KR20220142813A - Ceramic substrate, and preparing method thereof - Google Patents

Abstract

The present invention relates to a manufacturing method of a ceramic substrate and the ceramic substrate manufactured therefrom, wherein the manufacturing method of the ceramic substrate comprises: a step of forming a first bonding layer and a second bonding layer by printing each of a first paste and a second paste having different solid contents on each of both sides of the ceramic substrate; and a step of manufacturing and heat-treating a laminate by laminating each of a first metal layer and a second metal layer on the first bonding layer and the second bonding layer, wherein the first bonding layer is thinner than that of the second bonding layer. Therefore, the present invention is capable of reducing a defect rate of the ceramic substrate.

Description

Ceramic substrate and its manufacturing method {CERAMIC SUBSTRATE, AND PREPARING METHOD THEREOF}

The present invention reduces the defect rate of the ceramic substrate by controlling the solid content of the paste for the upper and lower bonding layers and/or the thickness of the bonding layer to reduce the warpage phenomenon caused by the difference in volume occupied by the upper and lower metal layers of the ceramic substrate. It relates to a manufacturing method that can be manufactured and a ceramic substrate manufactured therefrom.

Conventional power modules use alumina (Al ₂ O ₃ ) with excellent electrical and mechanical properties and heat dissipation properties to use a substrate manufactured by direct copper bonding (DCB). Specifically, DCB manufactures a substrate by directly attaching an oxidizable copper circuit to a ceramic substrate.

However, due to the problem of an increase in calorific value accompanying high density, high integration, and high speed of devices in recent years, a substrate manufactured by an active metal brazing method (AMB) is attracting attention. AMB is widely used because of its superior interlayer bonding strength and superior long-term reliability than a DCB-made substrate by forming a layer by brazing an active metal on a ceramic substrate. Ceramic substrates used in such AMB include AlN, H-AlN, and silicon nitride (Si ₃ N ₄ ) substrates. Among them, H-AlN or silicon nitride substrates with excellent strength and thermal conductivity are widely used.

Specifically, Korean Patent Application Laid-Open No. 2020-0127511 (Patent Document 1) suppresses the warpage phenomenon caused by the difference in volume occupied by the upper and lower metal layers of the ceramic substrate, and in particular, the upper and lower metal layers on the ceramic substrate. Disclosed are a ceramic substrate capable of reducing the defect rate of the ceramic substrate by controlling the areas of upper and lower metal layers when the thicknesses of the ceramic substrates are the same, and a method for manufacturing the same. However, the method of suppressing warpage by controlling the volume of the upper and lower metals of Patent Document 1 has a problem in that the manufacturing cost increases as the volume of the metal layer increases, and when the thickness of the upper and lower metal layers is different, the etching process There is a problem in that process conditions are complicated and productivity is lowered.

On the other hand, both DCB and AMB form a pattern layer through a photolithography process and an etching process after each metal layer is formed on both surfaces of the ceramic substrate. However, since a pattern is formed on the upper metal layer of the ceramic substrate and the lower metal layer does not form a pattern in order to maximize heat dissipation, the metal layers on both sides of the ceramic substrate are formed according to the pattern arrangement on each side. When a difference occurs and the difference exceeds a certain ratio, warpage of the ceramic substrate occurs in a high-temperature environment. As a result, when the degree of warpage of the ceramic substrate exceeds 0.4%, it is discarded as a defect, and such a waste ratio occupies a relatively large proportion in the total production, causing continuous production loss.

As an alternative to this, a method of designing the thickness of the upper metal layer to be thinner than that of the lower metal layer has been proposed. However, in recent years, due to the problem of increasing the amount of heat associated with device densification, high integration, and high speed, the thickness of both the upper and lower metal layers is increasing. is a very difficult situation.

Therefore, there is a need for a manufacturing method capable of reducing the defect rate of the ceramic substrate by suppressing the warpage phenomenon caused by the difference in volume occupied by the upper and lower metal layers of the ceramic substrate, and research and development of the ceramic substrate manufactured therefrom. to be.

Korean Patent Publication No. 2020-0127511 (published date: November 11, 2020)

The present invention provides a manufacturing method capable of reducing the defect rate of a ceramic substrate by suppressing a warpage phenomenon caused by a difference in volume occupied by an upper and lower metal layer of a ceramic substrate, and a ceramic substrate manufactured therefrom.

In order to achieve the above object, the present invention comprises the steps of forming a first bonding layer and a second bonding layer by printing each of the first paste and the second paste having different solid content on each of both surfaces of a ceramic substrate; and

Including; laminating a first metal layer and a second metal layer on the first bonding layer and the second bonding layer, respectively, to prepare a laminate and heat treatment;

The first bonding layer is thinner than the second bonding layer, and provides a method of manufacturing a ceramic substrate.

In addition, the present invention includes a laminated form in which a first metal layer, a first bonding layer, a ceramic substrate, a second bonding layer, and a second metal layer are laminated,

The first bonding layer is thinner than the second bonding layer, and provides a ceramic substrate.

The method of manufacturing a ceramic substrate according to the present invention controls the solid content of the paste for the upper and lower bonding layers and/or the thickness of the bonding layer in the warpage phenomenon caused by the difference in volume occupied by the upper and lower metal layers of the ceramic substrate. Thus, it is possible to reduce the defect rate of the ceramic substrate.

In addition, the ceramic substrate according to the present invention has excellent interlayer bonding strength, high thermal fatigue, excellent reliability as a substrate for electronic components, and excellent mechanical properties.

1 is an embodiment of a method of manufacturing a ceramic substrate according to the present invention.
Figure 2 is an embodiment of the etching of the manufacturing method according to the present invention.
3 is a cross-sectional view of a ceramic substrate according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

In the present specification, when a part "includes" a certain component, this means that other components may be further included rather than excluding other components unless otherwise stated.

In addition, in this specification, when a layer is said to be located "on" another layer, this includes not only a case in which a layer is adjacent to another layer but also a case in which another layer exists between two layers.

Method of manufacturing ceramic substrate

A method of manufacturing a ceramic substrate according to the present invention comprises the steps of forming a first bonding layer and a second bonding layer by printing each of the first paste and the second paste on each of both surfaces of the ceramic substrate; and laminating a first metal layer and a second metal layer on the first bonding layer and the second bonding layer, respectively, to prepare a laminate and heat treatment (see FIG. 1 ).

In the process of manufacturing ceramic substrates, even if the metal layers applied to the upper and lower surfaces of the substrate have the same thickness, the volume difference occurs due to the formation of the metal pattern, and in the high-temperature heat treatment process applied during product mounting, the difference in the coefficient of thermal expansion between the metal layer and the substrate Due to this, there is a problem in that the warpage of the laminate occurs. The warpage phenomenon is achieved by controlling the degree of thermal expansion of the first bonding layer and the second bonding layer by controlling the solid content of the first bonding layer and the second bonding layer, thereby reducing the difference in the degree of thermal expansion occurring in the first metal layer and the second metal layer. This can be prevented by offsetting each other. In addition, when the volume of the first metal layer to be stacked is lower than that of the second metal layer or when a difference in volume occurs compared to the second metal layer due to pattern formation on the first metal layer, a warpage phenomenon may also occur. The solid content of the paste for the first bonding layer applied between the first small-volume metal layer and the ceramic substrate and/or the thickness of the first bonding layer is determined by the second bonding applied between the relatively bulky second metal layer and the ceramic substrate. By controlling the solid content of the layer paste and/or the thickness of the second bonding layer, the bonding interface stresses are designed to cancel each other, thereby preventing the warpage from occurring.

forming a first bonding layer and a second bonding layer;

Referring to FIG. 1 , in this step, a first bonding layer 210 and a second bonding layer 220 are formed by printing each of the first paste and the second paste having different solid content on both sides of the ceramic substrate 100 , respectively. do.

The ceramic substrate may include at least one selected from the group consisting of silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), and Zirconia Toughened Alumina (ZTA).

The first paste and the second paste may have different solid content from each other. For example, the solid content of the first paste may be greater than the solid content of the second paste. Specifically, the solid content of the first paste may be 5 to 30 wt% or 8 to 20 wt% greater than the solid content of the second paste. When the difference between the solid content of the first paste and the solid content of the second paste is less than the above range, the degree of the curvature suppression effect that can be achieved by the difference in the solid content may be insignificant. That is, due to the difference in thermal expansion caused by the difference in solid content, the degree of effect required to suppress the occurrence of warpage may be insignificant. When the above range is exceeded, the second paste having a relatively low solid content may have insufficient solid content, resulting in poor sintering density, resulting in poor bonding. This may become impossible and a problem of poor printability may occur.

In addition, the solid content of the first paste and the second paste may each independently be 65 to 95 wt% based on the total weight of the paste. Specifically, the solids content of the first paste may be 80 to 95% by weight, and the solids content of the second paste may be 65 to 80% by weight.

When the solid content of the first paste and the second paste is less than the above range, that is, when the solid content is small, the sintering density is lowered due to the lack of solid content in the paste, and bonding defects may occur, and the paste contains a high content of organic matter In the post-treatment process, a void problem may occur due to the generation of bubbles, and when the above range is exceeded, that is, when the solid content is excessive, the dispersibility of the paste is too high because the solid content is too high, and the printability is poor because the viscosity is too high Problems can arise.

The first paste and the second paste are not particularly limited as long as they are generally applicable to the bonding layer of the ceramic substrate, and the first paste and the second paste each independently contain silver (Ag), copper (Cu) and an active metal. may include For example, the active metal may include at least one selected from the group consisting of titanium (Ti), zirconium (Zr), hafnium (Hf), titanium hydride (TiH ₂ ), and zirconium hydride (ZrH ₂ ). Specifically, the active metal may include titanium.

In addition, the first paste and the second paste may each independently contain 0.5 to 5% by weight or 1 to 5% by weight of the active metal based on the total weight of the paste. When the content of the active metal in the paste is less than the above range, a problem occurs that the heat resistance of the substrate is lowered. Economic problems may arise.

The printing is not particularly limited as long as it is applicable during brazing in the conventional AMB process, and for example, it may be performed by a method such as screen printing.

Laminating the first metal layer and the second metal layer and heat-treating

Referring to FIG. 1 , in this step, a laminate 10 is formed by laminating a first metal layer 310 and a second metal layer 320 on the first bonding layer 210 and the second bonding layer 220 , respectively. manufactured and heat treated.

The first metal layer and the second metal layer may include any material applicable to the AMB process without any particular limitation, and may include, for example, copper (Cu). Specifically, the first metal layer and the second metal layer may be a copper thin film.

In this case, the first metal layer and the second metal layer may have a thickness ratio of 1:0.8 to 1:1.2 or 1:0.9 to 1:1.1. When the thickness ratio of the first metal layer and the second metal layer is less than or greater than the above range, that is, when the thickness of the second metal layer with respect to the thickness of the first metal layer is thin or thick, the manufactured ceramic substrate may warp in a high temperature environment. have. When the application area of each of the first metal layer and the second metal layer is the same, the thickness ratio may be a volume ratio.

The heat treatment may be performed at a vacuum of 1 torr or less or 1X10 ^-3 to 0.1 torr and a temperature of 750 to 950 °C or 800 to 900 °C. When the pressure during the lamination exceeds the above range, that is, when the degree of vacuum is low, a void defect problem may occur. In addition, when the lamination temperature is less than the above range, a non-bonding problem may occur, and if it exceeds the above range, a problem of lowering bonding strength may occur.

The first bonding layer is thinner than the second bonding layer. In this case, the thickness of the first bonding layer and the second bonding layer is measured after heat treatment, and may be a thickness measured by observing a cross section of the heat treated ceramic substrate with SEM or the like.

Specifically, the first bonding layer and the second bonding layer may have a thickness ratio of 1:0.4 to 1:0.98, or a thickness ratio of 1:0.40 to 0.90. That is, the second bonding layer is thinner than the first bonding layer, so that the thickness of the second bonding layer applied between the relatively bulky second metal layer and the ceramic substrate is similar to that of the relatively small first metal layer. Since the thickness of the first bonding layer applied between the ceramic substrates is thinner than the thickness of the first bonding layer, the bending phenomenon of the laminate due to the volume difference between the first metal layer and the second metal layer can be prevented by allowing the bonding interface stress to cancel each other out.

When the thickness ratio of the first bonding layer and the second bonding layer is less than the above range, that is, when the thickness of the second bonding layer is excessively thin based on the thickness of the first bonding layer, it becomes thinner than the minimum thickness required to form a uniform thickness. 2 Since the bonding layer is not formed with a uniform thickness on the entire surface of the substrate, voids and micro-voids may occur, or bonding may not occur. In addition, when the thickness ratio of the first bonding layer and the second bonding layer exceeds the above range, that is, when the thickness of the second bonding layer is excessively thick based on the thickness of the first bonding layer, the curvature suppression effect is lowered and the degree of bending is rather becomes larger, which may lead to an increase in the defect rate.

In addition, the average thickness of the first bonding layer may be 10 to 18 μm or 14 to 18 μm, and the average thickness of the second bonding layer may be 5 to 18 μm or 6 to 18 μm. When the average thickness of the first bonding layer is less than the above range, the suppression of the occurrence of warpage is insufficient, and when it exceeds the above range, the bonding layer is too thick and cracks may occur during the heat resistance test. In addition, when the average thickness of the second bonding layer is less than the above range, there is a problem in that voids are generated or bonding is not performed.

In this case, the thickness of each of the first bonding layer and the second bonding layer may be adjusted by, for example, adjusting the size of a mesh used for printing.

The manufacturing method of the present invention is after heat treatment,

forming a pattern by etching at least a portion of the first metal layer and the first bonding layer of the heat-treated laminate;

etching a portion of the unetched first metal layer to expose at least a portion of the first bonding layer, and

The method may further include polishing the surface of the unetched first metal layer.

Referring to FIG. 2 , in the manufacturing method, after heat treatment, at least a portion of the first metal layer and the first bonding layer are etched to expose at least a portion of the ceramic substrate, and a portion of the unetched first metal layer is etched to obtain a first suitable At least a portion of the layer may be exposed and the surface of the unetched first metal layer may be polished.

etching at least a portion of the first metal layer and the first bonding layer;

Referring to FIG. 2 , in this step, at least a portion of the first metal layer 310 and the first bonding layer 210 is etched to expose at least a portion of the ceramic substrate to form a pattern.

The etching in this step can be applied without any particular limitation as long as it is a method of etching the brazing layer in the general AMB process, for example, Ag etching, Ti etching, secondary etching, and the like.

etching a portion of the unetched first metal layer;

Referring to FIG. 2 , in this step, a portion of the unetched first metal layer is etched to expose at least a portion of the first suitable layer.

Referring to FIG. 3 , a fillet a in which a portion of the bonding layer is minutely exposed may be formed on the outer portion of the pattern through partial etching of the first metal layer in this step. Such a fillet can improve the heat resistance of the ceramic substrate made of AMB. The fillet serves to suppress delamination due to a difference in coefficient of thermal expansion by reducing the volume of the metal layer at the edge of the pattern.

In this case, the etching of the first metal layer may be applied without any particular limitation as long as it is an etching method applicable to the AMB process, and for example, methods such as development, etching, and peeling may be used.

Polishing the surface of the unetched first metal layer

In this step, the surface of the unetched first metal layer is polished.

The polishing of the surface of the first metal layer has effects such as improvement of surface roughness of the ceramic substrate, improvement of surface unevenness, and improvement of glossiness.

In this case, the polishing may be applied without any particular limitation as long as it is a method applicable to improving the surface properties of the ceramic substrate in general, for example, a method of mechanically polishing using a diamond grinding machine may be mentioned. In addition, the polishing may be performed at a rotation speed of 1000 to 1200 rpm, and a processing speed of 0.7 to 4 μm/sec, and mechanical polishing using a diamond grindstone having a particle size of #600 may be performed.

In addition, the polishing may be performed so that the average surface roughness (Ra) of the first metal layer is 0.5 to 1 μm or 0.6 to 0.8 μm.

The method of manufacturing a ceramic substrate according to the present invention as described above controls the solid content and/or thickness of the upper and lower bonding layers to control the warpage phenomenon caused by the difference in volume occupied by the upper and lower metal layers of the ceramic substrate. Thus, it is possible to reduce the defect rate of the ceramic substrate.

ceramic substrate

The ceramic substrate according to the present invention includes a laminated form in which a first metal layer, a first bonding layer, a ceramic substrate, a second bonding layer, and a second metal layer are stacked, wherein the first bonding layer is thinner than the second bonding layer. . Specifically, the first bonding layer and the second bonding layer have a thickness ratio of 1:0.4 to 1:0.98, or a thickness ratio of 1:0.4 to 1:0.9. In addition, the ceramic substrate may be manufactured using two types of pastes having different solid content, which is the manufacturing method as described above. In addition, the ceramic substrate may prevent warpage of the laminate by adjusting the thickness ratio of the first bonding layer and the second bonding layer as described above.

When the thickness ratio of the first bonding layer and the second bonding layer is less than the above range, that is, when the thickness of the second bonding layer is excessively thin based on the thickness of the first bonding layer, it becomes thinner than the minimum thickness required to form a uniform thickness. 2 If the bonding layer is not formed with a uniform thickness on the entire surface of the substrate, voids and micro-voids occur, or a bonding problem occurs, and when the above range is exceeded, that is, the thickness of the second bonding layer is based on the thickness of the first bonding layer. If the thickness is thick, the curvature suppression effect is lowered and the degree of curvature is rather large, which may cause a problem in that the defect rate is increased.

Each of the first metal layer, the first bonding layer, the ceramic substrate, the second bonding layer, and the second metal layer is the same as described in the manufacturing method.

At this time, referring to FIG. 3 , as described in the manufacturing method, in the ceramic substrate, the first metal layer and a portion of the first bonding layer are etched to form a pattern, and a fillet (a) in which a portion of the first bonding layer is exposed. ) may be included. Typically, the fillet (a) formed through etching is formed for the purpose of improving the thermal properties of the product. The fillet (a) serves to suppress peeling due to a difference in coefficient of thermal expansion by reducing the volume of the metal layer at the edge of the pattern.

The ceramic substrate of the present invention as described above has excellent interlayer bonding strength and high thermal fatigue, so that it is highly reliable as a substrate for electronic components and has excellent mechanical properties.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for helping the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[Example]

Experimental Example 1.

Prepared by mixing TiH ₂ powder with alloy powder consisting of silver (Ag) and copper (Cu) to obtain metal powder, and then mixing α-terpineol and diethyl glycol monobutyl ether acetate with metal powder Paste (AS102, Mitsubishi Corporation, solid content 85% by weight) was used as the first paste.

The second paste was used after adjusting the solid content to 75 wt% by adding diethyl glycol monobutyl ether acetate to the first paste.

Thereafter, a first bonding layer was formed by printing a first paste on one surface of the aluminum nitride ceramic substrate through screen printing, and a second bonding layer was formed by printing a second paste on the other surface. Thereafter, a thin copper plate (first metal layer) having a thickness of 0.3 mm was laminated on the first bonding layer, and a thin copper plate (second metal layer) having a thickness of 0.3 mm was laminated on the second bonding layer to prepare a laminate. After that, the laminate was put into a vacuum furnace of 0.1 torr or less and a vacuum furnace at a temperature of 850° C.

After the heat treatment, the first bonding layer had a thickness of 16 μm, and the second bonding layer had a thickness of 6.4 μm.

Thereafter, the first metal layer was etched to form a predetermined circuit pattern, and the unetched first bonding layer was brazed and etched to expose a portion of the first bonding layer to form a fillet. Thereafter, the surface of the unetched first metal layer was chemically polished to prepare a ceramic substrate.

Experimental Examples 2 to 20.

As shown in Table 1, a ceramic substrate was prepared in the same manner as in Experimental Example 1, except that the thickness of the first bonding layer and the second bonding layer was adjusted by adjusting the solid content of the first paste and the second paste. .

division Solid content (% by weight) Average thickness (㎛) Thickness ratio of the first bonding layer and the second bonding layer first paste second paste first bonding layer second bonding layer Experimental Example 1 85 75 16 6.4 1: 0.4 Experimental Example 2 85 75 16 9.6 1: 0.6 Experimental Example 3 85 75 16 12.8 1: 0.8 Experimental Example 4 85 75 16 15.7 1: 0.98 Experimental Example 5 80 65 16 6.4 1: 0.4 Experimental Example 6 85 70 16 9.6 1: 0.6 Experimental Example 7 90 75 16 12.8 1: 0.8 Experimental Example 8 95 80 16 15.7 1: 0.98 Experimental Example 9 85 75 20 2 1: 0.1 Experimental Example 10 85 75 20 4 1: 0.2 Experimental Example 11 85 75 20 24 1:1.2 Experimental Example 12 85 75 20 30 1: 1.5 Experimental Example 13 70 73 16 6.4 1: 0.4 Experimental Example 14 75 73 16 9.6 1: 0.6 Experimental Example 15 96 73 16 12.8 1: 0.8 Experimental Example 16 98 73 16 16 1:1 Experimental Example 17 88 55 16 6.4 1: 0.4 Experimental Example 18 88 60 16 9.6 1: 0.6 Experimental Example 19 88 88 16 16 1:1 Experimental Example 20 88 50 16 9.6 1: 0.6

Experimental Example 1. Characteristic evaluation

The physical properties of the ceramic substrate prepared in Experimental Example were evaluated in the following manner, and the results are shown in Table 2.

(1) warpage

The ceramic substrate was placed on a flat glass plate and the maximum distance the ceramic substrate was separated from the glass plate was measured. After the ceramic substrate was treated at 250° C. for 1 minute, the maximum distance the ceramic substrate was separated from the glass plate was measured in the same manner as above.

(2) heat resistance

One cycle of treating the heat resistance of a ceramic substrate of size 6.5mmX4.5mmX0.32mm (width X length X thickness) at -50°C for 15 minutes using a thermal shock tester (TCT, TSA-71L) and then at 150°C for 15 minutes (cycle), a thermal fatigue test was conducted by measuring the number of cycles in which the substrate was not damaged while processing a total of 3,000 cycles.

(3) bonding strength

The commercial ceramic was mounted on a universal material testing machine (UTM), and the bonding strength between the first bonding layer and the first metal layer and between the second bonding layer and the second metal layer was measured. Specifically, the bonding strength between the bonding layer and the metal layer was measured at a peeling rate of 50 mm/min.

division Warpage (mm) heat resistance
(cycle) Bond strength (N/mm) before heat treatment after heat treatment first bonding layer second bonding layer target 0.19mm or less 0.19mm or less 1,000 or more 10N/mm or more 10N/mm or more Experimental Example 1 0.082 0.119 3,000 16.2 14.5 Experimental Example 2 0.095 0.139 3,000 16 16.6 Experimental Example 3 0.122 0.179 3,000 16.3 16.1 Experimental Example 4 0.128 0.189 3,000 16.5 14.9 Experimental Example 5 0.086 0.124 3,000 15.9 12.5 Experimental Example 6 0.117 0.170 3,000 16.1 14.4 Experimental Example 7 0.129 0.188 3,000 15.5 16.2 Experimental Example 8 0.127 0.187 3,000 15.4 15.7 Experimental Example 9 0.104 0.149 500 or less 11.9 2.9 Experimental Example 10 0.098 0.140 500 or less 12.4 4 Experimental Example 11 0.214 0.308 500 or less 12.5 10.5 Experimental Example 12 0.304 0.432 500 or less 13.2 9.8 Experimental Example 13 0.077 0.109 500 or less 9.2 14.1 Experimental Example 14 0.092 0.133 500 or less 9.4 16.1 Experimental Example 15 Measurable not printable 15.8 Experimental Example 16 Measurable not printable 15.7 Experimental Example 17 0.083 0.121 500 or less 16.3 3.9 Experimental Example 18 0.093 0.137 500 or less 16.2 4.3 Experimental Example 19 0.137 0.191 3,000 16.3 16.1 Experimental Example 20 0.125 0.216 500 or less 16.3 3.1

As shown in Table 2, the ceramic substrates of Experimental Examples 1 to 8 were excellent in interlayer bonding strength, curvature was suppressed, so the defect rate was low, and heat resistance was excellent.

On the other hand, in Experimental Examples 9 and 10, in which the thickness of the second bonding layer was thin based on the thickness of the first bonding layer, the heat resistance was insufficient and the bonding strength between the second bonding layer and the second metal layer was insufficient. In particular, in Experimental Examples 9 and 10, since the thickness of the second bonding layer was too thin, the amount of paste applied during the preparation of the second bonding layer was too small, and there were many unreacted parts, so heat resistance was very insufficient.

In addition, Experimental Examples 11 and 12, in which the thickness of the second bonding layer was thick based on the thickness of the first bonding layer, lacked heat resistance, and warpage occurred after heat treatment. Further, in Experimental Examples 11 and 12, the thickness of the second bonding layer was thick, making it difficult to implement one-time printing, and in particular, the thickness of the prepared second bonding layer was thick, so the bonding strength between the second bonding layer and the second metal layer was insufficient.

In Experimental Examples 13 and 14, in which the solid content of the first paste was less than the preferred range, the solid content of the first bonding layer was low and the organic material content was relatively high, so that bubbles were generated after bonding, resulting in poor bonding strength and very poor heat resistance.

In addition, in Experimental Examples 15 and 16, printing of the first bonding layer was impossible due to insufficient printability due to excessively high solid content of the first paste.

In Experimental Examples 17 and 18, since the solid content in the second paste was insufficient, the sintered density was lowered, and the bonding strength between the second bonding layer and the second metal layer was very insufficient, so bonding using the second bonding layer was impossible, and the heat resistance was also insufficient. .

In Experimental Example 19, since the solid content of the first paste and the second paste were the same, the effect of suppressing warpage was insignificant, and warpage failure occurred after heat treatment.

In Experimental Example 20, the solid content of the second paste was low and the sintered density was lowered, so that the bonding strength of the second bonding layer was poor, heat resistance was insufficient, and warpage after heat treatment was defective.

Claims (5)

forming a first bonding layer and a second bonding layer by printing each of the first paste and the second paste having different solid content on each of both surfaces of the ceramic substrate; and
Including; laminating a first metal layer and a second metal layer on the first bonding layer and the second bonding layer, respectively, to prepare a laminate and heat treatment;
The first bonding layer is thinner than the second bonding layer, the method of manufacturing a ceramic substrate. The method according to claim 1,
The solid content of the first paste is 5 to 30% by weight greater than the solid content of the second paste, the method of manufacturing a ceramic substrate. The method according to claim 1,
The solid content of the first paste is 80 to 95% by weight,
The second paste has a solid content of 65 to 80% by weight, a method of manufacturing a ceramic substrate. a first metal layer, a first bonding layer, a ceramic substrate, a second bonding layer, and a second metal layer in a laminated form,
wherein the first bonding layer is thinner than the second bonding layer. 5. The method according to claim 4,
The first bonding layer and the second bonding layer have a thickness ratio of 1:0.4 to 1:0.98, a ceramic substrate.

Images