JPS6364399A - Ceramic multilayer board - Google Patents

Abstract

(57) [Abstract] 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 a low temperature.

BACKGROUND OF THE INVENTION 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 in 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).

(a) Multi-layer printing method on ceramic sintered body (b) Multi-layer printing method on green sheet (C) Multi-layer printing method on green sheet lamination multi-layer method (a) Multi-layer printing method on ceramic sintered body To explain the entire manufacturing method of the board, as shown in Fig. 1, first the first conductor layer is printed, dried, and fired on the ceramic sintered body that will become the board (steps 1 to 3), and then the first Complete insulating layer printing, drying, and baking Steps 4 to 6)
, then print and dry a K M 2 M edge layer (step 7.8), print and dry a second conductor layer (step 9, 1).
0), the second insulating layer is fired all at once (step 11).

At this time, the first and second resuscitation layers are printed so that micropores called guiaholes are formed, and the second
The @11 conductive layer and the second conductive layer are connected by printing the second conductive layer so that it is filled with the material used for the conductive layer. Next, a third insulating layer is printed, dried, and fired on the second conductor layer, and the layers are stacked in the same manner as after the second insulating layer (steps 1 to 11).

The method for manufacturing a multilayer board using the printing multilayer method on a green sheet (b) is as shown in Figure 2.
First, print and dry the first conductor layer on the ceramic green sheet that will become the substrate after firing (step 12.13), then print and dry the first insulating layer thereon (step 14).
15), Continue printing and drying the second conductive layer and second insulating layer (steps 16 to 19), repeat the same procedure for each layer from then on (steps 12 to 19), and print the green sheet, conductor layer, and insulating layer. ? - Batch firing (step 20).

As shown in FIG. 3, the method for producing a multilayer board using the green sheet lamination multilayer method (C) first involves forming micropores with different patterns in each of a plurality of ceramic green sheets in steps 22 to 24. ), printing and drying conductor layers with different patterns (steps 26 to 30). Next, a desired number of green sheets with different conductor patterns are stacked together (step 31), crimped together under appropriate pressure and temperature (step 32), cut into desired external dimensions, and fired (step 33). 3
4). Electrical conduction between each conductor layer is achieved by conductors filled in micropores in the green sheet.

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

Comparing the three types of manufacturing methods (a), (mon), and (c), (,) 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 calendars is larger than that, the surface becomes too uneven to be used in practical use. ■) The process can be streamlined by firing the green sheet, printed insulating layer, and conductive layer at the same time. However, in case of b), similarly to (a), if the total number of layers is increased, the surface unevenness becomes larger, so the limit number of layers is still 4 to 6 layers. (C)
The number of layers is theoretically possible to be infinite, and realistically it is 3o ~
A multilayer substrate with about 40 layers has been reported. However, their production requires extremely advanced technology, and there are many process and material issues.

Among the above three manufacturing methods (a), (b), and (C), the present invention relates to (C) the green sheet lamination multilayer method. Since the ceramic insulator used for this type (C) board is mainly composed of Al2O3, the sintering temperature is extremely high at 1,500 to 1,600°C, so the conductor material that makes up the circuit also deteriorates at such a sintering temperature. No W
, Mo, and other metals must be used. These W, Mo
Because it is easily oxidized, it must be fired in a reducing atmosphere, resulting in poor workability. In recent years, proposals have been made for new low-temperature sintering type ceramic multilayer substrates that solve the workability problems described above (Japanese Patent Application No. 103075/1983).
Patent Application No. 1982-236744, Patent Application No. 58-17651
No., special title No. 1987-108792, patent application No. 1987-176
A mixture of glass and alumina is used for the 9541 ceramic insulator, and the sintering temperature is lowered to below 1000°C.As a result, it is possible to use A9/Pd-based non-oxidizing low melting point metals for the internal conductor, which allows for a reducing atmosphere. Firing is no longer necessary.

The problem that the invention seeks to solve However, using the prior art techniques as mentioned above.

If the insulating material is simply a mixture of glass and alumina, or glass ceramics, and the one-way conductor is Ag or Pd alone, or an alloy or mixture thereof, the third
Even if you create a ceramic multilayer board according to the diagram, the 4th 4k
) As shown in +), after firing, there are some parts where the conductor 36 is built-in and some parts where it is not built-in. In addition, the above-mentioned publications include those characterized simply in that the sintering temperature of the glass ceramics is 1000°C or less, and those characterized in that the softening temperature Ts of the glass ceramics is 400°C≦Ts≦750°C. However, the necessary contents to be controlled in combination with the internal conductor were not proposed.

In view of the above problems, the present invention uses glass ceramics, which is a mixture of glass and alumina, as an insulating material, and as a conductive material, A, g, Pd alone or an alloy thereof,
The present invention uses a mixture of non-oxidizing low melting point metals and uses the above combination to provide a ceramic multilayer substrate that can be fired in air at low temperatures without causing substrate deformation during firing.

Means for Solving the Problems In order to solve the above problems, the ceramic multilayer substrate according to the first aspect of the present invention has a glass softening point Ts of the glass ceramic used for the insulator and an internal conductor Ag/Pd (composition 2 ( 100-x')Ag-xPd.

Qwt%≦x≦sowt%), TS≦Cx+3
0), +464jiC]. The ceramic multilayer substrate according to the second aspect of the present invention contains 5 to 10 weight parts of an inorganic material having a glass softening point equal to or higher than that of the substrate insulator as a conductor. Further, in the ceramic multilayer substrate according to the third invention, the content of conductive metal powder contained in the conductor is 55 to 7Q by weight.

Function The ceramic multilayer substrate of the present invention is made of a single substance or an alloy of glass ceramics, which is a mixture of glass and alumina, which can be fired at 1000° C. or lower, and Ag and Pd.

It is composed of a conductor made of a mixture and can be fired at a low temperature in air.

Furthermore, in the ceramic multilayer substrate of the present invention, there is no difference in the amount of dimensional change between the portion where the conductor is built in and the portion where the conductor is not, especially during firing, and no change in the substrate occurs at all.

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

FIG. 6 shows the shrinkage curve during firing of the multilayer substrate.

It is shown in FIGS. 6 and 7. First, as shown in FIG. 5, when the contraction start point of the conductor is at a lower temperature than that of the insulator, the insulator begins to contract to some extent at temperature T1 as shown in Pa1nt a. At this point the insulating material is in a softened state. On the other hand, the conductor at T1, like Po1nt b, is already shrinking more greatly, and the surrounding insulator is dragged by the large change in the conductor and shrinks.If the temperature rises further and reaches T2, The conductor has already completed its contraction as in Palnt c. On the other hand, the shrinkage of the insulator continues unchanged at Po1nt d. Since the conductor has already completely contracted in response to the movement of the insulator at the temperature T2, no dimensional change occurs in the part of the substrate in which the conductor is built. However, the part of the board that does not have a built-in conductor continues to shrink until the insulator completes shrinking at temperature T3, and as a result, the fourth
After firing in Figure (b), the substrate is deformed such that the conductor built-in portion becomes larger than the non-conductor built-in portion.

On the other hand, when the contraction start point of the insulator is at a lower temperature than that of the conductor as shown in FIG. 6, the conductor begins to contract somewhat at temperature T1 as shown in Po1ntf. At this point, the conductor is in a softened state. On the other hand, the insulator at T1 has already undergone significant contraction as shown in Pa1ntg, and the multiconductor is dragged along by this large change in the insulator and contracts. Since the amount of the insulator constituting the substrate is much larger than that of the conductor, the shrinkage of the substrate at temperature T1 progresses uniformly as a whole regardless of whether a conductor is built-in or not. The temperature further rises
2, the insulator, such as Pa1nt i , has already finished shrinking and solidified, so that the substrate as a whole does not shrink in response to a change in the conductor, such as Po1nt h . Therefore, the substrate deformation during firing as shown in the fourth case) does not occur.

Further, when the contraction start points of the conductor and the insulator coincide as shown in FIG. 7, the change in contraction of the conductor is the same, so no substrate deformation occurs.

When the conductor material is AglPd-based, the shrinkage start point of the conductor explained in FIGS. 6, 6, and 7 changes depending on the content of Ag and Pd. Pd ratio 0-30wt%
The relationship between the shrinkage start point of Ag/Pd paste in
As shown in the figure. Pd content of Ag/Pd paste is xwt%
Ag/Pd paste (100-x) Ag
-x The contraction start point of Pd is determined by the following formula in Figure 8: H(X+30) + 464 [℃]...
It has become clear that it is calculated by ・・・・・・・・・・・・■. Furthermore, the shrinkage start point of an insulator refers to the temperature at which diffusion and rearrangement of substances at the atomic and ion level between the inorganic powders constituting the insulating material occur, and from a macroscopic perspective, it is the glass softening point TS of the material. matches. Therefore, the condition under which the above-mentioned substrate deformation does not occur is that the glass softening point Ts of the insulator is the same as the shrinkage start point of the conductor, which is expressed by the equation 0, or is at a lower temperature.

Ts≦-(X+30) 2+464 mouth c]...
... River ■Next, by incorporating an inorganic material with a softening point equal to or higher than the softening point Ts of the insulator into the internal conductor, the contraction start point of the conductor is shifted to a higher temperature than the Ts of the insulating material during firing. deformation can be prevented. However, if the content of the above-mentioned inorganic material is less than 5% by weight in the conductor, there is no effect.

On the other hand, if the amount exceeds 10% by weight, the electrical resistance will increase and the function as a conductor will deteriorate.

Furthermore, the content of conductive metal in the internal conductor is 56~
Must be 70 weight class. When the content exceeds 70% by weight, the conductive metal powders in the conductor layer printed on the green sheet are very close to each other and there are many contact points between the conductor powders. If engineering energy is applied during firing in such a state, atoms and ions between the powders will diffuse more easily than usual, and as a result, the starting point of firing shrinkage will be the glass softening point Ts of the insulating material. ,! :! Sl also shifts to lower temperatures, causing substrate deformation during firing. If the content of the conductive metal is less than 55% by weight, the electrical resistance will increase and the conductor function will be poor.

Example (Example 1) Powder 10 prepared by mixing approximately 50 wt% each of B2O3-8iO2 glass with a particle size of 0.5 to 5 μm and Al2O3.
10 parts by weight of polyvinyl butyral, 6 parts by weight of dibutyl phthalate, 3 parts by weight of isopropyl alcohol per 0M part
9 parts by weight, 1-1-1 parts') Chloreta 720 heavy parts were added and mixed in a ball mill for 24 hours to prepare a slurry. This slurry was applied onto a polyester film using a doctor blade method, dried to form a green sheet with a thickness of 100 Jim, and sufficiently aged. Next, the green sheet is cut into a suitable size, and then Ag/Pd paste is formed on the green sheet by screen printing. After drying the paste, a plurality of the green sheets are stacked and pressed together at a temperature of 80° C. with a pressure of 200 AIA. Next, after cutting the outer shape, it was fired at 900° C. for 1 hour to obtain a multilayer substrate. The printed pattern used here is one in which the internal conductor is offset to one side of the molded body, as shown in FIG. 4(a). Furthermore, six types of insulating materials (A, B, C, D, and E) were used, and the glass softening points of each were as follows.

Material A -soo℃ z B -520℃ z C -550℃ y D -600℃ z E -650℃ The internal conductor is AglPd based with a Pd content of 0.10゜2
Four types of paste were used at 0.30% by weight.

The shrinkage starting points of the four types of pastes on the chamber side were as follows.

1100A -601℃9 0A g・10Pd -531℃8 0Ag-20Pd -568℃7 0A g・3oPd -614℃As shown in Fig. 9, the multilayer base made as above has an internal conductor 36 built-in. The in-plane shrinkage rate eE of the substrate 37 in the portion where the internal conductor 36 is not built-in is measured.

The degree of substrate deformation in each material combination was determined by calculating the shrinkage rate difference Δ1 (=lD−4E).

The results are shown in Table 1. From Table 1, if the glass softening point Ts of the insulating material is lower than the contraction start point of the internal conductor material,
Shrinkage difference Δ! was 0. In other words, no substrate deformation occurred. Therefore, when the Pd content of the Ag/Pd paste is set to X, the formula is 0.

Ts≦2. It was confirmed that (x + 30) + 464 holds true.

Table 1 (Example 2) Material C used in Example 1 as the insulator material (Ts = 650°
Q), soAgaloPd (
Yield starting point = 631°C) was used. The degree of deformation of the multilayer substrate was measured when the internal conductor material contained 0 to 20 wt% of the insulating material C. The manufacturing method and evaluation method of the substrate are the same as in Example 1. The results are shown in Table 2.

Table 2 From Table 2, when the internal conductor material (90Ag/1oPd) contained the insulating material C, the firing shrinkage difference Δl was 0 when the content was 5 wt% or more, and no substrate deformation occurred.

However, if the content exceeds 5 wt%, the conductor resistance value is 14 mΩ/; if the conductor resistance value is 15 wt%.

In the case of a 20wt unit, the resistance was extremely large at 21.5mΩ/mouth, making it unsuitable for practical use. Therefore, a content of 5 to 10 wt% was appropriate.

(Example 3) Material A used in Example 1 as an insulator material (T3 = 500°C
), Ag, Pd 1ooAg (firing shrinkage start point = 5o1°C) was used for the internal conductor. Create an internal conductor with a conductive metal content of 50 to 80 wt% in the internal conductor material,
A multilayer board using each internal conductor was produced and evaluated using the same method as in Example 1. Table 3 shows the results.

Table 3 From Table 3, the content of conductive metal powder in the internal conductor is Owt.
%, the firing shrinkage difference Δl is no longer 0 and deformation of the substrate occurs. However, if it is less than 55wt%,
The conductor resistance value increased, making it unsuitable for practical use. Content rate is 55
In the case of ~70 wt%, no substrate deformation occurred and the conductor resistance value was also good.

Effects of the Invention As described above, according to the present invention, a ceramic multilayer substrate that can be fired at 1000° C. in air can be easily produced without deformation.

[Brief explanation of the drawing]

Figure 1 is a flowchart showing the manufacturing process of a multilayer board using the printed multilayer method on a ceramic substrate, Figure 2 is a flowchart showing the manufacturing process of a multilayer board using the printed multilayer method on a green sheet, and Figure 3 is a green sheet. Flowchart showing the manufacturing process of a multilayer board by the multilayer method, Figure 4 shows the deformation of the board during firing, (a) is a schematic diagram showing the state before firing, ■) is a schematic diagram showing the state after firing, Figure 5. Figures 6 and 7 are graphs showing shrinkage curves of conductors and insulators, Figure 8 is a graph showing shrinkage start points depending on the composition of Ag/Pd paste, and Figure 9 is a multilayer substrate for measuring firing deformation. FIG. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Temperature A□ Figure 8

Claims (3)

[Claims] (1) In a ceramic multilayer board in which ceramic insulators and conductors are alternately stacked to form a plurality of layers, the ceramic insulator is a glass ceramic that is sintered at 1000°C or less, and the conductor is at least one of Ag and Pd. When the composition of the conductor is (100-x)Ag, x・Pd (where x is the weight% of Pd and 0≦x≦30), the glass softening point Ts of the glass ceramic is Ts≦1/24.
(x+30)^2+464 [°C]. (2) In a ceramic multilayer board in which ceramic insulators and conductors are alternately stacked to form multiple layers, the ceramic insulator is a glass ceramic that is sintered at 1000°C or less, and the glass softening point is similar to that of the ceramic insulator. A ceramic multilayer board characterized by using a conductor containing 6 to 10% by weight of an inorganic material equal to or greater than that. (3) In a ceramic multilayer board in which ceramic insulators and conductors are alternately stacked to form multiple layers, the ceramic insulators are glass ceramics that are sintered at 1000°C or less, and conductive metals, organic binders, organic solvents, etc. A ceramic multilayer substrate characterized in that the content of conductive metal in the conductor is 56 to 70% by weight.