JPH02106990A - Ceramic board having low dielectric constant - Google Patents

Abstract

PURPOSE:To form space sections among a plurality of ceramic layers, and to obtain a ceramic board having a small dielectric constant as a whole by forming a through-hole penetrated through an insulator section constituting an insulator layer in the insulator layer shaped so that the space sections are formed and the ceramic layers on both upper and lower sides of the insulator layer and filling the inside of the through-hole with a conductor. CONSTITUTION:In a low-dielectric-constant ceramic board 12, through-holes 14 penetrated through insulator sections constituting insulator layers 6 are shaped in the insulator layers 6 and the ceramic layers 4 of the upper and lower sections of the insulator layers 6, and the insides of the through-holes 14 are filled with a conductor. The land sections 16a of conductor lines 16 formed to the surface of the board 12 and the lands 18a of conductor lines 18 shaped on the insides are connected electrically by using the through-holes 14. Since the conductor lines 16 and 18 need not be extended up to the end sections of the board 12, the degree of freedom of conductor line wirings is improved, thus reducing limitation in the design of a circuit, then also simplifying line constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low dielectric constant ceramic substrate used, for example, as a multilayer substrate.

[Background technology]

As circuit operations become faster, substrates with low dielectric constants are required. This is the propagation delay time τ of the signal traveling through the board.
is expressed as .=F/., where C is the speed of light, and if the dielectric constant ε is large, high-speed operation will be hindered.

To solve this problem, ceramic green sheets with a large amount of organic matter added are baked into a porous state, and glass paste is applied to the surface and baked to create a large number of pores with a low dielectric constant inside. The idea is to create a ceramic substrate with a low dielectric constant and a dense surface.

However, in such a low dielectric constant ceramic substrate, ■ If the temperature is raised rapidly when firing the ceramic green sheet, the combustion of organic matter will be intense and a crank will occur in the ceramic, so the temperature must be raised gradually. Therefore, a lot of time and energy are required; (2) Coating and baking of glass paste requires a process to make the surface dense, resulting in high manufacturing costs.

Therefore, the same applicant has separately proposed a low dielectric constant ceramic substrate that improves these points.

An example of this will be explained with reference to FIG. 3. This low dielectric constant ceramic substrate 2 has a lattice-shaped insulating layer 6 between two ceramic layers 4, thereby creating a gap between the upper and lower ceramic layers 4. A large number of spaces 8 are created in the space. Further, the structure shown in the figure may be stacked in several layers.

In this case, since the space portion 8 has a small dielectric constant, the dielectric constant of the substrate 2 as a whole becomes small.

Moreover, unlike when using a porous ceramic layer,
There is no need to spend a long time firing the ceramics, and therefore less energy is required for firing.

In addition, since the surface of the ceramic layer 4 is in a dense state,
The process of applying glass paste to the surface and baking it is no longer necessary.

[Purpose of the invention]

In the low dielectric constant ceramic substrate 2 as described above, when electrical connection is to be made between the conductor lines on the front and back surfaces, or between it and the internal conductor lines, normally the It is conceivable to extend the conductor line and form a conductor line for connection on the end face thereof.

However, with this method, the conductor line to be connected must be extended to the edge of the board 2, which limits the degree of freedom in wiring the conductor line, which increases restrictions on circuit design. , it is easy to create a complicated line configuration.

Therefore, an object of the present invention is to provide a low dielectric constant ceramic substrate that is further improved in these points.

[Means to achieve the purpose]

The low dielectric constant ceramic substrate of the present invention includes a plurality of ceramic layers, an insulator layer provided between each ceramic layer so as to create a space between the upper and lower ceramic layers, one or more insulator layers, and the insulator layer above and below the insulator layer. It is characterized in that it includes a through hole that penetrates the ceramic layers on both sides by an insulator portion constituting the insulator layer, and is filled with a conductor.

[Effect]

According to the above configuration, since the dielectric constant of the space formed between the ceramic layers is small, the dielectric constant of the ceramic substrate as a whole is also small.

Moreover, since it is equipped with a through hole filled with a conductor, by using this, it is possible to connect the conductor line between the front and back sides of the board, or between it and the internal conductor line.
Furthermore, an electrical connection can be made between the internal conductor lines and the ground.

〔Example〕

FIG. 1 is a perspective view partially showing a low dielectric constant ceramic substrate according to an embodiment of the present invention. The same reference numerals are given to the same or corresponding parts as in the example of FIG. 3, and the differences from the previous example will be mainly explained below.

In the low dielectric constant ceramic substrate 12 of this example,
A through hole 14 is provided which penetrates the insulator layer 6 as described above and the ceramic layers 4 above and below the insulator layer 6 through the insulator portion that constitutes the insulator layer 6. This through hole 14 is filled with a conductor (not shown).

Using this through hole 14, in this example, the land portion 16a of the conductor line 16 provided on the surface of the substrate 12 and the land 18a of the conductor line 18 provided inside are electrically connected. There is.

In this way, there is no need to extend the conductor lines 16 and 18 to the ends of the board 12, so the degree of freedom in wiring the conductor lines increases, which reduces constraints in circuit design and also allows the line configuration to be adjusted. It can be simplified.

In that case, the position and number of through-holes 14 to be formed are arbitrary as long as they are in the insulator constituting the insulator layer 6, and may be determined depending on the required line configuration and the like.

Further, in order to form the through hole 14 with good reliability, it is preferable that the diameter of the through hole 14 is 1/2 or less of the width W of the insulator at that portion.

Next, an example of a method for manufacturing a low dielectric constant ceramic substrate having the above structure will be explained with reference to FIG.

As the ceramic material, we used a material that can be sintered at low temperature and has been separately proposed by the same applicant. That is, cordierite (for example, see JP-A-61-234128) is 60% by weight, B20. is 20% by weight, CaO is 1% by weight, BaO
A raw material was prepared in which SrO was mixed in a proportion of 4% by weight and 15% by weight, and this was calcined and pulverized to obtain ceramic powder with an average particle size of 3 μm.

Then, a slurry was prepared by mixing 100 parts of the obtained ceramic powder, 3 parts of dioctyl phthalate, 15 parts of an acrylic binder, and 50 parts of toluene. A sheet was produced and cut into a predetermined size.

Further, an insulating paste was prepared by mixing 100 parts of the ceramic powder, 14 parts of terpineol, and 6 parts of etocel by weight.

Then, conductor lines for internal wiring are screen printed on the upper surface of the ceramic green sheet 24 obtained as described above, and then the insulating paste 26 obtained as described above is placed on top of this in a grid pattern. Printed. In that case,
The position or pattern at which the insulating paste 26 is applied is matched to the position of the land portion of the internal wiring conductor line and the surface wiring conductor line to be described later. Further, the width W of the insulating paste 26 is 200 μm or more, and the thickness T is 2 mrr.
It is preferable to make it less than L, because otherwise, the printing of the insulating paste 26 tends to be incomplete, and the insulating layer obtained when fired is likely to be damaged.

Then, on this lattice-shaped insulating paste 26, another
Place 24 pieces of ceramic green sheet and
The insulating paste 26 and the upper and lower ceramic green sheets 24 were bonded together by being left on a hot plate at .degree. C. for 1 hour. In addition, the ceramic green sheet 24 to be placed on top
On the top, conductor lines for surface wiring were screen printed in advance.

Next, in order to connect the land part of the conductor line for internal wiring and the land part of the conductor line for surface wiring, a through hole is formed using a drill machine, and then the inner wall of this through hole is formed by screen printing. I printed it.

The product printed in this way was heated to 500°C/11
The temperature was raised at 980°C and held at 980°C for 1 hour to form a fired body, thereby obtaining a low dielectric constant ceramic substrate with the structure shown in Figure 1.In this case, the conductor was Ag-P.
Since the d-conductor paste was used, it was possible to bake in the atmosphere. However, it is also possible to use Cu paste, but in that case it is necessary to sinter it in an H, O/N2 (i.e. nitrogen containing water vapor) atmosphere, and the key is to change the sintering conditions depending on the type of conductor. good.

Incidentally, the dielectric constant of the low dielectric constant ceramic substrate thus obtained was about 2.4, which was less than half that of a normal ceramic substrate without a space formed therein.

In the above description, one insulating layer is provided between two ceramic layers, but the present invention is not limited to this. An insulator layer as described above may be provided respectively. In that case, the through hole may be a through hole that penetrates all the insulator layers and the ceramic layers on both the upper and lower sides of the ceramic substrate, and may be a through hole that penetrates between the front and back surfaces of the ceramic substrate.
) It may be a hole-like type, and which type should be used can be determined depending on the required line configuration, etc.

In addition, in the above embodiment, since the insulating paste was applied in a lattice pattern, the planar shape of the space formed in the insulating layer was a quadrilateral. You can also make it so that

〔Effect of the invention〕

As described above, according to the present invention, similar to the low dielectric constant ceramic substrate separately proposed by the same applicant, the following effects can be obtained.

That is, since the spaces are formed between the plurality of ceramic layers, a ceramic substrate having a low dielectric constant as a whole can be obtained.

Furthermore, unlike the case where a porous ceramic layer is used, there is no need to spend a long time firing the ceramic, and therefore less energy is required for firing.

Furthermore, since the surface of the ceramic layer becomes dense, the process of applying glass paste to the surface and baking it becomes unnecessary.

In addition, chip components (e.g., chip capacitors, chip resistors, etc.) that are heat resistant up to the temperature at which ceramics are fired can be placed without stress by using the space between the ceramic layers (in other words, they are not surrounded by ceramics). (Since there is no such thing), it can be built-in.

Furthermore, since there is a space inside, a lightweight ceramic substrate can be obtained.

Moreover, in addition to the above-mentioned effects, this invention also provides the following effects:
Electrical connections can be made between the conductor lines on the front and back surfaces, between the conductor lines inside them, and even between the conductor lines inside the ground, using through-holes filled with conductor. It is no longer necessary to extend the conductor line to the edge of the board, increasing the degree of freedom in wiring the conductor lines, thereby reducing restrictions on circuit design and simplifying the line configuration.

[Brief explanation of drawings]

FIG. 1 is a perspective view partially showing a low dielectric constant ceramic substrate according to an embodiment of the present invention. FIG. 2 is an exploded perspective view for explaining a method of manufacturing a low dielectric constant ceramic substrate as shown in FIG. FIG. 3 is an exploded perspective view showing an example of a low dielectric constant ceramic substrate, which is the background of the present invention. 4...ceramic layer, 600. Insulator layer, 8...
Space part, 12... Low dielectric constant ceramic substrate according to the example, 14... Through hole.

Claims (1)

[Claims] (1) A plurality of ceramic layers, an insulating layer provided between each ceramic layer so that a space is created between the upper and lower ceramic layers, and one or more insulating layers and the ceramic layers on both sides of the insulating layer. 1. A low dielectric constant ceramic substrate comprising a through hole that penetrates through an insulator portion constituting a body layer, the through hole being filled with a conductor.