JPH0451485Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to an improvement of a ceramic substrate for a semiconductor package that hermetically seals a semiconductor element. [Prior Art] Semiconductor devices including high-density integrated circuits (ICs)
It is highly susceptible to external environment such as oxidation and pollution,
For this reason, performance deterioration or reliability is likely to deteriorate depending on the outside air environment. To prevent this, semiconductor devices are hermetically sealed using packages made of plastic, metal, or ceramic substrates. It relies on a ceramic substrate package that provides an airtight seal. In conventional ceramic substrates of this type, the corners are rounded and the edges have one minute step along the outer periphery of the ceramic substrate.
In addition, two rounded edges are formed to prevent chipping and cracking from occurring in the ceramic substrate (for example, Japanese Patent Publication No. 57-450062 and FIG. 4). [Problem to be solved by the invention] Ceramic substrates used in semiconductor packages are generally made by press-molding metal oxides and forming high-temperature sintered sheets, and they have good chemical resistance, heat resistance, good electrical insulation, and Has high thermal conductivity. On the other hand, their impact resistance and mechanical strength are relatively low, and as a result, when semiconductor packages collide with each other during the assembly process of semiconductor elements or during product transportation, chips may occur, especially at the corners and edges of the outer peripheral edge of the package. Cracks often occur, reducing reliability.
As a result, this resulted in a loss of marketability. Conventional ceramic substrates for semiconductor packages can be prevented from chipping and cracking to a certain extent compared to those formed simply in the form of a rectangular parallelepiped and flat plate. I can't hold back,
In this sense, there was a drawback that the yield of the product was low. The present invention was devised in view of the above-mentioned problems of the prior art, and its purpose is to prevent the edges and corners of ceramic substrates from being chipped during the assembly process of semiconductor devices and during product transportation. It is an object of the present invention to provide a ceramic substrate which has a very good yield of products because the occurrence of chips and cracks is extremely rare, and even when chips and cracks occur, the size of chips and cracks is extremely small. [Means for Solving the Problems] In order to achieve the above object, the ceramic substrate of the present invention has a cavity portion for accommodating a semiconductor element, and has a semiconductor substrate having a slightly rounded corner on its outer peripheral end surface. A ceramic substrate for a package, the ceramic substrate having a minute step along the outer periphery of the ceramic substrate at an edge on an end surface opposite to the surface in which the cavity portion is bored.
forming two step portions and three rounded ridge portions;
L ₁ and the width L ₂ of the second portion on the lower side are formed in a relationship such that L ₁ ≫L ₂ . [Example] An example will be described with reference to the drawings. 1 to 3, a ceramic substrate 1 for a semiconductor package has a width of 2 cm, a length of 5 cm, and a thickness of
It is formed in the shape of a rectangular parallelepiped plate with a diameter of 1.5 mm.
One end (side surface) in the longitudinal direction has a radius of approximately 1 mm.
A semicircular automatic insertion notch 2 is formed. The corners 3 of the outer peripheral end surface of this ceramic substrate 1 are each rounded with a radius of about 0.4 mm, and the corners 3 are rounded with a radius of approximately 0.4 mm, and the corners 3 are rounded on the opposite side to the surface where the cavity portion 4 for accommodating the semiconductor element A is formed. The edge 5 at the end surface of the surface has two step portions 6 and 7 along the outer periphery of the ceramic substrate 1, each having a minute step of about 0.1 mm, and a radius.
Three ridges 8 with roundness of about 0.04 to 0.06 mm,
9 and 10 are formed, and the width L ₁ of the first step 6 on the upper side and the width L ₂ of the second step 7 on the lower side are L ₁
≫It is formed in the relationship of L ₂ (see Figure 3). The code 1A indicates a cap made of a ceramic substrate.
1B indicates a base having the same shape as the cap 1A. 1
1 is a sealing glass that adheres the cap 1A and the base 1B and hermetically seals the inside of the package.
Further, 12 is a lead frame. The ceramic substrate 1 configured as described above is
Even if the ceramic substrates 1 randomly collide with each other during the assembly process of semiconductor packages or the process of transporting assembled semiconductor packages, the impact force applied to the corners 3 will be small because the corners 3 are rounded. The corners 3 are softened and therefore less prone to chipping and cracking, and the edges 5 are rounded ridges 8,
9 and 10 with two step parts 6 and 7, the impact force applied to the edge 5 is dispersed and alleviated by the three ridge parts 8, 9, and 10. Edge 5 is also less prone to chips and cracks. When impact tests were conducted on semiconductor packages assembled using the ceramic substrates described in the above embodiments, test results as shown in Table 1 were obtained.

[Table] The test method was to assemble 100 sets of semiconductor packages assembled using the conventional ceramic substrate shown in Fig. 4 and 100 sets of semiconductor packages assembled using the ceramic substrate 1 according to the embodiment of the present invention. Regarding the semiconductor package assembled using a ceramic substrate and the semiconductor package assembled using the ceramic substrate 1 according to the embodiment of the present invention, each semiconductor package was made of plastic formed as a hollow cylinder with a length of 50 cm and a concave cross section. After storing the semiconductor package in a semiconductor package storage tube and covering both end surfaces of the tube with ceramic substrates made of the same material,
The tube was repeatedly rotated 10 times in the vertical direction at an angular velocity of 180 degrees per second, and the number of chipped or cracked semiconductor packages was determined. As is clear from Table 1, semiconductor packages assembled using conventional ceramic substrates were hit an average of 6.3 times, resulting in chipping and cracking in 3 out of 100 packages, whereas the present invention's In the semiconductor packages assembled using the ceramic substrate 1 according to the example, only 2 out of 100 chips or cracks occurred after an average of 8.5 collisions.
Moreover, most of the particles were generated in extremely small sizes at the edges of the outer peripheral end face perpendicular to the longitudinal direction of the semiconductor package substrate. Further, ceramic substrates A, B, C, which are formed with two step portions having minute steps and three rounded ridge portions along the outer periphery of the ceramic substrate.
100 sets of each semiconductor package were assembled using D (a sample in which the relationship between the upper width L ₁ of the two steps and the width L ₂ of the lower second step) was assembled, and the above-mentioned test was performed. When a similar impact test was conducted using the same method, the test results shown in Table 2 were obtained.

【table】

[Effect of idea]

Since the present invention is configured as described above,
This produces the following effects. By forming two steps with different widths on the outer peripheral edge of the ceramic substrate, it is possible to disperse and weaken the impact force applied to the edge, thereby preventing chips and cracks that occur due to collisions between the ceramic substrates. It is possible to reduce the occurrence of chips, and to keep the size of chips etc. to be extremely small. Further, since the stepped portion is formed in two stages, it is possible to apply strong molding pressure to the end portion of the ceramic substrate during molding, and it is possible to increase the strength of the edge of the package.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a semiconductor package formed using a ceramic substrate according to the present invention, FIG. 2 is an enlarged cross-sectional view thereof, FIG. The figure is a schematic enlarged cross-sectional view of the main part of a conventional ceramic substrate.

Claims (1)

[Scope of utility model registration request] A ceramic substrate for a semiconductor package, which has a cavity portion for accommodating a semiconductor element, and has a slightly rounded corner on its outer peripheral end surface, the end surface being opposite to the surface where the cavity portion is bored. Two step portions having a slight step and three rounded ridge portions are formed on the edge along the outer periphery of the ceramic substrate, and the two step portions are connected to the first step portion on the upper side. 1. A ceramic substrate characterized in that a width L ₁ of the lower second step portion and a width L ₂ of the second step portion on the lower side are formed in a relationship such that L ₁ ≫L ₂ .