Casing with channel discontinuity that resists capillary action

1. A casing comprising first and second parts having respective mateable surfaces having one or more mateable edges, the mateable edges being arranged to define a channel therebetween in the mated condition, the channel extending from an exterior of the casing towards an interior of the casing, wherein the channel is arranged to narrow from the exterior of the casing, wherein the channel is arranged to comprise a discontinuity in a channel dimension which is formed at a point at which the channel is narrowing in a direction towards the interior, and wherein the discontinuity is arranged to provide an abrupt increased gap with respect to an adjacent portion of the channel.

2. A casing as claimed in claim 1 , wherein the discontinuity is arranged to re-orientate the direction of surface tension force in the channel to increase an amount of energy required for capillary flow from the casing exterior to the casing interior.

3. A casing as claimed in claim 1 , wherein the discontinuity comprises a corner.

4. A casing as claimed in claim 1 , wherein the discontinuity comprises opposing corners.

5. A casing as claimed in claim 1 , wherein the discontinuity is formed in the channel towards the exterior of the casing.

6. A casing as claimed in claim 1 , wherein the discontinuity is arranged to provide an abrupt increased gap with respect to an adjacent portion of the channel, the adjacent portion of the channel being towards the exterior of the casing.

7. A casing as claimed in claim 1 , wherein the discontinuity is formed in the channel towards the interior of the casing.

8. A casing as claimed in claim 1 , wherein the discontinuity is formed in the channel in the middle between the interior and exterior of the casing.

9. A casing as claimed in claim 1 , wherein the discontinuity is arranged to narrow towards the interior of the casing to provide a reduced gap towards the interior of the casing.

10. A casing as claimed in claim 1 , wherein the channel, after the discontinuity, is arranged to narrow towards the interior of the casing to provide a gradually reducing gap towards the interior of the casing.

11. A casing as claimed in claim 1 , wherein the discontinuity is arranged to comprise an abrupt narrowing of the channel gap towards the interior of the casing.

12. A casing as claimed in claim 1 , wherein the channel is arranged to define a first gap at the exterior of the casing, and a second narrower gap towards the interior of the casing, and wherein the discontinuity is formed at the second narrower gap.

13. A casing as claimed in claim 1 , wherein the channel is formed from an opening in the injection moulding tool used to form the casing.

14. A casing as claimed in claim 1 , wherein the first and second parts form an exterior casing for an electronic device.

15. A casing as claimed in claim 1 , wherein the first and second parts form an exterior casing for one or more components of an electronic device.

16. A casing as claimed in claim 1 , wherein the first and second parts form an interior casing for an electronic device.

17. A casing as claimed in claim 1 , wherein the first and second parts form an interior casing for one or more components of an electronic device.

18. A casing as claimed in claim 1 , wherein the first part is a Printed Wiring Board and the second part is a keypad dome sheet.

19. A casing as claimed in claim 1 , wherein the channel extends radially around the perimeter of the casing.

20. A casing as claimed in claim 1 , wherein the channel extends radially around the complete perimeter of the casing.

21. A casing part of a casing as claimed in claim 1 .

22. A mould for producing a casing as claimed in claim 1 .

23. An electronic device, comprising a casing as claimed in claim 1 .

24. A method comprising manufacturing a casing, the casing comprising first and second parts having respective mateable surfaces having one or more mateable edges, the mating edges being arranged to define a channel therebetween in the mated condition, the channel extending from an exterior of the casing towards an interior of the casing, wherein the channel is arranged to narrow from the exterior of the casing, wherein the channel is arranged to comprise a discontinuity in a channel dimension which is formed at a point at which the channel is narrowing in a direction towards the interior, and wherein the discontinuity is arced to provide an abrupt increased gap with respect to an adjacent portion of the channel.

25. An electronic device comprising a casing as claimed in claim 1 .

26. A means for housing one or more electronic components for an electronic device in the interior of the means for housing, the means for housing comprising:

first and second means for housing parts having respective conforming faces arranged to be able to be brought together such that the means for housing provides a housing for one or more of the electronic components, wherein the conforming faces are arranged to define one or more means for liquid access therebetween in the brought together condition, the one or more of the means for liquid access extending from an exterior of the means for housing towards an interior of the means for housing, wherein one or more of the means for liquid access is arranged to comprise a discontinuity in a dimension of the one or more of the means for liquid access; wherein the one or more of the means for liquid access is arranged to narrow from the exterior of the means for housing and wherein the discontinuity is formed at a point at which the one or more of the means for liquid access is narrowing in a direction towards the interior, and wherein the discontinuity is arranged to provide an abrupt increased gap with respect to an adjacent portion of the means for liquid access.

27. A method of assembling a casing for housing one or more electronic components for an electronic device in the casing interior, the casing comprising first and second parts having respective mateable surfaces having one or more mateable edges, the mateable edges being arranged to define a channel therebetween in the mated condition, the channel extending from an exterior of the casing towards an interior of the casing, wherein the channel is arranged to narrow from the exterior of the casing, wherein the channel is arranged to comprise a discontinuity in a channel dimension which is formed at a point at which the channel is narrowing in a direction towards the interior, wherein the discontinuity is arranged to provide an abrupt increased gap with respect to an adjacent portion of the channel, and wherein the method comprises assembling the first and second parts to define the channel between the first and second parts in the mated condition.