EP1088316A1 - Thin electret layer and corresponding production method - Google Patents
Thin electret layer and corresponding production methodInfo
- Publication number
- EP1088316A1 EP1088316A1 EP99920448A EP99920448A EP1088316A1 EP 1088316 A1 EP1088316 A1 EP 1088316A1 EP 99920448 A EP99920448 A EP 99920448A EP 99920448 A EP99920448 A EP 99920448A EP 1088316 A1 EP1088316 A1 EP 1088316A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- layer
- starting material
- deposition
- fluorine
- thin
- 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.)
- Withdrawn
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 229920000642 polymer Polymers 0.000 claims abstract description 27
- 239000000758 substrate Substances 0.000 claims abstract description 20
- 229910052731 fluorine Inorganic materials 0.000 claims abstract description 18
- 239000011737 fluorine Substances 0.000 claims abstract description 18
- 239000007858 starting material Substances 0.000 claims abstract description 16
- 238000004549 pulsed laser deposition Methods 0.000 claims abstract description 14
- 239000007787 solid Substances 0.000 claims abstract description 11
- 238000004132 cross linking Methods 0.000 claims abstract description 8
- 238000004544 sputter deposition Methods 0.000 claims abstract description 8
- 238000002679 ablation Methods 0.000 claims abstract description 3
- 238000001704 evaporation Methods 0.000 claims abstract description 3
- 230000008020 evaporation Effects 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 25
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 24
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 24
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 15
- 238000000151 deposition Methods 0.000 claims description 10
- 230000008021 deposition Effects 0.000 claims description 9
- 239000000843 powder Substances 0.000 claims description 7
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 6
- 230000005855 radiation Effects 0.000 claims description 2
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 abstract 3
- 238000007664 blowing Methods 0.000 abstract 1
- 239000006185 dispersion Substances 0.000 abstract 1
- 239000010408 film Substances 0.000 description 20
- 239000000463 material Substances 0.000 description 8
- 230000007547 defect Effects 0.000 description 7
- 230000007704 transition Effects 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000005566 electron beam evaporation Methods 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 239000010409 thin film Substances 0.000 description 3
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 229920002313 fluoropolymer Polymers 0.000 description 2
- 239000004811 fluoropolymer Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 238000000608 laser ablation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- -1 Polytetrafluoroethylene Polymers 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- MSKQYWJTFPOQAV-UHFFFAOYSA-N fluoroethene;prop-1-ene Chemical group CC=C.FC=C MSKQYWJTFPOQAV-UHFFFAOYSA-N 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 238000002329 infrared spectrum Methods 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013077 target material Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G7/00—Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture
- H01G7/02—Electrets, i.e. having a permanently-polarised dielectric
- H01G7/021—Electrets, i.e. having a permanently-polarised dielectric having an organic dielectric
- H01G7/023—Electrets, i.e. having a permanently-polarised dielectric having an organic dielectric of macromolecular compounds
Definitions
- the invention relates to a thin electret layer with a layer thickness of less than 200 ⁇ m, consisting of fluorine-containing polymers, and to a method for the production thereof.
- the electrets are electrically charged on the basis of fluorine-containing polymers, for example by a negative corona discharge in air or by irradiation with a high-energy electron beam in a vacuum (cf. GB 1 368 454 A).
- Thermal post-treatment of a charged electret makes it possible to produce membranes that are negatively charged on both sides, cf. DE 24 32 377 AI.
- a positive corona discharge at elevated temperatures also allows the production of positively charged electrets, cf. US 4,527,218 A).
- a negative charge is also possible only by temperature treatment without an electric field. This method leads to - 2 - Electrets with comparatively low charge stability (cf. DE 195 22 473 AI).
- the films have only a low charge stability the relatively short chain length, the high number of branches and the high proportion of other irregularities, such as double bonds or radicals, in these films.Chain ends and irregularities can form electrical charge traps, and if the number of defects is too large, the charge stability decreases because The mobility of the electrical charges in the material increases, which can then migrate from fault to fault in the bouncing process. Since the intramolecular charge transport efficiently - 3 - enter is the intermolecular, the conduction process is facilitated by the high degree of branching.
- the invention was therefore based on the object of providing good electrets in the form of thin layers of fluorine-containing polymers on substrates and a simple, effective process for producing such thin electret layers.
- the electret layer according to the invention is characterized in that the average chain length of the polymer chains contained in the layer produced by evaporation, sputtering, ablation, inflation or scattering from a solid starting material made of fluorine-containing polymers is at least half the chain length in the starting material and that Degree of crosslinking of the polymer chains contained in the layer is at most twice the degree of crosslinking in the starting material.
- the fluorine-containing polymer contains tetrafluoroethylene groups.
- the procedure in particular is such that a layer of fluorine-containing polymers is applied to a substrate by pulsed laser deposition, the wavelength of the laser radiation used being between 100 nm and 20 ⁇ m and the pulse length between 10 fs and is 1 ms.
- the temperature of the substrate during the deposition is preferably between 20 ° C. and 700 ° C., in particular between 100 ° C. and 700 ° C.
- the thin electret layer will - 4 - after their deposition on the substrate, preferably after a temperature treatment between 100 ° C. and 700 ° C.
- the dielectric constant of the thin films was 2.44 for electron beam evaporation, 1.5 to 3.0 for radio frequency sputtering and 1 to 5 for pulsed laser deposition compared to 2.1 for solid PTFE.
- PTFE materials have a typical average molecular weight of 10 4 to 10 7 , which corresponds to an average chain length of 10 2 to 10 5 tetrafluoroethylene groups.
- a particularly suitable starting material for the production of the electret layers according to the invention has been found to be a PTFE powder with an average molecular weight of 5.10 4 to 4.10 5 . Very few defects, such as chain breaks or branches, occurred during the production of electret layers from pressed and sintered targets from this powder. This could be demonstrated by measuring the two crystalline phase transitions of PTFE from the triclinine to the hexagonal phase at 19 ° C and from the hexagonal to the pseudohexagonal phase at 30 ° C.
- defects are chain ends, but also radicals, double bonds or branches that result from broken bonds. An estimate shows that halving the mean chain length and doubling the branches in each case - 7 - can accept the starting material, provided that the starting material is already a sufficiently good electret. If the defect density becomes even greater, the charges can be increasingly transported in the material from one defect to the next by means of a hopping process, and the charge stability decreases.
- the electret layers can be a decrease in the electret layers, especially of the very short-chain components compared to the starting material, so that the average chain length can even increase.
- the films in FIGS. 2 and 3 show a lower intensity for peaks compared to the starting material in the IR spectrum, which peaks are assigned to vibrations of the amorphous region.
- the amorphous area is especially formed by the short chain components. Therefore a decrease may indicate the loss of the short chain components during the deposition.
- a commercial PTFE film (film thickness 25 ⁇ m, source: Goodfellow) was provided with a back electrode made of aluminum in a vapor deposition system. The sample was then charged in a corona discharge as described above and the stability of the negative and positive charges was counteracted. - 8 - determined by increasing the temperature. A half-value temperature of 200 ° C for negative charges based on a potential of -22 V / ⁇ m, and a half-value temperature of 160 ° C for positive charges based on 22 V / ⁇ m.
- a layer with a thickness of 2.5 ⁇ m was deposited on a silicon substrate at a substrate temperature of 355 ° C. from a homogeneous PTFE target using the pulsed laser deposition method.
- a KrF excimer laser with a light wavelength of 248 nm was used as the laser.
- the energy density of the laser light on the target was 4 J / cm 2 . 27,000 laser pulses were used.
- Charge stability was measured as described above. For negative charges, a half-temperature of 127 ° C resulted from a potential of -17 V / ⁇ m. For positive charges, the charge stability was so poor at room temperature that it could not be measured.
- a layer with a thickness of 13 ⁇ m was deposited on a silicon substrate at a substrate temperature of 355 ° C from a sintered and pressed target made of PTFE.
- a KrF excimer laser with a light wavelength of 248 nm was used as the laser.
- the energy density of the laser light on the target was 4.5 J / cm 2 .
- 5000 laser pulses were used.
- the diameter of the spherulites in the layer was approximately 0.2 mm.
- Charge stability was measured as described above. For negative charges, a half-value temperature of 150 ° C resulted from a potential of -12 V / ⁇ m, and a half-value temperature of 165 ° C for positive charges, based on 13 V / ⁇ m.
- a layer was deposited under the same conditions as in Example 3. After the deposition, the sample was briefly heated to 500 ° C. Then the layer thickness was - 9 - 6 ⁇ m and the diameter of the spherulites was about 0.5 mm. Charge stability was measured as described above. For negative charges, a half-value temperature of 254 ° C resulted from a potential of -40 V / ⁇ m, and a half-value temperature of 178 ° C for positive charges, based on 35 V / ⁇ m.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physical Vapour Deposition (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Laminated Bodies (AREA)
- Semiconductor Integrated Circuits (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT80098 | 1998-05-12 | ||
AT80098A ATA80098A (en) | 1998-05-12 | 1998-05-12 | THIN ELECTRIC LAYERS AND A METHOD FOR THEIR PRODUCTION |
PCT/AT1999/000119 WO1999059172A1 (en) | 1998-05-12 | 1999-05-12 | Thin electret layer and corresponding production method |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1088316A1 true EP1088316A1 (en) | 2001-04-04 |
Family
ID=3500021
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99920448A Withdrawn EP1088316A1 (en) | 1998-05-12 | 1999-05-12 | Thin electret layer and corresponding production method |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1088316A1 (en) |
JP (1) | JP2002515643A (en) |
AT (1) | ATA80098A (en) |
AU (1) | AU3802599A (en) |
WO (1) | WO1999059172A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
AT406756B (en) * | 1998-12-21 | 2000-08-25 | Johannes Dr Heitz | FLUOROPOLYMER COATINGS WITH GOOD LIABILITY AND GOOD ABRASION RESISTANCE FOR USE IN MEDICINE AND A METHOD FOR THEIR PRODUCTION |
JP4670050B2 (en) * | 2004-11-26 | 2011-04-13 | 国立大学法人 東京大学 | Electret and electrostatic induction type conversion element |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5650408B2 (en) * | 1973-07-05 | 1981-11-28 | ||
FR2351191A1 (en) * | 1976-05-11 | 1977-12-09 | Thomson Csf | PERFECTED ELECTROPHORESIS DEVICE |
US4527218A (en) * | 1981-06-08 | 1985-07-02 | At&T Bell Laboratories | Stable positively charged Teflon electrets |
DE19522473C2 (en) * | 1994-06-22 | 1996-12-05 | Gregory Kinteraya | Method of making an electret |
-
1998
- 1998-05-12 AT AT80098A patent/ATA80098A/en not_active Application Discontinuation
-
1999
- 1999-05-12 AU AU38025/99A patent/AU3802599A/en not_active Abandoned
- 1999-05-12 EP EP99920448A patent/EP1088316A1/en not_active Withdrawn
- 1999-05-12 JP JP2000548896A patent/JP2002515643A/en active Pending
- 1999-05-12 WO PCT/AT1999/000119 patent/WO1999059172A1/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9959172A1 * |
Also Published As
Publication number | Publication date |
---|---|
ATA80098A (en) | 1999-06-15 |
WO1999059172A1 (en) | 1999-11-18 |
AU3802599A (en) | 1999-11-29 |
JP2002515643A (en) | 2002-05-28 |
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Legal Events
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: HEITZ, JOHANNES Owner name: BAEUERLE, DIETER, PROF. DR. |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: HEITZ, JOHANNES Owner name: BAEUERLE, DIETER, PROF. DR. |
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RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: BAEUERLE, DIETER, PROF. DR. Owner name: HEITZ, JOHANNES |
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18D | Application deemed to be withdrawn |
Effective date: 20041201 |