The rectifier diode is improperly installed by being tightly attached to the printed circuit board

During operation, the rectifier bridge cracked, and the filter capacitor began smoking. Further inspection revealed severe overheating of the rectifier bridge. Due to its pins being shortened and installed flush against the printed circuit board, the surrounding board had turned a charred yellow.diode

 1. Reason: During the positive half-cycle, D1 and D3 conduct; during the negative half-cycle, D2 and D4 conduct. The rectified current passes through both diodes simultaneously. Since the forward voltage drop of ordinary rectifier diodes is approximately 1V, the voltage drop across the rectifier bridge is about 2V. If the output current of the rectifier bridge is 1.5A, the power loss of the rectifier bridge is approximately 3W. Therefore, the heat dissipation of the rectifier bridge itself should be considered. If the rectifier bridge is tightly attached to the printed circuit board and too close to surrounding components (such as filter capacitors), its heat cannot be effectively dissipated, potentially leading to overheating damage.  2. Countermeasures: Do not cut the leads of heat-generating components too short; allow the bottom of the component to remain suspended above the printed circuit board. Additionally, increase the spacing between surrounding components. Figure 20 shows the relationship between the lead length of the rectifier bridge (S2VB20) and the current it can carry. It is evident that shorter leads allow for smaller current capacity. Furthermore, using Schottky barrier diodes (SBDs) with lower forward voltage drops (only 0.5V) can reduce losses and heat generationdiode