This is in addition to the good responses I have seen to this question. The electrodes need cleaning occasionally to remove the "spikes" that accumulate on the surfaces. The sparking initiates at those points. I have also seen low quality Carbon tetra fluoride (CF4) cause sparking. We use the CF4 in PWB fab. You might not use it in assembly operations. Regards, John F. DeBrita Director of Process Engineering DDi Global Corp. BUILDING TOMORROW'S TECHNOLOGY ... TODAY Tel: 714 688-7296 Mobile: 714 944-2214 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls Sent: Monday, August 16, 2010 6:07 AM To: [log in to unmask] Subject: [BULK] [TN] plasma question Importance: Low Good morning all, For those of you who have used plasma etching on circuit assemblies, I have a question. One of our operators observed "sparking" through the plasma chamber viewport and a transistor was fried. Any idea what causes this? First time we have seen this. Doug Pauls ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- This communication is for use by the intended recipient(s) only and may contain information that is privileged, confidential, proprietary and exempt from disclosure under applicable law. You are hereby notified that any dissemination, distribution, forwarding or copying hereof is strictly prohibited without the express written consent of DDi. If you have received this communication in error or are not the intended recipient, you should destroy the message and any attachments or copies, and you are prohibited from retaining, distributing, disclosing, or using any information contained herein. Please inform us of the erroneous delivery by return e-mail. Thank you for your cooperation. ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------