Here es little example to create a SSL Connection
<?php
$db = mysqli_init();
/*
When you want so use a separate cnf
$test = $db->options(MYSQLI_EAD_DEFAULT_FILE,'myother.cnf');
*/
$db->ssl_set('server-key.pem','server-cert.pem',
'cacert.pem',NULL,NULL);
$db->real_connect('localhost','root','','mydb');
//Here some query
$db->close();
?>