12.1 ATWILC1000-MR110PB Placement and Routing Guidelines

It is critical to follow the recommendations listed below to achieve the best RF performance:

  • The module must be placed on a host board and the printed antenna area must overlap with the carrier board. The portion of the module containing the antenna must not stick out over the edge of the host board. The antenna is designed to work properly when it is sitting directly on top of a 1.5 mm thick printed circuit board. Figure 12-2 shows the best, poor and worst case module placements in a host board.
  • If the module is placed at the edge of the host board, a minimum 22 mm by 5 mm area directly under the antenna must be clear of all metal on all layers of the board. “In-land” placement is acceptable; however, the depth of the keep-out area must groove to: the module edge to the host board edge plus 5 mm.
    Note: Do not place the module in the middle of the host board or far away from the host board edge.
  • Follow the module placement, keepout and host PCB cutout recommendation, as shown in Figure 12-1.
    • Avoid routing any traces in the highlighted region on the top layer of the host board, which is directly below the module area.
    • Follow the electrical keep-out layer recommendation, as shown in Figure 12-1. There must not be any copper in any of the layers of the host board in this region. Avoid placing any components (like mechanical spacers, bumpon, etc.) in the recommended electrical keep-out area.
    • Place GND polygon pour below the module with the recommended boundary in the top layer of the host board, as shown in Figure 12-1. Do not have any breaks in this GND plane.
    • Place sufficient GND vias in the highlighted area below the module for better RF performance.
    • It is recommended to have a 3 x 3 grid of GND vias solidly connecting the exposed GND paddle of the module to the inner layer ground plane. This will act as a good ground and thermal conduction for the ATWILC1000-MR110PB module. The GND vias must have a minimum via hole size of 0.3 mm.
    • Follow the mechanical boundary of the host PCB, as shown in Figure 12-1.
  • Keep large metal objects away from the antenna to avoid electromagnetic field blocking.
  • Do not enclose the antenna within a metal shield.
  • Keep any components that may radiate noise or signals within the 2.4 GHz – 2.5 GHz frequency band away from the antenna and if possible, shield those components. Any noise radiated from the host board in this frequency band will degrade the sensitivity of the module.
  • Make sure the width of the traces routed to the GND, VDDIO and VBAT rails are sufficiently larger for handling the peak TX current consumption.
Figure 12-1. ATWILC1000-MR110PB Placement Reference
Figure 12-2. ATWILC1000-MR110PB Placement Example