DE69734577T2 - Manufacturing Method for a Metal-Ceramic Circuit Substrate - Google Patents

Description

The The invention relates to a method of manufacturing a metal-ceramic circuit substrate and more particularly to a method of making an improved one Metal-ceramic circuit substrate, wherein in a semiconductor element generated heat effectively dissipated from this can be.

Several Methods are known in the art for joining metal parts known with ceramic parts.

One typical example of this is the direct bonding method in which the metal part is direct is connected to the ceramic part.

One another example of this is the intermediate material process in which the metal part with the Ceramic part by insertion an intermediate material is connected between them.

When direct bonding method is a method in U.S. Patent 4,811,893 etc., in which a copper plate directly with an alumina substrate in the atmosphere a shielding gas is connected and heated and cooled.

When Intermediate material processes are an active metal process and a metallization process is known.

At the Active metal process becomes an intermediate material with an element from the fourth group of the periodic table, such as Ti or Zr, etc., or an alloy with this element between the metal part and the ceramic part inserted.

To the Example becomes for the case of connecting stainless steel and silicon nitride, uses an Ag-Cu-Ti based alloy as the intermediate material, and for the case of joining copper and alumina, an alloy used on a Cu-Ti basis as intermediate material.

In recently, However, time is high with the use of semiconductor elements electrical performance and high integration capability required in the electronic equipment with the semiconductor device according to the miniaturization this electronic equipment are mounted, and in the activated semiconductor elements amount of heat generated gets big.

In the US 4,860,939 discloses a method of directly bonding a copper foil to a substrate of electrically insulating material by heating the copper / substrate assembly to produce a eutectic. The method involves cleaning the copper to remove traces of oxidation on its surface before the copper is applied to the substrate, heating the copper / substrate ensemble under a neutral atmosphere to a temperature above the eutectic temperature and application a reactive oxidizing gas only after reaching the temperature above the temperature to form the eutectic, such that this temperature is reached prior to any oxidation of the surface of the copper.

In the JP 7162105 For example, a circuit board is disclosed in which a metal circuit is connected to a surface of a ceramic substrate, and a metal heat radiation plate is bonded to the other surface of the ceramic substrate. The occupancy ratio of voids present in the common layer, the diameter of which is 1 mm or more, makes up 0.3-3% of the volume of the entire common layer.

In the GB 2 099 742 For example, a ceramic substrate is disclosed which is bonded directly between two copper parts by attaching the substrate between the copper parts, and heating in an appropriate atmosphere. To avoid the formation of bubbles, channels and / or holes are provided in the substrate or copper parts to allow the gas to escape therefrom during bonding between the components.

In the US 5,672,848 For example, there is disclosed a ceramic board in which a copper board is directly bonded and heat-deposited at a predetermined position on a ceramic substrate, or the copper board is integrally joined by a brazing material containing an active metal such as Ti, Zr and Hf and becomes a semiconductor element at a semiconductor element mounting area of the copper board ver and the semiconductor element is integrally connected to a surface of a grooved or perforated side of the copper plate member by a soldering layer. With the above-mentioned structure, when the semiconductor element is soldered to the copper board, the ceramic board prevents soldering defects, thereby reducing the dispersion of the thermal resistance values between the semiconductor element and the ceramic substrate and reducing or weakening the heat load applied or applied to the mounting region of the semiconductor element.

A The object of the invention consists in the solution of the above-mentioned technical Problems.

A Another object of the invention is to obtain an improved Metal-ceramic circuit substrate, at a common surface between the circuit metal plate and the voids formed on the ceramic substrate are kept as small as possible so that the amount of heat generated in the semiconductor can be efficiently dissipated can, the heat radiation ability of the semiconductor is not diminished and the weight of the substrate is not elevated will, and that the thermal resistance of the substrate without change the pattern size and without Magnification of the area of the substrate can be reduced.

The Inventors led intensive studies through to solve the tasks mentioned, and found out that the heat generated in the semiconductor without Problems dissipated could be by the vacancy rate as well as the hole diameter on the common surface between the metal plate and the ceramic substrate.

The Invention has been achieved on the basis of this finding.

To A first aspect of the invention is a method of manufacture of a metal-ceramic circuit substrate according to claim 1.

In the invention, at least one specific part selected from Al ₂ O ₃ , AlN, BeO, SiC, Si ₃ N ₄ and ZrO _{2 is used} as the ceramic part and a part having high electrical conductivity such as copper, aluminum or the like, used as metal plate.

If Alumina substrate as a ceramic part in the present invention is used, then the surface waviness of the alumina substrate should be not more than 25 μm / 20 mm, measured with the surface roughness tester, because at a greater value the surface ripple the maximum diameter of the space and the number of spaces, wherein each space has a diameter of not less than 100 μm, thereby elevated is that the vacancy rate per unit area proportional to it elevated.

If further, an aluminum nitride substrate or a silicon carbide substrate etc. are used instead of an alumina substrate as a ceramic part is, then the ceramic part with a metal plate using a brazing material bonded to Ag-Cu based at least one active metal selected from Ti, Zr, Hf and Nb. In this case, the braze material becomes used and applied in paste form.

Around the brazing material in paste form, becomes an organic solvent such as. Terpineol, BCA, DBP, methyl cellosolve etc. or an organic Binder such as ethyl cellulose, etc. in an appropriate amount Mixed powder of the brazing material added.

A such brazing material paste is applied by screen printing on the ceramic substrate and the metal plate will over put the paste and then heat in the oven.

The Amount of binder, especially the amount of carbon contained in the binder, which is to be removed, according to the heating temperature and the Time varies.

The Blank studies were conducted by changing the temperature in the oven to 550 ° C, 600 ° C and 650 ° C performed.

The Investigations show that the voids with a large diameter occur at the binder removal temperature of 550 ° C, however, the Blanking diameter as the binder removal temperature increases smaller.

Also, when prolonging the heating time at a constant temperature to remove the carbon reduced in the binder, the diameter of the void and the vacancy rate per unit area.

The The foregoing and other objects, features and advantages of the invention will become apparent from the following specific description of preferred embodiments of the invention.

(Embodiment 1)

When Metal parts became a 0.3 mm copper plate for the circuit side and a 0.25 mm thick copper plate for the heat sink side made. Also, as the ceramic parts, alumina substrates having the dimensions 30 × 50 × 0.635 mm, each having a different surface ripple value.

One required metal-ceramic circuit substrate was made by contacting the copper plates with both major surfaces of the alumina substrate obtained as well as by heating and cooling in the atmosphere an inert gas to form a common part, and by etching the common part to form a predetermined circuit.

For each of these metal-ceramic circuit substrates, the maximum void diameter and the number and rate of vacancies were measured using the supersonic rupture detector (mi-scope-I) manufactured by Hitachi Kenki, Japan, with each void having a diameter of has not less than 100 μm per 15 cm ² formed on the common surface between the alumina substrate and the copper plate for the circuit side at an area where the semiconductor element such as the Si tip, etc. is fixed.

The Results are shown in Table 1.

at These measurements were supersonic crack detection conditions set so that the detected by the supersonic crack detection device Picture of the spaces corresponding to the blanking diameter, the by actual Observation of the cutting surface is received at the vacancy area.

Gemessen mit dem Überschall-Risserfassungsgerät, hergesellt von Hitachi Kenki (mi-Scope-I) TABLE 1 Blanking rate of the direct connection substrate

Measured with the supersonic crack detection device, made by Hitachi Kenki (mi-Scope-I)

In of this Table 1, Sample Nos. 1-5 are different from Sample No. 6 preferred.

(Embodiment 2)

When Metal parts became a 0.3 mm copper plate for the circuit side and a 0.25 mm thick copper plate for the heat sink side made.

Also were ceramic sheets nine films of Aluminiumnitridsubstraten with the dimensions 30 × 50 × 0.635 each screen-printed with the brazing paste material was exposed to Ag-Cu-Ti-based and dried.

The Aluminum nitride substrates were subjected to the debinding process, by changing the heating temperature or the holding time in the oven, to remove the carbon contained in the binder.

One required metal-ceramic circuit substrate was made by contacting of the copper plates having the upper and lower surfaces of the aluminum nitride substrate and by heating at a constant temperature of 850 ° C for formation a common part and by etching the common part to Formation of a predetermined circuit.

In each of these metal-ceramic circuit substrates, the maximum void diameter and the number and rate of voids were measured using the supersonic crack detection apparatus shown in Embodiment 1, each void having a diameter of not less than 100 μm per 15 cm ² formed on the common surface between the aluminum nitride substrate with the brazing material and the copper plate for the circuit side at an area where the semiconductor element such as the Si tip, etc. is mounted.

The Results are shown in Table 2.

Gemessen mit dem Überschall-Risserfassungsgerät, hergestellt von Hitachi Kenki (Mi-Scope-I) TABLE 2 Vacancy rate due to the active metal method

Measured with supersonic crack detection apparatus manufactured by Hitachi Kenki (Mi-Scope-I)

To The measurement involved electrical energy to the composite substrate the Si tip as on the circuit surface applied to the substrate mounted semiconductor element. It is determine that the vacancy rate is at a temperature of not less than 600 ° C substrate heated not more than 1.5% for at least two hours is similar to in the embodiment 1, and that the void diameter is smaller than 0.7 mm.

According to the metal-ceramic circuit substrate of the present invention For example, the vacancy rate on the common area can be controlled so that it is not more than 1.5%, and the void diameter such that it does not exceed 0.7 mm, even if the same materials for joint bonding be used, so that the circuit substrate with high thermal resistance and high economic value at low cost can.

While the Invention particularly shown with reference to its preferred embodiments and has been described is for the skilled artisan clearly that here various modifications with respect to the Form and details possible without departing from the spirit and scope of the invention as they are in the attached claims is defined.

Claims (3)

A method of manufacturing a metal-ceramic circuit substrate, comprising the steps of: bonding a metal plate having at least one main surface of a ceramic substrate selected from the group consisting of Al ₂ O ₃ , AlN, BeO, SiC, Si ₃ N ₄ and ZrO ₂ by a brazing material containing at least one active metal from a group of Ti, Zr, Hf and Nb, and heating the substrate to a temperature of not less than 600 ° C to remove the carbon in the binder so that the rate of vacancies occurring at least of a common area at a semiconductor mounting area of the metal plate per unit area is not more than 1.5%, the method being characterized in that the substrate is heated to a temperature not lower than 600 ° C for at least two hours to remove the carbon in the binder. A method of manufacturing a metal-ceramic circuit substrate according to claim 1, wherein the substrate is at a temperature of not less than 600 ° C heated for binder removal so that the vacancy rate in the substrate does not exceed 1.5% is and the diameter of the voids is not greater than 0.7 mm. A method of manufacturing a metal-ceramic circuit substrate according to claim 1, wherein the substrate is at a temperature of not less than 600 ° C heated for binder removal so that the vacancy rate in the substrate does not exceed 1.5% is and the diameter of the voids is not greater than 0.5 mm.