The failure is short at test.the moment we apply 10 v-the capacitance value reads as normal value dropping to zero instaneously . since we are using voltmeter for DOE, the leakage current does not read out ( as infinity). We are not sure -what you mean by wet or dry type? We are testing as dry ? we did test s on some of them while wet with flux- no significant difference.Normally, the fabs are cleaned and dried after wave. incubation time is provided for self-healing to occur. We observed that one side(end) of cap is having flowlines-roughness while other end side (cross-section) is smooth. All other surfaces-top, bottom, left and right are smooth.There are no pinholes. No surface cracks or distorsions observed on any surface as such. We have not observed this problem on any other tantulam cap from the same vendor. The vendor has indicated to look on thermal and mechanical shock; moisture at cleaning etc. Another factor under observation is being thick board we are running wave at below 2 ftm (1.8 to 2 ftm) and because of two waves -- we are having peak of 220 degc at first wave -cool down to 170 degc and second peak of 250 degc at Lamda wave for 12 to 13 sec.Due to thich fab, it is difficult to achieve reduce time on lamda.It is this area which we are not fully sure ? Gluecure is at 150 degc for 88 sec with peak temp as 176 degc. Though this process does not affect as indicated in our DOE, we lowered temp further to 125 degc for 120 sec with peak of 150 degc. ---------- From: [log in to unmask] To: Dhawan, Ashok CA-WINPO2 Subject: RE: Bowing off Tantulam Caps Date: Monday, June 09, 1997 5:13PM Can you give some additional information? Are these wet or dry tantalums? When you say they are failing, what is failing? Are they shorts? If so, what sort of currents do you see? Have you let the items sit unbiased for a time for "healing" to occur? (Tantalums sometimes need time to recover.) ls it the capacitance value that is failing? We haven't had the same problem that l am aware of but will check the database. ---------- From: Dhawan, Ashok CA-WINPO2 To: IPC TechNet Subject: Bowing off Tantulam Caps Date: Monday, June 09, 1997 8:48AM We are facing acute problem on blowing off caps . Specifically, these caps are tantulam caps with high capacitance range of 220 MICROFARADS , rated at 10 voltage and tolerance in capacitance value is 20%.We have tried more than one vendor: one vendor was worse than the present one--however failures are always there. These caps are processed ( assembled) alongwith other tantulum caps and usually go through two heat cycles: first one on gluecure and second one at wave. The standards (temp profiles) followed at reflow and wave are as per process guidelines . These caps when tested after wave pass 100% at 5v test. Fails 20 to 25% for voltages above 7v . Dwell between wave and ATE does not matter much. Tried with and without wash -- it does not make significant difference. It is expected that the cap should pass 100% at rated voltage. Clearly there is deterioration after assembly process. we ran DOE and observed caps failing after wave. however our wave process does not seem to out of control. any one having experience on such a behaviour of Tantulum Caps -- we will appreciate your technical advise on this problem as we are running out of ideas and thinking to change process to bypass wave solder operation altogether.But that is not easy to do in short time. Please send your advise on this mail or email directly to me. [log in to unmask] Tel: 204-257-9199 *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** ------ Message Header Follows ------ Received: from ag.aes.com by iegate.aes.com (PostalUnion/SMTP(tm) v2.1.9e for Windows NT(tm)) id AA-1997Jun09.084816.1557.28682; Mon, 09 Jun 1997 08:48:16 -0700 Received: from kani.wwa.com by ag.aes.com (4.1/CERFnet-1.0) id AA09679; Mon, 9 Jun 97 08:35:18 PDT Resent-Date: Mon, 09 Jun 97 14:42:00 GMT Received: from ipc.org/ipc.ipc.org [209.42.29.23] by kani.wwa.com with smtp (Smail3.2.WWA) id m0wb6Xb-005rR0C; Mon, 9 Jun 1997 10:45:16 -0500 (CDT) Received: by ipc.org (Smail3.1.28.1 #2) id m0wb6NR-000BjeC; Mon, 9 Jun 97 10:29 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: "Dhawan, Ashok CA-WINPO2" <[log in to unmask]> To: IPC TechNet <[log in to unmask]> Subject: Bowing off Tantulam Caps Date: Mon, 09 Jun 97 14:42:00 GMT Message-Id: <[log in to unmask]> Encoding: 33 TEXT X-Mailer: Microsoft Mail V3.0 Resent-Message-Id: <"iB_pf.0.QQL.h42dp"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/13246 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************