GLAZING EQUIPPED WITH AN ELECTRICALLY CONDUCTIVE DEVICE WITH IMPROVED SOLDERING ZONES

Abstract

A glazing includes a glass substrate at least one portion of which includes an electrically conductive element including electrically conductive tracks made of a conductive metallic paste forming the electrical network and soldered to a connector by a soldering alloy based on tin, silver and optionally copper level with a soldering zone, the glazing including a single layer of silver paste level with the soldering zone, this single layer ensuring the electrical contact of the conductive element, the conductive metallic paste of the electrical network and the conductive metallic paste level with the soldering zone being silver pastes of different composition.

Claims

1. A glazing comprising a glass substrate at least one portion of which comprises an electrically conductive element consisting of electrically conductive tracks made of a conductive metallic paste forming an electrical network and soldered to a connector by a soldering alloy based on tin, silver and optionally copper level with a soldering zone, the glazing comprising a single layer of silver paste level with the soldering zone, the single layer ensuring the electrical contact of the electrically conductive element, the conductive metallic paste of the electrical network and the conductive metallic paste level with the soldering zone being silver pastes of different composition.

2. The glazing as claimed in claim 1, wherein the soldering alloy comprises from 90 to 99.5% by weight tin, from 0.5 to 5% by weight silver and from 0 to 5% by weight copper.

3. The glazing as claimed in claim 1, wherein the silver paste level with the soldering zone comprises between 60 and 88% by weight silver before fritting and between 90 and 97% by weight silver after fritting at a temperature comprised between 550 C. and 700 C., the rest being glass frit.

4. The glazing as claimed in claim 1, wherein the silver paste level with the soldering zone possesses a resistivity, measured at a temperature of 25 C., lower than or equal to 3.5.Math.cm.

5. The glazing as claimed in claim 1, wherein a thickness of the layer of conductive metallic paste forming the electrical network is different from a thickness of the layer of conductive metallic paste level with the soldering zone.

6. The glazing as claimed in claim 1, wherein the layer of conductive metallic paste level with the soldering zone has a thickness comprised between 5 and 20 m, said thickness being measured after fritting.

7. The glazing as claimed in claim 1, wherein a thickness of the layer of soldering alloy is smaller than or equal to 600 m.

8. The glazing as claimed in claim 1, wherein the connector is made of stainless steel.

9. A process for manufacturing a glazing as claimed in claim 1, comprising: depositing electrically conductive metallic tracks in order to form the electrical network on at least one portion of the glass substrate; depositing a single layer of conductive metallic paste level with the soldering zone between the electrically conductive tracks and the connector, the electrical contacts being formed level with the single layer; optionally drying the layers of conductive metallic pastes; and fritting the layers of conductive metallic pastes; then soldering the connector level with the soldering zone.

10. The process as claimed in claim 9, wherein the two depositing steps are carried out by screen printing or by digital printing.

11. The process as claimed in claim 9, wherein the depositing steps are carried out by screen printing, a drying step taking place before the fritting step.

12. The process as claimed in claim 11, wherein an intermediate drying step is carried out after the deposition of the electrically conductive tracks forming the network and before the deposition of the layer of conductive metallic paste level with the soldering zone.

13. The process as claimed in claim 10, wherein the two depositing steps are carried out with different screen-printing screens.

14. A method comprising arranging a glazing as claimed in claim 1 in a building or a vehicle.

15. The method as claimed in claim 14, wherein the glazing forms a heated windshield, a side window, a rear windshield or a roof, or a windshield, a side window, a rear windshield or a roof equipped with an antenna or any other electrical function placed on or in the glazing.

16. The glazing as claimed in claim 6, wherein the thickness is comprised between 7 and 15 m, said thickness being measured after fritting.

17. The glazing as claimed in claim 7, wherein the thickness of the layer of soldering alloy is comprised between 150 and 600 m.

18. The method as claimed in claim 14, wherein the vehicle is a motor vehicle, a rail vehicle or an airplane.

Description

[0036] The figures below illustrate the invention. FIG. 1 is a diagram of a type of electrical connection conventionally used in the case of lead-containing solders to meet the requirements of aging tests. FIGS. 2 to 4 are diagrams of types of electrical connections for glazings according to the present invention.

[0037] The glazing shown in FIG. 1 is a glazing 1 for example used as a rear windshield equipped with heating conductive wires 2 that are in particular used for defrosting. A black enamel frame 3 is deposited on the periphery of the glazing in order to mask the electrically connecting zones. During the manufacture of such a glazing, the layer deposited first is the layer corresponding to the frame 3, the heating wires 2 being deposited next in this frame. Two soldering and electrically connecting zones 4a and 4b are shown in this figure and have been enlarged. The zone 4a corresponds to a soldering zone on which a button shaped connector will be placed, whereas in the zone 4b the connector will be oblong shape. Level with the soldering zone 4a, a layer of conductive metallic paste 5a of the same composition as that of the heating wires 2 is deposited, in the form of a disk of the shame shape as the connector. This layer is then covered with a second silver paste 6a that possesses the characteristics required to allow the soldering alloy and the connector itself to be soldered. Level with the soldering zone 4a, two layers of conductive metallic paste 5a and 6a are therefore superposed, the zone 5a being the busbar zone and the zone 6a being the soldering zone of the connector. For the soldering zone 4b, two successive layers 5b and 6b of conductive metallic pastes are superposed while tailoring the shape of the soldering zone to that of the connector, the zone 5b being the busbar zone and the zone 6b being the soldering zone of the connector.

[0038] FIG. 2 shows a glazing according to the invention in which the soldering zones 7a and 7b comprise only a single layer of conductive metallic paste. The single layer 8a, 8b that is level with the soldering zone is the layer that allows the electrical connection to be made with the heating wires 2 via the busbar zone 2b corresponding to a conductive metallic paste of the same composition as that used for the heating wires 2.

[0039] FIG. 3 shows another diagram of a type of connection of a glazing according to the present invention. In this configuration, the soldering zone 9 comprises a portion consisting of a single layer 9a of conductive metallic paste, this portion making direct contact, in order to ensure an electrical connection, with a strip of conductive paste used for the heating wires 2. The connector is positioned on the portion 9a which comprises only a single layer. The transition zone 9b located around the portion 9a is the only zone in which two layers of conductive metallic pastes are superposed. This transition zone does not correspond to the soldering zone on which the connector will be positioned.

[0040] FIG. 4 shows yet another diagram of a type of electrical connection of a glazing according to the invention, in which the soldering zone 10 comprises only a single layer of conductive metallic paste 10a deposited directly on the black enamel layer of the frame 3. In the same way as in FIG. 3, the transition zone 10b is the zone level with which two layers of conductive metallic pastes are superposed, this transition zone not being the soldering zone. The connector is positioned on the zone 10a that comprises only a single layer of conductive metallic paste.