This is a survey and a question for those of you who have knowledge about printed board design practices. The design requirements for printed board conductor width and conductor spacing are mostly based on some regulatory requirement. What I would like to know is how are the specification's "minimum" design requirements implemented in actual design practices. Basically, are design requirement "minimums" use as "minimums" in the actual design or are they used as "nominals" knowing there is some tolerance "built-in" for manufacturing. Conductive Pattern Requirements: The current-carrying ability of conductors is generally based on a chart that appears as a figure in MIL-STD-275, IPC-D-275, or IPC-2221. This chart is based on thermal rise above ambient for a specified current. These requirements are converted into a minimum "conductor cross-sectional area", which is then converted into a minimum conductor width and minimum conductor thickness. The question is: "In your design practices/experience, are the 'minimum conductor width' and 'minimum conductor thickness' used as the "minimums" in the design requirements or are they used as "nominals" in the product definition data (or master drawing) ???? A simple response is located at the end of these writings. Conductor Spacing Requirements: A similar query is for conductor spacing" "In your design practices/experience, are the "minimum conductor spacings" used as the "minimum" or "nominal" design requirement in the product definition data (or master drawing) ???? Responses: We use minimum conductor thickness/width requirements as "minimum". ( ) We use minimum conductor thickness/width requirements as "nominal". ( ) We use minimum conductor spacing requirements as "minimum". ( ) We use minimum conductor spacing requirements as "nominal". ( ) Your response will be appreciated, Ralph, Ralph Hersey & Associates 3885 Mills Way Livermore, CA 94550-3319 PHN/FAX: 925.454.9805 e-mail: [log in to unmask] ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################