Method 1:

If you are only concerned with data in the tables and that to be used locally within the same database and server you can use below query to take backup of selected tables:

SELECT * INTO newtable1
FROM originalTable1

--- For table 2

SELECT * INTO newtable2
FROM originalTable2

and so on... for n number of tables

This statement WILL CREATE the tables called newtable1, newtable1,.. thus you do not have to previously create it.

Note* This method takes the backup quite fast but major disadvantage would be that it does not carry over the Keys, Indexes and Constraints of the table and backup is stored within the database not somewhere externally to a file

Method 2:

If you want to backup table over to other server for any disaster recovery solution or data loss prevention, then you can script the table using the Generate Scripts option from Tasks.

1. First, right click on the database that contains the tables you want to backup and choose Tasks -> Generate Scripts

2. Select you're database from the list whose tables needs to be backed up

3. The next screen that appears is the Script Options.

4. Scroll down on the script options until you see Table/View Options. We want the following to be true: Check Constraints, Script Data, Foreign Keys, Primary Keys, Triggers, & Unique Keys. (Or you can choose whatever you need of course). Select Next and we are presented with the Select Object Types Screen

5. Select Tables and hit next. Lastly, choose the table or tables you want to backup and hit next

Method 3:

You can use bcp utility for table backups as well.

You cannot backup specific tables to a .bak file, you can export them to csv or script them out or use bcp to put them into a file.

What you can do if you want to back up specific tables (and they are always the same) is move them into a separate file group and back up that file group.

See Back Up Files and Filegroups for the documentation.

For example if you want to back up specific files or filegroups using T-SQL you could use (from the link)

--Back up the files in SalesGroup1.
BACKUP DATABASE Sales
   FILEGROUP = 'SalesGroup1',
   FILEGROUP = 'SalesGroup2'
   TO DISK = 'C:\MySQLServer\Backups\Sales\SalesFiles.bck';
GO

and

--Backup the files in the SalesGroup1 secondary filegroup.
BACKUP DATABASE Sales
   FILE = 'SGrp1Fi2', 
   FILE = 'SGrp2Fi2' 
   TO DISK = 'G:\SQL Server Backups\Sales\SalesGroup1.bck';
GO

Building upon Method 1 from KASQLDBA's response:

Create a separate database to hold the backed up copy of the tables. Modify KASQLDBA's provided query so that you select from your original table and copy to the alternate database.

SELECT * INTO MyNewDatabase.dbo.newtable1
FROM OriginalDatabase.dbo.originalTable1

--- For table 2
SELECT * INTO MyNewDatabase.dbo.newtable2
FROM OriginalDatabase.dbo.originalTable2

You could create a script that drops the tables in the new database, then run the select into commands for every required table. If you wish to have indexes and other objects avalailable, then you could build those on your new database and truncate the tables prior to re-populating them. If you prefer truncation, then you would need to use insert statements in place of select into.

This option will provide you a method for creating a .BAK file. You simply run a backup database command after you have populated the tables in the new database.

Using the bulk export feature of SSMS, here is the best and easiest method mentioned

SQL Server import and export wizard: The SQL Server Import and export wizard provides a graphical user interface onto a SQL Server Integration Services (SSIS) package. Once created the package can be automated, to run on a schedule. It can be further configured and modified by using SQL Server Data Tools (SSDT)

To begin, open the Import and export wizard, right-click a database and select the Tasks sub-menu -> Export data command.

Another method is to use script/sproc: DumpDataFromTable.sql from: https://github.com/Zindur/MSSQL-DumpTable/tree/master/Scripts

 EXECUTE [dbo].[DumpDataFromTable] @SchemaName = 'dbo', @TableName = 'Table', @PathOut = 'c:\temp\Scripts'

You have to pass: schema name and table name, then output path where the created script will be saved (note folder must already created/exist and sql have permission see comment in sproc).

And if you would like you can add a condition to table (filter must start with AND for the moment)

Backup a single table with its data from a database in SQL Server 2008:

SELECT * INTO  [dbo].[tbl_NewTable] 
FROM [dbo].[tbl_OldTable]