Patent EA-005283-B1 (EA)
Title: Method for producing an electromagnetic shield
IPC: H05K9/00
Filed: 2001-01-22
Abstract: 1. A method of making a connection between a printed circuit board (6) and an electrically conductive cap (3) for electromagnetic shielding, wherein arranged between the printed circuit board (6) and the cap (3) is an electrically conductive mass (2), and by means of the electrically conductive mass the cap (3) is fixed on the printed circuit board (6), characterised in that the electrically conductive mass (2) comprises two different components (X, Y) and react with each other like a two-component adhesive and before the cap (3) and the printed circuit board (6) are assembled both the cap and also the printed circuit board are provided at the mutually facing locations with different material layers each of them is one of the electrically conductive mass (2) components. 2. A method as set forth in claim 1 characterised in that the method is carried out for automatically fitting the printed circuit board (6) with the cap (3). 3. A method as set forth in claim 1 or claim 2 characterised in that the method for automatically fitting the printed circuit board (6) with a cap (3) is carried out at an SMD fitting station. 4. A method as set forth in one of the preceding claims characterised in that the conductive mass (2) includes a silicone, epoxy, PU, Teflon, acryl, EPDM, EPM or other bonding substances or a mixture thereof and has an electrically conductive filler. 5. A method as set forth in claim 4 characterised in that the filler comprises carbon, metal, fiber balls of metal, for example aluminum, copper, silver, gold or multi-functional fillers such as for example silver-plated glass, copper, nickel, aluminum or nickel-plated graphite or the like. 6. A method as set forth in one of the preceding claims characterised in that the cap (3) for shielding purposes is a metal cap or a metallised cap or a cover comprising non-conducting material. 7. A method as set forth in one of the preceding claims characterised in that the electrically conductive mass (2) is applied to the appropriate locations on the printed circuit board (6) so that then the shielding cap (3) is fitted on to the locations at which the electrically conductive mass (2) is applied to the printed circuit board (6). 8. A method as set forth in one of claims 1 through 7 characterised in that application of the electrically conductive mass (2) to the printed circuit board (6) or however also the cap (3) is effected by a dispensing process, a printing process, a stencil printing process, a screen printing process, immersion, dipping, or a tampon printing process. 9. A method as set forth in one of the preceding claims characterised in that after the connection between the printed circuit board (6) and the cap (3) has been made with the electrically conductive mass (2), a durable connection between those components is made, with the mass being solidified and/or cross-linked and/or dried. 10. A method as set forth in claim 9 characterised in that the durable connection is effected by a hardening process, for which purpose treatment is effected by means for example of heat and/or alpha rays and/or beta rays and/or gamma rays and/or air humidity and/or light and/or ultraviolet light and/or infrared radiation. 11. A method as set forth in one of the preceding claims characterised in that the temperature in the hardening process is markedly lower than the temperatures which usually occur in the soldering procedure for connecting the cap (3) to the printed circuit board (6). 12. A method as set forth in one of the preceding claims characterised in that for fixing and electrical contacting between the cap (3) and the printed circuit board (6), a layer with a component X is applied to the printed circuit board (6) and a layer with a component Y is applied to the underside of a side wall of a cap (3), wherein the two components are such that they react with each other (chemically, physically) so that the desired mechanical fixing and electrical contacting of the cap (3) on the printed circuit board (6) is guaranteed. 13. A method as set forth in one of the preceding claims characterised in that arranged between the shielding cap (3) and the printed circuit board (6) is a shrinkable material (4) which upon shrinkage fixes or pulls together the shielding cap and the substrate beneath the shielding cap. 14. Connecting an electrically conductive cap (3) to a printed circuit board (6) by means of a method as set forth in one of the preceding claims. 15. A printed circuit board (6) on which there is arranged an electrically conductive cap (3) which has the function of a shielding element for components (5) arranged on the printed circuit board (6), and by means of the electrically conductive mass the cap (3) is fixed on the printed circuit board (6), characterised in that the electrically conductive mass (2) comprises two different components (X, Y) provided at the mutually facing locations of the printed circuit board (6) and the cap (3) correspondingly and react with each other like a two-component adhesive. 16. A printed circuit board as set forth in claim 15 characterised in that the cap (3) is arranged at a predetermined spacing relative to the printed circuit board (6) and the spaced space between the cap (3) and the printed circuit board (6) is filled by the electrically conductive mass (2). 17. An electrical apparatus including a printed circuit board as set forth in claims 15 or 16. 18. An electrical apparatus as set forth in claim 17 characterised in that the electrical apparatus has at least a transmitting device and/or receiving device. 19. Apparatus as set forth in claim 18 characterised in that the electrical apparatus is a mobile radio unit.