File Connection Manager Editor
Use the File Connection Manager Editor dialog box to specify the properties used to connect to a file or a folder.
You can set the ConnectionString property for the File connection manager by specifying an expression in the Properties window of SQL Server Data Tools (SSDT). However, to avoid a validation error when you use an expression to specify the file or folder, in the File Connection Manager Editor, for File/Folder, add a file or folder path.
To learn more about the File connection manager, see File Connection Manager.