What are solder cracks caused by heat cycle?
In applications where temperature changes are remarkable, such as in automobiles, when temperature change (= heat cycle) occurs, the difference in the linear expansion coefficient between the printed wiring board and the electronic component may cause cracks in the solder joint, leading to connection failure.
In the case of chip resistors, large size chip resistors are generally used when large rated power is required. However, the larger the chip resistor, the greater the absolute value of expansion/contraction and the higher the rate of failure.
In order to achieve both the high rated power and measures against solder cracks, multiple small-sized resistors are used in some cases to secure the required rated power, but it increases the number of parts and mounting area.
In such cases, we recommend the wide terminal type WK73R, WG73, WK73S and WU73, and the mold sealed type TSL, SL, SLN and SLZ, which are large rated power and resistant to the heat cycles.