Could someone please explain what the terms REF and BSC mean in the left figure. It's a drawing for 6 pin linear technologies Boost converter. I want to draw the symbol in Altium but I'm unsure what the correct dimensions are.enter image description here


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BSC (Basic Spacing between Centers) is a term that appears on IC package drawings in reference to dimensions between pins. "Basic" spacing is nominal and can change with conditions.

REF A reference dimension is a dimension on an engineering drawing provided for information only. Reference dimensions are provided for a variety of reasons and are often an accumulation of other dimensions that are defined elsewhere (e.g. on the drawing or other related documentation).

My recommendation is to start with making the CAD footprint using the dimensions on that drawing and see how it works in the assembly soldering process. The pad sizes sometimes need adjustment or the solder mask openings need adjustment as the overall artwork is optimized for re-flow soldering.


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