[log in to unmask] asked Is there a standard for the distance between SMD components in the wave soldering process to prevent shadowing? We are currently basing it on 1.5 times the component height. What is the shape of the "deadspace" behind these components, rectangular, conical, oval... ? Any help is greatly appreciated. ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::: Dean, Several people will give you a good "rule of thumb" for your question. However, I would suggest that you follow good engineering practice and determine what your customer can tolerate (that's the process boys in the factory). Many years ago I assisted a couple of engineers from a company whose design group had created an SMT wave solder design study PWB. The board started at one end with typical component layouts that gradually tightened in spacing as they moved to the other end. The objective was to try and determine the smallest spacing that still soldered without defects. The board was sent to all of the companies factories to determine what the limits of the current factory processes were, with the intent to design only what could be built. Many of us offer comments about design rules, saying how we use them day to day, without specifying the particulars of our process. The equipment, stencils, fluxes, solder pastes, etc... are all important parts of the process and directly impact the design rules. Just as important, in the wave solder SMT case, will be the shape of the lands used. The use of longer but narrower lands and selective use of robber pads will also impact the manufacturability of the design. For some good reading, try http://www.avxcorp.com/tech/smt.htm Steve Mikell Lead Ind. Eng. Plt 13 SCI Technology PS: to finish the story of that design study, the SOTA wave solder systems we tested soldered 100%, except where part misplacement issues were present. I do not currently have a copy of the design spacings, but that was 1990 data anyway. ################################################################ 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 ################################################################