GB2116328A - Electrical testing of capacitors - Google Patents
Electrical testing of capacitors Download PDFInfo
- Publication number
- GB2116328A GB2116328A GB08234244A GB8234244A GB2116328A GB 2116328 A GB2116328 A GB 2116328A GB 08234244 A GB08234244 A GB 08234244A GB 8234244 A GB8234244 A GB 8234244A GB 2116328 A GB2116328 A GB 2116328A
- Authority
- GB
- United Kingdom
- Prior art keywords
- capacitor
- liquid
- capacitors
- rate
- vapour
- 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
- 239000003990 capacitor Substances 0.000 title claims abstract description 32
- 238000012360 testing method Methods 0.000 title claims description 10
- 239000007788 liquid Substances 0.000 claims abstract description 13
- 238000009413 insulation Methods 0.000 claims abstract description 10
- 239000003985 ceramic capacitor Substances 0.000 claims abstract description 6
- 230000004044 response Effects 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 27
- 230000008569 process Effects 0.000 claims description 20
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 239000000700 radioactive tracer Substances 0.000 claims description 3
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 claims description 2
- 238000005259 measurement Methods 0.000 claims description 2
- 238000005375 photometry Methods 0.000 claims description 2
- 229910052722 tritium Inorganic materials 0.000 claims description 2
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 claims 2
- 230000002285 radioactive effect Effects 0.000 claims 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 claims 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims 1
- 239000002245 particle Substances 0.000 claims 1
- 239000002904 solvent Substances 0.000 description 15
- 239000000919 ceramic Substances 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 5
- 238000001035 drying Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910014033 C-OH Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-NJFSPNSNSA-N Carbon-14 Chemical compound [14C] OKTJSMMVPCPJKN-NJFSPNSNSA-N 0.000 description 1
- 229910014570 C—OH Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- PPWHTZKZQNXVAE-UHFFFAOYSA-N Tetracaine hydrochloride Chemical compound Cl.CCCCNC1=CC=C(C(=O)OCCN(C)C)C=C1 PPWHTZKZQNXVAE-UHFFFAOYSA-N 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000011928 denatured alcohol Substances 0.000 description 1
- 238000009658 destructive testing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000011877 solvent mixture Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
- 239000000080 wetting agent Substances 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
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/30—Stacked capacitors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/20—Investigating the presence of flaws
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/18—Subjecting similar articles in turn to test, e.g. go/no-go tests in mass production
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/30—Stacked capacitors
- H01G4/306—Stacked capacitors made by thin film techniques
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
- Ceramic Capacitors (AREA)
Abstract
Insulation faults in capacitors, e.g. ceramic capacitors, are determined by impregnating the capacitor with a mobile volatile liquid and measuring the rate of liquid vapour emission in response to an applied voltage stress. A high rate of emission is indicative of a dielectric fault.
Description
1
GB 2 116 328 A 1
SPECIFICATION Electrical testing
This invention relates to testing insulation faults such as may occur in electrical components and to 5 techniques for improving the quality control of such components.
A major problem with the manufacture of electrical components incorporating an insulating material is that of detecting insulation faults. Such 10 faults may, at the time of manufacture, be only minor and thus difficult to detect but can subsequently be a cause of failure of the component. It would therefore be a considerable advantage if an incipient insulation failure could 15 be detected by non destructive test procedure.
For example, Ceramic dielectric capacitors, and particularly multilayer ceramic capacitors are widely used in the electronics industry as they are relatively inexpensive and have a high 20 capacitance/volume ratio. It is usual to employ a multilayer structure when fabricating ceramic capacitors, so that layers of ceramic are interleaved with layers of metal electrode in such a way that an interdigitated two-electrode 25 component of high capacitance value is produced. Various methods are used to make the ceramic layers as thin 'leaves', usually formed from a mix of the finely powdered ceramic material and an organic binder solvent system. For example, in a 30 typical conventional process, a ceramic/binder/solvent mixture is coated on to polyethylene strip, by a tape-drawing process. After drying, the ceramic/binder film is peeled off and then silk screen printed with electrodes using 35 an ink formed from precious metal powders in an organic binder. A number of such 'leaves' are stacked and pressed together, diced, heated to remove the binder, then fired at a high temperature. End terminations and leads may be 40 attached following normal practice and such processes as described above are well known in the art of multilayer ceramic capacitor manufacture. Following the present industry trend to decrease dielectric thickness the dielectric film 45 integrity has assumed great importance. It is desirable to decrease the capacitor size for several reasons, mainly compatibility with microelectronic trends and economy of materials.
A problem that has arisen with presently 50 manufactured ceramic multilayer capacitors is that of occasional cracking of the dielectric, during the manufacturing process. This cracking provides an intrinsic breakdown path between the capacitor electrodes or between an electrode and 55 the opposite polarity end termination and can lead to subsequent failure in service. The mechanism of this failure is not fully understood, but it is thought to involve electrochemical dissolution and migration of the electrode or end termination 60 materials which then provides a low resistive breakdown path. This migration is thought to occur in those cracked regions to which there is access to the atmosphere.
In most instances cracking of the dielectric
65 cannot be detected by visual inspection and the defect only becomes manifest after the capacitor has been in use for an extended period. It is clearly desirable to reduce such long term failures to a minimum.
70 Previous attempts to detect insulation faults have generally involved some form of electrical destructive testing on a batch basis. Such tests cannot be employed to provide 100 percent screening of components. Furthermore since they 75 generally involve the provision of relatively costly precautions.
A number of techniques have for example been proposed for dielectric crack detection in ceramic capacitors. In one process acoustic emissions 80 from the capacitors are monitored. These acoustic emissions are then computer processed to determine the good and bad capacitors. Such a process is however costly and somewhat uncertain.
85 The object of the present invention is to minimise or to overcome the disadvantages of the prior art techniques by providing an insulating fault detection process that is inexpensive, reliable and non-destructive.
90 Our co-pending application No. 821705 {R.C. Chittick 2X) describes a process for testing for an insulation fault in an electrical component, the process including subjecting the component to a volatile mobile ionising solvent, measuring a 95 parameter associated with the electrical condition of the insulation, and comparing the parameter with a reference value to provide an indication of the presence of an insulation fault.
According to the present invention there is 100 provided a process for testing for an insulation fault in a capacitor, the process including impregnating the capacitor with a mobile volatile liquid and measuring the liquid vapour emitted from the capacitor in response to an applied 105 voltage stress.
An embodiment of the invention will now be described with reference to the accompanying drawing in which the single figure is a schematic diagram of a capacitor measurement and test 110 apparatus. It should be understood that this description is by way of example only and that the techniques described herein are in no way limited to capacitor applications.
Referring to the drawing, capacitors 11 to be 115 tested are mounted on a conveyor 12 and are carried via a treatment station 13, where they are immersed in or sprayed with a mobile ionising . solvent, to a drying station 14 whereby excess solvent is removed. Typically drying is effected in a 120 current of air at ambient temperature. In some applications the capacitors may be preheated e.g. to 100°C prior to immersion to enhance penetration by the solvent. In other applications the capacitors may be vacuum impregnated with 125 the solvent.
The treated capacitors are carried from the drying station 14 to a test station 15. A voltage, e.g. the maximum rated working voltage is applied to each capacitor and the rate at which solvent is
2
GB 2 116 328 A 2
evaporated from that capacitor is measured. The presence of a dielectric fault, e.g. a crack, in a capacitor results in electrical conduction via the solvent at that point. This causes a local 5 temperature rise thus enhancing the rate at which the solvent is evaporated from the capacitor. By comparing the evaporation rate from each capacitor with a reference value capacitors showing excessive vapour evolution, i.e. those 10 with dielectric faults, can be directed to a reject bin 16. The remaining capacitors are directed to a transfer station 17 for further processing.
A number of techniques may be used for measuring the vapour evolution rates. Typically 15 we employ infra red absorption or photometric measurements on the C—OH band stretching frequency where methanol is the impregnating liquid. In an alternative arrangement the liquid may be labelled with a radioactive tracer, e.g. 20 tritium or carbon 14 and the vapour evolution rate measured from an activity count. Other measurement techniques include, but are not limited to, flame ionisation and microwave absorption.
25 A variety of liquids may be employed in the technique. Typically we employ methanol, but ethanol, isopropyl alcohol, industrial methylated spirit or mixtures of any of these solvents may be used. The preferred liquid is methanol since it has a 30 higher conductivity than the other alcohols and a suitably low viscosity.
Less advantageously water containing a wetting agent can be employed, although in certain applications the use of water is 35 undesirable. This list of solvents is given by way of example only and is not to be considered as limiting. Preferably the solvent should be mobile, i.e. a low viscosity and low surface tension to allow rapid penetration. The solvent should also 40 be polar and of the ionising type. In some applications the efficiency of the solvent can be enhanced by the addition of a small quantity, e.g. 0.01 %, of an ionogen or mixtures thereof. Materials of this nature, such as triethylamine, 45 enhance the generation of ions in the solvent and hence increase the electrical conductivity.
It is preferred, although not essential, that the ionogen is relatively volatile so that subsequent removal of the material from the component can 50 be readily effected.
Claims (10)
1. A process for testing for an insulation fault in a capacitor, the process including impregnating the capacitor with a mobile volatile liquid, and
55 measuring the liquid vapour emitted from the capacitor in response to an applied voltage stress.
2. A process as claimed in claim 1, wherein the liquid is methanol, ethanol, isopropyl, alcohol or mixtures thereof.
60
3. A process as claimed in claim 1, or 2,
wherein the liquid contains an ionogen.
4. A process as claimed in claim 4, wherein said ionogen is methylamine.
5. A process as claimed in any one of claims 1 65 to 4, wherein the rate of vapour emission is determined from infra-red photometric measurements.
6. A process as claimed in any one of claims 1 to 4, wherein the liquid contains a radio-active
70 tracer, and wherein the rate of vapour emission is determined from nuclear particle measurement.
7. A method as claimed in claim 6, wherein said tracer is radioactive carbon or tritium.
8. A process as claimed in any one of claims 1 75 to 7, wherein the capacitor is a ceramic capacitor.
9. A process for capacitor testing substantially as described herein with reference to the accompanying drawings.
10. A capacitor when tested by a process as 80 claimed in any one of the preceding claims.
Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08206030A GB2115937A (en) | 1982-03-02 | 1982-03-02 | Testing for dielectric faults |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2116328A true GB2116328A (en) | 1983-09-21 |
| GB2116328B GB2116328B (en) | 1985-04-03 |
Family
ID=10528716
Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08206030A Withdrawn GB2115937A (en) | 1982-03-02 | 1982-03-02 | Testing for dielectric faults |
| GB08217105A Withdrawn GB2116729A (en) | 1982-03-02 | 1982-06-11 | Electrical testing |
| GB08234244A Expired GB2116328B (en) | 1982-03-02 | 1982-12-01 | Electrical testing of capacitors |
Family Applications Before (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08206030A Withdrawn GB2115937A (en) | 1982-03-02 | 1982-03-02 | Testing for dielectric faults |
| GB08217105A Withdrawn GB2116729A (en) | 1982-03-02 | 1982-06-11 | Electrical testing |
Country Status (1)
| Country | Link |
|---|---|
| GB (3) | GB2115937A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102018214719B4 (en) * | 2018-08-30 | 2020-06-18 | AUDI HUNGARIA Zrt. | Method for checking and producing a glow plug having a ceramic heating element |
-
1982
- 1982-03-02 GB GB08206030A patent/GB2115937A/en not_active Withdrawn
- 1982-06-11 GB GB08217105A patent/GB2116729A/en not_active Withdrawn
- 1982-12-01 GB GB08234244A patent/GB2116328B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2116328B (en) | 1985-04-03 |
| GB2116729A (en) | 1983-09-28 |
| GB2115937A (en) | 1983-09-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |