iPhone 4 features fracture flaw

With the issues of 'antennagate' firmly behind it, you'd be forgiven for thinking that Apple could get on with the business of selling massive quantities of iPhone 4s - but it looks like there's another problem on the horizon.

The rear of the iPhone 4 is made of a sheet of tough glass, which gives it a lovely feel in your hand - but which it appears has a minor design flaw, which manifests itself should the rear of the device become scratched.

It appears that, with certain types of scratches, the glass pane is weakened to the extent that a slight shock is enough to cause a crack to appear - or in some cases shatter the glass outright.

According to gdgt, which quotes "sources both inside and outside Apple," the problem is caused by third party cases which slide on to the iPhone for a snug fit. While there's no problem with the cases per se - and it's a design that has been used to great success with prior iPhone models - there's the possibility of grit getting between the case and the iPhone while the sliding takes place. If that grit is between the case and the rear, a scratch results - and the weakness takes hold.

To be fair, that's hardly Apple's fault - but it can be argued that a case that can shatter with nothing more than a small scratch is something of a design flaw in a consumer-oriented mobile device.

The unnamed sources claim that Apple is concerned enough by the problem that it has entered "lockdown", banning the sale of slide-on cases in its stores and forming a new test programme in its engineering labs to investigate the issue more thoroughly.

With no official word from Apple on the issue, but reports of cracked iPhone 4s increasingly prevalent, it's going to be interesting to see where this one goes.