WO2017122966A1 - Ceramic circuit board and method for manufacturing same - Google Patents

Abstract

The present invention relates to a ceramic circuit board and a method for manufacturing the same, the ceramic circuit board comprising: a ceramic board; a bonding layer arranged on the ceramic board and comprising NiCr; a metallic layer arranged on the bonding layer; and a metal foil arranged on the metallic layer.

Description

Ceramic Circuit Board and Manufacturing Method Thereof

The present invention relates to a ceramic circuit board and a method of manufacturing the same, and specifically, to a ceramic substrate, a bonding layer disposed on the ceramic substrate and including NiCr, a metal layer disposed on the bonding layer, and a metal foil disposed on the metal layer. It relates to a ceramic circuit board and a manufacturing method thereof.

In recent years, with the development of power electronics, as the power semiconductors are integrated and miniaturized, the amount of heat generated by the semiconductor devices to which they are introduced is also increasing. In order to efficiently dissipate the heat generated therein, a bonding between a ceramic substrate and a metal is introduced in a semiconductor device. Unlike general substrates using phenol or epoxy as the main material, ceramic substrates have excellent insulation and heat dissipation, such as alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), Ceramics such as zirconia (ZrO ₂ ) are used as the substrate material to withstand high temperatures, high currents and high insulation. For this reason, ceramic substrates in which metals are bonded are used in various fields such as power semiconductors, insulated gate bipolar transistors (IGBTs), high output light emitting diodes (LEDs), and solar cell modules.

The method of joining a metal and a substrate of a ceramic material includes a Mo-Mn method, an active metal bonding method, a direct bonding method, and the like. For example, a direct bonding method in which the copper plated surface is placed in contact with a ceramic substrate and then heated to a temperature lower than the melting point of copper and higher than the eutectic point of copper and oxygen to melt copper oxide to directly bond the copper plate to the substrate (Direct bonding copper (DBC) has been developed and commercialized.

On the other hand, in order to secure more heat dissipation, strong durability and improved electrical stability, a ceramic circuit board manufactured by an active metal bonding method for joining a metal circuit board through a brazing filler metal layer has also been developed and applied to power semiconductors. In the case of the active metal bonding method, since the bonding process temperature is lower than that of the direct bonding method, the residual stress of the metal-ceramic is small, and since the bonding layer is a soft metal, it is highly reliable against thermal shock and thermal changes, and is generated at the interface during bonding. The generation of micro voids is low, indicating improved electrical properties. However, in the case of the ceramic circuit board obtained by the active metal bonding method, the reaction layer is formed by the reaction with the ceramic when the active metal is bonded. In this case, the structure of the reaction layer is vulnerable, resulting in a decrease in mechanical strength.

In order to overcome the problems of the active metal bonding method, various studies on the bonding layer are being conducted, but the effect obtained in terms of mechanical properties and reliability is not sufficient.

[Preceding technical literature]

[Patent Documents]

Republic of Korea Patent Publication No. 2013-0132684

Republic of Korea Patent No. 10-0867756

The present invention provides a ceramic circuit board with improved durability, thermal reliability and electrical insulation, and a method of manufacturing the ceramic circuit board.

Ceramic circuit board according to an embodiment of the present invention,

Ceramic substrates;

A bonding layer disposed on the ceramic substrate and comprising NiCr;

A metal layer disposed on the bonding layer; And

Metal foil disposed on the metal layer, the weight ratio of Ni: Cr of the bonding layer is 90:10 to 75:25.

It is sufficient that each member of the ceramic circuit board according to one embodiment of the present invention is "arranged" as long as the member is disposed on the member below it, and other members ( E.g., including other functional layers) is not excluded.

In one embodiment of the present invention, the ceramic substrate is selected from the group consisting of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC), and zirconia (ZrO ₂ ). It includes one or more kinds.

Moreover, according to one embodiment of the present invention, the thickness of the bonding layer is in the range of 0.015 to 1.0 µm.

In addition, in one embodiment of the present invention, the metal layer includes Cu, and the thickness of the metal layer is in the range of 0.05 to 1.0 μm.

In addition, according to one embodiment of the present invention, the metal foil includes at least one member selected from the group consisting of Cu, Au, Ni, and Ag, and the thickness of the metal foil is in the range of 100 to 600 µm.

In addition, in one embodiment of the present invention, although not particularly limited thereto, the surface roughness R _z of at least one surface of the metal foil, more specifically, both surfaces may be 3.0 μm or less.

In addition, the electronic component may be mounted on the ceramic circuit board of the present invention, and may be used in industrial fields such as power modules.

According to another embodiment of the present invention, a method of manufacturing a ceramic circuit board is provided as follows.

Disposing a bonding layer comprising NiCr on a ceramic substrate,

Disposing a metal layer on the bonding layer,

Disposing a metal foil on the metal layer;

And pre-oxidation of the metal layer.

At least one of the bonding layer and the metal layer may be formed by a method selected from the group consisting of sputtering, printing, and chemical plating.

In addition, the pre-oxidation may be carried out by heat treatment in a temperature range of 100 to 1000 ℃.

The ceramic circuit board of the present invention has improved electrical reliability along with excellent mechanical properties, so that the metal film bonded to the ceramic substrate does not peel off even after repeated heat dissipation and excellent insulation property can be applied to semiconductor devices in various fields.

1 is a cross-sectional view showing a cross-sectional shape of a ceramic circuit board according to an embodiment of the present invention.

2 is a cross-sectional view showing a cross-sectional shape of a ceramic circuit board according to still another embodiment of the present invention.

As shown in FIG. 1, the ceramic circuit board 100 according to the embodiment of the present invention includes a ceramic substrate 101, a bonding layer 102 disposed on the ceramic substrate 101, and including NiCr. A metal layer 103 disposed on the bonding layer 102 and a metal foil 104 disposed on the metal layer 103, wherein a weight ratio of Ni: Cr of the bonding layer is 90:10 to 75:25. It may be.

As shown in FIG. 2, the ceramic circuit board 200 according to another embodiment of the present invention may include a structure of a bonding layer / metal layer / metal foil on both sides as well as one side of the ceramic substrate 201. And a bonding layer 202, a metal layer 203 disposed on the bonding layer 202, and a metal foil 204 disposed on the metal layer 203, respectively, on both surfaces of the ceramic substrate 201. It may be.

Hereinafter, each member of the ceramic circuit board of the present invention will be described with reference to FIG. 1 for convenience.

<Ceramic Substrate>

First, the material of the ceramic substrate 101 used in the present invention is not particularly limited thereto, but may include alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), and zirconia. (ZrO ₂ ) and the like, among these, inexpensive and excellent mechanical strength may be used alumina or aluminum nitride having excellent thermal conductivity. Although the thickness of the ceramic substrate 101 is not specifically limited, The range of 0.2-1.0 mm which is the thickness of the ceramic substrate normally used can be used.

<Bonding layer>

The bonding layer 102 may be disposed to improve adhesion to the ceramic substrate 101, and the bonding layer 102 may include NiCr as a metal having excellent adhesion with the ceramic substrate.

In addition, in the NiCr included in the bonding layer 102, the weight ratio of Ni: Cr may be 90:10 to 75:25. Thus, the Ni / Cr may be in close contact with the ceramic substrate 101 by varying the ratio of Ni and Cr. The strength can be optimized while minimizing residues that can occur after the process.

The thickness of the bonding layer 102 is not particularly limited, but according to an embodiment of the present invention may be in the range of 0.015 to 1.0 ㎛. When the thickness of the bonding layer 102 is less than 0.015 μm, and the thickness thereof is too thin, the adhesion to the ceramic substrate may be inhibited. When the thickness of the bonding layer 102 exceeds 1.0 μm, the substrate is thinned and unnecessary. Side effects, such as increased resistance, can occur.

The method for forming the bonding layer 102 is not particularly limited, but may be a sputtering method, a printing method, or a chemical plating method. The DC sputtering method may be used in view of high film growth rate and easy thickness control. Can be used.

In the DC sputtering method, the power is 1.0 to 2.0 kW, the voltage is 400 to 550 V, the current is 2.0 to 4.0 A, the amount of Ar is 100 to 300 sccm, the pressure is 3.0 to 4.0 mTorr can be used. .

<Metal layer>

The metal layer 103 may be disposed between the bonding layer 102 and the metal foil 104 to be described later to improve adhesion strength of the metal foil 104 to the ceramic substrate 101 and include Cu.

The metal layer 103 according to the present invention may be subjected to pre-oxidation before bonding the metal foil 104 to the ceramic substrate 101 including the bonding layer 102, wherein the pre-oxidation is in a temperature range of 100 to 1000 ° C. It can be carried out by heat treatment at. The preoxidation increases the oxygen content present on the surface of the metal layer 103, which may further improve the bonding strength with the metal foil 104. The improvement of the bonding property can reduce the occurrence of micropores present between the interfaces of the layers disposed on the ceramic circuit board, thereby ensuring partial discharge generation and excellent electrical insulation effect.

The thickness of the metal layer 103 is not particularly limited thereto, but may be in a range of 0.05 to 1.0 μm according to one embodiment of the present invention. When the thickness of the metal layer 103 is less than 0.05 μm, the adhesion improvement is insufficient and conversely, when the thickness exceeds 1.0 μm, there is a problem that the conduction efficiency of the ceramic circuit board is lowered due to the increase in the overall thickness.

The method for forming the metal layer 103 is not particularly limited, but may be a sputtering method, a printing method, a chemical plating method, or the like, and the DC sputtering method may be used in view of easy thickness control.

<Metal foil>

After the bonding layer 102 including NiCr is disposed on the ceramic substrate 101 by sputtering, printing, or the like, the metal layer 103 is disposed on the bonding layer 102, and the metal layer 103 is disposed on the ceramic layer 101. The metal foil and the ceramic substrate are joined by arranging and bonding the metal foil 104.

The metal foil 104 may be at least one selected from the group consisting of Cu, Au, Ni, and Ag as a metal having conductivity and ductility, and may preferably include Cu. The metal foil containing Cu may be a rolled copper foil or an electrolytic copper foil.

The metal foil 104 used in the present invention may have a 10-point average roughness R _z of surface roughness shown in JIS B0601 on both sides of 3.0 μm or less, 2.0 μm or less, and 0.3 μm or less. In the present invention, not only the metal foil having the smooth surface as described above can be disposed using the above-described bonding layer and the metal layer, but also sufficient adhesion property and electrical insulation with the ceramic substrate can be ensured.

Although the thickness of the metal foil 104 is not particularly limited thereto, it may be in the range of 100 to 600 μm according to one embodiment of the present invention. If the thickness of the metal foil 104 is less than 100 μm, the thickness thereof may be too thin to affect the durability of the metal foil 104. On the contrary, if the thickness of the metal foil 104 is greater than 600 μm, the thickness of the metal foil 104 is increased. Due to the increase in resistance, the efficiency of the ceramic circuit board 100 may decrease, and the adhesion force with the metal layer 103 may decrease. By setting the thickness of the metal foil 104 according to one embodiment of the present invention to 100 to 600 µm or less, the electrical insulating property can be improved together with the durability of the substrate produced by maximizing the adhesive force with the bonding layer 103.

The method of manufacturing the ceramic circuit board of the present invention,

Disposing a bonding layer comprising NiCr on a ceramic substrate,

Disposing a metal layer on the bonding layer,

It may include disposing a metal foil on the metal layer, and may include pre-oxidizing the metal layer.

At least one of the bonding layer and the metal layer may be formed by a sputtering method, a printing method, or a chemical plating method. Among them, the DC sputtering method is most suitable.

The pre-oxidation is carried out before the placement of the metal foil, it can be carried out by heat treatment in the temperature range of 100 to 1000 ℃.

In addition, the metal foil may be bonded to the ceramic substrate including the bonding layer and the pre-oxidized metal layer by energy ray irradiation and / or heat treatment of the bonding layer, the metal layer, and the metal foil disposed on the ceramic substrate, In this case, it can be carried out in the 800 to 1200 ℃ temperature range.

According to the exemplary embodiment of the present invention, the bonding layer, the metal layer, and the metal foil may be disposed on only one surface of the ceramic substrate, but are not limited thereto, and the layers may be formed on both surfaces of the ceramic substrate. For example, as illustrated in FIG. 2, the bonding layer 202, the metal layer 203, and the metal foil 204 may be formed on both surfaces of the ceramic substrate 201. Specifically, the bonding layer 202, the metal layer 203, and the metal foil 204 are formed on one side of the ceramic substrate 201, and at the same time or later, the bonding layer 202 on the other side of the ceramic substrate 201. ), The metal layer 203 and the metal foil 204 can be formed.

In FIG. 2, the bonding layer 202, the metal layer 203, and the metal foil 204 formed on both surfaces of the ceramic substrate 201 are denoted by the same reference numerals for convenience of description, and formed on both surfaces of the ceramic substrate 201. The constituent materials of the bonding layer 202, the metal layer 203, and the metal foil 204 are sufficient as long as they satisfy the scope of the present invention, and are not limited to each other.

The physical properties of the ceramic circuit board manufactured by the above method and the ceramic circuit board manufactured by the conventional method, such as TCT (partial cycle), partial discharge, bonding strength, and warpage of the board were measured.

TCT is a thermal stability test. Specifically, a thermal shock test of 1000 cycles was performed at a temperature range of -55 to 150 ° C., and the number of delaminations of ceramic circuit boards was confirmed by scanning acoustic microscopy.

Partial discharge is an insulation test. Specifically, a partial discharge tester (KPD2050, manufactured by Kyukui Denshi Kogyo Co., Ltd.) was used. Specifically, a voltage of 0.50 ㎸ / s from 0 ㎸ to 5 로 in one step was applied to the ceramic circuit board. After increasing the speed and maintaining the voltage of 5 로 for 2 hours in 2 stages, the voltage drops to 4.6 로 at 0.04 ㎸ / s in 3 stages and the voltage of 4.6 동안 for 4 hours in 4 stages. The voltage was applied in a pattern of simply dropping the voltage to 0 kV at a rate of 0.46 kV / s. At this time, energization and insulation were examined in step 2, and the discharge charge amount was measured in step 4.

In addition, the bond strength test was performed by a universal testing machine (UTM), and the substrate warpage test measured the warpage amount of the large ceramic metal bonded substrate using a three-dimensional measuring instrument.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the present invention is not limited by these examples.

Examples and Comparative Examples

Examples 1 to 4 and Comparative Examples 1 to 3: Preparation and evaluation of physical properties of metal bonded alumina (Al ₂ O ₃ ) substrate

Example 1

As a ceramic substrate, an alumina substrate having a thickness of 0.38 mm manufactured by a tape casting method was used. As a bonding layer, Ni _x Cr _{1 -x} (x = 0.8) was formed to a thickness of 0.05 μm by DC sputtering. It was. Subsequently, Cu was formed into a 0.1 micrometer thickness by DC sputtering method as a metal layer, and preoxidation was performed at 400 degreeC for 30 minutes. On the pre-oxidized metal layer, a copper metal foil having an average surface roughness (R _z ) of 1.5 μm and a thickness of 300 μm was disposed, followed by heat treatment at 1070 ° C. to prepare a metal bonded alumina substrate.

[Examples 2 and 3]

A metal bonded alumina substrate was prepared in the same manner as in Example 1 except that the thickness of the metal layer was changed as shown in Table 1 below.

Example 4

A metal-bonded alumina substrate was prepared in the same manner as in Example 1 except that the metal foil was subjected to oxidation treatment at 400 ° C. for 15 minutes instead of pre-oxidation of the metal layer.

Comparative Example 1

A metal bonded alumina substrate was produced by directly bonding a copper metal foil having an average surface roughness (R _z ) of 1.5 μm and a thickness of 300 μm to an alumina substrate having a thickness of 0.38 mm without arranging the bonding layer and the metal layer.

Comparative Example 2

A metal bonded alumina substrate was prepared in the same manner as in Example 1 except that the bonding layer was changed to Ti.

Comparative Example 3

A metal bonded alumina substrate was prepared in the same manner as in Example 1 except that the bonding layer was changed to Ni _x Cr _{1 -x} (x = 0.95).

TCT, partial discharge, bond strength, and substrate warpage amount of the Examples and Comparative Examples were measured and shown in Table 1 below.

	Example 1	Example 2	Example 3	Example 4	Comparative Example 1	Comparative Example 2	Comparative Example 3
Adhesive layer (㎛)	0.05	0.05	0.05	0.05	-	0.05	0.05
Metal layer (㎛)	0.1	0.5	1.0	0.1	-	1.0	1.0
Metal layer preoxidation	○	○	○	X	X	○	○
Bonding Strength (N / mm)	23.7	9.5	3.3	22.4	7.5	2.6	4.3
TCT (times)	90	65	55	90	60	60	60
Partial discharge (pC)	0.28	0.42	0.25	0.81	2.27	41.22	41.88
Substrate Warpage (mm)	0.5	0.5	0.5	0.6	One	0.7	0.7

* TCT test: -55 to 150 ℃ 1,000 Cycle

Partial Discharge Test: Discharge Charge at 4.6 mA

* Board Warp Test: Maximum Warp-Minimum Warp

As shown in Table 1, the ceramic circuit boards of Examples 1 to 4, in which an adhesive layer containing NiCr was disposed between the ceramic substrate and the metal foil, a metal layer was formed, pre-oxidized the metal layer, and the copper metal foil was bonded. Compared with 1 to 3, overall physical properties such as TCT, partial discharge, bonding strength, and substrate warpage amount were excellent.

Specifically, in the durability of the ceramic circuit board, when NiCr as in the present invention is used as the bonding layer, the composition of the bonding layer differs from that of Comparative Example 1 in which the TCT, the bonding strength, and the substrate warp amount are directly bonded. Significant improvement was found. In addition, in the pre-oxidation, Example 1, which pre-oxidizes the metal layer, shows excellent partial discharge properties compared to Example 4, which pre-oxidizes the metal foil, thereby improving the bonding properties and reducing the micropores between the interfaces through the pre-oxidation. It was confirmed that the metal layer is more effective.

[Description of the code]

100, 200: ceramic circuit board

101, 201: ceramic substrate

102, 202: bonding layer

103,203: metal layer

104, 204: metal foil

Claims (12)

1. Ceramic substrates;

   A bonding layer disposed on the ceramic substrate and comprising NiCr;

   A metal layer disposed on the bonding layer; And

   A metal foil disposed on the metal layer,

   The weight ratio of Ni: Cr of the bonding layer is 90:10 to 75:25 ceramic circuit board.
2. The method according to claim 1,

   The ceramic substrate includes at least one selected from the group consisting of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC), and zirconia (ZrO ₂ ). Ceramic circuit board.
3. The method according to claim 1,

   The metal layer is a ceramic circuit board containing Cu.
4. The method according to claim 1,

   The metal foil is a ceramic circuit board containing at least one selected from the group consisting of Cu, Au, Ni and Ag.
5. The method according to claim 1,

   The thickness of the bonding layer is a ceramic circuit board in the range of 0.015 to 1.0 ㎛.
6. The method according to claim 1,

   The thickness of the metal layer is a ceramic circuit board in the range of 0.05 to 1.0 ㎛.
7. The method according to claim 1,

   The thickness of the metal foil is a ceramic circuit board in the range of 100 to 600 ㎛.
8. The method according to claim 1,

   The surface roughness (R _z ) of at least one surface of the metal foil is 3.0 ㎛ or less.
9. An electronic material in which an electronic component is mounted on a ceramic circuit board according to any one of claims 1 to 8.
10. Disposing a bonding layer comprising NiCr on a ceramic substrate,

    Disposing a metal layer on the bonding layer,

    Disposing a metal foil on the metal layer;

    A method of manufacturing a ceramic circuit board is to pre-oxidize the metal layer.
11. The method according to claim 10,

    At least one of the bonding layer and the metal layer is formed by a method selected from the group consisting of a sputtering method, a printing method and a chemical plating method.
12. The method according to claim 10,

    The pre-oxidation is a method of manufacturing a ceramic circuit board which is carried out by heat treatment in the temperature range of 100 to 1000 ℃.

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