Hi Arnaud, This is a flex circuit- basically kapton and polyimide glue- I do not see where the glass would come from. Regards Steve Kelly Sent from my BlackBerry device on the Rogers Wireless Network -----Original Message----- From: arnaud grivon <[log in to unmask]> Date: Tue, 16 Sep 2008 18:15:20 To: <[log in to unmask]> Subject: Re: [TN] Bias voltage test in damp heat Steve, From the description you gave, the particles you detected may correspond to E-glass fibers (assuming Al instead of Cl in the elements ). You can refer to IPC-4412A to have a detailed description of a glass fiber composition. Dimensions you indicated fits also well with glass fibers and glass fibers do absorb moisture. Difficult to explain however how to include glass fibers into a polyimide film... Just a thought. Best regards, Arnaud Grivon Steve Kelly a écrit : > Good Day To All, > > I am back with this thread I started in April this year with some more > questions. > > After extensive analysis we have found evidence of what IPC 4203 and 4204 > calls inclusions in the raw material we use to make the flex circuits. These > inclusions are usually in the 5-10 micron range and they usually come in > groups (few particles in a group). From the SEM/EDX scans they consist of > Si, Mg, Ca and Cl. Carbon and oxygen are also present in the spectra. What > the exact possible formulations are - I am open to suggestions or theories. > > Our theory is that whatever these are they absorb moisture and the result > is they form ions and lower the dielectric breakdown between the adjacent > tracks which are at 100 micron space. Under the bias voltage we get a high > resistance short. > > Questions: a) does this theory make sense or any comments > > b)at the present time my customer believes this test > helps define that the part will work for 25 years and getting them to change > their mind is not likely to happen. On the next generation product they have > moved the spacing to 200 microns - my concern is they may just be postponing > the inevitable- may make it through 500 hours and fail at 750 for example. > Comments on this would be appreciated. Thanks again to the TechNet on this > issue- especially to Mr. Pauls and Mr. Ellis for previous help. > > > > Steve Kelly > > PFC Flexible Circuits Limited > > PH: (416) 750-8433 > > Fax: (416) 750-0016 > > Cell: (416) 577-8433 > > > > From: [log in to unmask] [mailto:[log in to unmask]] > Sent: Wednesday, June 25, 2008 12:37 PM > To: TechNet E-Mail Forum; Steve Kelly > Subject: Re: [TN] Bias voltage test in damp heat > > > > > Steve, > I agree that this is madness, unless the telecom supplier has an end use > environment of 85/85 where power-on in humid conditions is a reality. > > Assuming that the equipment is not functioning in a steam environment, here > is the "science" that you are looking for. > > Designers, when they have knowledge of the material characteristics, will > design spacings dependent on the dielectric strength or dielectric > withstanding voltage of the laminate. The values in the data sheets for the > laminates specify these parameters, but only for lab ambient conditions, not > after 85/85 conditioning. When you expose a hydrophilic material to a long > exposure in hot/humid conditions, then you don't have that same dielectric > strength (dramatically reduced) and you have violated the design > assumptions. Polyimide is such a hydrophilic material. I believe Brian > Ellis referred to it as blotter paper, in which I would concur. If you > allow the circuit to dry out, then you return to the expected dielectric > strength. You may already be at an unrealistic threshold with 2500 > volts/mm gradient, as Brian also pointed out. > > Unless the designer had a firm value for dielectric strength of the > substrate after 85/85 conditioning, which would change as the substrate > rapidly dried out, then the design would not and could not work. > > Doug Pauls > > > > > > Steve Kelly <[log in to unmask]> > Sent by: TechNet <[log in to unmask]> > > 06/25/2008 10:09 AM > > > Please respond to > TechNet E-Mail Forum <[log in to unmask]>; Please respond to > Steve Kelly <[log in to unmask]> > > > To > > [log in to unmask] > > > cc > > > > Subject > > [TN] Bias voltage test in damp heat > > > > > > > > > Good Day To All, > > Back in April I posted some queries on the tech-net about high voltage > testing after 85C/85RH testing and was basically told this test was > impossible and I agree with that assessment. But some things have a life of > their own. > > To re-iterate: We are building a 4 layer flex circuit. All layers are 18 > micron copper and all lines and spaces assuming perfect etch are 100 micron > lines and 100 micron spaces. My customer for some reason signed up to pass a > 250 volt test after 1000 hours of 85C/85RH damp heat test. My premise is > being in this case a polyimide build if they dried the circuit after this > test it should pass. They do not want to dry it and still have it pass. > > The previous threads in summary said this test was "madness" - I agree but > what is the scientific explanation of why this is madness. > > Please note this requirement is being driven by very large telecom companies > and the worlds largest provider of internet gear. > > Thanks again for the help. > > Regards Steve Kelly > > > > Steve Kelly > > (416) 750-8433 (work) > > (416) 750-0016 (fax) > > (416) 577-8433 (cell) > > > > > --------------------------------------------------- > 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 > ----------------------------------------------------- > > > --------------------------------------------------- > 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 > ----------------------------------------------------- > --------------------------------------------------- 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 -----------------------------------------------------