<script>
    function printPage() {
        for (var k = 0; k < window.frames.length; k++) {
            window.frames[k].focus();
            window.frames[k].print();
        }
    }
</script>

<div>
    <a href="../login/welcome.php">
        <button class="return" onclick="javascript:printPage()">
            Imprimir Documentos
        </button>
    </a>
</div>
<div>
<iframe id="formU" src="print_doc1.php"  marginheight="10" marginwidth="10" height="450" width="330"></iframe>
<iframe id="formV" src="print_doc2.php" marginheight="10" marginwidth="10" height="450" width="330"></iframe>
<iframe id="formW" src="print_doc3.php" marginheight="10" marginwidth="10" height="450" width="330"></iframe>
<iframe id="formX" src="print_doc4.php" marginheight="10" marginwidth="10" height="450" width="330"></iframe>
<iframe id="formY" src="print_doc5.php" marginheight="10" marginwidth="10" height="450" width="330"></iframe>
</div>