Bev- Iomega used to use something very similar in one of their designs, only they used conductive paint over copper. Sigma Circuits in California was the company that produced a lot of the boards for them at that time- you might check with them. > Bill Davis, Ph.D. > Diamond Multimedia Systems > Senior Scientist > Tel. 408.325.7868 > Cell. 408.888.5650 > e-mail: [log in to unmask] > > -----Original Message----- From: Bev Christian [mailto:[log in to unmask]] Sent: Thursday, February 11, 1999 9:24 AM To: [log in to unmask] Subject: [TN] Contact Force/Pressure TechNetters, This came from one of my lab customers. Any info you can give me to pass along? Thanks Bev Christian Nortel Networks We have a design for an "encoder gear" assembly, it is essentially a gear with some contact fingers (aka wiper arm) staked onto the gear. The wiper arm is made from one solid piece. Once in the final assembly the gear is driven by an outside motor, the wiper arm fingers are in contact with traces on a PCB. As the gear is rotated the wiper arm will result in various outputs as the traces are shorted to the inner ground connection. There are four outputs, one ground and three position outputs. Each of the four finger tips is bifurcated. The traces on the circuit board are gold plated with an approximate thickness of 40 microns, under the gold the is a nickel/ cobalt plating. We have been experiencing great heartache due to intermittence as the wiper arm is rotated. The intermittencies cause false outputs which cause our tester to fail modules. We have done many experiments to ensure that the PCB traces are sufficiently clean. We know must look at the system design. The information I am seeking is whether there are specifications or guidelines for the necessary or recommended contact pressure between the wiper fingers and the PCB traces to ensure reliable continuity. I have looked through the IPC manuals we have and found nothing. I would imagine that this type of information would apply to potentiometer and very low current switch manufacturing. I would be very grateful if you knew of any information on this subject or knew where I should look. ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################