JP3372566B2 - Jig made of carbon graphite - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig used for sealing glass of a lead frame of an electronic component, for example, a transistor or a diode. 2. Description of the Related Art A jig 1 as shown in FIG. 1 is used for sealing a lead frame of an electronic component with glass (hermetic sealing). With the jig 1, the shell ring 2 is mounted, the glass tablet 3 is sealed therein, and the lead wire 4 is inserted through the jig 1 and heated to 600 to 1100 ° C. in a non-oxidizing atmosphere. Sealed. When the metallic shell ring 2 or the lead wire 4 is placed at a high temperature, a carburizing phenomenon occurs from a contact surface with the jig 1, thereby changing the resistance value of the product or causing a short circuit. And so on. In addition, there is a problem that when a product is required to be plated, plating is not sufficiently applied. Accordingly, the present inventor has conducted various studies to develop a carbon graphite material which does not cause carburizing phenomenon. As a result, the bonding state of elements on the surface of the carbon graphite base material and impurities contained in the carbon graphite base material are considered. Are mutually responsible for promoting the carburizing phenomenon, and in particular, each element of Fe (iron), Co (cobalt), and Ni (nickel) is greatly involved in causing the carburizing phenomenon by acting like a catalyst. This led to the completion of the present invention. SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to suppress the occurrence of carburization and to reduce the rate of occurrence of defective products due to carburization. It is an object of the present invention to provide a carbon graphite jig capable of lowering the temperature. Means for Solving the Problems In order to solve the above-mentioned problems, a means adopted by the present invention is as described in claim 1 as "Carbon graphite based on X-ray photoelectron spectroscopy (ESCA)". A jig made of carbon graphite in which the intensity ratio O1S / C1S of the area intensity of the O1S band to the area intensity of the C1S band on the surface of the material is 0.10 or more, and the content of impurities contained in the carbon graphite base material Is 800 mass ppm or less, and F
e, a jig made of carbon graphite, wherein the content of each of the elements e, Co, and Ni is 60 mass ppm or less. First, the elements on the surface of the carbon graphite substrate and the parameters indicating the bonding state are determined by X-ray photoelectron spectroscopy (ESC).
It is represented by the intensity ratio O1S / C1S of the area intensity of the O1S band and the area intensity of the C1S band in A), and the value is 0.10 or more, preferably in the range of 0.12 to 0.40. . In order to obtain a carbon graphite substrate having an oxygen-containing functional group adjusted to a range of O1S / C1S = 0.10 or more,
Such a carbon graphite base material is arbitrarily selected or actively nitric acid, a chemical liquid oxidation method using a mixed acid of potassium permanganate and nitric acid, an acid, an alkali, an electrolytic oxidation method in various electrolytes of salts, Or air, ozone, nitrogen oxides,
There is a method using a gas phase oxidation method in which a halogen gas is oxidized in plasma or under a catalyst, and among these methods,
Since the chemical liquid oxidation method and the electrolytic oxidation method require a long-time cleaning for removing chemicals, a gas phase oxidation method is preferable as an actual method. Further, the adjustment of the range of O1S / C1S may be combined with the adjustment of the raw material system of the carbon graphite base material and the adjustment of the graphitization temperature to the above method. With these combinations,
It is possible to obtain carbon graphite having various O1S / C1S values, and it is also possible to adjust the raw material system. On the other hand, a carbon graphite substrate is kneaded by adding coal tar pitch or the like as a binder to petroleum-based or coal-based aggregate coke, carbon fiber, carbon black, or the like, and then kneading and kneading the kneaded product. , Calcined, and if necessary, graphitized. The impurities contained in the carbon graphite substrate include Fe, Co, Ni, V, Na, and C.
There are elements such as a, Al, B, and P. In the present invention, the content of these impurities needs to be 800 mass ppm or less. In addition, F which significantly promotes the carburizing phenomenon
The content of each element of e, Co, and Ni needs to be 60 mass ppm or less. That is, in the present invention, the content of impurities of 800 mass ppm or more is insufficient,
In particular, the content of each element of Fe, Co, and Ni is 60 mass pp.
If not less than m, the effect of suppressing the carburizing phenomenon cannot be obtained. Further, in the carbon graphite base material whose characteristics are set within the above-mentioned predetermined range, the porosity by the boiling method is 2
0% or less, 75 Å by mercury intrusion method
The average pore radius corresponding to 50% diameter of the calculated volume measured within the pore radius range of 75000 Å is 5 μm.
When the thickness is equal to or less than 3.5 μm, the carburizing phenomenon can be completely suppressed. The reason is that various impurity elements contained in the base material are transferred and diffused by heating when the jig is used, but if the porosity and the average pore radius are within the above ranges, the impurity elements are converted into vapor in a high-temperature atmosphere. Since the generated value is kept below the critical value, it is considered that the impurity element acts in advance to suppress the action as a catalyst against the carburizing phenomenon. In the jig made of carbon graphite according to the present invention, cracks are generated in the substrate due to severe conditions such as rapid heating and quenching, or repeated heating and cooling, and the cracks are contained in the substrate. In order to prevent the impurity element from being exposed to a high-temperature atmosphere, the carbon graphite base material used has a small anisotropic coefficient of thermal expansion coefficient (anisotropic ratio 1.20 or less) and has excellent dimensional stability. It is preferably an isotropic carbon graphite material. In the jig made of carbon graphite configured as described above, an O film is formed on the jig surface, which prevents a contact reaction with a lead wire or a shell ring. At the same time, since the contents of various impurity elements, particularly Fe, Co, and Ni, which act as catalysts for the carburizing phenomenon, are set within a low range, the occurrence of defective products due to carburizing can be drastically reduced. it can. Further, if the carbon graphite substrate has a porosity of 20% or less and an average pore radius of 5 μm or less, there is almost no fear of occurrence of carburization. EXAMPLE 1 Coal coke and coal tar pitch were kneaded by a conventional method, pulverized, molded and fired, then graphitized at 2600 ° C. and processed into a jig shape. Thereafter, heat treatment is performed in a vacuum furnace, and the content of the impurity element in the base material is measured using emission spectroscopy according to JIS K 0116, and the content of the impurity in the base material is 760 mass ppm, Fe, Co,
Ni content is 58 mass ppm and 30 mass pp, respectively.
m, 55 mass ppm, 150 ° C in 2% ozone
For 10 minutes to obtain a sample. Example 2 Petroleum coke and coal tar pitch were kneaded by a conventional method, pulverized, molded and fired, then graphitized at 2800 ° C. and processed into a jig shape. Then, it heat-processes in a vacuum furnace, The content of the impurity element in a base material is measured using emission spectroscopy according to JISK0116, and the impurity content is 380 mass ppm, Fe, Co, Ni The content is 19 mass ppm, 9 mass ppm, and 12 mass ppm, respectively.
And treated in 2% ozone at 150 ° C. for 10 minutes to obtain a sample. Comparative Example 1 Coal coke and coal tar pitch were kneaded by a conventional method, pulverized, molded and fired, then graphitized at 2600 ° C. and processed into a jig shape. After that, JIS K 0116
The content of the impurity element in the base material was measured using emission spectroscopy according to
0 mass ppm, the content of Fe, Co, and Ni is 9
The sample was adjusted to 8 mass ppm, 65 mass ppm, and 65 mass ppm, and treated in 2% ozone at 150 ° C. for 10 minutes to obtain a sample. Comparative Example 2 Petroleum coke and coal tar pitch were kneaded by a conventional method, pulverized, molded and fired, then graphitized at 2700 ° C. and processed into a jig shape. Then, it heat-processes in a vacuum furnace, The content of the impurity element in a base material is measured using emission spectroscopy according to JISK0116, and the impurity content is 710 mass ppm, Fe, Co, Ni The content is 51 mass ppm, 20 mass ppm, and 50 mass pp, respectively.
m, and treated in 2% ozone at 150 ° C. for 10 minutes to obtain a sample. The samples of Examples 1 and 2 and Comparative Examples 1 and 2 were sealed in a non-oxidizing atmosphere at 900 ° C., 1000 ° C., and 1100 ° C., and the presence or absence of a carburizing phenomenon was examined. Table 1 shows the results. [Table 1] According to the present invention, by the structure as described in claim 1, the action of the O film on the jig surface, the regulation of the total amount of impurities, and the interaction of the limitation of the specific impurity amount are performed. As a result, the incidence of defective products due to carburization can be reduced, and high-quality products can be manufactured.

[Brief description of the drawings] FIG. 1 is a cross-sectional view showing an example of a glass sealing jig. [Explanation of symbols] 1 jig 2 Shell ring 3 glass tablet 4 Lead wire

Claims (1)

(57) [Claims 1] The value of the intensity ratio O1S / C1S of the O1S band area intensity and the C1S band area intensity on the surface of the carbon graphite substrate in X-ray photoelectron spectroscopy (ESCA) is 0. .10
The jig made of carbon graphite described above, wherein the content of impurities contained in the carbon graphite base material is 800 mass ppm or less, and the content of each element of Fe, Co, and Ni is 60 mass ppm.
A carbon graphite jig characterized by the following.