There are only about 40 gates in the airport, everything is within easy walking distance, and since you are going Schengen to Schengen, there will be no passport control. You simply walk a few gates to the next flight. As long as your arriving flight is on time, no problem.

Note: in May I flew from USA to KBP via HEL. Since both flights were non-Schengen, I remained in the international/non-Schengen area of the terminal and did not have any security or passport checks. However, the AY HEL-KBP flight was an Embraer 170 RJ, too low for the jet bridges in that section of the terminal, which are built for large aircraft. As a result, we were bussed from a ground-floor gate (37b) to the aircraft, and the bus departed for the plane about 20 minutes before departure time. I don't know what would have happened to a connecting passenger who arrived at the gate after the bus had left. I recall that the gate agent remained at the gate after our bus departed, so perhaps that person would have remained at the gate until 5-10 minutes to assist any late-arriving passengers with a second bus. Do you know if your second flight is a full size jet or a regional jet?