While appealing, this will not fix your Home button and may, in fact, damage it far worse. The idea that repeatedly squirting WD-40 into your iPhone or iPad Home button could fix responsiveness began floating around the internet last month and has gotten some attention -- that needs to be stopped immediately. Keep in mind we're huge fans of DIY repair here at iMore. But putting WD-40 on your iPhone is not DIY repair. It's dangerous, particularly for iPhones and iPads that are built with moving, plastic parts.
WD-40 may be non-conductive but the solvent in it will break down plastic. Your home button is plastic as well as some of the internal parts. Your speaker assembly is plastic and sits directly below your home button. Also, WD-40 is a liquid and you're spraying it dangerously close to where the wiring for the dock -- the place you charge your iPhone or iPad -- sits. The only substance that should ever be applied to an iPhone or iPad is high concentrated alcohol to remove corrosion from a logic board after it has been damaged by another liquid. None of the other components should ever come in contact with liquid. Including WD-40.
To understand what causes a sticky home button you need to understand how the home button works. On an iPhone 4 there is a flex cable that connects to your dock and comes around the front. This piece has a contact on it that is connected to the home button with adhesive. When this button is depressed too many times, the contact starts to wear and get thin. Eventually, this results in a "tacky" home button or clicks not registering as the contact is not thick enough to apply the correct amount of pressure to register to trigger a click. It was bad design on Apple's part, especially after introducing the double-click to launch the Fast App Switcher in iOS 4.
The iPhone 4S Home button was re-designed to fix these problems. The button is actually stuck to the main assembly with a rubber gasket. Then a bracket is put into position behind that, similar to that of the iPad 2.
Your iPhone or iPad Home button isn't a squeaky old spring or noisy hinge that a couple of squirts of grease can easily fix. If the Home button flex cable wears down over time, nothing but replacing the Home button flex cable will solve the issue. Spraying a substance like WD-40 into your device will only make matters worse or damage other components inside of your device. If you're under warranty Apple will swap out your iPhone 4 at no cost. If you're not, you should repair it the correct way or send it into someone who can. Here are some good software fixes to try on your own first:
So put the WD-40 can down and slowly back away, then tell everyone you know — including the people who post these tips — to do likewise.