Jim, You should know better than to offer anything free to this Technet crowd. I would also appreciate a fax of your chart. thanks. Ralph Vaughan Boeing Fax 770 497-5555 > ---------- > From: James R. Paulus[SMTP:[log in to unmask]] > Reply To: TechNet E-Mail Forum.;[log in to unmask] > Sent: Wednesday, October 21, 1998 11:13 AM > To: [log in to unmask] > Subject: Re: [TN] FR4 thermal expansion > > I have a comprehensive chart which I can fax you, if you want to provide > the > phone #. > Generally, Z-axis is 60 to 80 ppm (or microinches/inch/C), X is 17-20 ppm, > and > Y is 15 to 18 ppm. Lots of variables however: > a. These values are for a temp ramp up to the Tg, which is 135C typically > for > FR4. > b. Remember that FR4 today can be a material with a Tg as high as 180C. > Higher Tg FR4's tend to exhibit a slightly lower Z-expansion below the Tg > than > 135C types. > c. Z-axis is particularly affected by resin:glass ratio. Higher Resin > content means greater expansion, which has to be considered in high layer > count designs. > d. Above the Tg, the X and Y movements get squirrelly because the > softened > resin allows the glass fabric to pull back against the expanding matrix, > resulting in much lower values. > jimpaulus > > ################################################################ > 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's web site (http://www.ipc.org) "On-Line Services" > section 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################