JPS63283193A - Multilayer interconnection board - Google Patents

Abstract

PURPOSE:To improve solder wettability by using glass ceramics mixed with specific chromate as an insulator. CONSTITUTION:Glass ceramics in which small quantity of chromate of chemical formula MCrO4, where M is bivalent metal element is mixed with glass containing as filler crystallized glass or crystalline substance are used as an insulating layer. When the layer and a thick film conductor are associated to form a multilayer interconnection board, solder wettability is remarkably improved.

Description

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

(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.

Thick film multilayer wiring boards are made of ceramic substrates such as alumina.
First, wiring is formed by printing and firing a thick film conductor paste such as Au, Ag/Pd, etc. On top of the wiring, an insulating paste made of glass with a filler such as crystallized glass or heat-resistant oxide is printed and fired. The process of forming a glass-ceramic layer and then forming a conductor thereon is repeated.

On the other hand, glass-ceramic multilayer wiring boards are manufactured by manufacturing a green sheet using a doctor blade method or the like using the same material as the insulating layer of a thick film multilayer wiring board, and printing a thick film conductor paste on this sheet. It is manufactured by stacking them and firing them for - times. The firing temperature for both is 800-1,
000℃.

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 often seriously impairs solder wettability, and only materials with very limited compositions can be used. , 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 various glass ceramics and thick film conductors.

(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, and the solder wettability was investigated when Ag/Pd-based conductors were used. Ta. As a result, it was found that additives consisting of Cr20h and divalent metal element chromate (M Cr O4) significantly improved the solder wettability of conductors even in small amounts.
r2O, cannot be used because it lowers the insulation properties of the glass ceramic. As MCrOa, heat-resistant Ca
ZrO3+ S r Cr 04. B a Cr
O,, P b Cr Oa.

CoCrO4 and Cu　Cr　O4 can be used.

CuCr0a releases oxygen at about 400℃ and becomes CuCr2.
Although it becomes O4, its effect on improving solder wettability is similar to that of other chromates, and it can also be expected to have an effect of aiding the combustion of organic matter through the released oxygen.

Many of these heat-resistant chromates are easily available as inorganic pigments. In this case, it may be a mixture of P b Cr O4 and P b S Oa, such as chrome yellow.

The glass-ceramic of the present invention includes crystallized glass (including filler-containing crystallized glass) or amorphous glass, Al,
Any mixture of fillers such as O. Further, the type of thick film conductor generally does not matter 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.

CaZr0. When mixed with glass and fired, it becomes Ca. ,
Is Z r O, sso 1. It changes into so-called stabilized zirconia with an Is crystal structure. This change is related to the viscosity of the glass, and the softening temperature of the glass (viscosity is 10
7.6 poise) or above, for example, the softening temperature is 5
For glass with a softening temperature of 00°C, it starts to change at 650°C or higher, and for glass with a softening temperature of 780°C, it starts to change at 800°C or higher.

For crystalline glass, it is sufficient to mix chromate in an amount of 5% or less. On the other hand, in the case of adding filler to amorphous glass, for example, a mixture of 10% each of A 1 z O3 and stabilized zirconia containing 5 to 10% CaO will not become a conductor unless 5% or more of chromate is added. Although the solder did not wet the solder, when CaZr0z was mixed instead of the stabilized zirconia, the solder wetting was good even with the addition of 0.5% chromate. For these reasons, the filler for amorphous glass is CaZr0z or, if several types of fillers are used, at least one of them is C.
It is preferable to use aZrO3. Moreover, the amount of chromate added is effective when it is 0.5% or more in crystallized glass and amorphous glass containing caZro:+ as a filler. However, as the amount added increases, the dielectric loss of the insulating layer increases, and it is necessary to avoid adding more than 10%.

(Example) Examples will be described in detail below.

Example l CaO-Zn0-Tie, -Af, O, -3in.

It consists of B2O3, and when fired, it produces Ca A 1zS i,
o.

The chromates shown in Table 1 were added to the glass paste for crossover in which crystals of (anorthite) were precipitated in the proportions shown in the table, and the mixture was kneaded in a three-roll mill. These pastes were screen printed twice on a 96% alumina substrate in a pattern of 20 x 201 m, and then 80% Ag
, 20% Pd conductor paste was printed and simultaneously fired at 850°C. The conductor pattern is 5 w x 5 mm for solder wettability evaluation and 21 x 5 mm for adhesive strength measurement.
'l It's a dragon. Separately, a lower electrode is printed and fired on an alumina substrate using the above conductive paste, and after the above glass paste is printed and fired, it is printed one more time, and then 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.

As can be seen from the comparison with the comparative example in which no additives were mixed, the solder wettability was improved at 0.5% of any additive. The adhesive strength of the conductor is sufficiently high, and other characteristics are the same as those of 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 8i layer. Is possible.

Example 2 Thick film multilayer glass with thermal expansion close to that of alumina ceramics, weight ratio S i 0255.6%, Bffi
a: 14.8%, Ca07.5%, MgO2,5%,
PbO17% = A j! zO318.5%, N
A glass having a composition of 2.5% azo and 1.5% K2O was prepared. The softening temperature of the glass was 780°C, and the coefficient of thermal expansion was 72×10-'/''C (25-300°C).

As a filler to this glass /l! 203. Zr
40% by weight of one or more of CaO. It was dissolved in α-terpineol and dispersed in a prepared medium, and kneaded in a three-roll mill to prepare a glass paste.

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) If there are no additives, no matter what filler is used, a large amount of glass will stick out on the conductor surface and will not get wet with solder at all. It can be seen that when CaZrOs is mixed with the filler, the solder wettability is somewhat good even when the additive is added at 0.5%, and even in other cases, the solder wettability is improved when the additive is added at 2% or more.

Filler CaZr0:+ is Cao, tsZr after firing
It changes into stabilized zirconia: o, as o +, as. As a result of examining by X-ray diffraction, the rate of change in resin after firing at 850°C was approximately 60% when no additives were added.
Addition of 1% chromate resulted in more than 90% change. When using stabilized zirconia as a filler, add 2% of additives.
Since there is no effect unless added above, it seems that the change of CaZrO3 during firing has a synergistic effect with the additives. The adhesive strength of the conductor is almost constant regardless of the type of filler and the type and amount of additives, and shows a practical value.

The characteristics of the insulating layer are that the dielectric loss increases as the amount of additives increases (
Therefore, when the addition amount is 10%, the dielectric loss exceeds 1%. Furthermore, the insulation resistance tends to decrease as the amount of additive increases. Therefore, in this glass, it is desirable that the amount of chromium hydrochloric acid added be 10% or less.

Example 3 CaOAQz() + SiO2B tzos system,
Al□03 and C were added as fillers to glass-ceramic multilayer wiring glass with a thermal expansion coefficient of 55X10-'/''C.
A mixture of aZr0z and Aβ203 was added as an additive to 13
Add a Cr Oa and pbCrO, ・Pb5O*,
A glass paste was prepared in the same manner as in Example 2, and the solder wettability and adhesive strength of the conductor were examined in the same manner as in Example 1. The results are shown in Table 3.

(Left below) 3rd expression solder wettability: O good to slightly good, × defective filler is Al
In the case of only 2O3, if the additive content is less than 1%, the solder will not wet, but if CaZrO3 is mixed with the filler, the solder will not wet.
．． It can be seen that even at 5%, it becomes wet. The adhesive strength is a value that can be used for practical purposes.

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 parts can be soldered can be easily manufactured.

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

Claims (5)

[Claims] (1) Consisting of an insulating layer made of glass ceramic made of crystallized glass or glass containing a crystalline substance as a filler mixed with chromate having the chemical formula MCrO_4 (M is a divalent metal element), and a thick film conductor. A multilayer wiring board characterized by: (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, in which the insulating layer is a glass ceramic according to claim 1. Board. (3) In 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, the green sheet is defined in claims 1 and 2. A multilayer wiring board made of glass ceramic. (4) Chromate is CaCrO_4, SrcrO_4,
Claims 1 to 3 are a mixture of one or more selected from BaCrO_4, PbCrO_4, CoCrO_4, and CuCrO_4, the amount of which is 0.5 to 10% by weight. The multilayer wiring board described. (5) One type of glass filler is CaZrO_3
By firing, 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 _8_5.