Sherman, I have encountered this once from a customer during design/proto phase, but steered them away from it in final layout by stressing concerns of overall reliability of assembly (they were working towards Bellcore compliance). Bellcore TR-NWT-000078, Sec 2.2 addresses general electrical and mechanical integrity and would probably consider this to be 'novel or new technology' which would require demonstrated reliability through accelerated testing or modeling. In addition, Sec 7.1.2.2.5 specifically prohibits 'piggybacking' of components in production assemblies. Talk to your designer and stress the fact that Bellcore standards are written to assure the highest quality and reliability levels, and should be used as a guideline for non-standard assembly practices even when building to IPC. Appeal to his obvious concern for the utmost product integrity (guilt trip) and he should see the light.... 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: Sherman Banks [SMTP:[log in to unmask]] > Sent: Monday, October 05, 1998 3:55 PM > To: [log in to unmask] > Subject: [TN] ASSY: stacking 1206 chip resistors > > Hi Folks, > > We've got an engineer who wants to stack 1206 resistors 3 high in > order to > achieve a larger power rating. While it is intuitively obvious to us > that > this is NOT the way to go, we are at a loss to find any published > documents > that caution or forbid the practice. > > Can anyone cite a published source that can give more specific "rules > or > guidelines" on this subject. > > We've searched, J-STD-001, SM-780, SM-782, A-610, and R-700 > > Help!!!!! > > REGARDS > Sherman Banks > [log in to unmask] > 408/481-6047 > > ################################################################ > 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 ################################################################