<asp:updatepanel id="udpSearch" runat="server" updatemode="Conditional">
<contenttemplate>
<table>
<tr>
<td>
<asp:button id="btnSave" runat="server" />
</td>
</tr>
</table>
</contenttemplate>
<triggers>
<asp:postbacktrigger controlid="btnSave" />
</triggers>
</asp:updatepanel>