Most modern products that are highly reliable are complex in their inner and outer structures. This situation indicates quality characterization by the interaction of multiple performance characteristics, which motivates the utilization of robust reliability models to obtain robust estimates. It is paramount to obtaining substantial information about a product's life cycle; therefore, when multiple performance characteristics are dependent, it is important to find models that address the joint distribution of performance degradation of such. In this paper, a reliability model for products with 2 fatigue-crack growth characteristics related to 2 degradation processes is developed. The proposed model considers the dependence among degradation processes by using copula functions considering the marginal degradation processes as inverse Gaussian processes. The statistical inference is performed by using a Bayesian approach to estimate the parameters of the joint bivariate model. A time-scale transformation is considered to assure monotone paths of the degradation trajectories. The comparison results of the reliability analysis, under both dependent and independent assumptions, are reported with the implementation of the proposed modeling in a case study, which consists of the crack propagation data of 2 terminals of an electronic device. the characteristics that its increments are independent and nonnegative, having a gamma distribution with an identical scale parameter. 3-6 Moreover, considering its monotonicity property and that performance can only decrease over time, this is why it is considered to be suitable to model wear, crack growth, corrosion, consumption, fatigue, etc. 7-13 Although the use of gamma process may be complicated when dealing with the first-time passage distributions, given that the obtained probability distribution function (PDF) has no explicit form. This implies the use of approximations to the Birnbaum-Saunders distribution and the inverse Gaussian distribution, which consider a discrete version of the first passage times of the gamma process and the central limit theorem to approach the passage time of the normalized cumulative degradation increments with a critical level to the Birnbaum-Saunders distribution. 8,14,15 The geometric Brownian motion as a degradation process has been presented as another important alternative. The sample path of this process, as in the case of the gamma process, is also monotone. Different applications of this process in degradation analysis can be found in the works of Park and Padgett, 9 Elsayed and Liao, 16 Park and Padgett, 17 and Chiang et al. 18 The inverse Gaussian (IG) process is another important choice for degradation modeling; this process also provides monotone degradation paths, and it is closely related to the Wiener process with drift. Indeed, it can be treated as the first passage distribution of a Wiener process. An important practical advantage of the IG process over the gamma process is the closed form of its first-time passage distributio...