JPS6247195A - Ceramic multilayer substrate - 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 the Invention The present invention relates to a ceramic multilayer substrate, particularly a ceramic multilayer substrate that can be fired at low temperatures.

2. Description of the Related Art In recent years, electronic circuits using ceramic substrates with excellent heat dissipation properties, which can be easily formed by thick film printing, have been used for electronic circuits. Multilayer electronic circuit boards are beginning to be used to achieve smaller size and higher performance.

The method for manufacturing multilayer circuit boards is generally described below (
There are three types: a), (b), and (C').

(,) Printing multilayer method on ceramic sintered body (b)
Printing multilayer method on green sheet (0) To explain the method of manufacturing a multilayer board by printing multilayer method on ceramic sintered body of green sheet lamination multilayer method (a), the process is shown in Figure 1. , firstly, a first
Steps 1 to 3) of printing, drying, and baking the conductor layer; then steps 4 to 6) of printing, drying, and baking the first insulating layer;
Print and dry the second insulating layer on top of it (step 7.8)
, the second conductive layer is printed and dried (step 9.10), and the second insulating layer is fired all at once (step 11). On this occasion,
The first and second insulating layers are printed so that micro holes called via holes are formed [7, The second conductor layer is printed so that the material used for the second conductor layer is filled into the micro holes. The first conductor layer and the second conductor layer are connected.

Next, a third insulating layer is printed, dried, and fired on the second conductive layer,
The number of layers is stacked in the same manner as for the second insulating layer and subsequent layers (steps 1 to 11).

Figure 2 shows the process for manufacturing a multilayer board using the printing multilayer method using a green sheet (0)).
Step 12: After firing, print and dry the first conductor layer on the ceramic green sheet soil that will become the substrate.
, 13), then print and dry the first insulating layer thereon (step 14.15), then print and dry the second conductor layer and second insulating layer (steps 15 to 19), and repeat the same procedure thereafter. Steps 12 to 19) in which the number of layers is repeated are repeated, and the green sheet, the conductor layer, and the insulating layer are collectively fired (step 20).

In the method for manufacturing a multilayer board using the green sheet lamination multilayer method (C), as shown in FIG. 22 to 24), respectively, printing and drying a conductor layer with a light pattern (steps 25 to 30).

Next, stack the desired number of green sheets with the conductor pattern (step 31), crimping them under moderate pressure and temperature (step 32), and cut them into the desired external dimensions [7]. Baking (steps 33, 34).

Electrical conduction between each conductor layer is achieved by conductors filled in micropores in the green sheet.

In both manufacturing methods (b) and (c), the thick film of the top layer is formed after baking the substrate (step 21.35).
).

Comparing the three manufacturing methods (a), (b), and (C), it is found that (cl) can be multi-layered with relatively simple technology, but the practical limit on the number of layers is 4 to 6 layers. If the number of layers is greater than that, the surface becomes extremely uneven and is not practical. (b
) can streamline the process by firing the green sheet, printed insulating layer, and conductive layer at the same time. However, in case of b), similarly to (a), increasing the number of layers increases surface irregularities, so the limit number of layers is still 4 to 6 layers. The number of layers in (C) is theoretically possible to be infinite, and in reality, multilayer substrates with about 30 to 40 layers have been reported. However, manufacturing them requires extremely advanced technology and there are many process issues.

Among the above-mentioned methods (a), (b), and (c') for producing three types of laminations, the present invention relates to (c) the green sheet lamination multilayer method. The prior art will be described in detail with reference to FIG.

(First example of prior art) First, micro holes that will become via holes are formed in a plurality of green sheets having a predetermined thickness formed from a mixture of alumina powder and an organic substance in different patterns 7 (steps 22 to 24). ), then print and dry the conductor layer with different patterns (step 2)
5-30). W and Mo are mainly used for conductor material.Filling of the conductor material tI into the via hole is done at the same time as the conductor printing process (steps 25 to 27), or the conductor material is filled into the via hole alone before the printing process. 11 = 'i is filled. After the conductor is dried, a predetermined number of green sheets each having a different conductor pattern are laminated (step 31).
They are integrated under pressure at an appropriate temperature (step 32). Next, step 33) cuts to the desired external dimensions, approximately 150 mm.
The multilayer substrate is baked in step 34) in a reducing atmosphere at 0° C. to form a multilayer substrate.

The fired substrate is thoroughly cleaned and then proceeds to the step of forming the second most layered film (step 36).

(Second example of prior art) As stated in the "Multilayer Ceramic Substrate" disclosed in Japanese Patent Publication No. 59-22399-Yumi Publication,
゛First, micropores that will become via holes are formed in different patterns on multiple green sheets made of a mixture of glass powder, alumina (April's composite composition, and organic matter) formed to a predetermined J= size. Formation Steps 22-24)
, print and dry conductor layers with different patterns (
Steps 26-30). Conductor materials include Ag, Au, and Pd.
, Pt, etc., or an alloy thereof may be used. The via holes are filled with the conductive material simultaneously with the conductor printing process (steps 25 to 2γ), or the via holes are filled with the conductive material alone before the printing process. After the conductors are dried, a predetermined number of green sheets each having a different conductor pattern are laminated (step 31), and then integrated under pressure at an appropriate temperature (step 32).

Next, step 33) and 70 cut to desired external dimensions.
Step 34) A multilayer substrate is obtained by firing in air at 0° C. to 1400° C. The fired substrate is thoroughly cleaned, and then proceeds to the step of forming a buried film in the uppermost layer (step 36).

Problems to be Solved by the Invention However, in the above-described first example of the prior art, the firing temperature is high and a reducing atmosphere is used, resulting in high equipment costs and inconvenience in handling. In addition, since alumina is used as the green sheet material and the firing temperature is high, only high melting point metals such as W and Mo can be used as conductor materials.
As a result, there was a problem in that the resistance value of the conductor became high.

-Also, in the second example of the prior art, the problems of the above-mentioned example - can be solved, but because it is a composite composition of glass material and alumina material, it has the disadvantage that the firing shrinkage rate is more difficult to control than with alumina alone. There was a problem that the yield was low. Incidentally, the variation in the firing shrinkage rate of the multilayer substrate according to the above-mentioned example 1 is ±0.5% to ±1.0%, and the firing shrinkage rate of the multilayer substrate according to the above second example is ±1.0% ~.
It was 12.5%.

In view of the above problems, the present invention uses Aq as a conductive material.

The purpose is to use low melting point metals with low resistance such as Au, Pd, Pt, etc. or their alloys, and to lower the firing temperature and enable firing in air, reducing equipment costs and making handling easier. and the variation in firing shrinkage rate is
, is to provide a ceramic multilayer substrate that can be fired in air at a low temperature of less than 0%.

Means for Solving the Problems In order to solve the above problems, the ceramic multilayer substrate of the present invention contains, in terms of oxides, Sio: 6 to 65% by weight, PbOO, 1 to 30% by weight.
.

At least one of Li2O, Na2O, and K2O.
01-10% by weight.

A basic composition consisting of 0.05 to 26% by weight of at least one of MgO, CaO, ZnO, and BaO, and at least one of Al2O3, ZrO2, and T102, also converted to oxides. The insulating layer is formed from a dielectric composition containing additives having a composition of 15 to 55% by weight.

Function: The ceramic multilayer substrate of the present invention can be heated to about 870°C to 980°C.
The insulating layer is formed of a dielectric composition that can be sintered at low temperatures, and also exhibits sufficient characteristics as a ceramic substrate for forming electronic circuits.

In the present invention, low melting point metals such as Ag, Au, and Pd are used.

It is possible to use a single substance such as PT or an alloy of these metals, and since these metals are difficult to oxidize even in the air, a reducing firing atmosphere is unnecessary.Au and Ag have a resistance value of W, Mo.
lower than. Therefore, low-temperature firing in air reduces equipment costs and facilitates handling.

Furthermore, since the ceramic multilayer substrate of the present invention has a variation in firing shrinkage rate of less than ±1.0%, the yield is high and mass productivity is good.

The reasons for the limitations in the composition of the present invention are as follows.

Sio2 is a substrate composition constituting the substrate and is the main material for forming glass. When Sio2 is less than 6%, the sintering temperature becomes high, and A g , A u + P t , P
The low melting point metal d cannot be used as an internal conductor, and the firing shrinkage rate varies greatly. Kada5lo2 is 66
If it exceeds %, the bending strength becomes too small, and the firing shrinkage rate also varies greatly, making it impractical as a substrate.

PbO is a component of glass formation and crystallization. PbO is 0
．． If it is less than 1%, devitrification occurs during melting of the glass and the dielectric loss tangent deteriorates.

Furthermore, if pbo exceeds 30%, the softening temperature and crystallization temperature will become high, resulting in an excessively high sintering temperature.

MqO, CaO, ZnO, and BaO are added for the purpose of improving the sinterability of the substrate, controlling the coefficient of thermal expansion, and improving the dielectric loss tangent. If at least one of MgO, CaO, ZnO, and BaO is less than 0.06%, sinterability is insufficient, and if it exceeds 25%, the dielectric loss tangent becomes large, making it undesirable.
~ Not. The coefficient of thermal expansion is controlled in various ways depending on the use of the substrate, but when used as a normal thick film hybrid integrated circuit, especially when forming a circuit using thick film conductor paste and thick film resistor paste, the coefficient of thermal expansion of alumina is 6. .0~6,6X
It is preferable to match the thermal expansion coefficient of silicon to 107°C, and when a silicon chip of an IC is directly mounted on a substrate, it is preferable to match the coefficient of thermal expansion of silicon to 4×107°C.

It is easy to judge the quality of a board based on the coefficient of thermal expansion alone, but a board with a value that is significantly different from both values cannot be put to practical use.

KO, Na 20 and L 120 are added for the purpose of improving the sinterability of the substrate, increasing the water absorbency, and suppressing deformation of the substrate. If at least one of K 2 O, Na 2 O, and Li 2 O is less than 0.01%, the substrate will be significantly deformed and the substrate will warp significantly. K O, N a 20. L!
If at least one of the 20 components exceeds 10%, sintering will be insufficient and water absorption will occur.

Al2O3, ZrO2, and TiO2 are used as substrate fillers and are added mainly to suppress variations in bending strength in the direction -L and firing shrinkage rate. Al2O3, ZrO2゜T
If at least one of iO2 is less than 15%, the bending strength is too low and the firing shrinkage rate varies too much to be practical. Dimensions A l 20 s, Z r○2,
If at least one of T102 exceeds 66%, the sintering temperature will be high and the sintering will be insufficient, resulting in water absorption.
Moreover, the bending strength is also reduced.

Examples Examples of the dielectric composition for multilayer substrates of the present invention will be described below.

First, in preparing the glass, prepare a batch by weighing each raw material of the basic composition so that it has the composition shown in Table 1 below. 3
The material is heated for a period of time to melt it, and then a glass plate is formed by, for example, a roll-out method. Next, the dielectric composition of the present invention is produced by powdering the above glass plate with an alumina ball or the like to have an average particle size of 0.6 to 6 μm, and adding additives 13/, having about the same particle size.

Note that the raw material powder used in this case is expressed in terms of oxide for clarity, but it goes without saying that minerals, oxides, carbonates, hydroxides, and other forms can also be used in the usual manner.

Next, an example of a method for manufacturing a ceramic multilayer substrate by a green sheet lamination multilayer method using the dielectric composition obtained in this manner will be described.

To 100 parts by weight of the above composition, add 1Q parts by weight of polyvinyl butyral, 6 parts by weight of dibutyl phthalate, 1 part of glyceryl monooleate) 0-4, 1-1-1
) 20 parts by weight of dichloroethane and 39 parts by weight of inpropyl alcohol were processed and mixed in a ball mill for 24 hours to prepare a slurry. Using this slurry, a green sheet with a thickness of 0.1 mm was produced on a polyester film by the doctor blade method, sufficiently aged, and micropores to become via holes were formed by mechanical processing. Next, this via hole is filled with a conductive material by a printing method using a metal mask. The conductor material used was 14.

The material was Au and the melting point was 1062°C.

Next, a conductive layer was printed on a green sheet using the same conductive material and dried. Via hole pattern.

A plurality of green sheets each having a different conductor printing pattern were brought into close contact with each other at a temperature of 80° C. and a pressure of 200 to 9/i to integrate them under pressure. Next, after cutting the outline, the maximum temperature is 870~1
Firing was carried out at 340° C. for a maximum temperature holding time of 60 minutes. After ultrasonically cleaning the fired multilayer board with pure water, a thick top layer was formed on the front and back sides of the multilayer board, completing the board that can function as an electronic circuit.

Table 1 shows the properties of the substrate produced by the above manufacturing method, along with the composition of the dielectric composition. Regarding the characteristics, the bending strength, water absorption rate, and dielectric loss tangent were measured for the substrate that functions as an electronic circuit, and the results are shown in Table 1. In addition, the sintering temperature in the same table is determined by estimating the approximate sintering temperature for each composition in advance from differential thermal analysis, and the water absorption rate is 0.
．． 0% and the sintering temperature at which the bending strength was maximized was selected. Regarding the presence or absence of warpage deformation, after sintering the substrate,
The external shape was visually observed, and it was judged that the substrate surface had irregularities 157, warped undulations, and large deformations were not suitable for practical use.

181. For reference, Table 2 shows the conventional material 96% Al2O3.
shows the characteristics of

Table 2 As shown in Tables 1 and 2 and as described above, the composition according to the present invention can be fired at a low temperature of 870 to 980°C, and moreover fully exhibits its characteristics as a ceramic substrate for forming electronic circuits. Its properties are comparable to the conventional material 96% Al2O.
It is better than 3.

19'.--Effects of the Invention As is clear from the above explanation, by using the material of the present invention, low melting point metals Ag, Au, and Pd can be produced.

It is possible to use a single substance such as PT or an alloy thereof, and since these metals easily oxidize even in the air, a reducing atmosphere is unnecessary, and the resistance value of Au and Ag is smaller than that of W and Mo. Therefore, low-temperature firing in air reduces equipment costs and makes handling easier.

Furthermore, since the ceramic multilayer substrate of the present invention has a variation in firing shrinkage rate of less than ±1.0%, the yield is high and mass productivity is good.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing the manufacturing process of a multilayer board by the printed multilayer method on a ceramic sintered body, Figure 2 is a flowchart showing the manufacturing process of the multilayer board by the printed multilayer method on a green sheet, and Figure 3 is a flowchart showing the manufacturing process of a multilayer board by the printed multilayer method on a green sheet. 2 is a flowchart showing a process for manufacturing a multilayer board using a green sheet lamination multilayer method. Figure 1 Figure 2

Claims (1)

[Claims] In terms of oxide, at least one of: 25 to 55% by weight of SiO, 0.1 to 30% by weight of PbO, Li_2O, Na_2O, and K_2O
A dielectric material having a composition of 0.01 to 10% by weight of seeds, 0.05 to 25% by weight of at least one of MgO, CaO, ZnO, and BaO, and 15 to 65% by weight of at least one of Al_2O_3, ZrO_2, and TiO_2. A ceramic multilayer substrate with an insulating layer formed from a composition.