- Email: [email protected]
Report on the symposium on glass in electronics
Classified
abstracts
487-498
atomic ions in a steady-state radio-frequency helium plasma is investigated spectroscopically. Electrodeless ring discharges are generated by a self-excited 28 Mc/sec oscillator in a quartz tube. The apparatus is operated in the range 0.2 to 0.6 torr helium-gas pressure. B Stafford et al, J Chem Phys, 45 (2), 15 July 1966,670-678. 40 487. Formation of excited molecular states in the positive cohunn of a helium discharge. (USA) Excited molecular states are shown to be populated in the positive column of a glow discharge in helium by electron excitation of metastable molecules. At higher pressures (2-20 torr), metastable atoms are form&d primarily by three-body conversion of metastable atoms, Hem-2He-Hems-He. The apparatus is described and the results are presented as functions of the pressure. M P Teter and W W Robertson, J Chem Phys, 45 (2), 15 July 1966, 661669. 40 488. Franck-Condon factors in ionization: experimental measurement using molecular photoelectron spectroscopy (USA) The photoelectron spectra excited by 21.2eV photons in argon, krypton, xenon, hydrogen, nitrogen, carbon monoxide, oxygen, and nitric oxide have been re-examined. A small 180” magnetic-field electron velocity analyzer with a deflection-type selector was used. Some statements on pressure conditions are made and more information is contained in previous publications which are referenced. D W Turner and D P May, J Chem Phys, 45 (2), July 1966,471-476. 40 489. The drift velocity of electrons in carbon dioxide at 293°K. (Australia) The drift velocity of electrons in carbon dioxide at 293°K has been measuredwithanerrorof lessthan0.5percent over therange0.1 Vcm-1 torr-‘< E/p,,,< 3.OVcm-Qorr-‘and 1 percentovertherange3.0Vcm-1 torr-I< E/p,,,< 7.0 Vcm-ltorr-l. The accuracy of the available data is discussed. M T Elford, Aus J Phys, 19, Ott 1966, 629. 40 490. Transport and ionization properties of molecular gases in a transversemagneticfield. (Australia) Measurements are reported of pre-breakdown ionization in E x B fields under conditions that permit unrestricted motion of the electrons in the Ex B direction. These measurements have been carried out in a coaxial cylindrical ionization chamber, details of which are given. An alternative method of examining the development of ionization as a function of pressure has been used, and a comparison is made of the results of such investigations with earlier spatial measurements using plane geometry. The use of an electromagnet capable of producing magnetic fields up to 1OOOOGsubstantially uniform over the required constant annular gap spacing has permitted an extension of earlier work to the “strong” magnetic field limit, ie values of B/p=25OOG/torr (“C). Details of measurements made in the molecular gases Hz and Na are given. J Fletcher and S C Haydon, Aus J Phys, 19, Ott 1966, 615. 41. Metals and alloys 41 491. Chemisorption of electronegative gases on refractory metals. (USA) Some aspects of the chemisorption of chlorine on tungsten and chlorine and hydrogen chloride on hafnium for temperatures of 1800-2200°K and pressures of 4.0-6.0 x lo+’ torr are discussed. For tungsten the sticking probability of chlorine was about 4 x lO-s and tended to decrease with temperature. For hafnium the sticking probability was about 1 x l0-a for both chlorine and hydrogen chloride and tended to increase with temperature. M L Shaw and N P Carleton, J Chem Phys, 44 (9), 1 May 1966,33873392. 41 492. Influence of the oxygen pressure on the barium oxide conductivity. (USSR) Measuring the (Ba, Sr)O conductivity at temperatures 890-1030°K and at oxygen pressures 5 x lO-0-l x IO-8 torr it was found that at 5 x lo-& torr oxygen pressure the type of conductivity is changing from p to n. Residual gases in the system were not measured. A B Kiselev and B P Niionov, Radiotekh Elektron, 11 (IO), Ott 1966, 1886-1888 (in Russian).
42. Gases, ceramics
and refractory
oxides
42 493. Report on the symposium on glass in electronics. (Great Britain) Recent developments in glass-metal seals, encapsulation of semiconductor devices, degassing and gas clean-up effects, new materials and devices are reported. H Rawson, Glass Technol, 7,1966, 115-120. 42 494. Sealing glass ceramics to metals: selection of materials and direct sealing methods. (Great Britain) The choice of particular glass-ceramic compositions for their use in sealing to metals is governed by various factors, including workability of the glasses, thermal expansion characteristics and the matching of these to appropriate metals and chemical and physical stability under processing and operating conditions. The special characteristics of glass-ceramics permit direct seals to be made to a number of metals. Properties of typical seals are outlined and a brief review of applications is given. P W McMillan el al, Gl.zss Technol, 7,1966, 121-127. 42 495. Sealing glass ceramics to metals: sealing by intermediate bonds. (Great Britain) The types of bond which can be used are determined by the characteristics of the glass-ceramics and, in general, sealing temperatures up to 800-900°C are permissible. Special bonding glasses or “active metal” brazes have been developed for this application. P W McMillan et al, Glass Technol, 7,1966,128-133. 43. Plastics
and elastomers
43 : 34 496. Stability of high polymers under simulated space conditions. Specific degassing properties by means of residual gas analyzer. (France) A series of high polymer materials, with prospective spacecraft applications, were subjected to ultrahigh vacuum conditions together with ultraviolet irradiation. Weight-loss and total pressure in the vacuum system were measured. In further experiments specimens were heated under vacuum and partial pressure of gas species observed on a CEC residual gas analyzer. Teflon exhibited the greatest stability. It was found that a long prior degassing under vacuum reduces the rate and extent of ultraviolet degradation. The quantitative data obtained is presented. M Rivera and A Biette, LX Vide, 21 (I24), July-Aug 1966, 340-347 (in French). 45. Soldering,
welding,
brazing, solders
45 : 23 Ceramic-to-metal joints soldered with titanium in high vacuum. See abstract number 336. 45 497. Electron beam welding of zirconium and its alloys. (Belgium) Welding of zirconium and its alloys is facilitated by the low thermal conductivity and coefficient of expansion of Zr, but contamination of the alloy by gases must be avoided. Electron-beam welding under high vacuum is a suitable method, although slower and more expensive than Ar-arc welding. Differences between welding under high and low intensity beams were studied. The low intensity method is found to be cheaper, but there may be loss of alloying elements because of vaporization. M Meulemans, Metallurgic, 5, 1965, 411-417 (in French). 47. Outgassing data, vapour pressure data, gettering data, residual gases in vacuum systems, residual gas analysis 47 : 20 Bakeout procedures for small glass ultrahigh vacuum systems. See abstract number 311. 47 498. Method of calculation of vapour pressure of metals during vacuum-thermal reduction of their oxides with alloys. (USSR) The title method was derived and applied to the calculation of the vapour pressure of magnesium during the vacuum reduction of MgO with Si-Al alloys. V V Zhukovetskii and A D Pogorelyi, Tsvetn Metal, 39 (4), 1966,6166 (in Russian). 125
abstracts
487-498
atomic ions in a steady-state radio-frequency helium plasma is investigated spectroscopically. Electrodeless ring discharges are generated by a self-excited 28 Mc/sec oscillator in a quartz tube. The apparatus is operated in the range 0.2 to 0.6 torr helium-gas pressure. B Stafford et al, J Chem Phys, 45 (2), 15 July 1966,670-678. 40 487. Formation of excited molecular states in the positive cohunn of a helium discharge. (USA) Excited molecular states are shown to be populated in the positive column of a glow discharge in helium by electron excitation of metastable molecules. At higher pressures (2-20 torr), metastable atoms are form&d primarily by three-body conversion of metastable atoms, Hem-2He-Hems-He. The apparatus is described and the results are presented as functions of the pressure. M P Teter and W W Robertson, J Chem Phys, 45 (2), 15 July 1966, 661669. 40 488. Franck-Condon factors in ionization: experimental measurement using molecular photoelectron spectroscopy (USA) The photoelectron spectra excited by 21.2eV photons in argon, krypton, xenon, hydrogen, nitrogen, carbon monoxide, oxygen, and nitric oxide have been re-examined. A small 180” magnetic-field electron velocity analyzer with a deflection-type selector was used. Some statements on pressure conditions are made and more information is contained in previous publications which are referenced. D W Turner and D P May, J Chem Phys, 45 (2), July 1966,471-476. 40 489. The drift velocity of electrons in carbon dioxide at 293°K. (Australia) The drift velocity of electrons in carbon dioxide at 293°K has been measuredwithanerrorof lessthan0.5percent over therange0.1 Vcm-1 torr-‘< E/p,,,< 3.OVcm-Qorr-‘and 1 percentovertherange3.0Vcm-1 torr-I< E/p,,,< 7.0 Vcm-ltorr-l. The accuracy of the available data is discussed. M T Elford, Aus J Phys, 19, Ott 1966, 629. 40 490. Transport and ionization properties of molecular gases in a transversemagneticfield. (Australia) Measurements are reported of pre-breakdown ionization in E x B fields under conditions that permit unrestricted motion of the electrons in the Ex B direction. These measurements have been carried out in a coaxial cylindrical ionization chamber, details of which are given. An alternative method of examining the development of ionization as a function of pressure has been used, and a comparison is made of the results of such investigations with earlier spatial measurements using plane geometry. The use of an electromagnet capable of producing magnetic fields up to 1OOOOGsubstantially uniform over the required constant annular gap spacing has permitted an extension of earlier work to the “strong” magnetic field limit, ie values of B/p=25OOG/torr (“C). Details of measurements made in the molecular gases Hz and Na are given. J Fletcher and S C Haydon, Aus J Phys, 19, Ott 1966, 615. 41. Metals and alloys 41 491. Chemisorption of electronegative gases on refractory metals. (USA) Some aspects of the chemisorption of chlorine on tungsten and chlorine and hydrogen chloride on hafnium for temperatures of 1800-2200°K and pressures of 4.0-6.0 x lo+’ torr are discussed. For tungsten the sticking probability of chlorine was about 4 x lO-s and tended to decrease with temperature. For hafnium the sticking probability was about 1 x l0-a for both chlorine and hydrogen chloride and tended to increase with temperature. M L Shaw and N P Carleton, J Chem Phys, 44 (9), 1 May 1966,33873392. 41 492. Influence of the oxygen pressure on the barium oxide conductivity. (USSR) Measuring the (Ba, Sr)O conductivity at temperatures 890-1030°K and at oxygen pressures 5 x lO-0-l x IO-8 torr it was found that at 5 x lo-& torr oxygen pressure the type of conductivity is changing from p to n. Residual gases in the system were not measured. A B Kiselev and B P Niionov, Radiotekh Elektron, 11 (IO), Ott 1966, 1886-1888 (in Russian).
42. Gases, ceramics
and refractory
oxides
42 493. Report on the symposium on glass in electronics. (Great Britain) Recent developments in glass-metal seals, encapsulation of semiconductor devices, degassing and gas clean-up effects, new materials and devices are reported. H Rawson, Glass Technol, 7,1966, 115-120. 42 494. Sealing glass ceramics to metals: selection of materials and direct sealing methods. (Great Britain) The choice of particular glass-ceramic compositions for their use in sealing to metals is governed by various factors, including workability of the glasses, thermal expansion characteristics and the matching of these to appropriate metals and chemical and physical stability under processing and operating conditions. The special characteristics of glass-ceramics permit direct seals to be made to a number of metals. Properties of typical seals are outlined and a brief review of applications is given. P W McMillan el al, Gl.zss Technol, 7,1966, 121-127. 42 495. Sealing glass ceramics to metals: sealing by intermediate bonds. (Great Britain) The types of bond which can be used are determined by the characteristics of the glass-ceramics and, in general, sealing temperatures up to 800-900°C are permissible. Special bonding glasses or “active metal” brazes have been developed for this application. P W McMillan et al, Glass Technol, 7,1966,128-133. 43. Plastics
and elastomers
43 : 34 496. Stability of high polymers under simulated space conditions. Specific degassing properties by means of residual gas analyzer. (France) A series of high polymer materials, with prospective spacecraft applications, were subjected to ultrahigh vacuum conditions together with ultraviolet irradiation. Weight-loss and total pressure in the vacuum system were measured. In further experiments specimens were heated under vacuum and partial pressure of gas species observed on a CEC residual gas analyzer. Teflon exhibited the greatest stability. It was found that a long prior degassing under vacuum reduces the rate and extent of ultraviolet degradation. The quantitative data obtained is presented. M Rivera and A Biette, LX Vide, 21 (I24), July-Aug 1966, 340-347 (in French). 45. Soldering,
welding,
brazing, solders
45 : 23 Ceramic-to-metal joints soldered with titanium in high vacuum. See abstract number 336. 45 497. Electron beam welding of zirconium and its alloys. (Belgium) Welding of zirconium and its alloys is facilitated by the low thermal conductivity and coefficient of expansion of Zr, but contamination of the alloy by gases must be avoided. Electron-beam welding under high vacuum is a suitable method, although slower and more expensive than Ar-arc welding. Differences between welding under high and low intensity beams were studied. The low intensity method is found to be cheaper, but there may be loss of alloying elements because of vaporization. M Meulemans, Metallurgic, 5, 1965, 411-417 (in French). 47. Outgassing data, vapour pressure data, gettering data, residual gases in vacuum systems, residual gas analysis 47 : 20 Bakeout procedures for small glass ultrahigh vacuum systems. See abstract number 311. 47 498. Method of calculation of vapour pressure of metals during vacuum-thermal reduction of their oxides with alloys. (USSR) The title method was derived and applied to the calculation of the vapour pressure of magnesium during the vacuum reduction of MgO with Si-Al alloys. V V Zhukovetskii and A D Pogorelyi, Tsvetn Metal, 39 (4), 1966,6166 (in Russian). 125