From SketchUp Make: Use a PDF printer driver (there are a zillion different available, commercial and free, I use Adobe Acrobat), select a standard view, switch your camera to parallel projection and print, setting the scale in the Print dialog. For crisp CAD-like lines, but no textures or shadows, you can use the “Use high-accuracy HLR” print setting (Vector Printing on a Mac).
SketchUp Pro has a PDF exporter of its own that also produces vector-only PDF files.
Anssi