WO2015067951A1

WO2015067951A1 - Electrical connector for a glazing

Info

Publication number: WO2015067951A1
Application number: PCT/GB2014/053306
Authority: WO
Inventors: Michael Lyon; Julie HOUGHTON
Original assignee: Pilkington Group Limited
Priority date: 2013-11-08
Filing date: 2014-11-06
Publication date: 2015-05-14
Also published as: EP3066718A1; EP3066718B1

Abstract

The invention relates to an electrical connector (1) for a glazing having a round base portion (11) and a lip portion (12) around the base portion (11), such that the lip portion (12) in cooperation with the base portion (11) defines a concave recess (13) suitable for receiving a solder deposit (14). The lip portion (12) may comprise a ring-shaped protrusion or groove suitable for defining a predetermined distance from the base portion to an object to be soldered. A holding portion (15) for holding a cable may be provided. The holding portion (15) in cooperation with a folding portion (16) may define a male portion of a spade connector. The holding portion (15) shape may be substantially cylindrical. All embodiments are for use with lead-free solder and reduce the number of breakages after thermal cycling.

Description

ELECTRICAL CONNECTOR FOR A GLAZING

Background of the invention [0001] The invention relates to an electrical connector, to make electrical connection to a conductive element on a glazing, a glazing and a method of manufacturing a glazing.

[0002] Electrical connectors are known which make an electrical connection between a conductive element on a vehicle glazing and a cable. For example, a T-piece connector may connect a conductive element, such as a busbar for a heating circuit or a solder pad for an antenna, to the wiring harness of a vehicle. A known T-piece connector comprises two feet which are soldered to a busbar using a conventional solder, containing lead.

[0003] A known problem is unacceptable concentrations of lead in waste electrical equipment recycling, especially related to end of life vehicles. High lead concentration in water supplies can cause lead poisoning of people and the environment. Therefore it is desirable to use a lead-free solder in combination with an electrical connector.

[0004] Thermal cycling in service can cause premature failure of a lead-free solder joint to a conventional T-piece connector, due to breakage of glass in the region of the solder. Therefore it is desirable to find an alternative electrical connector for lead-free solder.

[0005] US7909665 (Pilkington/Lyon) aims to improve the reliability of a lead-free solder joint between a T-piece connector and a busbar. The T-piece has a bridge, of height "h" above two feet, and the feet have protrusions, of height "d" in the direction of the glass. A more reliable lead-free solder joint is obtained by optimising "d" and "h".

[0006] US20120305311A1 (FEW/Jenrich) relates to a substantially two-dimensional electrical connector element for creating a contact via lead-free solder to a conductive structure. A soldering foot having a flat ring shape, not a flat solid shape, is found to reduce forces in a glass sheet which occur due to thermal expansion. The flat ring shape distributes stresses concentrically in the glass, thus reducing the danger of glass breakage. A solder blank on the soldering foot extends to an inner edge but does not extend to an outer edge. A distance exists between the respective outer edges of the soldering foot and the solder blank.

[0007] It is an object of the present invention to provide an alternative electrical connector, an alternative glazing and an alternative method of manufacturing a glazing, with improved reliability of lead-free solder joint and fewer breakages of glass in the region of the solder after thermal cycling in service.

Summary of the invention

[0008] According to a first aspect of the present invention, an electrical connector is provided comprising the features set out in claim 1 attached hereto.

[0009] The present invention offers an alternative electrical connector which, when attached to an electrical conductor on a sheet of glazing material by means of a lead- free solder, provides a durable product able to withstand thermal cycling in service.

[0010] A benefit is achieved by providing a soldering foot in the shape of a circle or oval having a lip portion in the shape of a ring which, in cooperation with a base portion, defines a concave recess suitable for receiving a solder deposit. When a solder deposit, in contact with an electrical conductor on a sheet of glass, is arranged in contact with an inner surface of the lip portion, stresses in the glass in the vicinity of the solder are significantly reduced compared with the prior art. [0011] Surprisingly, the inventors have found that provision of a soldering foot according to the invention reduces the number of glass breakages due to thermal stresses, which the connector is likely to encounter in service. Data from a thermal cycling test, using a test method known in the art, is evidence of this benefit. [0012] An electrical connector according to the invention comprising one circular foot causes fewer glass breakages than a conventional T-piece connector comprising two rectangular feet, when using lead-free solder in a thermal cycling test. [0013] An electrical connector according to the invention causes fewer glass breakages than a soldering foot having a lip portion turned upwards, having a solder deposit in the shape of a ring which is thickest at an upturned outer edge of the lip portion. [0014] Preferably the lip portion comprises a ring-shaped groove suitable for defining a predetermined distance from the base portion to an object to be soldered. Preferably an outer edge of the lip portion provides a ring-shaped protrusion suitable for defining a predetermined distance from the base portion to an object to be soldered. [0015] Preferably, the electrical connector further comprises a solder deposit arranged in contact with an inner surface of the lip portion. The solder deposit may be a solder blank may be applied to the electrical connector before being positioned relative to a glazing.

[0016] Preferably the solder deposit has the shape of a ring. In a preferable

embodiment, the solder deposit is in the shape of a ring-shaped fillet. An angle of the ring-shaped fillet subtended from the inner surface of the lip portion to a plane parallel to the base portion is preferably in the range 20 degrees to 90 degrees, more preferably in the range 30 degrees to 60 degrees. Preferably a height of the solder deposit measured within the recess is greater than 0.5 mm, more preferably greater than 1.0 mm. Preferably the shape of solder deposit is constrained by the recess and is defined at least partly by the lip portion. Preferably the solder deposit is confined within the recess.

[0017] Preferably the electrical connector further comprises a holding portion for holding a cable. An advantage of this embodiment is that the benefit of improved adhesion with lead-free solder due to the lip portion defining a recess is combined with the benefit of connectivity due to the holding portion.

[0018] Preferably the holding portion further comprises at least a foldable portion.

Preferably the holding portion in cooperation with the foldable portion defines a crimp connector for a permanent connection to a cable.

[0019] Preferably the holding portion in cooperation with two foldable portions defines a male portion of a spade connector for a releasable connection to a female portion of a spade connector. [0020] In a preferred embodiment, the holding portion shape is substantially a cylinder. [0021] Preferably the holding portion is connected to the base portion.

[0022] Advantageously, the base portion may comprise a hole.

[0023] In an advantageous embodiment the electrical connector comprises a second base portion and a second lip portion, wherein the base portion and the second base portion are connected by the holding portion.

[0024] According to a second aspect of the present invention, a glazing is provided comprising the features set out in claim 12 attached hereto. [0025] Preferably the solder deposit extends from an outer edge of the lip portion towards the concave recess and is substantially in the shape of a dome or a ring.

Preferably a height of the solder deposit measured from the electrical conductor within the recess is greater than 0.5 mm, more preferably greater than 1.0 mm. [0026] Preferably the solder deposit extends from the outer edge of the lip portion to the electrical conductor to form a solder pedestal. Preferably a height of the solder pedestal measured from the outer edge of the lip portion to the electrical conductor is less than 0.9 mm, more preferably less than 0.5 mm. [0027] Preferably an outer edge of the lip portion provides a ring shaped protrusion suitable for defining a predetermined distance from the base portion to the electrical conductor.

[0028] According to a third aspect of the present invention, a method of manufacturing a glazing is provided comprising the steps set out in claim 16 attached hereto.

[0029] An advantage of the method of manufacturing a glazing according to the invention is that when heat is applied to a solder deposit and the solder deposit flows, the shape of solder deposit is constrained by the recess, such that when the solder deposit is allowed to cool the solder deposit solidifies in the shape defined at least partly by the lip portion. In particular, the shape of the solder deposit confined within the recess results in a solder deposit with a defined height in the recess. A particularly advantageous shape is a ring-shaped fillet.

[0030] Preferably the method of manufacturing a glazing is characterised by the step of arranging an outer edge of the lip portion to provide a ring-shaped protrusion suitable for defining a predetermined distance from the base portion to the electrical conductor. An advantageous distance from the base portion to the electrical conductor is in the range 0.1 mm to 1 mm. A more advantageous range is 0.3 mm to 0.5 mm.

[0031] Preferably the method of manufacturing a glazing is characterised by the step of providing in the base portion a hole for a guide wire and guiding the electrical connector by means of the guide wire to a predetermined position on the electrical conductor where the solder deposit is applied.

[0032] An advantage of the guide wire method is that positioning of the electrical connector on the electrical conductor is more repeatable on successive glazings of a production run and more reproducible by successive operators of the manufacturing method.

Brief description of the drawings

[0033] The invention will now be described by means of non-limiting examples with reference to the attached figures:

Fig. 1 shows an electrical connector according to the invention, in cross-section;

Fig. 2 shows an electrical connector similar to Fig. 1, having an alternative lip portion;

Fig. 3 shows a glazing according to the invention, in cross-section, and a solder ring in the recess for solder;

Fig 4 shows a connector from the glazing of Fig. 3, in plan view from below;

Fig. 5 shows a glazing similar to Fig. 3; a holding portion is attached to the lip portion;

Fig. 6 shows a glazing similar to Fig. 3; a holding portion is attached to a base portion;

Fig. 7 shows a glazing according to the invention, comprising a holding portion in the shape of a cylinder; Fig. 8 shows a glazing similar to Fig. 3; the outer edge of the lip portion defines a distance from the base portion to an electrical conductor on the glazing;

Fig. 9 shows a glazing according to the invention, with a solder pedestal;

Fig. 10 shows a glazing similar to Fig. 9; the solder deposit having the shape of a ring. Fig. 11 shows a glazing according to the invention, comprising two electrical connectors joined by a holding portion.

Detailed description of the invention

[0034] Fig. 1 is a cross-section of an electrical connector 1 according to the invention comprising a base portion 11, having a substantially circular or oval shape, a lip portion 12 having the shape of a ring is arranged around the base portion 11, wherein the lip portion 12 in cooperation with the base portion 11 defines a concave recess 13 suitable for receiving a solder deposit.

[0035] The base portion 11 and the lip portion 12 may be formed of one or two pieces of a suitable material, such as a metal alloy. In an advantageous embodiment the material of the lip portion 12 is nickel plated for better adhesion to lead-free solder.

[0036] Fig. 2 is a cross-section of an electrical connector 1, having an alternative lip portion 12 providing a protrusion in the shape of a ring and an outer edge extending upwards away from an object to be soldered. In this embodiment, the upturned portion adjacent the outer edge is not to be used for soldering.

[0037] Fig. 3 is a cross-section of a glazing 10, comprising a sheet of glazing material 18, on which an electrical conductor 19 has been deposited. The glazing material 18 is preferably soda-lime-silicate glass, either annealed or toughened. The electrical conductor 19 is preferably silver paste, applied by a known silk screen printing method. The glazing 10 further comprises an electrical connector 1, bonded to the electrical conductor 19 by a solder deposit 14. The solder deposit 14 is preferably in the shape of a ring, as shown in plan view from below in Fig. 4.

[0038] Fig. 5 is a cross-section of a glazing according to the invention, in which the electrical connector 1 further comprises a holding portion 15 for holding a cable. The holding portion may be attached to the lip portion 12 or, as in Fig. 6, to the base portion 11. The holding portion 15 is suitable for holding a cable, preferably by soldering.

[0039] In an advantageous embodiment the holding portion 15 is attached to a foldable portion 16. The foldable portion 16 may fold over the holding portion 15, to form either a releasable connection of a permanent connection, as will be described as follows.

[0040] In a preferred embodiment, the holding portion 15 forms a male portion of a spade connector for a releasable connection to a female portion of a spade connector, attached to a cable. Advantageously in the embodiment with foldable portion 16, the thickness of the male portion of the spade connector may be doubled, to be more robust. Material thickness is preferably 0.4 mm so that the holding portion 15 and foldable portion 6 when folded together have combined thickness 0.8 mm, compatible with a female portion of a known spade connector. At least one hole is provided in the holding portion 15 to retain a spring clip on a female portion of a known spade connector.

[0041] In an embodiment for a permanent connection to a cable, the holding portion 15 and the foldable portion 16 together form a crimp connector. A cable is placed on the holding portion 15 and the foldable portion 16 is folded over the cable and pressed against the holding portion 15, with sufficient force to achieve permanent deformation of the cable. Such deformation results in friction forces between the cable, holding portion 15 and foldable portion 16, sufficient to prevent the cable becoming detached without the need to solder the cable.

[0042] In an advantageous embodiment, a hole 17 is provided in the base portion 11. The hole 17 is for configuring a guide wire to guide the electrical connector 1 to a predetermined position on the electrical conductor 19. [0043] Fig. 7 is a cross-section of a preferred embodiment, in which an electrical connector 1 comprises a base portion 11 and a lip portion 12, comprising a ring-shaped groove for defining a predetermined distance from the base portion 11 to an object to be soldered. The lip portion 12 in cooperation with the base portion 11 defines a concave recess 13 for receiving a solder deposit 14. A holding portion 15, having a substantially cylindrical shape, is connected to the base portion 11. Solder may extend into a hole 17 in the base portion 11, forming a solder ring inside the hole 17.

[0044] Fig. 8 shows a glazing 10 according to the invention in cross-section in which the solder deposit 14 is substantially within the concave recess 13 and in contact with an inside surface of the lip portion 12.

[0045] Fig. 9 shows a glazing 10 according to the invention in which a solder deposit 14 extends from an outer edge of the lip portion 12 to the electrical conductor 19 to form a solder pedestal. A solder pedestal is advantageous because stress is more equally distributed around the outer edge of the lip portion 12, through the electrical conductor 19 to the sheet of glazing material 18. A complete ring pedestal has the benefit that there is no point of stress concentration which could be a starting point for a crack in the sheet of glazing material 18. Solder deposit 14 extends from an outer edge of lip portion 12 to the centre of the concave recess 13 and is substantially in the shape of a dome.

[0046] Fig. 10 shows a glazing 1 in which the solder deposit 14 extends from an outer edge of the lip portion 12 towards the centre of the concave recess 13 and has an inner edge, in the shape of a ring. The combination of a solder pedestal and solder ring is particularly advantageous because the effect of equal stress distribution in the sheet of glazing material 18 is achieved concentrically, i.e. in the proximity of the inner edge of the solder ring and the outer edge of the solder ring. A benefit of the combination of solder ring and solder pedestal is a reduction in the amount of solder compared with a solder deposit in the shape of a dome.

[0047] Fig. 11 is a cross-section of a preferred embodiment, in which an electrical connector 1 comprises a second base portion 111 and a second lip portion 112, wherein the base portion 11 and the second base portion 111 are connected by a holding portion 15 to form a T-connector. This embodiment has an advantage over known T-connectors because the lip portion 12 and second lip portion 112 in cooperation with the base portion 11 and second base portion 111 respectively, each form a concave recess 13, 113 for receiving a solder deposit 14, 114. [0048] The solder deposit 14, 114 is lead-free solder composition, comprising for example tin-silver, or tin-bismuth or tin-indium, as is known in the art.

[0049] A method of manufacturing a glazing 10 according to the invention will now be described in more detail. The method comprises steps of:

- providing a sheet of glazing material 18

- providing an electrical conductor 19 on a surface of the sheet of glazing material 18, for example by silk-screen printing of a conductive ink

- bonding an electrical connector 1 to the electrical conductor 19 by applying a solder deposit 14 therebetween, wherein the solder deposit 14 is lead-free solder. wherein the electrical connector 1 comprises a base portion 11, having the shape of a circle or an oval, and a lip portion 12 having the shape of a ring arranged around the base portion 11, wherein an outer edge of the lip portion 12 is arranged to provide a ring-shaped protrusion to define a distance from the base portion 11 to the electrical conductor 19.

[0050] In an advantageous method of manufacturing a glazing 10, the electrical connector 1 has a base portion 11 provided with a hole 17 for a guide wire to guide the electrical connector 1 to a predetermined position on the electrical conductor 19 where the solder deposit 14 is applied. Such a hole 17 is shown in Fig. 6.

[0051] In an advantageous method of manufacturing a glazing 10, the connector 1 is as shown in Fig. 5, with the holding portion 15 attached to the lip portion 12. An advantage of this method is that the electrical connectors of Fig. 5 are flatter than those of Fig. 6 so multiple electrical connectors 1 may be threaded on a guide wire to make a stack.

Examples

[0052] The invention will now be further described by reference to test results on examples of the invention and comparative examples. Examples of electrical connectors according the invention were prepared, each having a lip portion turned downward at an outer edge. First comparative examples were prepared each having a lip portion substantially flat, i.e. in the same plane as the base portion. Second comparative examples were prepared each having a lip portion turned upward at an outer edge. [0053] Examples and comparative examples were made of steel, plated with

nickel/chrome and silver. Material thickness was 0.4 mm. Diameter of the electrical connector across the outer edge was 7 mm. Each electrical connector comprised two identical base portions and lip portions, connected by a holding portion, in the configuration known in the art as a T-piece. Further connectors were prepared, each having only base portion and one lip portion.

[0054] Lead-free solder deposits were applied by means of hot air soldering, a method known in the art. The composition of the solder was 96.5Sn 3Ag 0.5Cu. [0055] Examples according to the invention received solder deposits in a concave recess defined by the down-turned lip portion and the base portion, e.g. in a ring-shaped fillet around an inner edge of the down-turned lip portion. Comparative examples received the solder deposits in the up-turned lip portion, i.e. in a ring-shaped fillet around an outer edge of the upturned lip portion.

[0056] A test method known in the art for thermal cycling was used, industrially applicable for automotive glazing. The test specification was:

- 30 cycles of 90 minutes at -40 degrees C, 10 minutes at +90 degrees C - -1 degrees C per minute cooling from +20 degrees C to -40 degrees C

- +1 degrees C per minute heating from -40 degrees C to +20 degrees C

- +1.29 degrees per minute heating from +20 degrees C to +90 degrees C

[0057] Examples according to the invention resulted in no cracks or blisters in glazing material after thermal cycling tests of forty samples, i.e. zero failure.

[0058] First comparative examples (flat edge) resulted in three blisters in glazing material after thermal cycling tests of forty samples, i.e. 7.5% failure. [0059] Second comparative examples (upturned lip portion) resulted in thirty blisters in glazing after thermal cycling tests of forty samples, i.e. 75% failure. [0060] Samples were further analysed after these tests by cutting the electrical connector to reveal the solder deposits in cross-section. Examples according to the invention had solder deposits in a recess defined by the down-turned lip portion and the base portion. Shapes of such solder deposits included:

- a ring-shaped fillet around an inner surface of the lip portion

- a dome extending between opposite inner surfaces of the lip portion

- a pedestal in combination with either a ring-shaped fillet or a dome [0061] By contrast, the first comparative examples comprised ring-shaped solder deposits which had spread unconstrained under the flat edges. The second comparative examples comprised ring-shaped solder deposits which both had spread unconstrained in a region where the lip portion formed a down-turned protrusion, and were thicker at the outer edge of the lip portion than in the region of the protrusion.

[0062] A lip portion in cooperation with a base portion defining a concave recess suitable for receiving a solder deposit is essential to the invention. A recess for solder is not suggested by prior art US20120305311A1 (FEW/Jenrich), which is substantially two dimensional. In contrast to the flatness of the prior art, the present invention suggests a recess for solder, i.e. the electrical connector of the present invention has height.

Claims

1. An electrical connector (1) comprising: - a base portion (11), having the shape of a circle or an oval

- a lip portion (12), having the shape of a ring arranged around the base portion (11) characterised in that

- the lip portion (12) in cooperation with the base portion (11) defines a concave recess (13) suitable for receiving a solder deposit.

2. An electrical connector (1) according to claim 1, wherein the lip portion (12) comprises a ring-shaped groove suitable for defining a predetermined distance from the base portion (11) to an object to be soldered.

3. An electrical connector (1) according to claim 1 or claim 2, further comprising a solder deposit (14) arranged in contact with an inner surface of the lip portion (12).

4. An electrical connector (1) according to claim 3, wherein the solder deposit (14) has the shape of a ring.

5. An electrical connector (1) according to any proceeding claim, further comprising a holding portion (15) for holding a cable.

6. An electrical connector (1) according to claim 5, wherein the holding portion (15) further comprises at least a foldable portion (16).

7. An electrical connector (1) according to claim 6, wherein the holding portion (15) in cooperation with two foldable portions (16) defines a male portion of a spade connector for a releasable connection to a female portion of a spade connector.

8. An electrical connector (1) according to any one of claims 5 to 7, wherein the holding portion (15) shape is substantially a cylinder.

9. An electrical connector (1) according to any one of claims 5 to 8, wherein the holding portion (15) is connected to the base portion (11).

10. An electrical connector (1) according to any one of claims 1 to 9, wherein the base portion (11) comprises a hole (17).

11. An electrical connector (1) according to any one of claims 5 to 10, comprising a second base portion (111) and a second lip portion (112), wherein the base portion (11) and the second base portion (111) are connected by the holding portion (15).

12. A glazing (10) comprising:

- a sheet of glazing material (18)

- an electrical conductor (19) on a surface of the sheet of glazing material (18)

- a solder deposit (14) on the electrical conductor (19)

- an electrical connector (1) on the solder deposit (14), wherein the electrical connector (1) comprises:

- a base portion (11), having the shape of a circle or an oval

- the lip portion (12) in cooperation with the base portion (11) defines a concave recess (13) and the solder deposit (14) is arranged in contact with an inner surface of the lip portion (12).

13. A glazing (10) according to claim 12, wherein the solder deposit (14) extends from a outer edge of the lip portion (12) towards the concave recess (13) and is substantially in the shape of a dome or a ring.

14. A glazing (10) according to claim 12 or claim 13, wherein the solder deposit (14) extends from the outer edge of the lip portion (13) to the electrical conductor (19) to form a solder pedestal.

15. A glazing (10) according to claim 12 or claim 13, wherein an outer edge of the lip portion (12) provides a ring shaped protrusion suitable for defining a predetermined distance from the base portion (11) to the electrical conductor (19).

16. A method of manufacturing a glazing (10) comprising steps of:

- providing a sheet of glazing material (18)

- providing an electrical conductor (19) on the sheet of glazing material (18)

- providing an electrical connector (1) suitable for bonding to the electrical conductor (19) by applying a solder deposit (14) therebetween, wherein the electrical connector (1) comprises:

- a base portion (11), having the shape of a circle or an oval

- a lip portion (12), having the shape of a ring arranged around the base portion (11) characterised by the step of arranging the lip portion (12) in cooperation with the base portion (11) to define a concave recess (13) and arranging the solder deposit (14) in contact with an inner surface of the lip portion (12).

17. A method of manufacturing a glazing (10) according to claim 16, characterised by the step of arranging an outer edge of the lip portion (12) to provide a ring-shaped protrusion suitable for defining a predetermined distance from the base portion (11) to the electrical conductor (19).

18. A method of manufacturing a glazing (10) according to claim 16, characterised by the step of providing in the base portion (11) a hole (17) for a guide wire and guiding the electrical connector (1) by means of the guide wire to a predetermined position on the electrical conductor (19) where the solder deposit (14) is applied.