Hi JaMi, I do not know where you asked your questions, but obviously not at the right places [at least for some of them. Your questions are very pertinent, but incomplete--you also need to ask for physical properties such as modulus and ductility. Lets get the easy one out of the way: 1) Common rolled sheet copper, when annealed, can be relied on to have the 'book values' given for copper both in terms of the electrical and physical properties. If it is not annealed, there will be gross differences in the machine and cross-machine directions in terms of strength and ductility due the needle-like structure in the rolling direction--I do not know what the electrical properties are in this case. Perhaps Olin <[log in to unmask]> can be of help. 2) I do not know of values for electroless deposited copper--I would suspect it might behave similar to electrolytic copper, but I am not sure. 3) Electrolytic copper as plated in a PCB Fab house will be somewhat different from electrolytic copper as you find in commercial electroplated foil--the difference comes from significantly different plating chemistries and plating current densities. You certainly should look at IPC-4562, Metal Foil for Printed Wiring Applications, as well as IPC-TR-484, Results of IPC Copper Foil Ductility Round Robin Study. What they have in common is, that in both cases organic and other plating bath additives get co-deposited during the plating processes. The consequence is that the density of these deposits is lower than the copper 'book value' as well as the rolled copper foils--typically in the range of 8.8 to 9.0 g/cm3. That is the underlying reason why copper foil is sold in oz/sq-ft rather than a thickness. A further consequence is that the modulus of elasticity is about 30% lower than the Cu 'book value,' typically at 12e6 psi; still another is that the resistivity is higher--it varies from 0.181 to 0.155 ohm-gram/sq meter depending on thickness; as well as a higher etch rate. Because the amounts of co-deposited organics varies, these properties have ranges rather than a fixed values. In fact, IPC-4562 is specifying electrolytic copper foil so liberally, that 3-sigma production outliers can be shipped meeting the spec. When that happens, larger than normal amounts of organics are co-deposited with the following effects on properties happening all at once: a) reduced strength, b) reduced ductility, c) reduced density, d) increased resistivity, and e) increased etch rate. You combine d) and e) and your current carrying capacity goes down quite rapidly. No idea about effects on CTE, but given the inaccuracies I see with the resins going into PCBs, any variation in E-Cu CTE would be small potatoes. Whether the interfaces between electroless Cu and Cu foil on the one hand and electroless Cu and electrolytic Cu form some barrier is a very good question--alI I can say is that these interfaces are implicated for 2 out of the 3 inner-layer separation [formerly post separation] failure modes. Regards, Werner Engelmaier Former Chairman of the IPC Copper Foil Committee Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------