JPH04182367A - Ceramic substrate joined to metallic plate - Google Patents

Abstract

PURPOSE:To improve the thermal impact resistance of the above ceramic substrate by specifying the shape of the corner angle parts of metallic plates, the ratio of the margin widths on a packaging surface side and a heat radiating surface side and the thickness of the ceramic substrate at the time of producing the ceramic substrate by joining the metallic plates and the ceramic substrate. CONSTITUTION:The corner angle parts, plan-viewed, of the metallic plates 2, 3 are previously rounded at a radius of curvature of 0.5 to 2mm at the time of joining the packaging surface side metallic plate 2 to one surface of the ceramic substrate 1 and joining the heat radiation surface side metallic plate 3 to the other surface. The margin width (y) on the heat radiation surface side between the peripheral edge of the metallic plate 3 and the peripheral edge of the ceramic substrate 1 is set 0.3 to 10 times the margin width (x) on the packaging surface side between the peripheral edge of the metallic plate 2 and the peripheral edge of the ceramic substrate 1. Further, the thickness of the ceramic substrate 1 is specified to >=0.5mm. The thermal stresses generated by the difference between the coeffts. of thermal expansion of the metallic plates 2, 3 and the ceramic substrate 1 are relieved in this way. The ceramic substrate joined to the metallic plates having the excellent thermal impact strength is thus produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a metal-like bonded ceramic substrate, and relates to a structure in which thermal stress is alleviated.

[Prior art] Due to the difference in thermal expansion coefficient and Young's modulus between metal and ceramic substrates, thermal shock resistance tests (tests that measure the number of times a ceramic substrate cracks by repeating thermal shock from -65°C to +150°C) , thermal stress occurs on the ceramic substrate,
Cracks occur. Conventionally, thermal stress has been reduced by making the copper plate on the heat dissipation side thinner, by rounding the peripheral edge of the body fold into a concave shape in the thickness direction, or by forming a fillet of brazing material. However, these measures are still insufficient and cannot prevent the occurrence of cracks in demanding cases.

[Problems to be Solved by the Invention] An object of the present invention is to provide a simple and effective structure for alleviating thermal stress caused by the difference in coefficient of thermal expansion between a metal plate and ceramics, which could not be solved by conventional techniques.

[Means to solve the problem]

The present invention provides a substrate formed by bonding metal and ceramics, in which the metal plate has a radius of curvature of 0 at the corner portion when viewed in plan.
．． It has a roundness of 5 mm or more, and the width of the margin on the heat radiation surface side between the peripheral edge of the metal plate and the peripheral edge of the ceramic plate is 0.3 to 10 times the width of the margin on the mounting surface side, and This is a metal plate bonded ceramic substrate characterized by having a thickness of 0.5 mm or more.

[Effect]

In the present invention, the corner portion of the plane figure of the copper plate has a radius of curvature R-05.
It has a roundness of ~2.0 mm. Radius of curvature R is 0
．． Below 5 mm, the thermal stress is not reduced, and below 2.0 m
If it exceeds m, pattern accuracy will deteriorate.

FIG. 1 shows a schematic cross section of a metal plate ceramic bonded plate.

A mounting side metal plate 2 is attached to one side of a ceramic substrate 1, and a heat dissipation side metal plate 3 is attached to the other side.

Thermal stress generated in the ceramic substrate is determined by the ratio of the margin width y between the periphery of the metal plate 3 on the heat dissipation side and the periphery of the ceramic substrate and the margin width X of the metal plate 2 on the mounting side as shown in Fig. 2. It becomes like this.

As y increases, the thermal stress decreases due to the balance between the front and back metal plates, but it reaches a minimum value at a certain value of y/x, and when y/x increases beyond that, the heat generated in the ceramic substrate increases. Stress increases. 165 in Figure 2
11kg/mm' or less is shown as the thermal stress value when the number of repeated thermal shocks between ℃ and +150''C exceeds 100 times.From Figure 2, it is possible when 0.3 < y / x < 10. If it is less than 100 times, it cannot withstand actual use, so y / x is 0, which exceeds 100 times.
The range was limited to 3<y/x<10.

Next, make the ceramic substrate thicker (thus, the bending moment generated in the ceramic substrate can be reduced, and the number of thermal shocks it can withstand can be increased. Thickness t is 0.5
If it is less than mm, the thermal shock resistance is 50 to 100 times,
It cannot be used in practice because it does not stably exceed 100 times. Therefore, it was set to 0.5 mm or more.

Furthermore, n=0.5~2.0mm, 0.3<y/x<1
0.0, Al2N thickness≧0.5 mm Although each of these alone has an effect, when they are combined, the thermal shock resistance can be dramatically improved.

[Example] A bonded body of alumina, Al2N and copper plates measuring 50 mm x 50 mm was prepared and the following tests were conducted. t-0,635mm
, y/x=2.0 Table 1 shows a comparison of the thermal shock resistance numbers when the corners of the plane of the copper plate with y/x=2.0 are not rounded and when they are rounded.

In the thermal shock test, the bonded body was subjected to temperatures of -65°C and +150°C.
Thermal shock was repeatedly applied to the ceramic substrate at temperatures between 1 and 2°C, and the number of times it took for the ceramic substrate to crack was measured. When n=0.5 or more, the thermal shock resistance clearly exceeds 100 times and can withstand actual use.

The above-mentioned alumina, AρN and copper plate bonded body, R-2,0,
For the one with t = 0.635 mm, y / x = 0.0,
0.1.0.2.0.3.0.5.1.0.50.10
．． 0.11.0115. Table 2 shows the results of actually measuring the thermal shock resistance of a bonded body of a ceramic substrate prepared with O. When y/x is 03 or more, the thermal shock resistance exceeds 100 times and it can be used. If y/x exceeds 10, the thermal shock resistance decreases to less than 100 times and cannot withstand actual use.

In addition, the thickness t of the ceramic substrate in the above-mentioned bonded body of alumina, AgN, and copper plate is 0.25, 0.45.0, respectively.
, 5.0635.1, 0.1.5.2.0m and R=
Thermal shock resistance of the joined body with a thickness of 1 mm and y/x=2 was measured. As shown in Table 3, when t=0.45 mm or less, the thermal shock resistance was 50 times or less, but when t=0.5 mm or more, it showed good results exceeding 100 times.

Table 4 shows the effect on the thermal shock resistance number (n) when combining the R and y/x of the corners of the copper plate and the thickness t of the AffN substrate in a bonded body of an A42N substrate (50 mm x 50 mm) and a copper plate. R=1.0 mm and y/x=2.0. t
= 0.635 mm, n = 100-130 times, but when R and t are the same but y / x = 5.0, n = 130-150 times, /IN substrate thickness When t is 1.0 mm, n=150 to 200 times. Also, y/x = 2.0, t = 0.635m
If you leave m as is and change R from 1.0 to 2.0 m, then n
= increased to 150-200 times. Furthermore, n=2.0m
m in y/x = 5.0, t = 1.0 m m
In this case, the thermal shock resistance exceeds 250 times, making it possible to produce a bonded body with extremely excellent thermal shock resistance. Thus n=0.5-2.0.0.3 <y/x<10
, t = 0.5 mm or more, the thermal shock resistance can be dramatically improved by combining the conditions of the present invention.

Table 1 Table 4 [Effect of the Invention 1 According to the present invention, in a metal plate bonded ceramic substrate, the thermal shock resistance can be improved by simple structural improvement.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a metal plate ceramic bonded plate, Figure 2
The figure is a graph showing the y/x dependence of thermal stress generated in a ceramic substrate, which was determined from numerical calculations. 1...Ceramics board 2...Metal plate on the mounting surface side 3 -Metal plate on the heat dissipation surface side X...Margin width on the mounting surface side y/Margin width on the heat dissipation surface side

Claims (1)

[Claims] 1. In a substrate made by joining metal and ceramics, the metal plate has a radius of curvature of 0.5 to 2.0 mm at the corner of the plane.
roundness, the margin width on the heat dissipation surface side between the peripheral edge of the metal plate and the peripheral edge of the ceramic substrate is 0.3 to 10 times the margin width on the mounting surface side, and the thickness of the ceramic substrate A metal plate bonded ceramic substrate characterized in that the diameter is 0.5 mm or more.