KR20180131072A - Method for manufacturing of radiant heat circuit board - Google Patents

Abstract

The present invention relates to a method for manufacturing a heat dissipation circuit board, comprising the steps of: processing both sides of a ceramic substrate (Si_3N_4) and cleaning and drying the processed ceramic substrate; manufacturing a screen to conform to a pattern to print active metal (Ag-Au-Ti) uniformly on the dried ceramic substrate and then dry the same; bonding the ceramic substrate and copper metal (Cu) to the front surface and the rear surface in a vacuum atmosphere; and performing chemical etching to complete the pattern to produce a substrate, and then subjecting the copper metal surface to NiP plating and Au plating.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a radiating circuit board,

The present invention relates to a circuit board, and more particularly, to a method of manufacturing a high heat dissipation heat dissipation circuit board.

Conventionally, when an indirect bonding method is used as a ceramic-metal bonding method, there are the following problems. The ceramic is metallized (1400 ° C) and bonded to the metal using a brazing material. The ceramic metallization process is complex and must be bonded at a high temperature, resulting in warpage of the ceramic. Expensive metalizing equipment is required and ceramic deformation may occur during simultaneous sintering on the green sheet. In addition, cracks may occur due to the difference in thermal expansion coefficient of the joint. In addition, after metallization, the ceramic interface voids are formed, which reduces the reliability of the product.

In addition, as a problem of Al ₂ O ₃ and AlN substrate, thermal shock and mechanical strength may be weakened, and insulating resistance may remarkably drop below 200 ° C.

The present invention is directed to a method of manufacturing a heat dissipation circuit board capable of minimizing the number of times of etching and etching time in the production of a ceramic or silicon nitride substrate.

According to another aspect of the present invention, there is provided a method of manufacturing a heat dissipation circuit board, comprising: a step of processing both sides of a ceramic substrate (Si3N4), cleaning and drying the processed ceramic substrate; Drying the active metal (ag-cu-ti) uniformly on the dried ceramic substrate by drying the screen to conform to the pattern and drying; Bonding the ceramic substrate and the copper metal (cu) to the front surface and the rear surface in a vacuum atmosphere; And chemical etching to complete the pattern to produce a substrate, and then subjecting the copper metal surface to NiP plating and Au plating.

According to the present invention, in printing an active metal on a ceramic substrate, pattern printing is performed, and then copper metal is bonded to the front surface and the rear surface to etch the insulating substrate to produce an insulating substrate. It is possible to eliminate the problem that the process of manufacturing the substrate by performing the secondary etching after the first etching is performed. In other words, according to the present invention, it is possible to minimize the etching time by minimizing the portions to be removed from the etching by bonding after the pattern printing so as to implement the pattern by the first etching, thereby reducing the manufacturing cost of the ceramic substrate.

1 is a reference diagram for explaining a manufacturing process of a heat radiation circuit board using a general silicon nitride substrate (Si3N4).
2 is a reference view for explaining a manufacturing process of a heat radiation circuit board using a silicon nitride substrate (Si3N4) according to the present invention.
3 is a reference diagram showing a concept of junction of a silicon nitride substrate (Si 3 N 4) according to the present invention.
FIG. 4A is a reference view illustrating a copper (Cu) bonding state according to a conventional AMB process, and FIG. 4B is a reference view illustrating a copper (Cu) bonding state according to an AMB process according to the present invention.
5 is a reference view of an embodiment for explaining a method of manufacturing a heat radiating circuit board according to the present invention.
6A to 6C are reference views illustrating results of bonding interface analysis of a ceramic substrate manufactured by a method of manufacturing a heat radiating circuit board according to the present invention.
7 is a reference view illustrating an analysis image of an optical microscope for a ceramic substrate manufactured by the method for manufacturing a heat radiation circuit substrate according to the present invention.
8 is a reference view illustrating a state of a substrate in a manufacturing process of a heat radiating circuit board according to the present invention.

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas.

The terms " first ", " second " and the like are used to distinguish one element from another, and the terms " The scope of the right shall not be limited. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include " or " have " are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present invention.

BACKGROUND ART [0002] Recently, power devices that perform power conversion and control at a high rate are rapidly becoming popular due to advances in power electronics. Ceramics having both electrical insulation and high thermal conductivity have excellent functions as a heating medium, such as rapidly transferring, diffusing, and cooling generated heat of a device, so that it is possible to use a substrate material for a transport device, a substrate material for a highly integrated electronic circuit, a heat sink, a reaction vessel member of a semiconductor manufacturing apparatus, and a precision machine member.

Particularly, as the hybridization of automobile power and the development of electric motor are rapidly developed, the market of power module is rapidly expanding. Since the current used in the power semiconductor is tens or hundreds of amperes and the voltage is a high power as high as several hundreds of volts, the heat generated from the semiconductor is high, and the heat is effectively emitted to prevent the malfunction or destruction of the device due to the heat. It is becoming an issue.

The degree of integration of LSIs such as CPUs is increasing every year according to Moore's law, and with this, the operating frequency also rises, and the energy density of semiconductor chips is continuously increasing. That is, the major problem in the electronic component device due to the rapid increase in the density of heat generated in the semiconductor chip due to the high-performance and light-weight shortening is a deterioration in reliability, including performance deterioration caused by temperature rise of the device and shortening of life .

Further, when the power module is mounted on a vehicle or the like, the temperature of the use environment is greatly changed. In particular, since a high stress is generated in a joint portion between the board and the wiring, a circuit board material requires a high heat- In addition, thermal / mechanical characteristics are demanded that can bond with copper or aluminum, which is a wiring material, and can ensure reliability.

The aluminum nitride (AlN) substrate has a high thermal conductivity of 200 W / mK or more and is already applied to a circuit board of a power module having a high output density such as an automotive inverter. Silicon nitride (Si3N4) material, which is a second-runner, is known to be advantageous in terms of longevity and high reliability of a device because it has high thermal / mechanical characteristics in spite of relatively low thermal conductivity compared to aluminum nitride materials that have succeeded in industrialization first.

Table 1 shows the main characteristics of silicon nitride which has been recently put into practical use in addition to alumina and aluminum nitride which are generally used as insulating substrates for power semiconductors.

Currently, the thermal conductivity of silicon nitride, which is being applied to industrialization, is less than 1/2 of aluminum nitride but 3 to 4 times higher than that of alumina. In addition, the bending strength and fracture toughness are about two times higher than those of alumina and aluminum nitride, which is a strong advantage of heat cracking resistance. The thermal conductivity of silicon nitride has been continuously updated to the highest point, and most recently 177 W / mK has been reported.

It is necessary to reduce the thermal resistance of the ceramic substrate in the power module in order to cope with the increase in the current density and the emission density due to the high output of the semiconductor element. For this purpose, an alumina substrate having a thickness of 0.32 mm or an aluminum nitride substrate having an improved thermal conductivity of 70 to 170 W / mK has been applied. It is required to apply a silicon nitride substrate having high reliability reliability in order to achieve low heat resistance in a situation where the demand for high reliability is high, which mainly aims to improve the thermal fatigue characteristics of the power module.

Advances in power electronics have demanded the development of Si3N4 substrate as a device material with excellent thermal conductivity, thermal / mechanical strength and electrical insulation. Accordingly, an AMB (Active Metal Brazing) method or a DBC (Direct Bonding Copper) method is considered. The active metal brazing (AMB) process involves development of brazing paste, paste printing technology, SPS & 3 Zone Furnace, patterning (Chemical Etching Process) and reliability evaluation process. Alternatively, the Direct Bonding Copper (DBC) method involves a copper / Si3N4 treatment technique, a SPS & 3 Zone Furnace, a patterning (chemical etching process) and a reliability evaluation process.

1 is a reference diagram for explaining a manufacturing process of a heat radiation circuit board using a general silicon nitride substrate (Si3N4).

In this process, an active metal (ag-cu-ti) is printed on a silicon nitride substrate (Si3N4), Cu is bonded to the front and back surfaces, and chemical etching is performed to produce an insulating substrate.

At this time, when Cu is bonded to the ceramic and the active metal and the remaining except the pattern pits are removed by etching, the etching is not cleaned. Therefore, the process of manufacturing the substrate by performing the secondary etching after the first etching is performed. As a result, a process for manufacturing a general silicon nitride substrate (Si 3 N 4) has a higher manufacturing cost than quality. That is, according to the manufacture of the conventional silicon nitride substrate, etching is not easy and the manufacturing cost is high.

2 is a reference view for explaining a manufacturing process of a heat radiation circuit board using a silicon nitride substrate (Si3N4) according to the present invention.

In the present invention, the active metal (ag-cu-ti) is pattern printed on the silicon nitride substrate (Si3N4), Cu is bonded to the front and rear surfaces, and then chemical etching is performed to produce an insulating substrate.

Accordingly, when Cu is joined to the conventional ceramic and active metal to remove the remaining portion except for the pattern portion by etching, the etching is not cleaned, and the process of manufacturing the substrate by performing the secondary etching after the first etching is improved . That is, by minimizing the portions to be removed from the etching by bonding after the pattern printing, the pattern can be realized by the first etching, thereby minimizing the etching time and thereby lowering the manufacturing cost.

3 is a reference diagram showing a concept of junction of a silicon nitride substrate (Si 3 N 4) according to the present invention. Referring to FIG. 3, there is illustrated a structure in which a brazing material is pattern printed on both sides of a Si 3 N 4 substrate and an etched cu pattern is bonded.

FIG. 4A is a reference view illustrating a copper (Cu) bonding state according to a conventional AMB process, and FIG. 4B is a reference view illustrating a copper (Cu) bonding state according to an AMB process according to the present invention. Referring to FIG. 4A, a brazing material is cu-bonded to both sides of a Si3N4 substrate after front-printing. On the other hand, referring to FIG. 4B, a pattern of a brazing material is printed on both sides of a Si3N4 substrate, and a cu pattern etched is bonded.

5 is a reference view of an embodiment for explaining a method of manufacturing a heat radiating circuit board according to the present invention.

1. Ceramic substrate (Si3N4) is processed on both sides with a surface roughness Ra of 0.1 or less, cleaned and dried. If necessary, process the via hole.

2. Make the screen conform to the pattern so that the active metal (ag-cu-ti) is uniformly printed on the ceramic substrate and dried.

3. Bond the ceramic and cu to the front and back in a vacuum atmosphere.

4. When the bonding is completed, chemical etching is performed to complete the pattern to produce the substrate.

5. Finish the substrate by NiP plating and Au plating on Cu surface.

In the case of manufacturing according to the present invention, Cu etching and bonding can be economical since the etching process can be omitted after bonding.

6A to 6C are reference views illustrating results of bonding interface analysis of a ceramic substrate manufactured by a method of manufacturing a heat radiating circuit board according to the present invention.

7 is a reference view illustrating an analysis image of an optical microscope for a ceramic substrate manufactured by the method for manufacturing a heat radiation circuit substrate according to the present invention. Referring to FIG. 7, the SIN and Cu junction brazing material can be uniformly distributed to a thickness of 15 탆.

8 is a reference view illustrating a state of a substrate in a manufacturing process of a heat radiating circuit board according to the present invention. Referring to FIG. 8, the bonding state of Cu (0.2t) + Si3N4 (0.32t) + Cu junction (0.2t) can be confirmed, and the state of etching in this bonding state can be confirmed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (1)

Processing both sides of a ceramic substrate (Si3N4), cleaning and drying the processed ceramic substrate;
Drying the active metal (ag-cu-ti) uniformly on the dried ceramic substrate by drying the screen to conform to the pattern and drying;
Bonding the ceramic substrate and the copper metal (cu) to the front surface and the rear surface in a vacuum atmosphere; And
And performing chemical etching to complete a pattern to produce a substrate, and then subjecting the copper metal surface to NiP plating and Au plating.

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