tr, td { padding: 0px; }

    table {
    border-collapse: collapse;
    border-spacing: 0;
    margin: 0 auto;
     }

<table width="680" cellspacing="0" cellpadding="0" align="center">
    <table cellpadding="0" cellspacing="0" border="0" align="center">
       <tr>
          <td>
             <img alt="" src="1.png">
          </td>
       </tr>
    </table>
    <table cellpadding="0" cellspacing="0" border="0" align="center">
       <tr>
          <td><img alt="" src="2.png"></td>
          <td><img alt=""  src="3.png"></td>
          <td><img alt=""  src="4.png"></td>
          <td><img alt=""  src="5.png"></td>
          <td><img alt=""  src="6.png"></td>
       </tr>
    </table>
    <table cellpadding="0" cellspacing="0" border="0" align="center">
       <tr>
          <td>
             <img alt="" src="7.png">
          </td>
       </tr>
    </table>
 </table>