Health Condition (HC) estimation of discrete power electronic devices is an important task for ensuring their reliable operation in mission-critical applications. Assuming bond-wire failure as a specific type of package failure, we take a direct approach to address the HC estimation problem using a dataset from accelerated aging tests. We first present a new concept of HC reference curve, which intends to represent the general health status over the device's lifetime using a health score. In particular, it is defined in relation to the device's Remaining Useful Lifetime (RUL) and captures the nonlinear health degradation status. Based on the HC reference curve, we mathematically formulate the HC estimation problem, and then develop an HC estimation flow using random forest algorithm. Finally, in our experiments, we demonstrate the effectiveness of our HC estimation method and the suitability of estimating the device's health status in comparison with the RUL estimation, which is a common yet indirect approach.