using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var cs = @"Data Source=.\SQLEXPRESS;Initial Catalog=Target_Database;User Id=User;Password=MyPassword";

        var dicionario = cs.Split(';').ToDictionary(x => x.Split('=')[0], x => x.Split('=')[1], StringComparer.OrdinalIgnoreCase);

        foreach(var d in dicionario)

        {

            Console.WriteLine(d);

        }

    }

}