Very simplistic answers to your questions: 1) Invar is a primarily iron-nickel alloy. CIC is invar with copper on both sides. CIC comes in a variety of thicknesses of both the copper layers and the invar layer. 2) It is used as a heatsink material, and useful for controlling the X-Y movement of the PWB. As you know, the CTE of copper alone is very different from the epoxy-glass; the invar has a lower amount of movement. Other materials can be used for internal heatsinks, but they often have much higher CTEs than invar (aluminum for example). 3) There are many different processing methods required (at least from a PWB fab viewpoint). For example, it is difficult to drill through this very hard material. The sensitizing process is quite different than conventional epoxy-glass, as any copper in a sulfuric acid solution will deposit a copper smut on the exposed invar-you can imagine how this affects the microetch step. Ferric chloride microetches are frequently required. 4) It's expensive by itself, and the increase in processing pain-in-the-hind end factors increase board cost by quite a bit. There are a few places that have a lot of experience in fabricating with the stuff, but nobody I've ever seen builds a lot of it. Can't remember where people buy it from, tho. FJ >>> Robert Jordan <[log in to unmask]> 13:55 25 June 1998 >>> Good Afternoon! What is Copper Invar Copper? Why is it used? Are there any processing concerns differing from conventional copper? How does it compare cost wise to conventional copper? Thanks in advance, Bob Jordan ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################