JPS63283192A - Multilayer interconnection board - Google Patents

Abstract

PURPOSE:To remarkably improve solder wettability of a conductor by adding specific additive to glass ceramics to form an insulating layer. CONSTITUTION:Glass ceramics in which small quantity of composite oxide of crystal structure of copper chromite CuCr2O4 is mixed with amorphous glass containing as filler crystallized glass or crystalline substance are used as an insulating layer to form a multilayer interconnection substrate of the layer and a thick film conductor. The solder wettability of the conductor of the multilayer interconnection substrate is remarkably improved, thereby easily forming the multilayer interconnection substrate for the purpose of reducing the size and increasing the density of an electronic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multilayer wiring board, and more particularly to a thick film multilayer wiring board for electronic circuits and a glass ceramic multilayer wiring board.

(Background of the Invention) In recent years, demands for miniaturization and higher density of electronic circuits have increased, and in addition to multilayer thick film circuits, development of multilayer wiring boards using glass ceramic green sheets is progressing.

A thick film multilayer wiring board is made of A on a ceramic substrate such as alumina.
On the wiring formed by printing and firing a thick film conductor paste such as u, Ag/Pd, etc., an insulating paste made of amorphous glass with filler such as crystallized glass or heat-resistant oxide is printed and fired. It is manufactured by repeatedly forming a glass ceramic layer and then forming a conductor thereon.

On the other hand, glass ceramic multilayer wiring boards are manufactured by manufacturing green sheets using the same material as the insulating layer of thick film multilayers using the doctor blade method, etc., printing thick film conductor paste on these sheets, and stacking them. - Manufactured by firing twice. The firing temperature for both is 800 to 1000°C.

All of these multilayer wiring boards have electronic components such as semiconductors and capacitors mounted on the wiring conductors on the surface by soldering, and are used as hybrid ICs or modules. Therefore, the surface conductor must have good solder wettability.

However, with the combination of conventional glass-ceramic materials and thick-film conductor materials, a glass film forms on the conductor surface, which significantly inhibits solder wettability, and only materials with a limited composition can be used. However, development in this field is slow.

(Object of the Invention) The present invention solves the above-mentioned problems and provides a multilayer wiring board in which good solder wettability can be obtained by combining a multilayer glass ceramic and a thick film conductor.

(Summary of the invention) In order to achieve the above object, various additives were added to the conventional thick film multilayer glass paste and newly created glass to improve the solder wettability when using Ag/Pd based conductors. Examined. As a result, Cr2o3 and CuO, Mn01Cr2
It has been found that an additive having a copper chromite (CuCr20.) crystal structure consisting of 03 can significantly improve the solder wettability of conductors even in small amounts, but Cr2o3 cannot be used because it lowers the insulation properties of glass ceramics. . Although we do not understand why such additives improve solder wettability, it is clear that a glass film is no longer formed on the conductor surface.

The glass-ceramic of the present invention can be applied to crystallized glass (including filler-containing crystallized glass) and amorphous glass.
O! , Zr0=, Sin, etc., and there are no particular limitations on the properties such as the thermal expansion coefficient and softening temperature of the glass. In addition, any type of thick film conductor is generally applicable as long as it can be soldered.

Furthermore, in the above experiment, it was found that when CaZrO3 was used as a filler added to the amorphous glass, the effect of the additive was particularly remarkable.

When Ca Z r O3 is mixed with glass and fired, Ca
. , +sZ r o, aso+, ms. This change is related to the viscosity of the glass, and the softening temperature of the glass (viscosity is 107
・Starts at a softening temperature of 6 poise) or higher, for example, a softening temperature of 500
For glass with a softening temperature of 780°C, it begins to change at 650°C or higher, and for glass with a softening temperature of 780°C, it begins to change at 800°C or higher.

For crystalline glass, it is sufficient to mix the additive in an amount of 5% or less. On the other hand, in a type of amorphous glass in which a filler is added, for example, if AffizCh and stabilized zirconia containing 7% CaO are mixed at 20% each, the solder will not wet the conductor unless 5% or more of double oxide is added. When CaZr0:+ was mixed instead of stabilized zirconia, the solder wetting was good even with the addition of 0.5%. For these reasons, it is preferable that the amorphous glass filler is CaZr0t, or if several types of fillers are used, one of them is CaZrO3. Further, the amount of the double oxide added is as follows: crystallized glass and CaZr0. 0 for amorphous glass with filler
．． It is effective at 5% or more. However, as the amount added increases, the dielectric loss of the insulating layer increases, so adding more than 10% must be avoided.

(Example) Examples will be described in detail below.

Example 1 Ca OZ n OT i Oz A lz O3S
i Consists of 203 OzB, and when fired, CaA
1 zS 1208 (anorthite) crystals are precipitated in the crossover glass paste, which has a copper chromite type crystal structure and is composed of CuO, Mn01Cr203. 5, 2, 5, 8, and 10%, respectively, were added and kneaded using a three-roll mill. These pastes were placed on a 96% alumina substrate in a 20 mm x 2 (hl
Screen print twice with the pattern, and then add Ag on top.
80% Pd and 20% Pd conductor paste printed at 850℃
Simultaneous firing was performed. The conductor pattern is 5** x 5 ms for solder wettability evaluation and 21 x 5 ms for adhesive strength measurement.
1X 2**. Separately, a lower electrode is printed and fired on an alumina substrate using the above conductive paste, the above glass paste is printed and fired, another printing is performed, and a conductive paste is printed on top of that and simultaneously fired. A capacitor was created using the same method, and the characteristics of the insulating layer were measured.

The firing temperature is 850°C. The results are shown in Table 1.

(Left below) Table 1: As you can see from the comparison with the comparative example where no additives are mixed, are the additives added? IO, 5-10% all have improved solder wettability. The adhesive strength of the conductor is sufficiently high, and other properties are the same as the comparative example except that the dielectric loss (tan δ) increases slightly as the amount of addition increases, making it possible to connect electronic components to the conductor on the insulating layer. It is.

Example 2 SiO□55.6% and 82034.8% by weight as thick film multilayer glass with thermal expansion close to that of alumina ceramic
, C: a07.5%, MgO2,5%, PbO17%.

A12031.8, 5% + NazO2, 5%, 2
A glass having a composition of 0.01.5% was prepared. The softening temperature of glass is 780℃, and the coefficient of thermal expansion is 72x 10-'/'c.
(25-300°C).

Add Al□Q to this glass as a filler 3. Z r
OlCa0o, +5Zro, ssO+, ss (Ca
Stabilized zirconia containing 7% O) and 1 of CaZr0z
40-50% by weight of the seed or two or more and the same additives as in Example 1 were mixed in various proportions, dispersed in a medium prepared by dissolving ethylcellulose in α-terpineol, and milled in a three-roll mill. A glass paste was prepared by kneading. Using these, the solder wettability of the conductor, adhesive strength, and characteristics of the insulating layer were investigated in the same manner as in Example 1. The results are shown in Table 2.

(Left below) Addition ■ If there is no item (1. 5. 7. 10. 14.
), a large amount of glass stands out on the conductor surface and it does not wet with solder at all.If CaZrO3 is not mixed as a filler, even if 2% of the additive is added, the solder wettability is not sufficient, but if CaZrO1 is present, , 0 additives
．． It can be seen that the effect appears even when 5% is added, and complete wetting is achieved when 1% is added.

When CaZr01 is used as a filler, Ca g
, +sZ r o, mso+, ms, but as a result of investigating by X-ray diffraction, when no additive was added, this rate of change was approximately 60% when fired at 850°C, but when 1% was added, the rate of change was approximately 90%. % or more changed. Cab from the beginning, 5Zr. ,
Since addition of 2% or more is also required when sso+ and ms are added (case 8.9), it seems that the change in CaZrO3 during firing has a synergistic effect with the additive. When only Ca Z r O3 is used as filler (
N114.15) causes peeling at the conductor ends, so it is necessary to add other fillers (eg A 12 z Os) to -II.

The adhesive strength of the conductor wet with solder is almost constant regardless of the type of filler and the amount of additive, and shows a value that can be used for practical purposes.

As for the characteristics of the insulating layer, the dielectric loss increases as the amount of the additive increases, and when the amount of the additive is 10%, the tan δ exceeds 1%. Furthermore, the insulation resistance tends to decrease as the amount of additive increases. Therefore, in this glass, the additive is 10
% or less.

Example 3 CaO-AI! zOz-31oz-B 1zo3 series,
40% Al2O2 was added as a filler to glass-ceramic multilayer wiring glass with a thermal expansion coefficient of 55xlO-'/°C to prepare a glass Z paste in the same manner as in Example 2. When I checked the solder wettability, it did not get wet at all. Al as a filler
Example 1 using t0320% and CaZr0s20%
When the paste was made by adding 1% of the same additive as above, the conductor was completely wetted by the solder.

Note that when this glass is fired with AltO3 added, Ca
AJ! It is a type that precipitates is 1sOs (anorthite) crystals.

In this example as well, there was no change in the properties of the insulating layer due to the addition of additives. It is easy to form a glass ceramic green sheet in the same manner as in this example, and a glass ceramic multilayer wiring board having a surface conductor to which electronic components can be connected by soldering can be easily manufactured.

(Effects of the Invention) As explained in detail above, the present invention adds a small amount of additives to crystallized glass or filler glass to improve the solder wetting of conductors in multilayer wiring boards using these glasses as insulating layers. Because it can significantly improve sex,
The effect of easily manufacturing a multilayer wiring board for the purpose of downsizing and increasing the density of electronic circuits is extremely large.

Claims (5)

[Claims] (1) Copper chromite (CuCr_2O_
4) A multilayer wiring board comprising an insulating layer made of glass ceramic mixed with a double oxide having the crystal structure of item 4) and a thick film conductor. (2) A thick film multilayer wiring board formed by alternately printing and firing a thick film conductor paste and an insulating paste on a ceramic substrate, wherein the insulating layer is a glass ceramic according to claim 1. . (3) A ceramic multilayer wiring board formed by printing a thick film conductor on a glass ceramic green sheet, laminating a plurality of sheets, and then firing the green sheet, wherein the green sheet is the glass according to claims 1 and 2. A multilayer wiring board made of ceramic. (4) The double oxide has a crystal structure of copper chromite (CuCr_2O_4) consisting of CuO, MnO and Cr_2O_3, and the content in the glass ceramic is 0.5 by weight.
The multilayer wiring board according to claims 1 to 3, wherein the content is 10%. (5) One type of filler in amorphous glass is CaZr
O_3, and Ca_0_. _1_5Zr
＿0＿． _8_5O_1_. 5. The multilayer wiring board according to claim 1, wherein the multilayer wiring board is made of stabilized zirconia having a crystal structure of _■_5.