Resolving Component POLARITY PROBLEMS

摘要

I have heard complaints about "backwards" parts on assemblies and unclear drawings, and the response from Engineering has been "Use the data." This is not a thoughtless solution, because when software has been debugged properly computers don't make mistakes, and humans often do. In an ideal situation, a good set of CAD-generated data files will provide enough information to mount components on a bare board correctly. Theoretically, a board should be able to be assembled using only computer-generated data; without silkscreen, without polarity marks and without the need to visually inspect a drawing. If the data provided by CAD are not reliable, the assembler is forced to add manual processes using various types of drawings and visual inspection to ensure the assembly is correct. Even AOI equipment is ineffectual if it's not loaded with good data. Attempts to resolve problems caused by CAD-generated data files are time-consuming and error-prone; therefore, it is in our best interest to examine ways to improve their accuracy and usefulness. To better understand where the data come from, a brief explanation of the design process is required.