Tightening down the tolerance gets expensive and can effect the PCB yields considerably. Maybe the nominal value should be offset alittle. i.e., I've seen 55 Ohms called out and when I asked the customer why 55? They said that the "lump sum" was 50 Ohms including pad capacitance and all (Measured by Network Analyser on the "Critical" Traces). But the single ended TDR target was 55 Ohms. There was no price difference of just shifting the nominal. Dave -----Original Message----- From: Ken Patel [mailto:[log in to unmask]] Sent: Thursday, August 26, 1999 2:51 PM To: [log in to unmask] Subject: [TN] Any connection: Impedance Control value & RF Board Experts, We have couple of RF boards which are relatively new to us. Many times, we have to replace passive components to make it work. Hence, I have this hypothetical question for you. Is it due to not having correct impedance value even though measured value on coupon falls within 50+/-10 ohms%? Do you think we may to have tighten our current impedance specification (50+/-10 ohms%) if there is a relationship? Being a mechanical kind of guy this question may sound stupid! Hope to hear from many of you. re, ken patel ______________________________________________________ Ken Patel Phone: (408) 490-6804 1708 McCarthy Blvd. Fax: (408) 490-6859 Milpitas, CA 95035 Beeper: (888) 769-1808 ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################