How to crack the back of my iPhone but not the front? - 1

I want to crack the back of my phone. I tried just cracking the back of my phone once but ended up cracking the front. I want an effective way to crack just the back. I tried hitting the back lower left corner with a screwdriver handle but it didn't work.

The best way is to give it away then no need to figure out how to crack the back cover.

Throw it as high as you can, make sure it lands on cement. Should be interesting.

Idiot

Put it on a sponge and the hit it with a hammer