User Manual

Advanc
e
Information

2015 Microchip Technology Inc.
page
22
BM78SPPS5MC2 , RN4678
11.0 Mounting Details
The BM78 SPPS5NC2 physical dimensions are shown in Figure 11-1, recommended host PCB footprint
in Figure 11-2, and mounting suggestion in Figure 11-3. There should not be top copper layer near the
test pin area shown in Figure 11-2. When laying out the host PCB, the areas under the antenna should
not contain any top, inner layer, or bottom copper as shown in Figure 11-3. A low-impedance ground
plane will ensure best radio performance (best range, lowest noise). Figure 11-3 shows a minimum
ground plane area to the left and right of the module for best antenna performance. The ground plane
can be extended beyond the minimum recommended as need for host PCB EMC noise reduction. For
best range performance, keep all external metal away from the ceramic chip antenna at least 31 mm.
The BM78SPP03MC2 physical dimensions are shown in Figure 11-4, recommended host PCB footprint in
Figure 11-5, and mounting suggestion in Figure 11-6. It is highly recommended to layout the host PCB as
suggested in Figure 11-6. A low-impedance ground plane will ensure best radio performance (best
range, lowest noise). Pin 30 (BT_RF) is a 50 ohm connection to an external antenna connector, PCB
trace antenna, or component (ceramic chip) antenna through a host PCB 50 ohm micro-strip trace. This
trace can be extended to include passive parts for antenna attenuation padding, impedance matching,
or to provide test posts. It is recommended that the micro-strip trace be as short as possible for
minimum loss and best impedance matching. If the micro-strip trace is longer, it should be a 50 ohm
impedance. Figure 11-6 shows an example connection to U.FL connector.
Soldering Recommendations
The BM78 wireless module was assembled using standard lead-free reflow profile IPC/JEDEC J-STD-020.
The module can be soldered to the host PCB using standard leaded and lead-free solder reflow profiles.
To avoid damaging the module, the following recommendations are given:
• Microchip Technology Application Note AN233 Solder Reflow Recommendation (DS00233)
provides solder reflow recommendations
• Do not exceed peak temperature (T
P
) of 250 deg C
• Refer to the solder paste data sheet for specific reflow profile recommendations
• Use no-clean flux solder paste
• Do not wash as moisture can be trapped under the shield
• Use only one flow. If the PCB requires multiple flows, apply the module on the final flow.