CN102060573B - Manufacture method for copper-coated ceramic substrate on basis of electronic paste - Google Patents

Abstract

The invention relates to a method for manufacturing a copper-clad ceramic substrate based on electronic paste, and belongs to the technical field of microelectronic packaging. Coating the oil-based or water-based electronic paste prepared from cuprous oxide powder on the surface of the ceramic substrate to form a coating with a thickness of 80-120 μm; after high-temperature sintering and reduction treatment, a copper layer is obtained on the surface of the alumina ceramic; By processing the obtained substrate by means of electroplating or electroless plating, a copper-clad ceramic substrate with a dense interface and a smooth surface can be obtained. The invention has simple process, no need for large-scale equipment, cheap raw materials, low cost, and the yield rate can be as high as 90% or more. The interface oxygen content can be adjusted by the content of cuprous oxide powder and the sintering atmosphere. The copper layer at the interface of the substrate is dense and continuous, and the thickness is controllable, which makes the power electronic devices work more stably.

Description

A method of manufacturing copper-clad ceramic substrate based on electronic paste

technical field

The invention relates to a method for manufacturing a copper-clad ceramic substrate based on electronic paste, and belongs to the technical field of microelectronic packaging.

Background technique

In the field of power electronics, typical power circuit applications mainly include power semiconductor modules, DC/DC converters, optical ballasts, motor drive controllers, and automotive control systems. The rated current values of various power circuits are different, and the range of variation can range from a few amperes to hundreds of amperes or even thousands of amperes, which causes the functional requirements of various power circuits to vary widely. Modern microelectronic packaging is almost always performed on or in relation to a substrate. With the emergence of new high-density packaging forms, many functions of electronic packaging, such as electrical connection, physical protection, stress relaxation, heat dissipation and moisture resistance, size transition, normalization and standardization, etc. are gradually being partially or fully undertaken by the substrate. The substrate plays the most important role in the heat dissipation process. If the heat dissipation performance of the substrate is not good, it will cause the components on the printed circuit board to overheat, thereby reducing the reliability of the whole machine or even failing. In addition to bearing heat dissipation, the substrate must also have a coefficient of thermal expansion (CTE) that matches Si and GaAs to reduce the thermal stress between the chip and the substrate, better electrical insulation and a lower dielectric constant for application For high-frequency circuits, reduce time delay. In this context, PCB substrates, which have always been in a dominant position, obviously cannot meet the above requirements. Especially in terms of heat dissipation requirements, substrate materials with high thermal conductivity must be selected, so ceramic substrates have entered the ranks of first choice.

Among the practical ceramic substrate materials, the price of alumina is relatively low, and its comprehensive performance is the best in terms of mechanical strength, insulation, thermal conductivity, heat resistance, thermal shock resistance, chemical stability, etc., and it is most used as a substrate material. , and its processing technology is also the most advanced compared to other materials. Companies such as Lamina Ceramics in the United States and Curmilk in Germany have applied ceramic substrates to high-power LED chip packaging. Since the eutectic solder layer, electrostatic protection circuit, drive circuit and control compensation circuit are integrated on the substrate, it is not only simple in structure, but also due to The material has high thermal conductivity and less thermal interface, which greatly improves the heat dissipation performance, and proposes a solution for high-power LED array packaging.

At present, there are mainly thick film method and molybdenum-manganese method to realize metal and ceramic bonding in industry. The thick film method is composed of fine particles of precious metals by crimping together, and then adhered to the ceramic by molten glass, so the conductivity of the thick film is worse than that of metal copper. The molybdenum-manganese method is relatively mature. Some metal particles in the molybdenum-manganese slurry are oxidized by the moisture in the wet hydrogen. The manganese as the activator is oxidized into manganese oxide, and part of it diffuses to the inner surface of the ceramic and some oxides in the ceramic. A glass phase is formed, a part of which forms an intermediate layer, and interdiffusion between the ceramic and metallization layers achieves good adhesion between the ceramic and metallization layers. However, the middle layer formed by this method is thick and has a large thermal resistance, which is not conducive to rapid heat dissipation in the fields of high-power circuits and power modules, and the thickness of the metal layer formed by the molybdenum-manganese method is often very thin, less than 25 μm. It limits the surge withstand capability of high-power module components. In recent years, alumina direct copper (DBC) substrates have combined the excellent properties of copper and alumina ceramics, and are used in high-power devices. The bonding principle of the DBC substrate is to introduce an appropriate amount of oxygen element between the copper and the ceramic before or during the bonding process. In the range of 1065°C to 1083°C, copper and oxygen form a Cu-O eutectic liquid. DBC technology utilizes the eutectic liquid, on the one hand, chemically reacts with the ceramic to form an intermediate phase (CuAlO ₂ or CuAl ₂ O ₄ ), on the other hand, it infiltrates the copper foil to realize the combination of the alumina ceramic substrate and the copper plate. Therefore, the key factor in its preparation process is the introduction of oxygen, but it is difficult to directly control the oxygen content in industrial production.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the existing direct copper-clad technology, the technical problem to be solved by the present invention is to provide a copper-clad ceramic substrate production method that can indirectly control the interface oxygen content, facilitate metal patterning, and low cost.

A method of manufacturing a copper-clad ceramic substrate based on electronic paste, characterized in that it comprises the following steps:

(1) Prepare cuprous oxide oil-based electronic paste: Mix 75.75-83.9 parts by weight of functional phase, 15.1-22.73 parts by weight of organic vehicle, 0.5-0.76 parts by weight of thixotropic agent, and 0.5-0.76 parts by weight of wetting agent Finally, through ball milling, the slurry is obtained with a viscosity of 45Pa·s~100Pa·s;

Prepare cuprous oxide water-based electronic paste: mix 48.7-65.5 parts by weight of functional phase, 33.2-49.4 parts by weight of organic carrier, 0.65-0.95 parts by weight of thixotropic agent, and 0.65-0.95 parts by weight of wetting agent, and then ball mill to prepare Obtain a slurry with a viscosity of 0.1Pa·s~10Pa·s;

(2) Take the cuprous oxide oil-based or water-based electronic paste prepared in step (1), and form a coating with a thickness of 50-120 μm on the surface of the ceramic substrate by spin coating or screen printing. It can be adjusted according to the rotation speed and the thickness of the stencil;

(3) The ceramic substrate prepared in step (2) is taken, and subjected to high-temperature sintering and reduction treatment to obtain a copper layer on the surface of the alumina ceramic;

(4) Preparation of electroplating solution: 15-16 parts by weight of copper sulfate pentahydrate, 5-6 parts by weight of concentrated sulfuric acid, 0.4 parts by weight of glucose, and 77.6-79.6 parts by weight of distilled water are evenly mixed for later use;

Preparation of electroless plating solution: 1.5 parts by weight of copper sulfate pentahydrate, 1.5 parts by weight of 36% formaldehyde solution, 1.4 parts by weight of sodium hydroxide, 1.2 parts by weight of potassium sodium tartrate, 2 parts by weight of EDTA-2Na, 0.015 parts by weight of ferrocyanide Potassium, 0.05 parts by weight of polyethylene glycol, and 92.34 parts by weight of distilled water are mixed uniformly for subsequent use;

(5) Take the ceramic substrate prepared in step (3) and perform electroplating with the electroplating solution prepared in step (4) or electroless plating with an electroless plating solution to obtain a copper-clad ceramic substrate with a dense interface and a smooth surface.

The aforementioned method of manufacturing copper-clad ceramic substrates based on electronic paste is characterized in that the functional phase adopted in the cuprous oxide oil-based electronic paste is cuprous oxide powder; the organic carrier is 57 parts by weight of terpineol, 28.5 parts by weight of A mixed solution of carbitol acetate, 9.5 parts by weight of dibutyl phthalate and 5 parts by weight of ethyl cellulose; the thixotropic agent is hydrogenated castor oil, oleic acid, fish oil; the wetting agent is polyethylene glycol ;

The functional phase used in the cuprous oxide water-based electronic paste is cuprous oxide powder; the organic carrier is a mixed solution of 5 parts by weight of 5% polyvinyl alcohol aqueous solution, 1.32 parts by weight of dibutyl phthalate and 93.68 parts by weight of distilled water; The thixotropic agent is hydrogenated castor oil, oleic acid, fish oil; the wetting agent is polyethylene glycol;

The aforementioned method for manufacturing a copper-clad ceramic substrate based on electronic paste is characterized in that the particle size of the cuprous oxide powder is 6-10 μm.       

The aforementioned method of manufacturing a copper-clad ceramic substrate based on electronic paste is characterized in that the material of the ceramic substrate is aluminum oxide, silicon oxide, silicon nitride, aluminum nitride, and glass.

The aforementioned method for manufacturing copper-clad ceramic substrates based on electronic paste is characterized in that: the specific process of step (3) is: put the substrate in a tube-type electric furnace, heat it to 1150°C under air, sinter it for 2 hours and then The furnace is cooled to achieve an effective bond between the coating and the ceramic. After the sintered sample was cooled to room temperature, the tube furnace chamber was evacuated and heated to 600°C, and reduced for 2 hours in an atmosphere of H ₂ +N ₂ (flow ratio 1:2).

Using electroplating or electroless plating, the difference in performance of the finished product lies in: using electroplating copper technology, the coating is thicker, and a copper layer of up to 150 μm can be achieved; using electroless copper plating technology, the coating is thinner and the surface smoothness is high. Compared with the currently used DBC forming process, the present invention does not require large-scale equipment, the process is simple, the price of raw materials is low, the cost is reduced, the yield of the finished product reaches more than 99%, the oxygen content of the interface is effectively controlled, the metal patterning is convenient, and the surface finish is high. In particular, the copper layer at the substrate interface is dense and continuous, and its thickness is controllable, which makes the power electronic device work more stably.

Description of drawings

Fig. 1 is the interface phase analysis of the sample prepared by Example 1 of the present invention after high-temperature sintering

Fig. 2 is the microscopic morphology of the sample surface prepared by Example 1 of the present invention;

Fig. 3 is the microscopic morphology of the sample interface prepared by Example 1 of the present invention;

Fig. 4 is the circuit pattern on the surface of the sample prepared in Example 2 of the present invention.

Detailed ways

Cuprous oxide powder, terpineol, butyl carbitol acetate, ethyl cellulose, hydrogenated castor oil, polyethylene glycol, dibutyl phthalate, polyvinyl alcohol used in the following embodiments of the present invention , copper sulfate pentahydrate, concentrated sulfuric acid, glucose, formaldehyde, sodium hydroxide, potassium sodium tartrate, and potassium ferrocyanide are all obtained through the market. the

Example 1

Step 1: Preparation of cuprous oxide water-based electronic paste: 53.6 parts by weight of cuprous oxide powder (analytical pure) with a particle size of 6 μm, 44.3 parts by weight of 5% polyvinyl alcohol aqueous solution, and 0.5 parts by weight of dibutyl phthalate , 0.8 parts by weight of hydrogenated castor oil and 0.8 parts by weight of polyethylene glycol were mixed, and ball milled on a planetary ball mill for 2 hours to obtain a cuprous oxide water-based electronic slurry with a viscosity of 1 Pa·s.

Step 2: Put the 96 alumina ceramic sheet into the ethanol solution, and ultrasonically clean it in an ultrasonic cleaner for 30 minutes, take it out and dry it in the sun; then spin-coat the cuprous oxide water-based electronic slurry prepared in step 1 on the coating machine The material was uniformly hung and coated on the surface of alumina ceramics at a spin-coating speed of 500 rpm to obtain a coating thickness of 50 μm.

Step 3: Put the coated substrate prepared in step 2 into a tubular electric furnace, heat it to 1150°C under air, sinter for 2 hours and cool with the furnace, so as to form a layer with a thickness of 10~ at the interface between the coating and the ceramic. 20μm _CuAlO2 transition layer, as shown in Figure 1, this process is similar to the DBC technology, except that the introduction of oxygen content at the interface is not through the external atmosphere, but through the introduction of oxygen in cuprous oxide, thus realizing the coating Effective combination with ceramics. After the sintered sample was cooled to room temperature, the tube furnace chamber was evacuated and heated to 600°C, and reduced for 2 hours in an atmosphere of H ₂ +N ₂ (flow ratio 1:2).

Step 4: Add 15.6 parts by weight of copper sulfate pentahydrate, 5.9 parts by weight of concentrated sulfuric acid, and 0.4 parts by weight of glucose into 78.1 parts by weight of distilled water, and stir evenly to prepare an acidic copper sulfate solution. The pure copper sheet is used as the anode, the substrate sample prepared in step 3 is used as the cathode, the DC power supply is set to 5A/dm ² , and the plating is carried out for 30 minutes in a collector type constant temperature heating magnetic stirrer, and the ambient temperature is 40°C. The interface of the prepared copper-clad ceramic substrate is shown in Figure 3. The copper layer at the interface is dense and the thickness is up to 80 μm. The surface morphology is shown in Figure 2. The surface is smooth and smooth without holes.

Example 2

Step 1: Preparation of cuprous oxide oil-based electronic paste: 4.63 parts by weight of butyl carbitol acetate, 9.27 parts by weight of terpineol, 1.54 parts by weight of dibutyl phthalate, and 0.81 parts by weight of ethyl cellulose 1.22 parts by weight of hydrogenated castor oil, 1.22 parts by weight of polyethylene glycol and 81.3 parts by weight of cuprous oxide powder with a particle size of 10 μm are fully mixed and stirred to obtain a cuprous oxide oil-based electronic slurry, and ball milled to obtain a slurry, The viscosity is 60 Pa·s.

Step 2: Use the cuprous oxide paste prepared in step 1 to print circuit patterns on the surface of 96 alumina ceramics through a 300-mesh screen, and the printing thickness can be adjusted according to the thickness of the stencil.

Step 3: Sintering and reducing the printed substrate prepared in Step 2 is exactly the same as Step 3 of Example 1, and the circuit pattern is shown in FIG. 4 .

Step 4: Electroplating the substrate prepared in Step 3 is exactly the same as Step 4 of Example 1, and the thickness of the obtained copper layer reaches 120 μm.

Example 3

Step 1: Prepare cuprous oxide oil-based electronic paste, the preparation process is exactly the same as Step 1 of Example 2.

Step 2: Form a circuit pattern on the surface of the silicon oxide ceramic by screen printing, and the printing process is exactly the same as Step 2 of Example 2.

Step 3: Sintering and reducing the printed substrate prepared in Step 2, which is exactly the same as Step 3 of Example 1.

Step 4: 1.5 parts by weight of copper sulfate pentahydrate, 1.5 parts by weight of 36% formaldehyde solution, 1.4 parts by weight of sodium hydroxide, 1.2 parts by weight of potassium sodium tartrate, 2 parts by weight of EDTA-2Na, 0.015 parts by weight of potassium ferrocyanide, Add 0.05 parts by weight of polyethylene glycol into 92.34 parts by weight of distilled water, and stir evenly to prepare an electroless plating solution. Subsequently, the substrate sample prepared in step 3 was suspended in the plating solution, and plated in a collector type constant temperature heating magnetic stirrer for 1 hour, and air was constantly blown in during the plating process, and the temperature was controlled at 50°C. The interface copper layer of the prepared copper-clad ceramic substrate is dense, the thickness reaches 90 μm, and the surface is flat and smooth.

The materials and preparation methods used in Examples 4 to 6 are as follows. Except for the content in Table 1, the rest of the content is the same as that in Example 1.

the Example 4 Example 5 Example 6 ceramic substrate aluminum nitride Silicon nitride Glass way of plating plating Electroless Plating Electroless Plating slurry Water system oil system Water system Thixotropic agent hydrogenated castor oil Oleic acid fish oil Wetting agent is polyethylene glycol polyethylene glycol polyethylene glycol Coating method spin coating screen printing spin coating Copper Thickness 70μm 80μm 60μm

The six examples of the present invention have been listed above, but the above-mentioned embodiments of the present invention can only be considered as illustrations of the present invention and cannot limit the present invention, and the claims point out the scope of the present invention. Therefore, without violating the basic idea of the present invention, in the production process of the metal-bonded ceramic substrate, as long as the cuprous oxide powder is used as the raw material, and the additives used in the present invention are the same, and through the use of electroplating and chemical Any processing technology in plating should be considered as belonging to the protection scope of the present invention. the

Claims (5)

1. deposited copper ceramic substrate manufacture method based on electric slurry is characterized in that may further comprise the steps:

(1), prepares Red copper oxide oil series electron slurry: after 75.75 ~ 83.9 weight part function phases, 15.1 ~ 22.73 weight part organic carriers, 0.5 ~ 0.76 weight part thixotropic agent, 0.5 ~ 0.76 weight part wetting agent are mixed, through ball milling, make slurry, viscosity is 45Pas ~ 100Pas; The function that Red copper oxide oil series electron slurry adopts is cuprous oxide powder mutually; Organic carrier is the mixed solution of 57 weight part Terpineol 350s, 28.5 weight part diethylene glycol monobutyl ether acetic esters, 9.5 weight part dibutyl phthalates and 5 weight part ethyl cellulose; Thixotropic agent is hydrogenated castor oil, oleic acid, fish oil; Wetting agent is polyoxyethylene glycol;

Preparation Red copper oxide water system electric slurry: 48.7 ~ 65.5 weight part function phases, 33.2 ~ 49.4 weight part organic carriers, 0.65 ~ 0.95 weight part thixotropic agent, 0.65 ~ 0.95 weight part wetting agent are mixed by ball milling, make slurry, viscosity is 0.1Pas ~ 10Pas; The function that Red copper oxide water system electric slurry adopts is cuprous oxide powder mutually; Organic carrier is the mixed solution of 5 weight parts, 5% polyvinyl alcohol water solution, 1.32 weight part dibutyl phthalates and 93.68 weight part distilled water; Thixotropic agent is hydrogenated castor oil, oleic acid, fish oil; Wetting agent is polyoxyethylene glycol;

(2), get Red copper oxide oil system or the water system electric slurry of step (1) preparation, apply or the mode of silk screen printing by rotation, forming thickness at ceramic base plate surface is the coating of 50 ~ 120 μ m, coating thickness can be adjusted according to speed of rotation and web plate thickness;

(3), get the ceramic substrate of step (2) preparation, through high temperature sintering, reduction processing, at alumina-ceramic surface acquisition copper layer;

(4), prepare electroplate liquid: standby after 15 ~ 16 weight part Salzburg vitriols, 5 ~ 6 weight part vitriol oils, 0.4 weight part glucose, 77.6 ~ 79.6 weight part distilled water are mixed;

Prepare chemical plating fluid: standby after 1.5 weight part Salzburg vitriols, 1.5 weight parts, 36% formaldehyde solution, 1.4 weight part sodium hydroxide, 1.2 weight part Seignette salts, 2 weight part EDTA-2Na, 0.015 weight part yellow prussiate of potash, 0.05 weight part polyoxyethylene glycol, 92.34 weight part distilled water are mixed;

(5), get the ceramic substrate of step (3) preparation, adopt the electroplate liquid of step (4) preparation to electroplate or adopt chemical plating fluid to carry out electroless plating, can obtain the interface densification, ganoid deposited copper ceramic substrate.

2. the deposited copper ceramic substrate manufacture method based on electric slurry according to claim 1 is characterized in that the cuprous oxide powder particle diameter is 6 ~ 10 μ m.

3. the deposited copper ceramic substrate manufacture method based on electric slurry according to claim 1, the material that it is characterized in that described ceramic substrate is aluminum oxide, silicon oxide, silicon nitride, aluminium nitride, glass.

4. the deposited copper ceramic substrate manufacture method based on electric slurry according to claim 1, the concrete technology that it is characterized in that step (3) is: substrate is put into electric tube furnace, under air, be heated to 1150 ° of C, sintering 2 hours and furnace cooling, realize the effective combination between coat and the pottery, after sample to be sintered is cooled to room temperature, the tubular type furnace chamber is evacuated, and be heated to 600 ° of C, at H ₂And N ₂Reductase 12 hour under the atmosphere.

5. the deposited copper ceramic substrate manufacture method based on electric slurry according to claim 4 is characterized in that H ₂And N ₂Throughput ratio be 1:2.

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