Hi All, I take it that the failures are found in production test under controlled conditions.
Just some thoughts for you... Is the inductor symmetrical with respect to its mounting? Is the coil, say, at one end or the other... This would confirm John's suggestion regarding reversing the installation. Are the in/out connections flying lead or board terminations. If flying lead, look for variation in coupling to other parts of the circuit. Are some of the leads twisted together (It might sound strange, but in the process of testing the bad inductors, the leads might be untwisted to make the connection...) Are the other components physically positioned the same on good and bad boards - this might affect coupling. How does the process of changing the inductor affect these components? Regards Tim From: [email protected] [mailto:[email protected]] On Behalf Of Conway, Patrick R (Houston) Sent: 06 October 2006 19:59 To: [email protected]; [email protected]; [email protected] Subject: RE: Inductor mystery *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Maybe it is not an inductor problem at all... Could the installation process be at fault? For instance- could it be a soldering problem? Bad solder joints? Or maybe good solder joints that get cracked by poor handling after installation? Perhaps the inductors use lead-free solder? If your board and the solder process are not compatible with lead-free, this can cause bad solder joints. ( Not that I have ever made a mistake like that... :> ). Best Regards, Patrick Conway [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Friday, October 06, 2006 7:02 AM To: [email protected]; [email protected] Subject: Inductor mystery Dear Experts, We use the inductor part "1812CS-102XJLC" of Coilcraft in our RFID product as EMI filter. Continuously we face one issue, about 20 to 30 % products are functionally failing due to this inductor. While we change the inductor alone the product passes the functional tests. Hence we studied the characteristics of the inductor. Measurements carried out using the Agilent Impedance analyser 4294A shows the failing inductors and passing inductors are identical with respect to the below listed parameters for the entire measuring range of 40 Hz to 110 MHz. Our frequency of operation is 13.56 MHz and both the failing inductors and passing inductors are identical in this particular frequency also with respect to the below parameters. Is there anything else than the below listed parameters critical for an inductor? Has any one of you come across such an issue in your devices? I request your help. a. Ra.c b. Conductance - 'G' c. Reactance - 'X' d. Susceptance - 'B' e. Impedance - 'Z' f. Phase angle of the impedance g. Value of R, L & C measured using the equivalent circuit method of measurement. Sincerely K.Balasubramanian Project Leader - Hardware. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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