Impedance control is accomplished by copper height, trace width and separation and dielectric thickness with certain Er. Normal production usually means that the fab vendor uses their standard stack-up with default copper thickness so the resulting impedance won't match what you need/specify. If you are trying to save cost, you can ask specifically what stackup, dielectric material and copper thickness your vendor is using and adjust your layout to meet your impedance requirements with those parameters. If your vendor uses the same parameters when you submit your board, you can get your impedance numbers from a normal production too. But beware that you won't get a test coupon nor a test report which shows what the actual measured impedance values are from your vendor. So unless cost is an extreme concern, it's best not to use normal production for impedance controlled boards. Kal -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Jayasuryan KG Sent: Monday, January 02, 2012 5:57 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Impedance Controlled Board Production Vs Normal Board Production Importance: High Dear Experts, Happy New Year!! I have question regarding the impedance controlled board production! Is there any special process to produce impedance controlled board rather than the normal production? Suppose if I go with normal production for a impedance controlled board (the design has been done to meet the impedance) what are the possible issues can happen? Looking for your immediate response. Thanks in advance. Best Regards, - Jayasuryan ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu