EP0028802A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Electrically insulating substrate and a method of making such a substrate
Assignee: Hitachi Ltd
•
Filing: 1980-11-04
•
Granted: —
•
Expires: 2000-11-04
Abstract
Abstract From 0.1 to 3,5 % by weight of beryllium oxide powder, calculated as beryllium, are added to silicon carbide powder containing up to 0.1 % by weight of aluminum, up to 0.1 % by weight of boron and up to 0.4 % by weight of free carbon, and the mixed powder is pressure-molded. The resulting molded article is heated to a temperature of 1,850°C to 2,500°C till there is obtained a sintered body having at least 90 % relative density of silicon carbide. Thus, the sintered body having a thermal conductivity of at least 1.67 J / cm.sec.°C at 25°C, an electrical resistivity of at least 10 7 Ohm.cm at 25°C and a coefficient of thermal expansion of 3.3~4×10 -6 /°C at 25°C to 300°C can be obtained.
Inventors
- 👤 Yasuo Matsushita
- 👤 Tukio Takeda
- 👤 Kousuke Nakamura
- 👤 Tokio Okoshi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 02:11
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/575; H; H01; H01B; H01B3/00; H01B3/02; H01B3/12; H10; H10W; H10W99/00; H05; H05K; H05K1/00; H05K1/02; H05K1/03; H05K1/0306; H10W72/00; H10W72/50; H10W72/531; H10W72/5363; H10W72/551; H10W72/552; H10W72/5522; H10W72/851; H10W72/874; H10W72/884; H10W90/00; H10W90/701; H10W90/731; H10W90/734; H10W90/751; H10W90/754
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
129 words
An electrically insulating substrate comprising a sintered body, characterized in that said sintered body consists of 0.1 to 3.5 wt.% of beryllium and silicon carbide as the principal component; that said silicon carbide contains up to 0.1 wt.% of aluminum, up to 0.1 wt.% of boron and up to 0.4 wt.% of free carbon; and that said sintered body is sintered such that a density of at least 90 % relative density with respect to the theoretical density of said silicon carbide is obtained and said sintered body has a thermal conductivity of at least 1.67 J/cm·sec· C at 25°C, an electrical resistivity of at least 10 7 Ohm·cm at 25°C and a coefficient of thermal expansion of up to 4 x 10 -6 /°C from 25°C to 300°C.
Claim 2
Dependent Claim
129 words
An electrically insulating substrate comprising a sintered body, characterized in that said sintered body consists of 0.1 to 3.5 wt.% of beryllium and silicon carbide as the principal component; that said silicon carbide contains up to 0.1 wt.% of aluminum, up to 0.1 wt.% of boron and up to 0.4 wt.% of free carbon; and that said sintered body is sintered such that a density of at least 90 % relative density with respect to the theoretical density of said silicon carbide is obtained and said sintered body has a thermal conductivity of at least 1.67 J/cm·sec· C at 25°C, an electrical resistivity of at least 10 7 Ohm·cm at 25°C and a coefficient of thermal expansion of up to 4 x 10 -6 /°C from 25°C to 300°C.
Claim 3
Dependent Claim
20 words
The substrate of claim 1, characterized in that said silicon carbide consists of alpha-type silicon carbide as the principal component.
Claim 4
Independent Claim
88 words
A method of making an electrically insulating substrate, characterized by mixing 0.5 to 14 wt.% of beryllium oxide powder with silicon carbide powder containing up to 0.1 wt.% of aluminum, up to 0.1 % of boron and up to 0.4 % of free carbon; pressure-molding the mixed powder; sintering the resulting molded article at 1,850 to 2,500 C in a non-oxidizing atmosphere in such a manner as to obtain a sintered body having at least 90 % relative density with respect to the theoretical density of silicon carbide.
Claim 5
Independent Claim
88 words
A method of making an electrically insulating substrate, characterized by mixing 0.5 to 14 wt.% of beryllium oxide powder with silicon carbide powder containing up to 0.1 wt.% of aluminum, up to 0.1 % of boron and up to 0.4 % of free carbon; pressure-molding the mixed powder; sintering the resulting molded article at 1,850 to 2,500 C in a non-oxidizing atmosphere in such a manner as to obtain a sintered body having at least 90 % relative density with respect to the theoretical density of silicon carbide.
Claim 6
Dependent Claim
26 words
The method of claim 3, characterized in that said molded article is hot-pressed at 1,900 to 2,300°C and at a pressure of 100 to 700 bar.
Claim 7
Dependent Claim
25 words
The method of claim 4, characterized in that beryllium oxide powder and silicon carbide powder have an average grain size of up to 10 um.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.