Why does the keyboard flex

Referring to my notebook keyboard. Some complain of flex, but what actually causes it?
Has the keyboard not been inserted properly?
Is there no component such as a hard drive directly under the keyboard?
Can flex get worse?
Is there empty space under the flex area?

That said, those notebooks with no flex. Is the base they are situated on, reinforced evenly? For example, laid upon a thin metal base such as titanium alloy which does not move. I believe this is probably why no flex occurs on certain high end notebooks. Whereas, which cheaper notebooks, the keyboard is simply laid upon the motherboard and its components. Those areas of the keyboard that press against a hard drive appear to have no flex, whilst those above empty space experience some flex.
This is just my theory as far as my knowledge of the inner workings of a notebook go.

If anyone has an alternative, I would eagerly listen.

 

when a lot of keyboards are fitted they bulge upwards ever so slightly due to the construction of the keyboard, so when you type on it some flexing is noted.
This is a lot worse on older models as some have some empty spaces underneath but all of the modern ones have keyboards that are on top of another piece of plastic (upper cover without big gaps) to reduce this and give a more quality feel to the unit.

 

pretty much bang on there mate

 

Yet most laptops except IBM have keyboard flex?

The keyboards are cheap, and you get for what you pay for.

Nick.