I am uncertain as to the manufacturing specifications that I will need for a PCB I am hoping to get produced. The most complex component is the MCU (STM32151RCT) which has a recommended footprint for the LQFP64 ordering option as shown in the figure below:
Most of the online PCB manufacturers that I have compared have ordering options for "Min Tracking/Spacing" of 4/4mil (~0.1016mm), 5/5mil(~0.127mm) or 6/6mil(0.152mm).
The recommended gap between the pads is 0.2mm which is wider than all of the above Min spacing options. Does this mean I can use the lowest tolerance 6/6mil spacing? Are there any rule of thumb design rules that are appropriate to this issue?
I have also referred to the discussion here Trace width and spacing, which suggests that it is best to avoid using the minimum size available due to quality issues that can arise.
Please also bear in mind that the cost increase in going from 6/6mil to 4/4mil is quite large, so if possible the wider spacing would be preferred.