TWI654914B - Method for improving adhesion of ceramic carrier board and thick film circuit - Google Patents

Abstract

The invention relates to a method for improving the adhesion between a ceramic carrier board and a thick film circuit, in particular to an environment in which a solid phase diffusion bonding is used to accelerate the generation of ceramic between a ceramic carrier and a metal circuit when the atmosphere is used in a positive pressure state. The method of metal eutectic phase mainly consists of a metal conductive paste or an oxide slurry thereof, which is printed on a surface of a ceramic carrier board by a thick film screen printing circuit, and then the carrier board is placed into a programmable circuit. The atmosphere is controlled in an atmosphere oven, and the ambient atmosphere condition is set to a positive pressure inert gas, including nitrogen, hydrogen or a nitrogen/hydrogen mixed gas. After high temperature eutectic conditions, a common relationship between the ceramic carrier and the metal circuit is generated. The crystal phase can improve the adhesion of the ceramic carrier to the thick film circuit.

Description

Method for improving adhesion of ceramic carrier board and thick film circuit

The present invention relates to a method for improving the adhesion of a ceramic carrier to a thick film of a metal, in particular, for a high-temperature eutectic condition, a solid-phase diffusion bonding is used to produce a ceramic-metal eutectic phase under a high-pressure eutectic atmosphere. Improve the adhesion of ceramic carrier and metal thick film circuits.

Ceramic heat sinks have been widely used in various electronic related fields such as LEDs and power modules. The thick film technology uses screen printing circuit on various types of carrier boards, and then is fixed on the ceramic surface by LTCC (low temperature co-fired multilayer ceramics) or HTCC (high temperature co-fired multilayer ceramics); as for direct bonding technology (Direct Bonded) Copper) mainly produces a eutectic phase of copper oxide in a copper metal circuit and a ceramic substrate at a eutectic temperature of an atmosphere, and the two are closely joined to improve the adhesion of the circuit.

At present, the bonding of the ceramic heat-dissipating substrate and the circuit includes a metallization process such as DBC, DPC (direct copper plating technology), LTCC, and HTCC. Although the DBC process has the advantages of high mechanical strength, it still needs to use the high-cost process technology such as yellow lithography and etching to remove the excess copper foil on the surface. DPC technology is also the same, and the thickness of the circuit is not limited due to the limitations of its own process conditions. The method is larger than 150μm, which has limitations for high-power applications; LCTT and HTCC are generally only suitable for the combination of copper circuit and alumina carrier plate due to physical conditions. If aluminum nitride with higher thermal conductivity is used, The sintering temperature is much larger than the melting point of metallic copper, and it is not easy to form a circuit pattern.

In order to improve the adhesion between the circuit and the carrier, the conventional screen printing circuit needs to use an interposer to balance the excessively large thermal expansion coefficient, thereby improving the circuit strength. However, due to the relationship between the interposers, the process must still be necessary. Consider etching or lithography and other related steps.

Therefore, there is a need in the industry for a method of efficiently increasing the adhesion between a ceramic carrier and a metal circuit, and reducing time and process costs.

It is an object of the present invention to provide a method of combining thick film screen printing with a ceramic-metal eutectic phase process, including a method of improving adhesion.

In view of the above-mentioned shortcomings of the prior art, the present invention develops a method for improving the adhesion of a metal circuit to a ceramic carrier, and reduces the time and process cost by the formation of a ceramic-metal eutectic layer.

In order to achieve the above object, according to the solution proposed by the present invention, a process for improving the adhesion of a ceramic-metal copper circuit is provided. In a first implementation, the method comprises providing a ceramic carrier board, wherein the surface containing the screen has been screen-printed The copper copper oxide circuit pattern generated by the membrane technology; the surface is dried in an oven to remove excess solvent in the metal copper oxide layer; placed in a high temperature furnace in an atmosphere, and simultaneously added to 40 kgf/cm ² or less The pressure in the vertical direction of the carrier; and the temperature of the high temperature furnace is set within ±10 ° C of the eutectic temperature of the metal copper and the ceramic carrier, so that a metal copper-ceramic eutectic layer is formed between the ceramic carrier and the metal copper.

In the above method, the method can generate a metal copper-ceramic eutectic layer between the metal copper and the ceramic carrier, and the eutectic layer is used to improve the adhesion between the metal copper circuit and the ceramic carrier, thereby avoiding differences in thermal expansion coefficients or It is the metal copper circuit that is easily caused by external force to peel off from the ceramic carrier; in addition, the pressure in the direction of the vertical carrier can improve the solid diffusion bonding efficiency, thereby helping the formation of the metal copper-ceramic eutectic layer.

The method of the invention comprises the steps of: (A) providing a carrier material of a ceramic material; (B) cleaning the ceramic carrier, and smoothing it through a polishing and grinding process; (C) metallic copper or metal Copper oxide is printed onto the surface of the ceramic carrier by screen printing technology to make the circuit pattern closely adhere to the surface of the ceramic carrier; (D) the ceramic carrier is placed in an oven to be lower than 105 ° C (E) placing the ceramic carrier in a high temperature furnace in an atmosphere, while applying a pressure of 40 kgf / cm ² or less and perpendicular to the direction of the carrier; (F) setting the temperature of the high temperature furnace in the metal copper and ceramic loading The eutectic temperature of the plate is within ±10 ° C, so that a metal copper-ceramic eutectic layer is formed between the ceramic carrier and the metal copper.

The above summary and the following detailed description and drawings are intended to further illustrate the manner, means and effects of the present invention in achieving its intended purpose. Other purposes and advantages of this creation will be explained in the following description and drawings.

1‧‧‧Heat fins

2‧‧‧thermal adhesive

3‧‧‧Ceramic carrier

4‧‧‧Metal circuits

5‧‧‧ solder layer

6‧‧‧Semiconductor components

7‧‧‧Metal copper-ceramic eutectic layer

S101-S106‧‧‧Steps

The first figure is a schematic cross-sectional view of the components of the first embodiment of the present invention.

The second figure is an enlarged explanatory view of the joint portion of the metal copper and the ceramic carrier in Fig. 1.

The third figure is a schematic flow chart of a method for improving the adhesion of a ceramic carrier board and a thick film circuit.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and effects of the present invention from the disclosure of the present disclosure.

The existing metallization circuit uses ceramics on the ceramic carrier board, and uses semiconductor processes such as lithography, yellow light, and etching. It is not only time-consuming and labor-intensive, but also costly; traditionally, thick film technology such as screen printing is used because of many raw materials. Different characteristics, resulting in compatibility problems, often cannot be a single process technology, and must be matched with composite materials or processes. The invention develops a method for improving the adhesion of a ceramic carrier board and a thick film circuit, which uses a eutectic condition between a metal copper and a ceramic carrier plate at a high temperature to produce a metal copper-ceramic eutectic layer at the interface. And simultaneously using the forward pressure perpendicular to the surface of the carrier plate to improve the formation efficiency of the metal copper-ceramic eutectic layer; the invention can improve the adhesion of the metal circuit on the ceramic carrier board by a process technology, without additional Material or process technology, and can be used to solve the thin film process applied to ceramic carrier gold The cost incurred in the process of chemical processing, and the problem that aluminum nitride and metallic copper cannot be co-fired.

Please refer to the first and second figures, which are cross-sectional views showing elements of an embodiment of the present invention.

Referring to the first figure, the semiconductor component 6 is fixed on the metal circuit 4 by the solder layer 5, and the metal circuit 4 is fixed on the ceramic carrier 3 by the method for improving the adhesion between the ceramic carrier and the thick film circuit of the present invention. The ceramic carrier is attached to the back plate of the heat dissipation fin 1 via the thermal conductive adhesive 2 .

Please refer to the second figure, using a pressure of 40kgf/cm ² or less and perpendicular to the direction of the ceramic carrier 3, and simultaneously setting the eutectic temperature of the metal copper-ceramic to the eutectic temperature of the metal copper-ceramic, and performing the solid phase diffusion bonding process to complete the metal copper- The formation of the ceramic eutectic layer 7 further enhances the adhesion of the ceramic carrier 3 and the thick film circuit 4.

Please refer to the second figure. This method is applicable to ceramic carrier plates including: aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), tantalum nitride (Si ₃ N ₄ ), tantalum carbide (SiC) or niobium oxynitride. (SiON).

Referring to the third figure, a flow chart of a method for improving the adhesion of a ceramic carrier to a thick film circuit is provided. As shown, the present invention provides a method for improving the adhesion of a ceramic carrier to a thick film circuit, the steps comprising: (A) providing a ceramic carrier 3 body of a ceramic material; (B) cleaning the ceramic carrier 3, and via Polishing and grinding process to make it smooth and smooth; (C) printing metal pattern or metal copper oxide to the surface of the ceramic carrier 3 via screen printing technology, so that the metal circuit 4 having the circuit pattern is closely attached On the surface of the ceramic carrier 3; (D) placing the ceramic carrier 3 in an oven and drying at less than 105 ° C; (E) placing the ceramic carrier 3 in a high temperature furnace in an atmosphere environment, Applying a pressure of 40 kgf/cm ² or less and perpendicular to the direction of the carrier; (F) setting the temperature of the high temperature furnace within ±10 ° C of the eutectic temperature of the metal copper and the ceramic carrier 3 so that the ceramic carrier 3 and the metal circuit 4 are The metal copper-ceramic eutectic layer 7 is produced; (G), after the temperature is lowered, the obtained ceramic carrier 3 can improve the adhesion to the metal circuit 4 by the metal copper-ceramic eutectic layer 7. The thickness of the obtained metal copper-ceramic eutectic layer can be 2 to 20 μm.

In the above, combined with the traditional screen printing circuit and eutectic layer process technology, combined with the forward pressure high temperature program, the sandwich interlayer pressure method is used to simultaneously reduce the metal oxide circuit and the eutectic layer to form a stable metal circuit. Solve time and cost waste on ceramic carrier boards while avoiding the use of ceramics with low thermal conductivity. In addition, the circuit metallization process of the conventional screen printing ceramic substrate is refined, and the two-step high temperature program is simplified into a program, which reduces the time cost and overcomes the problem of circuit peeling and the like. In addition, the ceramic material with high thermal conductivity is used to rapidly transfer the waste heat generated by the components, lower the working temperature and improve the life of the product.

The ceramic carrier 3 in this embodiment may be an aluminum-based ceramic carrier, taking aluminum nitride as an example. In the step (B) of the embodiment, the aluminum nitride ceramic carrier 3 is polished and polished, and the flatness is TTV. Less than 100μm, the flatness and roughness can be adjusted according to different requirements; in the step (C) of the embodiment, the metal copper or the metal copper oxide can be in the form of a slurry or a rubber compound, and is uniformly mixed with the polymer material. Wherein the metal copper or the metal copper oxide accounts for more than 90% of the total weight; in the step (D) of the embodiment, the drying temperature is set below 105 ° C, and the vaporization of the polymer material in the metal copper or metal copper oxide slurry is performed. The ceramic carrier 3 is completely bonded to the metal copper or the metal copper oxide; in the step (E) of the embodiment, the ceramic carrier 3 is placed in a high temperature furnace in an inert atmosphere, wherein the atmosphere may be nitrogen, containing less than 10%. Nitrogen gas of hydrogen or nitrogen gas containing ammonia of 30% or less; in the step (E) of the embodiment, the pressure applied may be a vertical force perpendicular to the direction of the carrier plate, or the internal pressure of the high temperature furnace may be increased to 40 kgf/cm. ² or less; set high in step (F) of Example The furnace temperature is within ±10 ° C of the eutectic temperature of the metal copper and the ceramic carrier 3 . The ceramic carrier material used in the embodiment is an aluminum nitride ceramic, and the eutectic temperature of the aluminum ceramic and the metal copper is 1065 ° C. The high temperature eutectic temperature set by the implementation force is within 1065 ° C ± 10 ° C, that is, the metal copper-ceramic eutectic layer 7 (AlN-Al ₂ O ₃ -Cu) is produced between the aluminum ceramic carrier 3 and the metal copper. ). After the steps of this embodiment are completed, a highly adherent metallized ceramic carrier can be obtained.

In summary, the present invention prints a metal or metal oxide onto a ceramic substrate, and when the metal oxide is subjected to high-temperature reduction, a solid eutectic phase interface can be formed by using a ceramic-metal eutectic temperature, and the positive force is matched. Pressurize, simultaneously complete the metallized ceramic carrier process and enhance the adhesion of the circuit, simplify the process, reduce the equipment and labor costs, and at the same time improve the heat transfer efficiency, so that the waste heat of high-power modules or 3C components can quickly cool down and extend the life of the components. And improve reliability. In addition, the present invention is based on the metal-ceramic eutectic theory and is combined with a forward pressure to produce a strong and strong eutectic interface at a metal-ceramic eutectic temperature (adding a small amount of O ₂ ) to overcome the difference in thermal expansion coefficient. Process problems. In addition, this method can reduce equipment and labor costs compared to DBC or DPC, which requires high-heat-conducting aluminum nitride ceramics. Plate material (and LCTT and HTCC must be alumina).

The above-described embodiments are merely illustrative of the features and functions of the present invention and are not intended to limit the scope of the technical content of the present invention. Any person skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the creation. Therefore, the scope of protection of this creation should be as listed in the scope of the patent application described later.

Claims (10)

A method for improving the adhesion of a ceramic carrier to a thick film circuit, the steps comprising: (A) providing a ceramic carrier body of a ceramic material; (B) cleaning the ceramic carrier and smoothing it through a polishing and grinding process Smooth (C) printing a metal pattern or a metal copper oxide onto the surface of the ceramic carrier via a screen printing technique that does not require an interposer, so that a metal circuit is closely attached to the ceramic carrier (D) placing the ceramic carrier in an oven for drying; (E) placing the ceramic carrier in a high temperature furnace in an atmosphere environment while applying a vertical direction of the carrier; (F) setting a high temperature furnace temperature is within ±10 ° C of the eutectic temperature of the metal copper and the ceramic carrier, such that a metal copper-ceramic eutectic layer is formed between the ceramic carrier and the metal circuit; (G) after cooling, The resulting ceramic carrier plate utilizes the metallic copper-ceramic eutectic layer to improve adhesion to the metal circuit. The method for improving the adhesion of a ceramic carrier and a thick film circuit according to the first aspect of the invention, wherein the ceramic carrier comprises aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), tantalum nitride ( Si ₃ N ₄ ), niobium carbide (SiC) or niobium oxynitride (SiON). The method for improving the adhesion between a ceramic carrier and a thick film circuit according to the first aspect of the patent application, wherein the ceramic carrier has a flatness TTV (Total Thickness Variation) of less than 100 μm after the polishing process, according to different requirements. Adjustment of flatness and roughness. The method for improving the adhesion of a ceramic carrier board and a thick film circuit as described in claim 1, wherein the metal copper or the metal copper oxide is in the form of a slurry or a compound, and a polymer The material is uniformly mixed, wherein the metallic copper or the metallic copper oxide accounts for more than 90% of the total weight. The method for improving the adhesion of a ceramic carrier board and a thick film circuit as described in claim 4, wherein in the step (D), the slurry or the vaporization of the polymer material in the compound is performed, The ceramic carrier is completely bonded to the metal circuit. The method for improving the adhesion between a ceramic carrier and a thick film circuit as described in claim 1, wherein the atmosphere is nitrogen, nitrogen containing 10% or less of hydrogen, or nitrogen containing 30% or less of ammonia. The method for improving the adhesion between a ceramic carrier and a thick film circuit as described in claim 1, wherein the pressure applied in the high temperature furnace adopts a positive force perpendicular to the direction of the carrier or increases the inside of the furnace. The gas pressure is up to 40 kgf/cm ² or less. The method for improving the adhesion of a ceramic carrier board and a thick film circuit according to the first aspect of the patent application, wherein the ceramic carrier board is an aluminum ceramic carrier board, The temperature of the high temperature furnace is within a eutectic temperature of the metal copper and the aluminum ceramic carrier plate of 1065 ° C ± 10 ° C. The method for improving the adhesion between a ceramic carrier and a thick film circuit as described in claim 8 wherein the metal copper-ceramic eutectic layer is AlN-Al ₂ O ₃ -Cu. The method for improving the adhesion between a ceramic carrier and a thick film circuit according to the first aspect of the patent application, wherein the metal copper-ceramic eutectic layer has a thickness of 2 to 20 μm.