Rick, Look for a few major problems. The first is the wicking away of a large volume of solder through the via, with potential opens or minimal contact as a result. The second is a virtual guarantee of extremely large voids in any joint that contains a via in the pad, with the possibility of short/long term reliability issues. Finally, unless you temporarily mask off the vias on the bottom side before wave, any via-in-pad joints will see a secondary reflow cycle during wave solder. This will duplicate/increase the first two problems of wicking and voids, and may entrap wave solder flux within the voids. I have had to process such assemblies before, and it is no picnic. Impress upon your customer the need for redesign to improve quality and reliability. Mike McMonagle PCA Process Engineering Supervisor K*Tec Electronics 1111 Gillingham Lane Sugar Land, TX 77478 (281) 243-5639 Phone (281) 243-5539 Fax [log in to unmask] > -----Original Message----- > From: Rick Thompson [SMTP:[log in to unmask]] > Sent: Tuesday, September 21, 1999 4:50 PM > To: [log in to unmask] > Subject: [TN] Via in BGA Pad? > > We have a customer who wants us to run a board that uses a 256 pin BGA. > The > problem is, he has placed vias for signal routing in the center of the BGA > pads. The vias are plated with a 10mil finished size. There is no solder > mask tenting these vias on the bottom of the PCB. I realize this isn't > normally recommended, but as they already have the boards, re-layout isn't > an option. My question is basically, what types of problems will I have? > I > know I may get wicking of solder through the PTH, but given the hole size, > how bad is it likely to be? Anyone have any experience attaching BGAs to > this type of pad configuration? > > Thanks in advance. > > > Rick Thompson > Ventura Electronics Assembly > 2665A Park Center Dr. > Simi Valley, CA 93065 > > +1 (805) 584-9858 voice > +1 (805) 584-1529 fax > [log in to unmask] > > ############################################################## > TechNet Mail List 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://www.ipc.org/html/forum.htm) for > additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## ############################################################## TechNet Mail List 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://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################