User Manual

Jennic
JennicJennic
Jennic
© Jennic 2008 JN-DS-JN5139 v1.5 79
• The second layer is Ground and has no tracks on it. This allows the best return path for all RF signals and will
reduce noise effects.
• The bottom layer contains all other signals and the V
cc
power supply for the module.
• The ground planes on all layers stop BEFORE the antenna, so that the performance of the antenna is not
affected. The recommended antenna clearance for a surface-mounted ceramic antenna is shown below.
ANTENNA
CHIP
CLEARANCE
(no ground plane)
CLEARANCE
(no ground plane)
50 Ω transmission line
Dimensions in mm
20
20
20
Figure 52: Antenna Clearance Recommendations
B.3.11 Manufacturing Considerations
The TQFN package must be considered carefully when using reflow solder techniques. The following are
recommendations:
• The decal is shown in Figure 53. The pad stacks used are 0.25 mm by 1 mm for the smaller pads, and a 6.4-
mm square pad for the paddle.
Figure 53: Recommended PCB Decal for 56QFN Package
• The solder mask used is shown in Figure 54. The pad stacks used are 0.25 mm by 1 mm for the smaller pads,
and two 2-mm square pads to apply paste to the paddle. The solder paste mask has a thickness of 6 thou
(0.152 mm).