nrf51822 custom pcb layout help

[Punit]

I am using the nfr51 dk and a standalone nrf51822 based ble module for prototyping & testing purpose.I plan to make my own custom pcb for final production.In both the above boards, i have observed that the components around the radio have been placed only on the side on which radio is placed.Is there any specific reason for the same? if i use a multisided board can i place the components on either side to save space & reduce the board side? Also, can i use different package size for components?

[Ole Bauck]

There is a specific reason for that the components are placed like they are, and that is that this design is optimized to give the best radio performance. The DK (and probably the BLE module) is based on the reference layout found here. All customers should use this reference layout unless it is absolute necessary to not do so.

For example, changing the size of the components and/or the side the components are on will greatly affect the inductance of the matching network.

[Punit]

ok, one more question, i could also see a lot of thermal vias below the radio chip & the antenna in the third party module, but not in the nrf51dk,... any specific reason apart from heat dissipation for adding those?

[Ole Bauck]

A good connection between the two ground planes is important. The reason there are so many vias is probably this rather than heat dissipation.