GB2283243A - Casting material for an electrical assembly - Google Patents
Casting material for an electrical assembly Download PDFInfo
- Publication number
- GB2283243A GB2283243A GB9421396A GB9421396A GB2283243A GB 2283243 A GB2283243 A GB 2283243A GB 9421396 A GB9421396 A GB 9421396A GB 9421396 A GB9421396 A GB 9421396A GB 2283243 A GB2283243 A GB 2283243A
- Authority
- GB
- United Kingdom
- Prior art keywords
- casting material
- filler
- wax
- material according
- assembly
- 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- Withdrawn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
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/22—Secondary treatment of printed circuits
- H05K3/28—Applying non-metallic protective coatings
- H05K3/285—Permanent coating compositions
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
- C08K3/013—Fillers, pigments or reinforcing additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Paints Or Removers (AREA)
- Casings For Electric Apparatus (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Description
CASTING MATERIAL FOR AN ELECTRICAL ASSEMBLY 2283243 This invention relates
to a casting material incorporating a filler for potting an electrical assembly in a housing which at least partly surrounds 5 the assembly.
EP-A-0113465 discloses an electrical assembly mounted on a printed circuit board, which is potted in a housing by means of a synthetic resin based casting material containing quartz sand as filler. After the casting material has set, the assembly is combined integrally with the housing and is protected from environmental influences such as, for example, moisture. While the known casting material enables a long useful life of the assembly to be obtained, subsequent disposal of such components gives rise to difficulties, since separation of the electrical assembly from the casting material or of the casting material from the housing is only possible with great technical effort. The recycling of the components of the assembly is therefore made considerably more difficult or is not economically practicable.
DE-A-3913388 discloses a casting material for potting electrical and electronic components, which comprises a cycloaliphatic epoxy resin containing a proportion of filler of 57 to 61 by weight, based on the weight of the other ingredients of the casting material. In addition, hollow glass spheres are added to counter the tendency of the filler to sedimentation in the epoxy resin mixture. This addition is said also to minimise the susceptibility of the casting material to cracking. This casting material forms upon curing a solid block surrounding the components, which can only be removed again with considerable effort.
DE-A-3239872 discloses a flexible epoxy resin based casting material for the avoidance of cracking, the resin of which has epoxidised cyclohexane rings --2- each with one methyl group and which contains quartz flour and aluminium compounds as filler. The casting material comprises approximately equal proportions by weight of epoxy resin, quartz flour and aluminium 5 compound.
DE-C-856647 discloses an insulating material based on paraffin wax and containing quartz powder or natural or synthetic resins as fillers. However, the paraffin wax is used to form a coating inside a gas mask insert for the absorption of aerosols, or for the production of electrets. The potting of an electronic circuit in paraffin wax is not disclosed in this document and it is not disclosed in this document what proportion of filler in the wax is needed for a crack-free casting. 15 The object of the present invention is to cast an electrical assembly into a housing with a casting material in such a way that both crack-free setting and also subsequent separation of the casting material from the assembly are possible. 20 The object is achieved in that the casting material contains wax as binder for the filler and the proportion by volume of the filler in the casting material is greater than that of the wax. The advantage of the invention is essentially that the use of wax as a binder for the filler makes subsequent separation of the potted assembly possible by heating, so that both the assembly and the liquefied casting material can be recycled. Using- thiFproportions of the ingredients in accordance with the invention, crack-free setting of the casting material is obtained. Suitably, the casting material is made by mixing heated molten wax with the filler in a stirred vessel and the potting of the assembly in the housing is then performed.
Suitably, the proportion of the filler in the casting material is greater than 70% by volume, thereby 1 pc further reducing any tendency of the filler to sediment.
Advantageous proportions for the ingredients of the casting material are about 20 wax and 80 filler. The upper limit of the proportion of filler is given by the fact that, depending on the particle size of the filler, at a particular proportion of filler the socalled "closest packing density" is obtained at which the particles touch one another and the wax serves for bridge building between the particles.
The filler may suitably consist of particles of quartz, glass, ceramic or plastics materials. However, other inert solids which do not melt or dissolve in the hot wax and which have electrically insulating properties can also be used as fillers. Another example of a suitable filler is mica.
It is advantageous to select a filler with a particle size smaller than 3 millimetres. The upper limit of the particle diameter is given essentially by the fact that the components within the electrical assembly must be surrounded by the filler and that if the particle diameter is too large inhomogeneities can occur in the casting material due to wax bridges which do not contain any particles of filler. Advantageously, the filler particles are spherical in shape and have a preferred diameter between 0.1 and 1.5 millimetres. If_glass spheres are used as filler, a preferred particle size is about 1.4 millimetres. The glass spheres have, for example, a specific gravity 30 of between 2.4 and 2.6 g/cm3 and a bulk density of 1.4 g/cm3. If the casting material consists of 80% of glass spheres as filler and 20% of wax by volume, the glass spheres lie upon one another approximately in "close-packed sphere" arrangement. 35 The wax used is advantageously a branched-chain lowmelting polyethylene wax, such as is available commercially, for example under the name "Hoechst-Wachs VP PE 720". This polyethylene wax has a specific gravity of about 0.93 g/cm3 and a viscosity of 350 mPa.s at 1400C. The melting point is about 1300C. Depending on the application, however, other waxes with relatively low melting points, e.g. paraffin wax, can be used.
An exemplary embodiment of the invention will now be described with reference to the drawing.
The sole Figure shows in longitudinal section a side view of a housing 1 on a hotplate 2. The housing is filled with a casting material 3 for the potting of an electrical assembly 4. The assembly 4 comprises electrical components 6 on a printed circuit board 5.
The casting material 3 comprises a mixture of 20% by volume of polyethylene wax 8 and 80% by volume of filler 7 in the form of glass spheres 1.4 millimetres in diameter. The polyethylene wax 8 has a specific gravity of 0.93 g/cm3 and the filler 7 has a specific gravity of 2.5 g/cm3.
The casting material 3 is made in the following manner. Firstly, the polyethylene wax 8 is heated to its melting temperature and charged into the housing 1. In so doing, the temperature of the hotplate 2 is adjusted to be such that the wax 8 remains in the molten state. The filler 7 is then added. Because of the greater specific gravity of the filler 7 compared with the wax 8, homogeneous "Idyers of f il-let-7 -iffe - -built up, starting from the bottom of the housing 1, with the wax 8 as the binder for the filler 7. The assembly 4 is then inserted into the casting material 3 made in this way in the direction of the arrow 9. After removal of the housing 1 from the hotplate 2 the casting material solidifies to a block enclosing the components 6 in the housing 1.
t c
Claims (10)
1. A casting material comprising a filler for the potting of an electrical assembly in a housing which at least partly surrounds the assembly, wherein the casting material further comprises a wax as a binder for the filler and wherein the proportion by volume of the filler in the casting material is greater than that of the wax.
2. A casting material according to claim 1, wherein the proportion of the filler in the material is greater than 70% by volume.
3. A casting material according to claim 2, wherein the casting material comprises 20 by volume of wax and 80% by volume of filler.
4. A casting material according to any of claims 1 to 3, wherein the filler comprises quartz flour or particles of glass, or of a ceramic material or of a plastics material.
5. A casting material according to any of claims 1 to 4, wherein the particle size of the filler is smaller than 3 millimetres.
6. A casting material according to any of claims 1 to 5, wherein the filler comprises spherical particles. 25
7. A casting material according to claim 6, wherein the spherical particles have a diameter of from 0.1 to 1.5 millimetres.
8. A casting material according to any of claims 1 to 7, wherein the wax is a polyethylene wax. 30
9. A casting material according to claim 1, substantially as hereinbefore described with reference to the drawing.
10. An electrical assembly which has been potted in a housing containing a casting material according to any of claims 1 to 9.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4336749A DE4336749A1 (en) | 1993-10-28 | 1993-10-28 | Potting compound for an electrical assembly |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9421396D0 GB9421396D0 (en) | 1994-12-07 |
| GB2283243A true GB2283243A (en) | 1995-05-03 |
Family
ID=6501195
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9421396A Withdrawn GB2283243A (en) | 1993-10-28 | 1994-10-24 | Casting material for an electrical assembly |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE4336749A1 (en) |
| FR (1) | FR2711663B1 (en) |
| GB (1) | GB2283243A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT522905A1 (en) * | 2019-09-12 | 2021-03-15 | Waxell Gmbh | Casting material |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19846774A1 (en) * | 1998-10-10 | 2000-04-20 | Cognis Deutschland Gmbh | Polymer processing additive comprises a granulate in the form of bead or cylindrical particles having a specified length/diameter ratio |
| DE10110062A1 (en) * | 2001-03-02 | 2002-09-05 | Abb Research Ltd | Production of electrical insulation in high voltage device, e.g. transformer, comprises filling space between device components with granular solid insulator, and filling spaces between with gaseous or liquid insulator |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB632211A (en) * | 1947-02-28 | 1949-11-17 | Anglo Iranian Oil Co Ltd | Improvements relating to electrical insulating materials |
| GB1171236A (en) * | 1967-10-23 | 1969-11-19 | Doulton & Co Ltd | Cap and Pin Disc Insulators |
| GB1559504A (en) * | 1975-09-17 | 1980-01-23 | Gen Electric | Potting compounds and devices using such compounds |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1050052B (en) * | 1957-08-28 | 1959-02-05 | Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius &. Brüning, Frankfurt/M | Process for improving the mechanical properties of hydrocarbon waxes by adding olefin polymers |
| GB856834A (en) * | 1958-02-03 | 1960-12-21 | Westinghouse Brake & Signal | Improvements in and relating to thermo-plastic sealing compounds |
| GB1153939A (en) * | 1966-12-07 | 1969-06-04 | Matsushita Electric Ind Co Ltd | Insulating Impregnation Composition For Electric Equipment |
| GB1283412A (en) * | 1969-01-23 | 1972-07-26 | Dussek Brothers Ltd | A mastic for use in encapsulating electric cable joints |
| DD99879A1 (en) * | 1972-07-10 | 1973-08-20 | ||
| SU625252A1 (en) * | 1977-03-14 | 1978-09-25 | Предприятие П/Я А-7186 | Composition for impregnating paper insulation |
| DE3517082A1 (en) * | 1985-05-11 | 1986-11-13 | Wolff Walsrode Ag, 3030 Walsrode | SEALABLE MULTILAYER FILMS FROM POLYOLEFINES |
| DE4006688A1 (en) * | 1990-03-03 | 1991-09-05 | Kali Chemie Ag | COMPOSITIONS WITH DICHLORPENTAFLUOROPROPANES |
-
1993
- 1993-10-28 DE DE4336749A patent/DE4336749A1/en not_active Withdrawn
-
1994
- 1994-10-12 FR FR9412379A patent/FR2711663B1/en not_active Expired - Fee Related
- 1994-10-24 GB GB9421396A patent/GB2283243A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB632211A (en) * | 1947-02-28 | 1949-11-17 | Anglo Iranian Oil Co Ltd | Improvements relating to electrical insulating materials |
| GB1171236A (en) * | 1967-10-23 | 1969-11-19 | Doulton & Co Ltd | Cap and Pin Disc Insulators |
| GB1559504A (en) * | 1975-09-17 | 1980-01-23 | Gen Electric | Potting compounds and devices using such compounds |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT522905A1 (en) * | 2019-09-12 | 2021-03-15 | Waxell Gmbh | Casting material |
| AT522905B1 (en) * | 2019-09-12 | 2022-11-15 | Waxell Gmbh | casting material |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2711663A1 (en) | 1995-05-05 |
| DE4336749A1 (en) | 1995-05-04 |
| FR2711663B1 (en) | 1996-07-12 |
| GB9421396D0 (en) | 1994-12-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |