VC7 PCB Layout Guidelines Manual
R31UH0017EU0100 Rev.1.00
Aug 4, 2022
Page 5
Figure 5. XIN Overdrive with an LVCMOS or an LVPECL Clock Source
4. VC7 Device Electrical and Thermal Pad Handling
VC7 devices come with an ePad – a ground island directly beneath the device on the same layer the IC is
soldered on the PCB. The ePad is both a grounding pad and a thermal relief pad for the device. ePad patterns
are different in different part numbers. Separate discussions on ePad handing are included in the following
sections.
4.1
RC21008A/RC31008A – 40-LGA
[3]
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Device land pattern is shown below:
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PCB pad width: 0.20mm
●
PCB pad length: 0.45mm
○
Toe extension (beyond package edge): 0.05mm
○
Heel extension (toward package center): 0mm
■
Stencil recommendations (Unit: mm):
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Thickness: 0.125
●
Aperture for thermal pads: 0.84 × 0.84 (x9, each aperture centered on corresponding land pattern of each
pad)
●
Aperture for pins: 0.22 × 0.58 (x40, heel coincides with package pin heel)
■
Via placement and connections:
●
Place a thermal/ground via on each thermal pad.
●
This implementation is called via-in-pad, which is the option for this package because there is no extra
space for the vias outside of pads.
