MATERIAL WITH RADIATION-SHIELDING PROPERTIES

Abstract: The invention relates to a combination of materials that can be applied as an additive in plastic compounds, coatings and fibres that are used for totally or partly encapsulation of electric apparatus, wherein one or more high-speed switching elements are being utilized, providing that negative effects on the autonomous nervous system of persons that are exposed to the electromagnetic radiation, originated by said apparatus, are being eliminated.

Description: MATERIAL WITH RADIATION-SHIELDING PROPERTIES BACKGROUND OF THE INVENTION The invention relates to a combination of materials that can be utilized as an additive in plastic compounds or coatings that are used for total or partly encapsulation of electrical apparatus, wherein high-speed switching elements are being applied, providing that negative effects on the autonomous nervous system of persons that are exposed to the electro-magnetic radiation, originated by these apparatus, are being eliminated. Encapsulation of electrical and electronic components or circuitry, in which high-speed switching elements are used, is commonly known and utilized in packaging compounds for transistors and integrated circuits and is described in Japanese patent nr: JP-A-62-105610. An other well-known method of embedding electronic and electrical citcuitry is described in US Patentnr. 4,587,140. The number of product/market combinations of electrical and electronic apparatus where one or more high-speed switching elements are being utilized is numerous and divers. Two important groups of products can be characterized: 1. High-speed switching Electronic Power Supplies (e.g. Switched Mode Power Supplies) : This group of products is strongly growing for a number of years. In compact Co puterapplications this type of power supply is already "state of the art" for many years. In other markets like "Automotive Electronics", "Entertainment" ( Audio/ Video and Multimedia) , "Domestic Appliancies" and "Lighting Electronics" there is an explosive grow in quantities for Electronic Power Supplies. Especially in the area of "Lighting" where in several countries national energy-saving programs have been developed to stimulate the application of electronic power supplies as substitution for classical electromagnetic ballasts. 2. A second group of apparatus where high-speed switching elements are being utilized is the group of products wherein digital signal processing is applied. The two mentioned groups of products wherein high-speed switching elements are utilized follow a similar technological trend of miniaturization. In a general sense one can conclude that, in order to shrink the physical dimensions of the electrical and electronic components in an electronic circuit, it is necessary to increase the switching frequency , in other words : the number of switching functions (on-off) per second increases. Two major problems are related to this evolution; 10 1. Heat; the lifetime of the components in electronic circuitry depends on the thermal load of these components. It is obvious that an increasing number of switching functions per second without special technological solutions will lead to a proportional increase of heat dissipation as a ** - consequense of switching losses. Therefore the temperature of the "silicon die", wherein the high-speed switching element (s) are realized, will increase and the life-time will decrease. Per ten degrees temperature rise the life-time will be halved. Basicly one can say that these kind of problems Q can only be solved by proper measures that lead to a lower temperature level of the critical part of the electronic component, such as utilization of cooling elements or by increasing the thermal conductivity of the materials that are used to encapsulate (or package) this high-speed switching p r- components. 2. Electromagnetic radiation; As a consequence of the increasing switching frequenties of electronic elements, in combination with the modern submicron-technology in integrated circuits, where electrical currents are being TΛ switched in physical dimensions in the order of (sub-) microns, one can expect electromagnetic radiation in the same micrometer-wavelength area. With respect to the harmful effects of electromagnetic radiation the existing regulation institutes are playing an - - important role. Starting-point for regulation is that electric apparatus should not interfere with eachother and existing systems of wireless communication may not be hindered by electromagnetic radiation of electric products. No priority has been given to the fact that non-ionizing electromagnetic radiation from electronic products or systems can also interfere with biological functions or processes in a human being or animal. An important point in this respect 5 is the fact that most of the vital biological processes in living organisms are controlled by socalled "biophotons", being electromagnetic signals in the wavelength area of 0.2-2 micrometers. Weak to very weak monochromatic non-ionizing radiation in the micronwavelenght area will have an effect 0 limited to the outer microns of the skin tissue. Electromagnetic radiation in low to very low frequencies is passing a human body unhindered. In most apparatus where high-speed switching elements are utilized a combination of both types of radiation are present: A 50 or 60 c/s ripple of = "mains-supplied" products as well as a 28 Kc/s resonant frequency of an electronic compact fluorescent lamp can act as a wave carrier for "micrometer"-radiation coming from high-speed switching elements in the electric circuitry and passes the skin tissue. Qualification of the "harmfulness" of 0 these kind of superimposed radiation is extremely complex and strongly dependent on individual and environmental parameters. In the last decades a lot of experience has been build up with socalled electrodermal measuring techniques, where 5 via selectively placed electrodes on the human body information can be gained related to wanted or unwanted effects on biological functions, caused by all kinds of external influences. As far as these effects show changes of electrical properties of the skin (conductance, potential, 0 impedance) they can be recorded. Examples of such measuring techniques are EEG, ECG, EMG, Brain apping and Decoder- Dermografics. The last mentioned method has the advantage that for each person individually can be determined if one (or more) electrical products will have an effect on the ~ autonomous nervous system. For this purpose the electrical skin conductance and skin potential are being measured on different locations of the body. Response to a tiny, well defined electric signal is being recorded. In this way information is gathered on the differential activity of the ortho-sympatic system (Ref. Wiegant F en van Wijk R, Nederlands Tijdschrift voor Integrale Geneeskunde; 7(3):91- 104,1991 De decoder-dermografische meting, in dutch language) . With respect to the already mentioned heat- and the related lifetime problems of electrical apparatus, wherein high-speed switching elements are utilized, the industry has developed a number of solutions. One important example is the encapsulation of electronic circuits with plastic materials, that can guarantee sufficient lifetime for certain vulnerable components, specifically heatproblems from dissipating high¬ speed switching elements. In encapsulation (or packaging) of electronic components and/or circuitry a lot of other problem-areas play a role such as; mechanical vibrations and shock; influence of humid atmosphere; chemicals; mechanical stress; electrostatic discharges. It will be clear that the requirements for encapsulation materials are divers and must be optimized for each specific application. In development of recipees for this kind of materials a lot of variations is possible by specific choicin polymers and filler materials and other additives. SUMMARY OF THE INVENTION The invention provides a solution for shielding that part of the electromagnetic radiation spectrum, originated by electric apparatus wherein high-speed switching elements are utilized, that has negative effects on the autonomous nervous systems of persons that are exposed to said radiation. In the invention the elimination of this potentially hazardous effects, is accomplished by utilizing a specific combination of materials, that can be applied as an additive in plastic compounds or coatings that are being used for encapsulation or shielding of electronic components or circuitry. The amount of this combination of materials has to be optimized for each application. In order to accomplish the desired effect of effective shielding various solutions are possible: 1. Encapsulation of high-speed switching transistors and integrated circuits via utilizing the invented material in a 5 small but effective amount as an additive in socalled packaging compounds. 2. Additional shielding of packaged components or circuits by applying a protective coating with an optimized amount of the invented material in the coating. 10 3. Coating of metal or plastic housings of electrical and electronic apparatus, wherein high-speed switching elements are utilized. 4. Application of the invented material as an additive in plastic compounds (engineering plastics) that are being 1:? utilized for the housing of electric apparatus. 5. Application of the invented material as an additive in laminates, used for making printed circuit boards for electrical and electronic circuitry. 6. Application of the invented material as an additive 20 in textile fibres in order to protect people against potentially hazardous radiation from electric apparatus via protective clothing. 7. Application of the invented material as an additive in paintings, that can be used for coating or painting of 2~ houses to protect people against harmfull electromagnetic radiation that is coming from outside (f.i. TV- and mobile communication transmitters) . DETAILED DESCRIPTION OF THE INVENTION A combination of materials, which has shown to be 30 effective in shielding electromagnetic radiation that has a negative effect on the autonomous nervous system of human beings, exposed to the radiation of electrical apparatus wherein high-speed switching elements are being utilized, is socalled ilmenitesand, preferably in dried form. The Α> ^> composition of ilminitesand in standard, non-dried form is the following; H20 : 21- 17 % "Dry material" : 79- 83 % pH-value (10% solution) : 5- 8 The "dry material" has the following composition: Fe20 18 - 23 % Ti02 22 - 26 % Si02 15 - 25 % MgO 5 - 7 % A1203 3 - 4 % CaO (Silicatic, CaC03, CaS04) 3 - 5 % Zr02 0,1 -0,3 % Cr 400 -1100 ppm Cu 100 - 300 ppm Mn 1300 -2000 ppm Ni 200 - 400 ppm V 500 - 800 ppm Zn 100 -1000 ppm Pb 1 - 6 ppm Cd < 1 ppm Hg < 1 ppm A combination of materials with this composition can be combined with other filler materials like titaniumdioxide in compounds or coatings. Dependent on the composition of the compound or coating with respect to the applied polymers and filler materials, the optimal concentration of the invented material has to be determined. In a practical application example, namely the electronic power supply of the Philips Compact Energy-saving lamp, type PLC-9W, a combination of filler materials from 80% Ti02 (anataas cristals) and 20% dried ilmenitesand (percentages by weight), has proven to be very effective. It is self-evident that other combinations can be made with other filler materials, such as fumed or precipitated silica, aluminum trihydrate and others. The basic polymer that is utilized in this practical example is a synthetic thermoplastic resin (Necires LX type 801-100 from Nevcin Polymers BV, Uithoorn, Netherlands) .

Claims: What is claimed is: 1. An electric apparatus, containing one or more high¬ speed switching elements, totally or partly surrounded by plastic material, providing that in this plastic material a combination of materials is added in the right concentration, whereby negative effects on the autonomous nervous system of human beings that are exposed to the electromagnetic radiation of said electric apparatus, are being eliminated. 2. An electric apparatus of claim 1 wherin the combination of materials is ilminitesand, preferably in dried form. 3. An electric apparatus of claim 1 or 2 wherein the combination of materials consists of a composition of the three main constituents of ilminitesand, namely FeO, Ti02 and Si02 in approximately equal percentages. 4. An electric apparatus of claim 1 or 2 wherein a few percentages MgO (5-9) and A1203 (3-5) by weight are present in the combination of materials. 5. An electric apparatus of claim 1 or 2 wherein a few percentages of CaO (3-5) by weight are present in the combination of materials. 6. An electric apparatus of claim 1 or 2 wherein a few tenths of a percent of Zr02 by weight is present in the combination of materials. 7. An electric apparatus of claim 1 or 2 wherein the elements Cr (400-1000 ppm), Cu (100-300 ppm), Mn (1300-2000 ppm), Ni (200-400 ppm), V (500-800 ppm), Zn (100-1000 ppm), Pb (1-6 ppm) are present in the combination of materials. 8. An electric apparatus of claim 1 or 2 wherein the combination of materials is combined with Ti02 fillers in the plastic encapsulation material. 9. An electric apparatus of claim 1 or 2 wherein the basic polymer of the encapsulating plastic is dicyclopentadiene in more than 50 percentage by weight from the total amount of polymer content. 10. A combination of materials that can be applied as filler material in plastic compounds and coatings to be utilized for totally or partly encapsulation of electrical apparatus wherein one or more high-speed switching elements are applied, providing that the negative effects on the autonomous nervous system of human beings that are exposed to the electromagnetic radiation of said apparatus, are being eliminated. 11. A combination of materials that can be applied as filler material in printed circuit boardlaminates for electrical and electronic circuitry wherein one or more high¬ speed switching elements are applied, providing that the negative effects on the autonomous nervous system of human beings that are exposed to the electromagnetic radiation of said electrical and electronic circuitry are being eliminated. 12. A combination of materials that can be applied as an additive in textile fibres to be utilized in clothing for totally or partly encapsulation of human beings that are exposed to electromagnetic radiation, providing that negative effects on the autonomous nervous system of said huming beings are being eliminated. 13. A combination of materials of claim 10, 11 or 12 wherein the combination of materials is ilmenitesand, preferably in dried form. 14. A combination of materials of claim 10, 11 or 12 wherein the combination of materials consists of a mixture of the three main constituents of ilmenitesand, namely FeO, Ti02 and Si02 in approximately equal concentrations. 15. A combination of materials of claim 10, 11 or 12 wherein a few percentages MgO (5-9) and A1203 (3-5) by weight is present in the combination of materials. 16. A combination of materials of claim 10, 11 or 12 wherein a few percentages of CaO (3-5) by weight are present in the combination of materials. 17. A combination of materials of claim 10, 11 or 12 wherein a few tenths of one percent of Zr02 by weight are present in the combination of materials. 18. A combination of materials of claim 10, 11 or 12 wherein the elements Cr (400-1000 ppm), Cu (100-300 ppm), Mn (1300-2000 ppm), Ni (200-400 ppm), V (500-800 ppm), Zn (100-1000 ppm), Pb (1-6 ppm) are present in the combination of materials. 19. A combination of materials of claim 10, 11 or 12 wherein this combination of materials is applied with titaniumdioxide pigment as filler materials in plastic compounds, coatings and textile fibres. 20. A combination of materials of claim 10, 11 or 12 wherein a dicyclopentadiene polymer is utilized as a basic polymer in the compound or coating for more than 50 percent by weight from the total polymer content.

Inventors: IDING WILHELMUS HERMANUS, IDING, WILHELMUS, HERMANUS
Applicants: IDING WILHELMUS HERMANUS, IRIS MATERIALS B V I O, IDING, WILHELMUS, HERMANUS, IRIS MATERIALS B.V. I.O.
Application year: 1996
Main classification: A61N1
IPC codes: A61N1, H05K9