JPH054819B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a ceramic substrate, and more particularly to a ceramic substrate for mounting and storing circuit elements, which is suitably used as a package substrate for mounting and housing semiconductor integrated circuit elements. (Problems to be Solved by the Prior Art and the Invention) As is well known in the art, ceramics have excellent insulation properties, wear resistance, chemical stability, high hardness, and low coefficient of thermal expansion. It is extremely excellent and widely used as a material for package substrates for housing semiconductor integrated circuit elements. However, ceramic has the disadvantage of being weak in impact resistance, so for example, when viewed from the top, the ceramic substrate shown in FIG. ′ forms one plane, when ceramic substrates 1 collide with each other in a semiconductor package manufacturing line, the end surfaces 1 ′ or the end surfaces 1 ′ of one substrate collide with the corner R of the other substrate. By doing,
Cracks, cracks, chips, etc. often occur in these ceramic substrates 1. In particular, semiconductor integrated circuit elements are mounted on a ceramic substrate 1.
When the semiconductor device mounting process, which includes many operations such as mounting on top and wire bonding, is carried out on an automated assembly line, when the ceramic substrate 1 is moved sequentially on the line, it may fall under its own weight on an inclined surface. In order to force the ceramic substrates 1 to move or move them by blowing compressed air, the ceramic substrates 1 repeatedly collide violently with each other, resulting in frequent cracks and cracks in the ceramic substrates 1, resulting in reduced product yield and reliability. This was causing major problems such as lowering the performance. The causes of cracks and chips caused by collisions between ceramic substrates include (1) differences in the compression ratio between the upper and lower parts in the case of press forming, (2) temperature conditions during firing, and (3) outer surface roughness. , (4) Although many factors are involved, such as the particle size and compounding ratio of the raw materials, the inventor has conducted various experiments and found that even if the end surfaces 1' of the ceramic substrates 1 collide head-on, no cracking or chipping will occur. Although it is rare, in the case of an inclined collision, that is, when the corner portion R of the following ceramic substrate collides with the end face 1' of the ceramic substrate stationary in front, the corner portion R
It was also found that cracks, cracks, and chips frequently occur at each ridgeline, and based on these results, it was discovered that the occurrence of cracks, breaks, and chips can be effectively prevented by adjusting the shape of the outer end surface of the ceramic substrate. . (Means for Solving the Problems) As a result of research, the inventor of the present invention found that the outer end face of a rectangular substrate made of ceramic for mounting and storing circuit elements is susceptible to impact from collision, when viewed from above,
In addition to forming an arc-shaped convex portion, a corner portion forming the base end of the convex portion is rounded, and the height of the convex portion is set to be 0.05 mm to 1.0 mm. Therefore, it has been found that the occurrence of cracks, chips, etc. between the substrates due to impact when the substrates collide with each other can be significantly reduced. Therefore, the purpose of the present invention is based on the above findings,
To provide a ceramic substrate for mounting and storing circuit elements, which is designed to prevent the occurrence of cracks, cracks, and chips to the maximum extent possible. The present invention comprises a planar ceramic substrate on which a semiconductor integrated circuit element is mounted, a ceramic substrate shaped to form a recess for mounting the element in the center, or a plurality of raw ceramic sheets stacked together. This method is particularly effectively applied to ceramic substrates that are sintered and integrated, where cracks, breaks, and chips in the substrate can be a fatal defect in terms of product reliability. (Examples) Hereinafter, the present invention will be described in detail based on examples shown in the accompanying drawings. The ceramic substrate shown in FIG. 1 is a plan view showing an example of a ceramic substrate for mounting a semiconductor integrated circuit element on the top surface.A ceramic substrate 2 has an arc-shaped convex portion 3 on the entire outer end surface of the ceramic substrate 2. form. The bulge of the arc-shaped convex portion 3 in FIG.
Located in the center of the outer end surface, the convex height D is usually about
A suitable value is 0.05 mm or more, preferably 0.1 mm or more. A substrate 2 with such a convex portion formed on the outer end surface
If these collide with each other, for example, as shown in FIG. 2, the arc-shaped convex portions 3, 3' on the outer peripheral end surfaces of the substrates 2, 2' will collide with each other, and the corners of the substrate where cracks, chips, etc. are likely to occur will be affected. It is possible to avoid applying an impact force to the portion and each side ridgeline portion. Furthermore, even if there is a collision in a somewhat inclined manner, the presence of the arcuate convex portions 3, 3' prevents the right-angled corner portions from colliding, which could cause cracks or chips. Even if the corner portions collide, the convex portions 3, 3' can alleviate the impact force, effectively preventing cracks, breaks, and chips in the ceramic substrates 2, 2'. In addition, as shown in FIG. 2, if the corner portions Ra forming the base ends of the convex portions 3 and 3' are rounded,
This effect is further enhanced. As an example, it is a rectangular shape of 24.0 mm x 24.0 mm with an outer shape as shown in Fig. 1, the thickness T = 1.52 mm, and the radius of curvature of Ra at the corner part is 0.381.
A ceramic substrate having an arcuate convex height D=0.1 mm (example) and a convex arcuate portion 3 having a height D=0.02 mm (comparative example) is formed on the outer end surface of the ceramic substrate, which is susceptible to collisions. A collision test was conducted on a conventional ceramic substrate as shown in FIG. 4 having a straight end face, and the results are shown in Table 1. The conditions for this collision test are: length 100cm;
A test group of 20 test boards were arranged in a flat 50cm section at the top of a tray with an inclination of 70°, and were allowed to slide down (fall) using their own weight toward a nylon stopper installed at the bottom of the tray. This kind of downhill skiing is repeated 10 times, and if any cracks, cracks, or chips occur during up to 9 downhill runs, they are replaced with new boards after each downhill run. The number of cracks, cracks, and chips that occurred on the 20 initial boards was counted.

[Table] As is clear from the above test results, in the case of ordinary ceramic substrates, by forming an arc-shaped convex portion with a convex height of D = 0.1 mm on the outer end surface of the substrate, it is possible to improve the distance between the substrates. The occurrence of cracks, cracks, chips, etc. due to collisions can be significantly reduced compared to the case of conventional substrates. In addition, the height of the convex upper part D is
It has been confirmed that even when the thickness is larger than 0.1 mm, the occurrence of cracks, breaks, chips, etc. caused by collisions between boards is significantly reduced. It was also confirmed through experiments that if the height D of the arcuate convexity was 0.05 mm or more, the total defective rate would be 10% or less. In particular, when the thickness is 0.1 mm or more, the effect of preventing cracks, cracks, chips, etc. is extremely excellent, as is clear from Table 1, with a single-digit defective rate. However, as the convex height D increases, the shape of the board, especially the shape of the outer end surface, becomes such that it cannot maintain the original rectangular shape of the ceramic board for mounting and storing circuit elements, that is, it exceeds about 1.0 mm. The deformation becomes noticeable and the molding of the substrate becomes troublesome. Therefore, the height D of the circular convex shape is preferably in the range of 0.05 mm to 1.0 mm. Forming methods for such ceramic substrates include powder pressing, punching from a green sheet using a doctor blade method, or other extrusion methods, followed by cutting with a circular blade, or after sintering. The most suitable method may be used for each method, such as polishing to form a convex portion. As described above, according to the ceramic substrate for mounting and accommodating circuit elements of the present invention, an arcuate convex portion is formed in plan view on the outer end surface which is susceptible to impact from a collision, and the base of the convex portion is formed. The corners forming the ends are rounded, and the height of the convex portion is set to 0.5.
By setting it to be mm or 1.0 mm,
Even if ceramic substrates collide with each other, it is possible to significantly reduce the occurrence of cracks, cracks, chips, etc., and significantly improve yields even under harsh conditions such as assembly processes using automated assembly lines. It is also possible to improve quality and reliability, so it is suitably used for semiconductor devices and the like. In addition, in the present invention, an arc-shaped convex portion is formed in a plan view on the outer end surface which is susceptible to impact due to a collision of a ceramic substrate for mounting and storing circuit elements, and a base of the convex portion is formed. The corner portion forming the end portion is rounded, and the height of the convex portion is
As shown in FIG. 3, it was experimentally possible to form an arcuate rounded convex portion 31 on the entire thickness direction end face of the ceramic substrate 2 in the case where the thickness was set to be 0.05 mm to 1.0 mm. In view of the above results, even if the ceramic substrates collide with each other, it is more preferable because it exhibits the effect of significantly reducing the occurrence of cracks, cracks, chips, etc. The tip of the arc-shaped convex portion 31 in Fig. 3 is located at the center of the end surface in the thickness direction, but the convex height d is also related to the thickness T of the substrate 2, and when the thickness T = 1.52 mm, the convex At height d=0.05~0.1mm, d/T≒
It has been experimentally found that 0.032 to 0.066 is appropriate. When the substrates 2 having such convex portions formed on the end faces in the thickness direction collide with each other, for example, the substrates 2, 2'
Collision between the convex portions 31 and 31 on the outer circumferential end surface can prevent impact force from being applied to corner portions and ridgeline portions of each side where cracking, chipping, etc. are likely to occur. Furthermore, even if a collision occurs in a somewhat inclined manner, the presence of the convex portion 31 can prevent collision at a right-angled corner, which could cause cracking or chipping. Even if there is a collision, the impact force can be alleviated by the convex portion 31, and cracks, breaks, and chips in the ceramic substrates 2, 2' can be effectively prevented. (Effects of the Invention) As described above, according to the ceramic substrate for mounting and accommodating circuit elements of the present invention, even if the ceramic substrates collide with each other, the occurrence of cracks, cracks, chips, etc. can be significantly reduced. It becomes possible. Therefore, it is possible to significantly improve yield even under harsh conditions such as assembly processes using automated assembly lines, and at the same time improve quality and reliability, making it suitable for use in semiconductor devices, etc. be done.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a ceramic substrate according to an embodiment of the present invention, FIG. 2 is a diagram illustrating an example of how the ceramic substrates collide with each other, and FIG. 3 is an end view of a ceramic substrate according to another embodiment of the present invention. 4A is a plan view of a conventional ceramic substrate, and FIG. 4B is a side view of the same. 1: Conventional ceramic substrate, 1': End surface, 2,
2': Ceramic substrate of the embodiment of the present invention, 3, 3':
Convex portion having an arc shape in plan view, 31: Convex portion having an arc shape in cross section, R, Ra: Corner portion.

Claims (1)

[Claims] 1. An arcuate convex portion is formed on the outer end surface of the rectangular ceramic substrate, which is susceptible to shocks caused by collision, when the substrate is viewed from above, and a corner portion forming the base end of the convex portion is rounded. and the height of the convex portion is set to 0.05 mm to 1.0 mm to prevent mutual cracking or chipping of the substrates due to impact when the substrates collide with each other. A ceramic substrate for mounting and storing circuit elements.