Data Sheet

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4. Electrical Characteristics
4.4. Reflow Profile

Figure 4-1. ESP-WROOM-02D/ESP-WROOM-02U Reflow Profile
📖 Notes:
① Modem-sleep is used when such applications as PWM or I2S require the CPU to be working. In cases
where Wi-Fi connectivity is maintained and data transmission is not required, the Wi-Fi Modem circuit can
be shut down to save power, according to 802.11 standards (such as U-APSD). For example, in DTIM3,
when ESP8266EX sleeps for 300 ms and wakes up for 3 ms to receive Beacon packages from AP, the
overall average current consumption is about 15 mA.
② Light-sleep is used for applications whose CPU may be suspended, such as Wi-Fi switch. In cases
where Wi-Fi connectivity is maintained and data transmission is not required, the Wi-Fi Modem circuit and
CPU can be shut down to save power, according to 802.11 standards (such as U-APSD). For example, in
DTIM3, when ESP8266EX sleeps for 300 ms and wakes up for 3 ms to receive Beacon packages from
AP, the overall average current consumption is about 0.9 mA.
③ Deep-sleep is for applications that do not require Wi-Fi connectivity but only transmit data over long time
lags, e.g., a temperature sensor that measures temperature every 100s. For example, when ESP8266EX
sleeps for 300 s then wakes up to connect to AP (taking about 0.3 ~ 1 s), the overall average current
consumption is far less than 1 mA. The current consumption of 20 μA was obtained at the voltage of 2.5
V.
50
150
0
25
1 ~ 3℃/s
0
200
250
200
-1 ~ -5℃/s
Cooling zone
100
217
50
100 250
Reflow zone
217℃ 60 ~ 90s
Temperature (℃)
Preheating zone
150 ~ 200℃ 60 ~ 120s
Ramp-up zone
Peak Temp.
235 ~ 250℃
Soldering time
> 30s
Time (sec.)
Ramp-up zone — Temp.: <150℃ Time: 60 ~ 90s Ramp-up rate: 1 ~ 3℃/s
Preheating zone — Temp.: 150 ~ 200℃ Time: 60 ~ 120s Ramp-up rate: 0.3 ~ 0.8℃/s
Reflow zone — Temp.: >217℃ 60 ~ 90s; Peak Temp.: 235 ~ 250℃ (<245℃ recommended) Time: 30 ~ 70s
Cooling zone — Peak Temp. ~ 180℃ Ramp-down rate: -1 ~ -5℃/s
Solder — Sn&Ag&Cu Lead-free solder (SAC305)
Espressif
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2020.07