On http://www.php.net//manual/en/mssql.requirements.php It states:
On Windows, the DBLIB from Microsoft is used. Functions that return a column name are based on the dbcolname() function in DBLIB. DBLIB was developed for SQL Server 6.x where the max identifier length is 30. For this reason, the maximum column length is 30 characters. On platforms where FreeTDS is used (Linux), this is not a problem.
Please switch to the new MSSQL driver for PHP from http://www.microsoft.com/en-us/download/details.aspx?id=20098 that would support modern SQL Server.