how to create database(1 CDB and 2 PDB) by dbca silent mode with response file, oracle 12c
I think you need to add a 'pdbAdminPassword' parameter to your response file.

The following worked for me:

[oracle@ora12c66 CDBORCL]$ dbca -silent -createPluggableDatabase -sourceDB cdborcl  -pdbName pdb4 -createPDBFrom default  -pdbAdminUserName pdb4  -pdbAdminPassword qwe123 -createUserTableSpace true -sampleSchema true -TEMPLATENAME General_Purpose.dbc
Creating Pluggable Database 
4% complete
12% complete
21% complete
38% complete
85% complete
Completing Pluggable Database Creation
100% complete
Look at the log file "/u01/cfgtoollogs/dbca/cdborcl/pdb4/cdborcl0.log" for further details.