> Hello All, > > We currently have a workmanship spec that was derived partly from > the NASA spec which requires the use of a filler wire for the support of a > via on double-sided PWB's. This requirement has caused some double-sided > boards to needlessly become multilayer boards to avoid using a stitch > wire. I noticed that the J-STD-001B 9.2.5 makes no distinction between > double-sided or multilayer when it comes to interfacial connection > definition. > Is there something I am missing or is there a reliability difference > between a PTH VIA on a double-sided and a PTH VIA on a multilayer that I > am not aware of? My assumption is that this NASA spec addressed an issue > that may have been previlent in the earlier years of the PWB industry. > > NASA-STD-8739.3 > December 1997 > 11.2.4. Interfacial Connections. > > a. Double-Sided PWB's. Functional PTH's on > double-sided PWB's require the use of filler wire for support if the PWB > coupon has not been evaluated by construction analysis. No dedicated > effort need be expended to remove solder in unused holes. > > b. Multilayer PWB's. Multilayer PWB PTH's > used as vias do not require the use of filler wire nor shall they be > solder filled. No dedicated effort need be expended to remove solder in > unused holes. > > Your comments are always appreciated. > Thanks, > Dave Brocious <<...OLE_Obj...>> Space Systems Co. Advanced Development Design Specialist 100 Campus Drive Newtown, Pa. 18940 Phone: 215-497-1732 Fax: 215-497-2719 [log in to unmask] --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------