My money is also on electrical/mis-application failure, unrelated to your solder process, since you've already ruled out the obvious process issues. Maybe this one designer always uses this part in an unsuitable application. And he carries the same piece of circuitry over from one design to the next. We once had a customer who reported field failures of a 35V Tantalum cap on a 5V line. After much trouble-shooting, we ultimately discovered that the part was designed in with the wrong polarity. And the lay-out correlated to the design, so the board showed (+) and (-) incorrectly as well. As a result every single part placed on that circuit location was in reverse, but since the part polarity matched the layout polarity we never suspected reverse voltage as the cause of failure. Until the customer finally tracked all the way back to the design error. To make matters worse, that piece of circuitry had been a standard building-block used on many products. They still have the occasional field failure even today although the design was corrected many years ago. I have no knowledge of film cap failure mechanisms, but I am sure that they have certain weaknesses just like other components. If this designer is using this part incorrectly in a design that he uses over and over, that could be a potential explanation why only his part fails. Maybe he uses different derating guidelines than the other designers and consequently, his parts see higher stresses. Suggest you get your quality folks and the design engineer and the Roederstein applications experts in a room together to see if they can figure it out. Good luck! Nancy Reynolds Phil Nutting <[log in to unmask]>@IPC.ORG> on 10/11/2001 12:53:40 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: Re: [TN] failing capacitors I'm not sure if this is an electrically induced failure. I can tell you that when the cap is replaced the system works well and the cap no longer shows signs of failing. An interesting thought... used in an application it cannot support. I don't have the answer to this one or the knowledge to analyze the design. Well, the EE specified what parts to use and the board layout designer placed the components with the approval of the EE. So I guess they are both at "fault". -----Original Message----- From: Guy Ramsey [mailto:[log in to unmask]] Sent: Thursday, October 11, 2001 10:09 AM To: [log in to unmask] Subject: Re: [TN] failing capacitors Are we sure that this is not an electrically induced failure? Is the component serviing in an application that it cannot support? By designer are we talking EE or board layout designer? Guy Ramsey Senior Lab Technician / Instructor E-Mail: [log in to unmask] <mailto:[log in to unmask]> Ph: (610) 362-1200 x107 Fax: (610) 362-1290 -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Phil Nutting Sent: Thursday, October 11, 2001 10:17 AM To: [log in to unmask] Subject: [TN] failing capacitors Here is an interesting question. We use Roederstein film capacitors (through hole configuration) in many of our boards. Typically all boards are run through our wave solder machine with the same recipe. The weird thing is that some of these caps fail either open or shorted but only on the boards belonging to one design engineer. Is this "full moon residue", a circuit design issue or is it possible a regular failure that no one else is complaining about? We keep track of our test failures and if this were happening on many other boards we should be seeing the data, but there is none. I'm interested in what your thoughts may be. Thanks in advance. Phil Nutting ------------------------------------------------------------------------ ---- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ------------------------------------------------------------------------ ---- ----- ------------------------------------------------------------------------ --------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ------------------------------------------------------------------------ --------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------