The invention is concerned with electrical connections made to devices such as resistive heaters and antennas which are incorporate on vehicle glazings.

Incorporation of electrical elements such as heating elements and radio antennas, in vehicle glazings is a well established practice. Typically, such elements are connected to other electrical equipment on the vehicle, such as power supplies or amplifiers and radio signal receivers, by a soldered connection located on a surface of the vehicle glazing. The soldered connection might conveniently be located in the obscuration band - a region of dark ceramic ink in the periphery of the glazing. Thus the soldered connection is rendered invisible from the exterior of the vehicle, giving a more aesthetically pleasing result.

Traditional solders contain lead. These perform well but lead is known to be poisonous and lead free alternatives providing similar performance would be preferable. The use of lead free solders is known in the automotive industry and elsewhere but in many cases, they fall short of the performance demanded by vehicle manufacturers.

Often, lead free solders have a high tin content. Such solders perform well in some respects, exhibiting good wettability and strength of bond, but for automotive applications, a high occurrence of stress faults are associated with such solders.

These stress faults may manifest themselves as blisters in the black ink of the obscuration band (particularly on toughened glass) or as cracks in a ply of laminated glazings. The stress faults are associated with differential thermal expansion and contraction between the solder and glass during the soldering operation.

Soldered joints may also be weakened by the temperature fluctuations experienced in service and by other mechanisms such as corrosion.

The resistance of lead free solders to thermal stress faults in particular may be increased by incorporating other elements such as indium in the solder alloy. However, there is an associated trade-off as the melting point of the solder, and its performance at higher temperatures, is reduced. The in-service temperatures encountered in some applications, e.g. in southern Europe, are frequently high enough to cause creep of the solder to the extent that the joint is unacceptably compromised.

Thus, a lead free solder which meets all of the requirements laid down by vehicle manufactures and legislators remains undiscovered.

Other approaches to the problem of achieving reliable electrical connections in automotive applications without the use of lead in solders, include supplementing or complementing the solder with other bonding means. For example, adhesive may be used to supplement the bonding action of the solder or the adhesive may be arranged to provide substantially all of the bond strength with the solder providing good electrical continuity. Nevertheless, there remains an ongoing requirement for soldered connections to electrical elements on vehicle glazings which are more robust and reliable. According to the invention, this solution is provided by apparatus according to claim 1.

In a preferred embodiment, the soldered electrical connector is arranged to engage a portion of the body upon securing the glazing thereto.

A further preferred embodiment comprises a resilient member arranged to engage the soldered connector upon securing the glazing to the body. In another embodiment the vehicle body includes a protrusion arranged to engage the soldered connection when the glazing is secured to the vehicle body. The protrusion may be resilient. The protrusion may be realised as a discrete component, fastened to the vehicle body or it may by an integral part of the body. The vehicle body may include a flange or lip, suitable for securing the glazing thereto. Another embodiment comprises a resilient component secured to the glazing, the resilient component being arranged to engage the vehicle body upon securing the glazing to the body and thereby to be biased against the connector, clamping the same against the glazing.

Preferably, the soldered connector comprises a lead free solder.

By the current invention the vehicle body is designed to provide physical support to a soldered connector on a glazing when the latter is installed in the vehicle. Thus, the forces employed to retain the glazing in situ are also exploited to retain the connector. Should the solder fail, the connector is still held in place.

The invention is particularly useful when used in combination with lead free soldered connections, thus avoiding the negative consequences of using lead while still providing a connection of satisfactory reliability.

The invention will now be described, by non-limiting example, with reference to the attached figures in which: figure la illustrates a typical vehicle glazing installation of the prior art; figure lb is a cross-sectional view on the line XX of figure la; figures 2, 3, 4a and 5 show a similar views to figure lb and illustrates various embodiments of the invention; figure 4b shows a view of the embodiment shown in figure 4a, as seen along the direction indicated by the arrow and figure 4c illustrates a variation on the embodiment shown in figures 4a and 4b. Any feature appearing in more than one figure is represented by the same numeral throughout. The figures are not to scale and the relative sizes of some components are exaggerated for illustration purposes. Referring to figures la and lb, in a typical motor vehicle, a glazing 1 such as a windscreen, backlight or sunroof is located in a suitably adapted location of the vehicle body 2 and secured by a bead 3 of bonding material such as polyurethane adhesive.

The location may include a recessed lip or flange 4, incorporated in the vehicle body, which provides the bonding site. However, in some designs there is no discrete lip and the glazing is simply secured over a suitably shaped aperture. The invention is applicable to both of these designs and to designs incorporating other features.

The skilled person will be aware that other features such as additional sealing beads or glazing support features incorporated in the vehicle body may be included but these are omitted for clarity. Their realisation is within the knowledge of a skilled person without further description here.

Referring to figure 2, in a simple embodiment of the invention, a soldered connection 5 is arranged to engage with a part of the vehicle body (in this case, against lip 4) when the glazing is installed. Thus the connector 5 is clamped between glazing 1 and lip 4 and additional support for retaining connector 5 in place is provided. It will be apparent to the skilled person that some form of electrical insulation may be required between the conducting parts of connector 5 and the typically metal vehicle body such as lip 4. This insulation could be realised in many ways, for example as a feature of the connector; an insulated region of lip 4 or an additional element incorporated between the connector 5 and the lip 4. In figure 2, the insulation is represented schematically by heavy line 6.

Referring to figure 3, a preferred embodiment of the invention includes a resilient element 7 located between the vehicle body (in this case, lip 4) and the connector 5. Element 7 is arranged to provide a biasing force on connector 5 when the glazing 1 is installed and thereby to provide additional retaining support. Use of a resilient member 7 provides protection from damage due to excessive force on the connector 5 and reduces the likelihood of damage in service due to vibration.

Resilient member 7 is typically formed in an elastomeric material which may also provide the necessary electrical insulation between connector 5 and lip 4. Prior to installation of glazing 1 , it may conveniently be located on the connector or at a suitable location on the vehicle body and held in place by bonding.

Referring to figures 4a and 4b, another preferred embodiment employs a protrusion 8 extending from the vehicle body (in this case, from lip 4) to engage connector 5 and provide additional retaining support. Protrusion 8 may be formed in a resilient material such as polymer or spring steel. Insulation may be included as required.

Figures 4a and 4b suggest that protrusion 8 is a discrete component which is attached to lip 4. Attachment could be achieved inter alia by bonding, resistance welding or riveting. However, protrusion 8 may conveniently be realised as in integral part of the vehicle body, for example the lip 4 (see figure 4c).

Referring to figure 5, in an alternative embodiment, protrusion 8 is fixed to the glazing 2 by bonding material 9. Finger 8 is arranged to engage with lip 4 on installation of glazing 2 and thereby to push against connector 5 to provide additional retaining support. Again, finger 8 may be formed in resilient material.