Hi , If you are getting the error when exporting Oracle data to SQL Server using SSIS package. You need to use Data conversion to Transform Data.
Using Data Conversion change the string Data Type from "Unicode String[DT_WSTR]" to "string[DT_STR]".
Below Link for Article may help: http://www.mssqltips.com/sqlservertip/1393/import-excel-unicode-data-with-sql-server-integration-services/