VSSOP 0.4 mm Pitch pad design & Stencil aperture

Hi, where can I find info about how to make the pad design to work for VSSOP48 0.4 mm Pitch & TSSOP56 0.5 mm pitch components? I should also mention that we are working in a project that this 14 layers High-Frequency RoHS board is included. The pad capacitance and conductance of ours is critical. The numbers I have just don't add up... We use 2 ground planes and are carefully when we get "to close" to each other and also the angel of the traces. But still... We would also like to do a proper gerber file for the stencil design, so the production people don't have to do to much changes to it for the prototype run. Of course they need to adjust/tweak some of the apertures to maximize the yeild, but that will be done in the NPI process. Any suggestions would be greatly apreciated. /Thanks,

reply »