Scripted version of qfn-52 7x8

The footprint is currently not used by any symbol. But the assigned datasheet is well enough to create a scripted version of it.

Script PR: https://github.com/pointhi/kicad-footprint-generator/pull/250

https://www.analog.com/media/en/package-pcb-resources/package/pkg_pdf/ltc-legacy-qfn/QFN_52_05-08-1729.pdf

QFN-52-1EP_7x8mm_P0.5mm_EP5.41x6.45mm:
  device_type: 'QFN'
  #manufacturer: 'man'
  #part_number: 'mpn'
  size_source: 'https://www.analog.com/media/en/package-pcb-resources/package/pkg_pdf/ltc-legacy-qfn/QFN_52_05-08-1729.pdf'
  ipc_class: 'qfn' # 'qfn_pull_back'
  #ipc_density: 'least' #overwrite global value for this device.
  # custom_name_format:
  body_size_x:
    nominal: 7
    tolerance: 0.1
  body_size_y:
    nominal: 8
    tolerance: 0.1
  body_height:
    nominal: 0.75
    tolerance: 0.05

  lead_width:
    nominal: 0.25
    tolerance: 0.05
  lead_len:
    nominal: 0.4
    tolerance: 0.1

  EP_size_x:
    nominal: 5.41
    tolerance: 0.1
  EP_size_y:
    nominal: 6.45
    tolerance: 0.1
  # EP_paste_coverage: 0.65
  EP_num_paste_pads: [4, 5]
  #heel_reduction: 0.1 #for relatively large EP pads (increase clearance)

  thermal_vias:
    count: [5, 6]
    drill: 0.2
    # min_annular_ring: 0.15
    paste_via_clearance: 0.1
    # EP_num_paste_pads: [2, 2]
    #paste_between_vias: 1
    #paste_rings_outside: 1
    EP_paste_coverage: 0.6
    #grid: [1, 1]
    # bottom_pad_size:
    # paste_avoid_via: False

  pitch: 0.5
  num_pins_x: 12
  num_pins_y: 14