Hi again Nicole, Personally I don't care who the Vendor is (they all have some issues to worry about and still produce a good product). But since these are relatively high value, large footprint devices I can only suggest checking dielectric type (the variable you didn't tell me, though I will guess Z5U due to your leakage comment), and looking for a lower height device you could use. There seems to be some correlation between device thickness and reliability during processing. I also think John Maxwell (forgive me John if I'm overstepping here) might of done some stuff on micro cracks and their effect on leakage. The effects of thermal shock (even that recommended by the manufacture), stress of de-panelization, flexure during test, etc. seems to be increased tremendously on caps that are taller in height than equal value caps of shorter stature. The micro cracks caused by these stresses could be a part of your problem. Hope this helps FNK Frank N Kimmey, C.I.D. Senior PCB Designer Powerwave Technologies PH. 916-941-3159 Fax 916-941-3195 -----Original Message----- From: Nicole Landreville [mailto:[log in to unmask]] Sent: Tuesday, June 26, 2001 10:10 AM To: [log in to unmask] Subject: Re: [TN] Multilayer Ceramic Chip Capacitors Quality Since Frank and Genny are interested in knowing what type of capacitors we had encountered problem with and since I believe most of you should be aware of the following risks: First of all, ceramic multilayers capacitors are extremely sensitive to high heat. The heat profile temperature is specified by each manufacturer. As you probably understand, I don't feel comfortable revealing the manufacturer's name since, as pointed out by Steven, these manufacturing defects might not be a problem. We observed random issues with 10 microfarads / case 2220 / for 50 V. The capacitors we have used often showed leakage after a certain usage. Also, we observed very constant manufacturing issues with 22 microfarads / case 3025 / for 50 V. Electrodes are made of silver for both types. I suspect the reliability of these capacitors is inversely proportional to size, value and voltage. Hope this helps more people. Nicole -----Original Message----- From: Frank Kimmey [mailto:[log in to unmask]] Sent: Tuesday, June 26, 2001 12:14 PM To: TechNet E-Mail Forum.; [log in to unmask] Subject: RE: [TN] Multilayer Ceramic Chip Capacitors Quality Hi Nicole, Could you give a little more data? What sizes, dielectric, values? I have seen many cap issues related to these variables and might have some suggestions. Call me if I can help. FNK Frank N Kimmey, C.I.D. Senior PCB Designer Powerwave Technologies PH. 916-941-3159 Fax 916-941-3195 -----Original Message----- From: Nicole Landreville [mailto:[log in to unmask]] Sent: Tuesday, June 26, 2001 8:37 AM To: [log in to unmask] Subject: [TN] Multilayer Ceramic Chip Capacitors Quality Bonjour a tous! We have found some internal manufacturing defects in some Multilayers Ceramic Chip Capacitors. After discovering reliability problems with these types of capacitors (extreme leakage increasing with time) we have decided to perform a construction analysis. The type of issues found relates to misalignment of electrodes, electrode layers varying in length, warping of dielectric plates. Unfortunately, to be able to find these manufacturing defect we had to do a caps microsection. Now that we know that these capacitor are prone to manufacturing defects, I would like to know if there is any way (processes, low cost equipment or service house) to detect these defects without scraping or damaging the caps? Originally I was thinking that these could be X-rayed but I am not sure that the resolution would be sharp enough. I would really appreciate if anyone could help me with this important problem. Thank you and good day! Nicole Landreville, Eng. Electrical & Supplier QC Engineer World Heart Corporation Ottawa, Ontario ---------------------------------------------------------------------------- ----- 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 ---------------------------------------------------------------------------------