hi, i'm not sure i'm visualizing this properly, but couldn't you cut the wires longer than you need, tetra-etch the insulation (without immersing the cut ends into the tetra-etch, and finally trimming them to the desired length? personally, i'd have a warm feeling if the teflon jacket was brown, because that would be an indicator that you were going to have a good bond to the polyurethane potting compound. phil -----Original Message----- From: DUTTON Phil [mailto:[log in to unmask]] Sent: Wednesday, March 21, 2001 4:03 PM To: [log in to unmask] Subject: [TN] Potting in PTFE enclosure Hello Technetters, A problem that I hope that some of you assembly experts can help me with. I have a Printed Board Assy that is to be potted in a PTFE based enclosure. The wires connecting the board to the outside world are also PTFE insulated. The entire unit will spend it's life attached to, and partially immersed in a lead acid battery. We need a fairly good bond between the potting compound (polyurethane)and the PTFE to ensure that none of the corrosive liquids/vapours can travel by capilliary to the PB. Using a flouropolymer etch solves this problem, but turns the colour coding on the wires to brown. Also there are some concerns about how far the etchant can wick up the wires, possibly affecting their soldering. A suggestion has been made to sleeve the wires for a short length, within the encapsulant using adhesive lined polyolefin heatshrink to provide a seal, rather than etching the wires. The idea being that the polyolefin will bond to the potting compound, and the heatshrink adhesive will bond sufficiently with the PTFE wire insulation. Is there any problem with this approach, or are there any suggestions for a better way? Thankyou, Phil. Phil Dutton C.I.D. Senior CAD Technician IPC Certified Interconnect Designer Tenix Defence Systems Pty Ltd Systems Division - Adelaide Second Avenue, Technology Park, Mawson Lakes. SOUTH AUSTRALIA 5095 ================================ Phone (08) 8300 4400 (reception) (08) 8300 4481 (direct) Fax (08) 8349 7420 email [log in to unmask] Internet Page http//www.tenix.com ================================ --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------