EP0129997A1 - Process for the production of PTC thermistors - Google Patents
Process for the production of PTC thermistors Download PDFInfo
- Publication number
- EP0129997A1 EP0129997A1 EP84303796A EP84303796A EP0129997A1 EP 0129997 A1 EP0129997 A1 EP 0129997A1 EP 84303796 A EP84303796 A EP 84303796A EP 84303796 A EP84303796 A EP 84303796A EP 0129997 A1 EP0129997 A1 EP 0129997A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- glass
- pbo
- air
- sealing
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 239000011521 glass Substances 0.000 claims abstract description 36
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 12
- 239000001301 oxygen Substances 0.000 claims abstract description 12
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 11
- 239000004065 semiconductor Substances 0.000 claims abstract description 11
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 238000007789 sealing Methods 0.000 claims description 20
- 238000002844 melting Methods 0.000 claims description 5
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 4
- 229910002113 barium titanate Inorganic materials 0.000 claims description 4
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims description 4
- 229910020615 PbO—SiO2 Inorganic materials 0.000 claims description 2
- FAWGZAFXDJGWBB-UHFFFAOYSA-N antimony(3+) Chemical compound [Sb+3] FAWGZAFXDJGWBB-UHFFFAOYSA-N 0.000 claims description 2
- 229910052797 bismuth Inorganic materials 0.000 claims description 2
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 239000010955 niobium Substances 0.000 claims description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 2
- 150000002910 rare earth metals Chemical class 0.000 claims description 2
- 229910052715 tantalum Inorganic materials 0.000 claims description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 2
- 239000000463 material Substances 0.000 claims 2
- 238000003780 insertion Methods 0.000 claims 1
- 230000037431 insertion Effects 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000006121 base glass Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
- H01C17/02—Apparatus or processes specially adapted for manufacturing resistors adapted for manufacturing resistors with envelope or housing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
- H01C1/024—Housing; Enclosing; Embedding; Filling the housing or enclosure the housing or enclosure being hermetically sealed
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
- H01C7/022—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient mainly consisting of non-metallic substances
- H01C7/023—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient mainly consisting of non-metallic substances containing oxides or oxidic compounds, e.g. ferrites
- H01C7/025—Perovskites, e.g. titanates
Definitions
- the present invention relates to a process for the production of PTC thermistors.
- a thermistor aimed at sensing temperature alone includes a thermistor element sealed in glass or resin so as to keep it from being affected by other factors such as humidity or gas.
- NTC thermistors there are available glass-sealed type thermistors which are inexpensive, easy to mass-produce and have stabilized properties, in addition to resin-sealed type disc-form thermistors.
- PTC thermistors glass-sealed type PTC thermistors are still not produced, and instead use is made of resin-sealed disc-form PTC thermistors or PTC thermistors in which metals are mechanically pressed onto electrodes.
- NTC thermistors are prepared by glass sealing in vacuum or a reducing atmosphere such as N 2 or Ar gas so as to prevent Dumet wires or heaters from being oxidized.
- a reducing atmosphere such as N 2 or Ar gas
- a main object of the present invention is to provide inexpensive glass-sealed type PTC thermistors which show a great change in resistance, especially a markedly increased change in resistance at switching temperatures, and which have stabilized properties .
- a process for the production of PTC thermistors by sealing a positive temperature coefficient (PTC) semiconductor ceramic material in glass in the presence of air, oxygen or an air/oxygen mixture (wherein 0% ⁇ the volume of air > 100%).
- PTC positive temperature coefficient
- a process for the production of PTC thermistors by sealing a positive temperature coefficient semiconductor ceramic material in low-melting glass having a softening point of no higher than 560°C.
- a process for the production of PTC thermistors by sealing a positive temperature coefficient semiconductor ceramic material in low-melting glass having a softening point of no higher than 560°C in the presence of air, oxygen or an air/oxygen mixture (wherein 0% ⁇ the volume of air> 100%).
- the semiconductor ceramic material having a positive temperature coefficient used in the present invention there are mentioned those obtained by adding to barium titanate base compositions any one of trivalent antimony, trivalent bismuth, pentavalent tantalum, pentavalent niobium or a rare earth metal.
- the glass used has a softening point of 450°C-560°C inclusive, and includes those glasses based on B 2 O 3 -PbO-ZnO, B 2 O 3 -PbO-SiO 2 , B 2 O 3 -PbO-Ti 2 O, B 2 O 3 -PbO-SiO 2 -Al 2 O 3 -ZnO, B 2 O 3 -PbO-V 2 O 5 , SiO 2 -PbO-K 2 O, SiO 2 -PbO-Na 2 O and SiO 2 -PbO-K 2 O-Na 2 O.
- Preference is given to a SiO 2 -PbO-K 2 O base glass, since this glass shows desirous thermal expansion and wettability with respect to lead wires (Dumet wires, viz., Fe-Ni alloy wires plated with Cu).
- a semiconductor barium titanate ceramic material 1 is first sliced to any suitable thickness having regard to the length of a glass tube 4 in which the finished thermistor element is to be sealed.
- Silver electrodes 2 and 2 are applied to both sides of the thus obtained element, and deposited thereto for 20 minutes at 600°C.
- Figure l(a) shows a section of the electrode-provided element.
- the element is then cut to any length corresponding to the diameter of the glass tube 4.
- the element is placed in the tube 4 of a glass having a softening point of no higher than 560°C, into both ends of which Dumet wires 3 and 3 are inserted. Finally, the glass tube 4 is sealed by means of a carbon heater jig.
- the sealing temperature is determined depending upon the softening point of the glass used, and is generally higher than the softening point of the glass used by 50°C or more.
- NTC glass sealed thermistors a glass having a softening point exceeding 560 0 C is used and sealing is carried out at a temperature exceeding 610°C. If sealing of a PTC thermistor is carried out under such conditions, there is a marked drop in the properties of the resulting PTC thermistor. According to the present invention, however, it is possible to obtain stable PTC thermistors whose properties drop only slightly by sealing the thermistor elements in a low-melting glass having a softening point of no higher than 560°C.
- Figure 2 shows the results of an experiment run wherein PTC thermistor elements having a Curie point of 120°C were sealed in glasses in the art.
- Figure 3 is a characteristic diagram of a PTC thermistor sealed in glass in various atmospheres.
- the PTC thermistor used had a Curie point of 120°C, and sealing was carried out at 610°C.
- Figure 4 is a graphical view showing the relation between the specific resistance and the temperature of PTC thermistors obtained by sealing a PTC thermistor element having a Curie point of 120 0 C in glass in air and/or oxygen gas. The results of Figure 4 are numerically given in Table 3.
- the present invention makes it possible to inexpensively prepare PTC thermistors having excellent properties, and is therefor of industrially high value.
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Ceramic Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Thermistors And Varistors (AREA)
- Ceramic Products (AREA)
- Glass Compositions (AREA)
Abstract
A process for the production of glass sealed types PTC thermistors is disclosed wherein a positive temperature coefficient semiconductor ceramic material (1) is sealed in a glass (4) having a softening point of no higher than 560°C in the presence of air, oxygen or an air/oxygen mixture.
Description
- The present invention relates to a process for the production of PTC thermistors.
- As is well-known in the art, a thermistor aimed at sensing temperature alone includes a thermistor element sealed in glass or resin so as to keep it from being affected by other factors such as humidity or gas. Referring especially to NTC thermistors, there are available glass-sealed type thermistors which are inexpensive, easy to mass-produce and have stabilized properties, in addition to resin-sealed type disc-form thermistors.
- Turning to PTC thermistors, however, glass-sealed type PTC thermistors are still not produced, and instead use is made of resin-sealed disc-form PTC thermistors or PTC thermistors in which metals are mechanically pressed onto electrodes.
- This may be attributable to the properties of PTC thermistors which are significantly affected by the temperature and atmosphere at and in which the thermistor elements are sealed in glass.
- Conventional NTC thermistors are prepared by glass sealing in vacuum or a reducing atmosphere such as N2 or Ar gas so as to prevent Dumet wires or heaters from being oxidized. In consequence of the studies made by the present inventors, it has been revealed that the application of such glass sealing in a reducing atmosphere to PCT thermistors causes the properties thereof to deteriorate to a considerable extent. It has also been found that, under such conditions, the glass sealing temperature reaches as high as 650°C, at which temperature the properties of PTC thermistors deteriorate significantly.
- In view of the foregoing, a main object of the present invention is to provide inexpensive glass-sealed type PTC thermistors which show a great change in resistance, especially a markedly increased change in resistance at switching temperatures, and which have stabilized properties .
- According to one aspect of the present invention, there is provided a process for the production of PTC thermistors by sealing a positive temperature coefficient (PTC) semiconductor ceramic material in glass in the presence of air, oxygen or an air/oxygen mixture (wherein 0% < the volume of air > 100%).
- According to another aspect of the present invention, there is provided a process for the production of PTC thermistors by sealing a positive temperature coefficient semiconductor ceramic material in low-melting glass having a softening point of no higher than 560°C.
- According to a further aspect of the present invention, there is provided a process for the production of PTC thermistors by sealing a positive temperature coefficient semiconductor ceramic material in low-melting glass having a softening point of no higher than 560°C in the presence of air, oxygen or an air/oxygen mixture (wherein 0% < the volume of air> 100%).
- The invention wil be more particularly described with reference to the accompanying drawings, in which:-
- Figure 1 is a schematic view showing one embodiment of the steps of a process according to the present invention; and
- Figures 2 to 4 inclusive are views showing the temperature-specific resistance characteristics of the products prepared under different conditions.
- As the semiconductor ceramic material having a positive temperature coefficient used in the present invention, there are mentioned those obtained by adding to barium titanate base compositions any one of trivalent antimony, trivalent bismuth, pentavalent tantalum, pentavalent niobium or a rare earth metal. The glass used has a softening point of 450°C-560°C inclusive, and includes those glasses based on B2O3-PbO-ZnO, B2O3-PbO-SiO2, B2O3-PbO-Ti2O, B2O3-PbO-SiO2-Al2O3-ZnO, B2O3-PbO-V2O5, SiO2-PbO-K2O, SiO2-PbO-Na2O and SiO2-PbO-K2O-Na2O. Preference is given to a SiO2-PbO-K2O base glass, since this glass shows desirous thermal expansion and wettability with respect to lead wires (Dumet wires, viz., Fe-Ni alloy wires plated with Cu).
- When a glass having a softening point of below 4500C is used, certain limitations are imposed upon the temperature at which the resulting glass-sealed type PTC thermistors are employed.
- Referring now to Figure 1, a semiconductor barium titanate
ceramic material 1 is first sliced to any suitable thickness having regard to the length of aglass tube 4 in which the finished thermistor element is to be sealed.Silver electrodes - As shown in Figure l(b), the element is then cut to any length corresponding to the diameter of the
glass tube 4. - The element is placed in the
tube 4 of a glass having a softening point of no higher than 560°C, into both ends of which Dumet wires 3 and 3 are inserted. Finally, theglass tube 4 is sealed by means of a carbon heater jig. The sealing temperature is determined depending upon the softening point of the glass used, and is generally higher than the softening point of the glass used by 50°C or more. - In the prior art NTC glass sealed thermistors, a glass having a softening point exceeding 5600C is used and sealing is carried out at a temperature exceeding 610°C. If sealing of a PTC thermistor is carried out under such conditions, there is a marked drop in the properties of the resulting PTC thermistor. According to the present invention, however, it is possible to obtain stable PTC thermistors whose properties drop only slightly by sealing the thermistor elements in a low-melting glass having a softening point of no higher than 560°C.
- Figure 2 shows the results of an experiment run wherein PTC thermistor elements having a Curie point of 120°C were sealed in glasses in the art.
- Although the resulting properties having slightly dropped from the initial ones (prior to sealing), yet the PTC thermistor element sealed in a glass having a softening point of 5360C or 560°C has been found to show excellent properties. It has also been found that similar results are obtained with PTC thermistor elements having different Curie points. The results of Figure 2 are also numerically given in Table 1.
- Figure 3 is a characteristic diagram of a PTC thermistor sealed in glass in various atmospheres. The PTC thermistor used had a Curie point of 120°C, and sealing was carried out at 610°C.
- It is clear from the diagram that sealing in air or oxygen gas yields a better PTC thermistor as compared with one treated in vacuo or in an inert or reducing gas atmosphere. The results of Figure 3 are numerically given in Table 2.
- It is to be understood that similar results are obtained in an air/oxygen mixture and/or with a PTC thermistor element having a different Curie point.
- Figure 4 is a graphical view showing the relation between the specific resistance and the temperature of PTC thermistors obtained by sealing a PTC thermistor element having a Curie point of 1200C in glass in air and/or oxygen gas. The results of Figure 4 are numerically given in Table 3.
- From these results, it is found that by a process according to the present invention PTC thermistors are obtained which show a large change in resistance, which is comparable to the properties prior to sealing.
- It is to be understood that similar results are obtained in an air/oxygen mixture and/or with PTC thermistor elements having a different Curie point.
- It is to be understood that, in place of a carbon heater jig, other heater jigs, for instance, a metal heating jig, may be used for sealing the
glass tube 4.
- As explained above, the present invention makes it possible to inexpensively prepare PTC thermistors having excellent properties, and is therefor of industrially high value.
Claims (10)
1. A process for the production of PTC thermistors characterised by sealing a positive temperature coefficient semiconductor ceramic material (1) in glass (4) in the presence of air, oxygen or an air/oxygen mixture (wherein 0% the volume of air 100%).
2. A process for the production of PTC thermistors characterised by sealing a positive temperature coefficient semiconductor ceramic material (1) in a low-melting glass having a softening point of no higher than 560°C.
3. A process for the production of PTC thermistors characterised by sealing a positive temperature coefficient semiconductor ceramic material (1) in a low-melting glass (4) having a softening point of no higher than 560°C in the presence of air, oxygen or an air/oxygen mixture (wherein 0% the volume of air 100%).
4. A process according to claim 1, 2 or 3, characterised in that the glass (4) has a softening point of from 450°C to 560°C inclusive.
5. A process according to any one of the preceding claims, characterised in that the glass (4) is in the form of a tube sealed at both ends.
6. A process according to claim 5, characterised in that lead wires (3) are inserted into opposite ends of the glass tube (4) prior to the sealing thereof.
7. A process according to claim 5 or 6, characterised in that electrodes (2) are applied to opposite sides of the semiconductor material (1) prior to its insertion in the glass tube (4).
8. A process according to any one of the preceding claims, characterised in that the glass used is based on B2O3-PbO-ZnO, B2O3-PbO-SiO2, B2O3-PbO-Ti2O, B2O3-PbO-SiO2-Al2O3-ZnO, B203-PbO-V2051 Sio2-PbO-K20, SiO2-PbO-Na2O or SiO2-PbO-K2O-Na2O.
9. A process according to any one of the preceding claims, characterised in that the semiconductor material (1) is a barium titanate ceramic material.
10. A process according to claim 9, characterised in that the barium titanate ceramic material has added thereto any one of trivalent antimony, trivalent bismuth, pentavalent tantalum, pentavalent niobium or a rare earth metal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58104483A JPS59229803A (en) | 1983-06-11 | 1983-06-11 | Method of producing ptc thermistor |
| JP104483/83 | 1983-06-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0129997A1 true EP0129997A1 (en) | 1985-01-02 |
| EP0129997B1 EP0129997B1 (en) | 1988-08-31 |
Family
ID=14381803
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP84303796A Expired EP0129997B1 (en) | 1983-06-11 | 1984-06-05 | Process for the production of ptc thermistors |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0129997B1 (en) |
| JP (1) | JPS59229803A (en) |
| KR (1) | KR900005267B1 (en) |
| DE (1) | DE3473801D1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3717248A1 (en) * | 1986-05-23 | 1987-11-26 | Murata Manufacturing Co | Chip-like thermistor having a negative temperature coefficient |
| EP0443618A2 (en) * | 1990-02-22 | 1991-08-28 | Murata Manufacturing Co., Ltd. | Method for producing a PTC thermistor |
| EP0824258A1 (en) * | 1996-08-09 | 1998-02-18 | Hitachi, Ltd. | Structure of electronic device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB992926A (en) * | 1962-08-11 | 1965-05-26 | Constructa Werke Gmbh | Improvements relating to electrical heating elements |
| US3377561A (en) * | 1965-07-13 | 1968-04-09 | Bell Telephone Labor Inc | Positive temperature coefficient titanate thermistor |
| LU69220A1 (en) * | 1973-06-18 | 1974-04-08 | ||
| US4276536A (en) * | 1979-09-04 | 1981-06-30 | Scully Electronic Systems, Inc. | Self-heating thermistor probe for low temperature applications |
-
1983
- 1983-06-11 JP JP58104483A patent/JPS59229803A/en active Granted
-
1984
- 1984-05-21 KR KR1019840002770A patent/KR900005267B1/en not_active IP Right Cessation
- 1984-06-05 DE DE8484303796T patent/DE3473801D1/en not_active Expired
- 1984-06-05 EP EP84303796A patent/EP0129997B1/en not_active Expired
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB992926A (en) * | 1962-08-11 | 1965-05-26 | Constructa Werke Gmbh | Improvements relating to electrical heating elements |
| US3377561A (en) * | 1965-07-13 | 1968-04-09 | Bell Telephone Labor Inc | Positive temperature coefficient titanate thermistor |
| LU69220A1 (en) * | 1973-06-18 | 1974-04-08 | ||
| US4276536A (en) * | 1979-09-04 | 1981-06-30 | Scully Electronic Systems, Inc. | Self-heating thermistor probe for low temperature applications |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3717248A1 (en) * | 1986-05-23 | 1987-11-26 | Murata Manufacturing Co | Chip-like thermistor having a negative temperature coefficient |
| EP0443618A2 (en) * | 1990-02-22 | 1991-08-28 | Murata Manufacturing Co., Ltd. | Method for producing a PTC thermistor |
| EP0443618A3 (en) * | 1990-02-22 | 1992-08-05 | Murata Manufacturing Co., Ltd. | Ptc thermistor and ptc thermistor producing method, and resistor with a ptc thermistor |
| US5210516A (en) * | 1990-02-22 | 1993-05-11 | Murata Manufacturing Co., Ltd. | Ptc thermistor and ptc thermistor producing method, and resistor with a ptc thermistor |
| EP0824258A1 (en) * | 1996-08-09 | 1998-02-18 | Hitachi, Ltd. | Structure of electronic device |
| US6344790B1 (en) | 1996-08-09 | 2002-02-05 | Hitachi, Ltd. | Electronic device such as a thermistor and the like with improved corrosion resistance |
| CN1123014C (en) * | 1996-08-09 | 2003-10-01 | 株式会社日立制作所 | Structure of electronic components |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0145962B2 (en) | 1989-10-05 |
| KR900005267B1 (en) | 1990-07-21 |
| DE3473801D1 (en) | 1988-10-06 |
| JPS59229803A (en) | 1984-12-24 |
| EP0129997B1 (en) | 1988-08-31 |
| KR850000811A (en) | 1985-03-09 |
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