JPS6028790B2 - Metallization method for high alumina ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a co-firing method for simultaneously sintering and metallizing a metallizing ink with alumina green tape, particularly a method for forming metallization having high metallization strength on high alumina ceramics. It depends.

More particularly, the present invention relates to a method of manufacturing an integrated circuit board having particularly high insulation resistance, heat dissipation properties, and high packaging density. In general, methods for metallizing ceramics include the ``Telefunken method,'' in which a metallization base mainly composed of Mo-Mn is phosphorized on a pre-sintered ceramic substrate in wet hydrogen gas, and the It is made of an alloy of Ti or Zr, Ni, Cu, Ag, etc., and a relatively low melting point metal.

There was an ``active metallization method'' in which ceramics were soldered directly using corrugated wood. However, although these techniques are effective when manufacturing a single-layer ceramic substrate, they cannot be applied to a case where a complex electronic circuit board in which multi-layer ceramic substrates are laminated is required.

In this case, a flexible ceramic tape (green tape) made by mixing ceramic powder and organic resin is pre-metalized, and then multiple layers are laminated.
By pressing, the green tapes can be bonded to each other by the organic resin contained therein and can be integrated. The laminated ceramic-organic resin laminate is fired, and at this time, the ceramic and the metallization coated on the inside and surface of the ceramic are simultaneously sintered (hereinafter referred to as "simultaneous sintering method"). Among these methods, the known methods for metallizing high alumina ceramics of 90-94%A and 203 for use in integrated circuit boards include CaO, Mg○
, Si02 and other mineralizers, Ti02, Mo or MO03,
After printing a desired pattern on a high alumina porcelain green tape containing colorants such as Fe203, Cr203, and Mn02 using a metallizing ink consisting mainly of No or W powder mixed with Si02 or Si02-containing frit, non-oxidized There is a method of sintering in an atmosphere at a temperature at which both sinter.
[Schwarez & Wilcox, The Buddha's Cape
dCeramics〃)) Due to the recent rapid development of the electronics industry, it has higher insulation resistance and heat dissipation than before,
There is a need for higher packaging density.

In order to increase the packaging density, substrates with particularly excellent surface smoothness have become required for mounting thin film elements. Such a substrate can be made by reducing the magnetizing agent of alumina porcelain as much as possible and increasing the alumina content to 9% by weight or more. Regarding the improvement of heat dissipation, A2039
9% ceramics have about twice the heat dissipation property as ceramics with a purity of about 90%, and are therefore suitable for mounting high-density elements. However, when this is subjected to a known metallization treatment, the adhesion of the metallization to the alumina is weak, and furthermore, metallization cannot be performed by the metallization method using simultaneous firing as disclosed in the present invention. That is, the conventional 90-94
% of high alumina porcelain, M is blended as a locking agent.
g○, Ca0, SiQ and metallization react to form a strong metallized surface.

However, when the alumina content in the substrate reaches 99% or more, the keying agent, which is originally the main reaction partner with the metallization, becomes extremely concentrated, which inhibits the reaction with the metallization of the substrate, making it difficult to use conventional metallization. A strong metallization cannot be obtained by the method. Conversely, if a large amount of mineralizing agent is contained in the subordinate metallizing sink, the potting agent in the metallizing will be rapidly diffused and absorbed into the porcelain substrate during the firing process, making it impossible to obtain strong metallizing strength. It also became clear.

On the other hand, the ``Telefunken method'' is also known, which is a method in which metallizing ink is applied and sintered after the individual firing of an alumina porcelain substrate, and then recombined (Klaes 1 Helgeson, ``Study of the bonding mechanism between metals and ceramics'' [ CIae
s I Helgesson, Investigat
ion of the Bonding Mechanism
ism techniques tweenMe Tsumugi sand Ceramics]
).

However, in this case, the small warpage of the board that inevitably occurs,
The distortion reduces the accuracy of the circuit pattern created by the metallized ink. Furthermore, this not only lowers the packaging density but also requires firing twice, resulting in coarser crystal grains of the ceramic and deterioration of surface smoothness. In addition, this method also makes multilayering difficult and is disadvantageous from the viewpoint of packaging density. Another method to obtain only surface smoothness is to apply a glaze to the ceramic substrate, but this method has poor heat dissipation properties and causes extremely high electrical loss in the gigahertz-level ultra-high frequency range, making it unusable. The present invention aims to overcome the above-mentioned drawbacks of the conventional method and provides metallization formation by co-firing on high alumina porcelain with good heat dissipation, surface smoothness, and high insulation resistance.

That is, the metallization method for high alumina ceramics of the present invention uses A-203 with a purity of 99.5% by weight or more and adds an organic binder to the raw material powder of high alumina ceramics containing 99% by weight or more of alumina. In addition, the surface of the produced alumina green tape was coated with 0.1 to 25% by weight of A-203, mainly composed of Mo and/or W, and Ti.
, Ta, Y, or one or more of these compounds as metal components in a total amount of 0.1 to 2% by weight based on the total inorganic matter. After printing a desired pattern, the temperature is 1450 to 170 p The method is characterized in that metallization is formed together with alumina ceramics in a hydrogen atmosphere containing water vapor. The present invention will be explained in detail below.
In the present invention, unlike the raw material alumina with a purity of 98 to 99% that is used as a raw material for manufacturing an alumina ceramic substrate that accounts for about 90% of the conventional alumina, high-purity high alumina with a purity of 99.5% by weight (the same applies hereinafter) is used. Use. The alumina fine powder used is A20399, which does not contain any impurities, in order to obtain the effect of adding a brooding agent such as M mosquito, Si02, Ca0.
．． It is necessary to use alumina with a purity of 5% or more. In addition, by setting the composition of the substrate to A20399% or more, both thermal conductivity and surface smoothness can be kept good.

That is, as the A-203 component increases, the thermal conductivity improves, but this is because the amount of mineralizing agent decreases, and the grain boundaries containing glass with low thermal conductivity decrease. - It was observed that the number of 203 crystals increased. The reason why the smoothness improves as the A-203 component increases is that microcrystals of the QA-203 are mainly formed. The particle size of the alumina used is
For example, when a high surface smoothness is required, such as when providing a thin film circuit element, a particle size of 1 μm or less is preferable.
As a keying agent for the high alumina ceramic substrate, for example, a mixture of alkali metals such as Ca0 and Mg○ and Si02 can be used.

By adding these components in sufficient quantities, it is possible to promote sintering without deterioration of electrical properties, suppress grain growth of the A-203, and ensure a smooth surface. These mineralizers are added within a range where the aforementioned substrate raw material powder contains 99% or more of alumina. Other known mineralizing agents such as Cr203, Buddha203, Ta205, Fe203, Ca○, Y203, etc. can also be used. Further, within the range of the above alumina composition, a known alumina grain growth inhibitor such as Ni◯ or Mg◯ may be contained in a sufficient amount. Further, when the alumina content of the substrate is 99% or more, not only is the smoothness and thermal conductivity excellent, but also the strength of the applied metallization tends to increase. Next, for the above-mentioned reasons, metallization strength due to glassy formation by known mineralizers such as M, Si02, and Ca0 cannot be expected for the high alumina ceramic substrate of the present application.

In the present invention, the intermediate layer between metallization and ceramics is formed of a material other than glass. That is, Ti, Zr, Ta, Y
Alternatively, these compounds diffuse appropriately into the boundary between the alumina substrate and form a strong metallization. It was found that Ti dissolves in solid solution in alumina and forms an intermediate layer composed of Ti components at the boundary, and Zr, Ta, and Y also moderately diffuse into alumina and form a strong metallization at the boundary. It was done. That is, the above-mentioned crystallized metal component has a slow diffusion rate with respect to ASO2Q compared to Si02, and has an appropriate diffusion rate with respect to W, M
It was recognized that the time necessary for the dawning of o.
In particular, materials to which Ta is added are a little weaker than Ti in terms of strength, but are advantageous in terms of production because they allow a particularly wide range of firing conditions. These additive metals or compounds thereof can be used alone or in combination of two or more, and in either case, the total content is 0.1 to 20% of the total inorganic substances in terms of metal components.

If it is less than 0.1% or more than 20%, the metallization strength will be insufficient, and if it exceeds 20%, the surface insulation resistance will decrease due to a diffusion phenomenon.

It was also confirmed that the alumina content is effective in preventing microcracks at the boundary between the ceramic substrate surface and the metallized surface due to the difference in shrinkage rate that appears when metallized and ceramic are fired simultaneously.

Even if these microcracks are small defects, they have a large effect on the mechanical strength of the metallization, and unless they are prevented, sufficient strength cannot be obtained. however,
In the present invention, the metallization strength is still high even with the addition of 0.1% A and 2Q, but this is due to the above-mentioned Tj, Ta, Y
or by addition of these compounds. However, in this case, it is necessary to follow predetermined narrow firing conditions that do not cause microcracks. In other words, the addition of A203 helps prevent microcracks and, in turn, greatly expands the range of firing conditions. Furthermore, the addition of A No. 3 suppresses the abnormal diffusion of Ti, Ta, and Y in the metallization into the ceramic, making it possible to maintain the strength of the metallization stably and without variation. As disclosed in the examples, the content of AI203 is 0.1 to 25% of the total amount of all metallized metal components.
It is.

The metallization strength is generally about 5 to 2030.1%.
It shows an increasing tendency up to 10%, and shows a decreasing tendency as it increases beyond that, but it naturally depends on the composition of the added metal component.
When the content of A203 is 30%, the metallization strength decreases and the specific resistance increases, which is no longer preferable. Ti, Zr,
Ta or Y is one of these compounds, i.e. oxide, hydride,
It can also be used as carbide, nitride, etc.

The oxide diffuses into the alumina porcelain to form a sufficiently strong metallization. Hydride has gas partial pressure ratio PH2/PH20
In a humidified hydrogen atmosphere in the range of 30-300℃, it becomes an oxide by the time the firing temperature reaches a high temperature. Similarly to oxides, carbides and nitrides also change to oxides during firing, making it possible to form a sufficiently strong metallization on the same machine. Form. For example, it was confirmed by X-ray diffraction that these compounds had become oxides after being calcined at 1500qOPH2/PH2060 for 1 hour. It was also confirmed that when a single metal is added, it turns into a metal oxide in the same way. However, when such a compound is used as the above-mentioned finalizing metal, it is added as a metal equivalent component. The content herein refers to the content in all the inorganic components in the metallized base. Regarding the firing conditions, the sintering range of the substrate alumina porcelain is 1450 ~
Gas partial pressure ratio PH2/PH2030-300 in hydrogen atmosphere containing water vapor for about 1 hour at 1700oo
It needs to be fired. Gas partial pressure ratio PH2/P ratio ○ is 3
When the thickness is 0, grain growth of alumina porcelain occurs and the surface smoothness deteriorates. At the same time, Ti, Zr, Ta,
Evaporation of Y increases significantly and scatters into these atmospheres and into the alumina substrate, deteriorating metallization strength. P
When H2/PH20 exceeds 300, the metal additive of the metallization component evaporates and the metal adheres to the substrate surface, resulting in a decrease in insulation resistance. High insulation resistance and surface smoothness can be obtained with a P string/P ratio of 030 to 300, preferably PH2/PH
It is 2040-240. For the sake of convenience, the present invention has so far described a method of applying metallization on a single layer of ceramic green tape. It is also possible to manufacture a laminated board by connecting the circuit patterns of each layer with through holes as necessary.

Since the present invention enables simultaneous firing, it is particularly suitable for manufacturing laminated substrates. The lamination process can be performed by a known method, preferably by pressure bonding in a direction perpendicular to the layer surfaces. Furthermore, the metallization according to the present invention can also be applied to through holes. The present invention thus provides a method of manufacturing a laminated integrated circuit board. Examples will be described below. Example 1 M or M with an average particle size of 0.5 mm was used as a locking agent for 100% powder of Q-A 203 (weight ratio, the same applies hereinafter) with a purity of 99.8% and an average particle size of 0.8 mm. , Ca0, Si02 at 1:1
: 0.5% of the mixture of 1 was added to prepare a raw material powder.

Butyral resin was added to this raw material powder together with trichlorethylene to form a slurry, and a tape with a thickness of 1 rib was produced using the doctor blade method and cut into a rectangular shape measuring 5 m x 4 m to form a green tape substrate. On this main surface, W or Mo with an average particle diameter of 1.3 mounds was blended with Aso203 in the proportions shown in Table 1, and further Ti or T
Contain 3% of compound i (oxide) as a subcomponent.
The metallized base obtained by adding an organic binder and a solvent to this and kneading it was printed with a thickness of 20 mm on a 2 side x 2 side metallized strength measurement pattern using a screen printing method, and this was printed in a hydrogen atmosphere and with a gas content. Pressure ratio PH2/PH20
The green tape substrate is sintered and the surface of the metallized base is sintered to form a metallized surface. Various properties of the sample thus obtained were measured, and the results are shown in Table 1. This example mainly shows the effect of the content of A-203. Microcracks that tend to occur at the boundary between the metallized surface and the free image of the ceramic substrate were not observed in this example. As is clear from Table 1, A-2
There is an intensity peak around 5% between 030.1 and 20%. The surface insulation resistance is 2×1 and 40 to 1×1 and 30, which is much higher than that of the control example with the Si02 subcomponent (on the order of 1 and IQ). It should be noted that when the A thickness reaches 20330%, the metallization strength decreases and the metallization specific resistance also increases (outside the range). The tendency is almost the same for both W and Mo. When W and Mo are used in combination, the metallization strength is lower than when each is used alone, but the overall effect is the same. Example 2 Samples manufactured in the same manner as in Example 1 with A〆203 fixed at 5%, the value at which the metallization strength peaked in Example 1, and at the lowest value, 0.1%, were similarly prepared. The measured results are shown in Table 2.

Here, the quantitative effect of Ti is shown. At A〆2030.1% and 5%, each characteristic value with respect to the quantitative change of Ti shows the same tendency. The upper limit of Ti is about 20%, the lower limit is about 0.1
It's in %. Also, 5% for A and 2030.1%.
% generally shows a more stable value. Here A evening 20
3 is because titanium diffused into the alumina ceramic suppresses abnormal grain growth of ceramic grains, and as a result, the occurrence of heterogeneity due to abnormal grain growth, which is one of the causes of microcracks, is also suppressed. Those containing A〆203 have the effect of reducing the grain size of abnormal grain growth in the ceramic by about 20% and making the abnormal grain growth layer thinner, thereby suppressing microcracks. In addition, when A-203 is added at about 5%, compared to 0.1%, it has the effect of further reducing the grain size in the abnormal grain growth area and making the abnormal grain growth layer even thinner, so no microcracks occur. Not yet. Example 3 The subcomponent of metallization was replaced with Ti and Ta was used in Example 1.
Samples were prepared and tested in the same manner as above, and the results are shown in Table 3.

Ta exhibited properties almost similar to Ti. Example 4 Table 4 shows the test results for a sample obtained in the same manner as in Example 1 except that Ti as a metallization subcomponent was replaced with Y.

Although it is low (compared to Ti and Ta), YO. 1-20
%, A-203 showed stable values in the range of 0.1 to 25%. Example 5 In place of the subcomponent Ti in Example 1, Ti, Ta, Z
Used as a combination of two of the four components r and Y,
Other measurements are shown in Tables 5 to 7 for samples obtained using the same machine as in Example 1.

Although the metallization strength of each combination was slightly lower than that of one component alone as a subcomponent, it was shown to be effective within a total range of 0.1 to 20%. In addition, A〆203 was also shown to be effective in the range of 0.1 to 25% for the combination of these subcomponents as well as when each subcomponent was used alone. Example 6 Samples obtained in the same manner as in Example 1 except that two and three combinations of Ti, Ta, and Y were used as subcomponents were measured, and the results are shown in Tables 8 to 10. show.

In this case as well, the total of the above three types of subcomponents is 0.1 to 20%
It was shown that it is effective when A-Soyu 3 also showed effects in the range of 0.1 to 25% for these combinations. In Examples 1 to 6, there was a slight difference between W and Mo, and when W and Mo were mixed in a 1:1 ratio, the value was almost the same as when they were used alone.

In the above Examples 1 to 7, the metals Ti, Ta, and Y were added as simple substances, but the present invention further provides for the addition of oxides of these metals within the same total content range in terms of metals. , it was found that almost the same results were produced.

Examples are shown below. Example 7 Table 11 shows the measurement results for a sample obtained in the same manner as in Example 1, except that Ti in Example 1 was replaced with Ti02 and the amount added was expressed as metal.

As is clear from the results, even in the case of oxide addition,
Metal fusuma table 1 note *Surface insulation resistance Green tape.

The substrate was cut into a rectangle of 50 pieces x 40 pieces, and a pair of belt-shaped metallized layers of length 30 pieces x 3 pieces in length x about 20 pieces thick were printed and phosphorized in parallel at a spacing of 25 pieces on the main surface. The insulation resistance between the pair of metallizations was measured using a 250V supermeter. *Specific resistance The specific resistance of both end faces of the above band-shaped metallized surface was measured using a bridge. *Menurise strength measurement test After applying Ni plating to a thickness of 3 to 5 mm on the metallized surface of the square menurise strength measurement pattern, the end of the Kovar ribbon was cut into a size of 1.8 side x 1.8 inch. Silver.
The solder was applied with tension in a direction perpendicular to the waxed surface, and the load at the time of peeling was measured. Table 2 Table 3 Table 4 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table 10 Table 11 Table 13 There is virtually no significant difference from the case where the same amount of metal alone is added.

This was also confirmed when the subcomponents were added as nitrides, hydrides, and carbides, but theoretically, under the firing conditions of the present invention, for example, these metal nitrides
The fact that it ultimately takes the form of an oxide is supported by its Frienersky value (see "Electrochemistry Handbook Ichimaruzen,""Phase Equilibrium of Oxides in Iron and Steel Manufacturing" by A. Muan,
Co-authored by E.F. Osborne, translated by Shigeyuki Sokan, pages 9-10). The same applies to other carbides and hydrides. In addition,
Items 5 to 1 have also been described where Zr is included, but in the present invention, Zr can also be used in combination with Ti, Ta, and Y. Control Example 1 Table 13 shows the results of measurements on a sample obtained in the same manner as in Example 1 using only Si02 as a known subcomponent of metallization.

Claims (1)

[Scope of Claims] 1. The surface of an alumina green tape manufactured by using alumina with a purity of 99.5% by weight or more and adding an organic binder to a raw material powder of high alumina ceramics containing 99% by weight or more of alumina. , mainly composed of Mo and/or W, and Al_2O_30.1 to 25% by weight, and Ti,
After printing a desired pattern with a metallizing ink containing 0.1 to 20% by weight of one or more of Ta, Y, or one or more of these compounds as a metal component in total inorganic matter, the temperature is 1.
A method for metallizing high alumina ceramics, characterized by sintering metallization together with alumina ceramics at 450 to 1700°C in a hydrogen atmosphere containing water vapor. 2. Metallization of high alumina ceramics according to claim 1, characterized in that one or more of oxides, hydrides, nitrides, or carbides of these metals is used as the compound of Ti, Ta, and Y. Law. 3 Mo and/or W are added to the surface of alumina green tape produced by adding an organic binder to the raw material powder of high alumina ceramics containing 99% by weight or more of alumina using alumina with a purity of 99.5% by weight or more. Mainly contains Al_2O_30.1 to 25% by weight, and Ti, T
After printing a desired pattern with a metallizing ink containing a total of 0.2 to 20% by weight of one or more components of a, Y, or these compounds in total inorganic substances as a metal component, the printed substrates are laminated. A method for metallizing high alumina ceramics, which comprises press-bonding and sintering the metallization together with alumina ceramics at a temperature of 1450 to 1700° C. in a hydrogen atmosphere containing water vapor. 4. Metallization of high alumina ceramics according to claim 3, wherein one or more of oxides, hydrides, nitrides, or carbides of these metals is used as the compound of Ti, Ta, and Y. Law.