Electronic cigarette

An electronic cigarette, comprising:

• a housing,
• an atomizer accommodated in the housing;
• an e-liquid cavity, and
• an airflow sensing device disposed on a bottom end of the housing;
• wherein a smoking port is defined on a top end of the housing;
• the atomizer is spaced apart from the smoking port;
• the e-liquid cavity is disposed between the atomizer and the smoking port;
• a through hole communicated with an outside is defined on the bottom end of the housing;
• wherein the airflow sensing device comprises a first circuit board fixed to the bottom end of the housing, a micro-electro-mechanical system (MEMS) airflow sensor fixed to the first circuit board, and a main control integrated circuit (IC) electrically connected to the first circuit board;
• the MEMS airflow sensor comprises a second circuit board;
• the second circuit board is electrically connected to the first circuit board;
• wherein the second circuit board is stacked and fixed onto the first circuit board;
• the second circuit board comprises a first surface facing the first circuit board, a first bonding pad and a second bonding pad are disposed in the first surface of the second circuit board;
• the second bonding pad is a closed ring-shaped structure;
• the second bonding pad is disposed around an outer side of the first bonding pad;
• the first bonding pad comprises a first pin;
• the second bonding pad comprises a second pin;
• the main control IC is electrically connected to the second circuit board through the first pin;
• the second pin is grounded;
• wherein the first bonding pad is recessed in a direction away from the first circuit board;
• the second bonding pad is recessed in a direction away from the first circuit board;
• the first bonding pad and the second bonding pad are spaced apart:
• the first bonding pad and the second bonding pad are electrically connected to the first circuit board and the second circuit board by solder paste, such that the second circuit board seals the first circuit board to prevent condensate generated during use of the electronic cigarette from contacting the first pin within the first circuit board.