you have to understand the different between sending/transfer BTC and importing an address.
kraken provides you a deposit address, you have to send BTC to that address (can't simply import)
if you have BTC on paperwallet, you need to import to a wallet that support importing address (most does)
then you can use the wallet (as a tool) for sending the BTC to your deposit address on kraken
does kraken charge fee on deposit?
I haven't tried copay, but I've used Mycelium to read a QR-code from a paper wallet, then read another QR-code from the site I want to send it to. This way, the phone wallet is only used to create the transaction, and never used to store funds.
Note that you have to send the entire balance at once. In Mycelium, I click "Max", and it only takes out the transaction fee. If you were to use a part of the paper wallet, the change is send to a change address, and not back to your paper wallet.
Thank you both, I get it now.