Seems like there is a lot of confusion as to what thieving is. So, here is what it is. Thieving is copper added to outer layers of a PCB to create a uniform distribution of copper across the surface. The reason this is done is to make sure the copper plating in the holes is uniform. If the copper distribution in the artwork is not uniform, areas with little exposed copper will plate very heavy while areas with large amounts of copper, such as BGAs or connector pin fields will not plate properly. So, "thieving" steals some of the plating current that would otherwise concentrate on features that are sparse and be spread thin in areas with areas that are dense with features. Again, thieving is an outer layer only process. All of the discussions that mention doing things to inner layers are not thieving. They are signal layer fills to even out the resin flow from the prepreg. I have designed thousands of complex PCBs with many signal layers in each one and have never encountered a stackup that required inner layer signal layer fill to achieve a usable, flat PCB. Long ago, before call plates were inserted between PCBs in a laminator opening, it was possible to have PCBs with low spots where there was little copper on inner signal layers. That problem has pretty much gone away, so it is not necessary to do inner layer fills. When a fabricator is allowed to add thieving to outer layers, one only need to keep it away from other features on that layer to comply with typical spacing standards and away from traces enough that it does not adversely affect impedance. If the next layer down is a plane layer, that is all that is needed. If the next layer down is a signal layer (buried microstrip) thieving should not be placed over traces in the buried layer. I hope this helps clear up this issue. Lee Ritchey -----Original Message----- From: Jack Si Sent: Thursday, March 06, 2014 11:53 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Impact on Copper Thieving on 10G Routing Hi Experts, What are the major impact created by Copper Thieving in the 10G signals and the precautions to avoid it. Thanks and Regards, Jack ------------------------------------------------------------------ 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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 ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4335 / Virus Database: 3722/7159 - Release Date: 03/06/14 ------------------------------------------------------------------ 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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