Recently my customer asked question around SSDB. As you may know, When you install SQL Server Engine only, when you go to management studio, you see, Integration Services Catalogs option.
If you try to create one without installing SSIS, you will get following error message about SSISDBBackup.bak
The catalog backup file ‘C:\Program Files\Microsoft SQL Server\110\DTS\Binn\SSISDBBackup.bak’ could not be accessed. Make sure the database file exists, and the SQL Server service account is able to access it. (Microsoft.SqlServer.IntegrationServices.Common.ObjectModel)
In some sites, as a workaround, they suggest to restore SSISDBBackup.bak to be able to use SSISDB. It is true that you can restore bak file from machine which SSIS 2012 installed however you can not use SSISDB even you restore database successfully.
Some users say, they just want SSISDB to store packages but this is not possible as well. When it comes to deployment of this package to SSISDB, deployment will fail with ISServer.exe not found error message:
As conclusion, in order to functionality of SSISDB like store, deploy, run packages through SSISDB Catalog, you have to install SQL Server Integration Services 2012.
Let me know if you have any questions.