CN112624786B - Method for manufacturing composite substrate - Google Patents

Abstract

The invention discloses a manufacturing method of a composite substrate. The method for manufacturing the composite substrate by bonding the copper foil and the ceramic substrate through eutectic reaction comprises the steps of cleaning the surface of the copper foil to remove oil stains or dirt on the surface; then treating the surface of the copper foil by using a liquid medicine with the pH value of less than 3, etching and roughening the surface of the copper foil by using the liquid medicine, and forming a copper oxide film layer of an organic metal compound with a macadam-shaped microstructure on the surface of the copper foil; and then the copper foil is heated to the eutectic temperature, so that the copper foil and the copper oxide film on the surface of the copper foil generate eutectic reaction, and the copper foil and the ceramic substrate are bonded.

Description

Manufacturing method of composite substrate

technical field

The invention relates to a method for manufacturing a composite substrate, in particular to a method for manufacturing a composite substrate in which copper foil and a ceramic substrate are bonded by eutectic reaction.

Background technique

温度下于真空炉中共晶烧结，铜箔将直接键合于陶瓷基板表面，此种作法铜箔两面都会形成氧化铜，不利铜箔单面与陶瓷基板共晶键合。再者，亦有相关业者利用碱性药水让铜箔表面长出由氧化铜与氧化亚铜所组成的黑色绒毛所构成，让铜箔能单面形成氧化铜层，但此种作法有下列缺失：The method of forming a composite substrate between copper foil and ceramics is direct copper bonding technology (DCB, Direct Copper Bonding or DBC, Direct Bonding Copper). Under the oxygen atmosphere, copper oxide is formed on the surface, and then the copper foil containing the copper oxide layer is attached to the surface of the ceramic substrate with the oxide surface layer.

Eutectic sintering in a vacuum furnace at high temperature, the copper foil will be directly bonded to the surface of the ceramic substrate. In this way, copper oxide will be formed on both sides of the copper foil, which is not conducive to the eutectic bonding of the copper foil to the ceramic substrate on one side. In addition, there are also related companies using alkaline potions to make the surface of the copper foil grow black fluff composed of copper oxide and cuprous oxide, so that the copper foil can form a copper oxide layer on one side, but this method has the following shortcomings. :

1. Since the copper oxide film is grown directly from the surface of the copper foil, the roughness of the surface of the copper foil is insufficient. Before making the copper oxide film, the surface of the copper foil must be roughened to increase the eutectic reaction. The bonding force makes the process complicated.

2. The black fluff of the copper oxide film grows slowly and is easy to break and fall off. In addition to the increase in the production time, the bonding force during the eutectic reaction will also be greatly reduced, and the copper foil will be placed in the air. Continued proliferation, making its thickness difficult to control.

3. The wastewater generated after the use of alkaline potion is less environmentally friendly, and the cost of wastewater treatment is high.

4. Many small voids will be formed in the copper oxide film layer. During eutectic sintering, the flowability of the eutectic liquid phase will be poor, so that the gas in the voids cannot be discharged, resulting in the formation of the composite substrate. The inclusion of many air gaps between the ceramics will not only reduce the thermal conductivity, but also reduce the bonding strength.

Therefore, how to solve the above-mentioned problems and deficiencies in the prior art is an urgent research and development issue for the relevant industry.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to treat the surface of the copper foil with a potion with pH less than 3, so that the surface of the copper foil is roughened and a copper oxide film layer of an organic metal composite with a crushed stone-like microstructure is formed, and the copper foil and the ceramic substrate are improved. The bonding force is good, and the thickness of the copper oxide film is easy to control, and the cost can be reduced and the production speed can be increased.

The secondary purpose of the present invention is to use the shielding area set on the surface of the copper foil to form an escape space in the copper oxide film layer formed on the surface of the copper foil, so that when the copper foil is eutectic bonded to the ceramic substrate on one side , increase the flow capacity of the eutectic liquid phase, reduce the number of air gaps between the copper foil and the ceramic when the composite substrate is made, and greatly improve the thermal conductivity and bonding strength of the composite substrate.

In order to achieve the above-mentioned purpose, when the manufacturing method of the composite substrate of the present invention is implemented, the surface of the copper foil is firstly cleaned to remove the oil or dirt on the surface; The surface of the foil is etched and roughened by the potion, and the copper oxide film layer of the organometallic composite with the crushed stone-like microstructure is formed on the surface of the copper foil; Heating to the eutectic temperature makes the copper foil and the copper oxide film layer on the surface produce eutectic reaction, and then bond the copper foil and the ceramic substrate.

The manufacturing method of the aforementioned composite substrate, wherein the medicinal solution at least contains hydrogen peroxide with a content of 2% to 20% by weight, sulfuric acid of 2% to 20% by weight, and nitrogen content of 0.5% to 5% by weight Heterocyclic compound accelerator, the accelerator is used to enhance the bonding force of the copper oxide film.

In the aforementioned method for manufacturing a composite substrate, the accelerator contains an alkyl group, a phenyl group, an amino group or a hydroxyl group.

In the method for manufacturing the aforementioned composite substrate, the ceramic substrate is an aluminum nitride ceramic substrate, an alumina ceramic substrate or a silicon nitride ceramic substrate.

The manufacturing method of the aforementioned composite substrate, wherein after the surface of the copper foil is cleaned, a shielding area is arranged on the surface of the copper foil, and then the surface of the copper foil is treated with a liquid with a pH of less than 3 to make the copper oxide film. The layer will not be formed in the shielding area, so that an escape space is formed in the copper oxide film layer.

In the manufacturing method of the aforementioned composite substrate, the shielding regions on the surface of the copper foil are provided in plural numbers.

Description of drawings

Fig. 1 is the flow chart of the first embodiment of the present invention;

FIG. 2 is a schematic flowchart of the first embodiment of the present invention;

3 is a schematic diagram of setting a shielding area on the surface of the copper foil according to the second embodiment of the present invention;

4 is a schematic diagram of forming a copper oxide film on the surface of the copper foil according to the second embodiment of the present invention;

5 is a cross-sectional view of a copper oxide film formed on the surface of the copper foil according to the second embodiment of the present invention;

6 is a partial cross-sectional view of a copper oxide film formed on the surface of the copper foil according to the second embodiment of the present invention;

FIG. 7 is a schematic diagram of the eutectic bonding of the copper foil and the ceramic substrate according to the second embodiment of the present invention.

Symbol Description:

10. Composite substrate

1. Copper foil

2. Ceramic substrate

3. Copper oxide film

4. Sheltered area

5. Air escape space

Detailed ways

Please refer to FIG. 1 and FIG. 2 , it can be clearly seen from the figures that the manufacturing method of the composite substrate 10 according to the first embodiment of the present invention is implemented according to the following steps:

(A) Prepare the copper foil 1 and the ceramic substrate 2, and the ceramic substrate 1 may be an aluminum nitride ceramic substrate, an alumina ceramic substrate or a silicon nitride ceramic substrate.

(B) The copper foil 1 is washed to remove contamination or dirt on the surface of the copper foil 1 .

(C) Treat the surface of the copper foil with a liquid medicine with a pH of less than 3, the liquid medicine contains hydrogen peroxide in an amount ranging from 2% to 20% by weight, sulfuric acid in an amount of 2% to 20% by weight, and 0.5% to 5% by weight. Accelerator of nitrogen-containing heterocyclic compound in weight ratio, the accelerator contains alkyl, phenyl, amino or hydroxyl; and the potion and the surface of copper foil 1 will produce two reactions at the same time, namely etching reaction and film forming reaction, etching reaction Etching will be generated on the surface of the copper foil 1 to roughen the surface of the copper foil 1, and the film forming reaction will form a copper oxide film layer 3 of an organometallic composite with a crushed stone-like microstructure and a compact structure on the surface of the copper foil 1. , by roughening the surface of the copper foil 1, the copper oxide film layer 3 and the surface of the copper foil 1 have a good bonding force, and by the action of the accelerator, the bonding force of the copper oxide film layer 3 is enhanced.

(D) The copper oxide film layer 3 of the copper foil 1 is bonded to the surface of the ceramic substrate 2, and the copper foil 1 is heated to the eutectic temperature, so that the copper foil 1 and the copper oxide film 3 layers on the surface have an eutectic reaction, and then The composite substrate 10 is formed by bonding the copper foil 1 and the ceramic substrate 2 .

Please refer to FIG. 3 to FIG. 7 , the difference between the second embodiment of the present invention and the aforementioned first embodiment is that after the surface of the copper foil 1 is cleaned, a plurality of shields are set before the surface of the copper foil 1 In area 4, the surface of the copper foil 1 is treated with a potion with pH less than 3, and the shielded area 4 on the surface of the copper foil 1 is removed after the treatment with the potion, so that the copper oxide film layer 3 is not shielded by the shielded area 4 on the copper foil 1 A copper oxide film layer 3 is formed on the surface of the copper oxide film 3, and an escape space 5 is formed in the copper oxide film layer 3. Therefore, when the copper oxide film layer 3 of the copper foil 1 is attached to the surface of the ceramic substrate 2, and the copper foil 1 When heated to the eutectic temperature, the flow capacity of the eutectic liquid phase of the copper oxide film layer 3 is increased, and the generation of air gaps is reduced, so that the composite substrate 10 is reduced during the manufacturing process of the composite substrate. The number of air gaps between the substrates 2 greatly improves the thermal conductivity and bonding strength of the composite substrate. Furthermore, in this embodiment, the shielding regions 4 are arranged in a plurality of circles, but the invention is not limited to this. The shielding regions 4 can be set according to factors such as the thickness of the copper oxide film layer 3, the area of the copper foil, etc., to adjust the shielding. The shape and number of zones 4.

Claims (5)

1. A method for manufacturing a composite substrate includes the following steps:

cleaning the surface of the copper foil to remove oil stains or dirt on the surface; after cleaning, arranging a shielding area on the surface of the copper foil;

treating the surface of the copper foil by using a liquid medicine with the pH value of less than 3, etching and roughening the surface of the copper foil by using the liquid medicine, and forming a copper oxide film layer of an organic metal compound with a macadam-shaped microstructure on the surface of the copper foil, wherein the copper oxide film layer cannot be formed in a shielding area, so that an air escape space is formed in the copper oxide film layer;

and (3) attaching the copper oxide film layer of the copper foil to the surface of the ceramic substrate, heating the copper foil to an eutectic temperature, so that the copper foil and the copper oxide film layer on the surface of the copper foil generate an eutectic reaction, and further bonding the copper foil and the ceramic substrate.

2. The method of claim 1, wherein the chemical solution comprises at least 2-20 wt% of hydrogen peroxide, 2-20 wt% of sulfuric acid, and 0.5-5 wt% of an accelerator of a nitrogen-containing heterocyclic compound, wherein the accelerator is used to enhance the bonding strength of the copper oxide film.

3. The method as claimed in claim 2, wherein the accelerator comprises alkyl, phenyl, amino or hydroxyl.

4. The method of claim 1, wherein the ceramic substrate is an aluminum nitride ceramic substrate, an aluminum oxide ceramic substrate, or a silicon nitride ceramic substrate.

5. The method as claimed in claim 1, wherein the shielding regions are disposed in plural numbers.

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