Espressif provides the SMD module—ESP-WROOM-02 that integrates ESP8266EX. The module has been adjusted to get the best RF performance. We recommend using ESP-WROOM-02 for tests or for further development.
The module size is (18.00 ± 0.10) mm x (20.00 ± 0.10) mm x (2.80 ± 0.10) mm. The type of flash used on this module is an SPI flash with a package size of SOP 8-150 mil. The gain of the on-board PCB antenna is 2 dBi.