown in Fig. 4, the protrusion of the conductor paste is covered by the thickness of the wiring pattern. Therefore, there is no problem in practical use.

After printing the wiring pattern, a plurality of predetermined green sheets are laminated and fired to form a ceramic package for a semiconductor device.

FIG. 5 shows a green sheet used in another embodiment.

The above-mentioned green sheet 10 is a double-structured carrier film in which a thick (approximately 50 μm) shape-retaining film 14 is removably attached to the surface of a thin (approximately 12 μm) protective film 11 using an adhesive 15. It is molded using the doctor blade method.

If the thickness of these 15 layers of adhesive is about 20 μm, the total thickness will be about 80 μm, so the green sheet 1
It can withstand even dimensional shrinkage of 0, allowing for highly accurate processing.

In this embodiment, as described above, the two films are brought into close contact with each other to prevent dimensional shrinkage and deformation of the green sheet, and only the upper layer shape-retaining film 14 is peeled off during processing such as drilling the through holes 12. Then, as in the previous embodiment, the manufacturing process up to filling the conductor paste is carried out with the protective film 11 in close contact with the green sheet 10, and then the protective film 11 is peeled off and a wiring pattern of the conductor paste is screen printed on the surface of the green sheet 10. Then, a ceramic substrate can be manufactured by laminating a plurality of layers and firing them.

When the shape-retaining film 14 is peeled off, the adhesive 15 adheres to the shape-retaining film 14 side, and the protective film 1
It is peeled off from 1.

Furthermore, since the protective film 11 can be made as thin as about 12 μm, the droop at the upper edge of the patterned portion can be made extremely small, and the protruding portion of the head of the conductive paste can be made even lower.

(Effects of the Invention) As described above, according to the method for manufacturing a ceramic substrate according to the present invention, the necessary die-cutting process and the drilling of through-holes for filling the conductive paste are performed while the protective film remains in close contact with the green sheet surface. Foreign matter such as processing debris does not adhere to the side, and since the conductive paste is filled from the protective film side using the through holes in the protective film, the protective film also serves as a mask, so it can be used as a metal mask. Enlarge the opening to allow the green sheet to pass through,
The positioning of the hole and the metal mask can be made easier, and the problems of misalignment and bleeding can be solved, thereby eliminating short-circuit defects.

Furthermore, by peeling off the protective film, a conductive paste wiring pattern can be printed on the surface of the green sheet, which is completely free of foreign matter adhesion, and the problem of bleeding or chipping of the wiring pattern due to foreign matter adhesion is solved.

In addition, by using a green sheet with a shape-retaining film pasted on top of the protective film, it is possible to prevent dimensional shrinkage and deformation of the green sheet during storage, allowing more precise processing and making the protective film thinner. Not only can the sagging of the upper edge of the die cut portion be extremely small, but also the protruding portion of the head of the conductive paste can be further lowered.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a green sheet used in the method of the present invention. Fig. 2 is an explanatory diagram showing the sagging of the processing edge of the green sheet when a thick protective film is used; Fig. 3 is an explanatory diagram showing the protruding state of the head of the filled conductive paste; FIG. 4 is an explanatory diagram for screen printing a conductor paste wiring pattern, and FIG. 5 is a sectional view of a green sheet used in another method. FIG. 6 is an explanatory diagram showing an outline of a conventional manufacturing method, and FIG. 7 is an explanatory diagram showing a state when a short circuit occurs according to the conventional method. 1...Green sheet 2...Support film,
3...Through hole, 4...Guide hole,
5... Wiring pattern, 10... Green sheet, 11... Protective film, 12... Through hole, 13... Screen. 14... Shape-retaining film, 15... Adhesive.

Claims (1)

[Claims] 1. Using a green sheet with a protective film adhered to one side, a through hole for filling the conductive paste is drilled with the protective film in close contact with the green sheet. A method for manufacturing a ceramic substrate, comprising filling the through holes of the ceramic substrate with conductive paste, then peeling off the protective film, and printing a wiring pattern of the conductive paste on the surface of the green sheet. 2. The method of manufacturing a ceramic substrate according to claim 1, wherein the wiring pattern of the conductive paste is printed on the surface of the green sheet on the side to which the protective film was in close contact. 3. A shape-retaining film that is thicker than the protective film is releasably attached to the surface of the protective film, and a green sheet with the protective film surface adhered to one side is used, at least before drilling the through-hole. The method for manufacturing a ceramic substrate according to claim 1 or 2, characterized in that only the shape-retaining film is peeled off. 4. A green sheet for manufacturing ceramic substrates, comprising a shape-retaining film that is thicker than the protective film and is releasably attached to the surface of a thin protective film, and the surface of the protective film is adhered to one side.