The x hatching thing was very popular on two sided boards way long ago as the liquid, non-photoimageable sm was over tin lead plating that was fused (still the most solderable surface on earth to me but I'm old and imfermed and how do you spell that on a midget laptop keyboard). The problem was, molten metals, as tin lead fused metals reflowed during assembly thus rendering the solder mask a bit unstable. This meant using x hatching was needed to ensure better solder mask adhesion. Really, the solder mask had to be used as a boat anchor to hold the solder down and for it to do its job - the solder mask that is. This also was a problem with the advent of direct IR reflow, instead of peanut oil or hydrosqueegee methods used in fab shops at the time. Damned IR would have worked too if only it had been convection. Should have seen those boards explode or popcorn at the very least. Multilayer x hatching on inners reached great popularity in the early '80's, partly thankfully to me of course, in the ECL days when impedance was just getting started. I could post an example but why bother. Simply, my thesis (am I using that word?) was we needed to satisfy both electrical/impedance requirements and innerlaminar integrity along with dimensional stability. On the ground plane's 100 mil centers were "traces," forming a grid, however but usually 40 mils leaving an open square area of 60 mils. This area allowed using a 40 mil square pad with 10 mils all around, or whatever depending on the ground plane trace width. This left everyting on a 100 mil grid. Now, the next layer down were the signal traces. You could run two 10 mil, or so, traces directly under the 40 mil, or so, wide plane "traces" on the layer above or below. Hel, I'm getting tired of writing this. I can say it did work at that time for the right reasons of the time and innerlaminar bond was great as was registration and dimensional stability. As for thieving, just don't let those R/F buys find you using it in your designs. Whew, MoonMan And I do know that was much more information than you needed. --------------------------------------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------