# Radiation Qualification by Means of the System-Level Testing: Opportunities and Limitations
## 1 Introduction  
In recent years, we could observe a huge increase in the number of small/micro-/nano-satellites that were launched and that are built of non-space grade electronics, but from COTS (commercial off the shelf) components. COTS components are manufactured without following as strict procedures (e.g., testing and inspection) as space-grade electronic components. In addition, the traceability of COTS components is very often limited, giving the end-user reduced knowledge on the manufacturer and manufacturing process of the product. The use of COTS is primarily driven by the requirement (and possibility) to reduce the cost and development time of missions. In addition, COTS components may enable much higher performance than available with the use of space-grade electronics. However, to assure mission success, radiation hardness assurance (RHA) schemes need to be applied [1], otherwise, the risk induced by the space radiation effects on the COTS-based systems might be out of control. This risk is related to the radiation environment in space, i.e., particles trapped by the Earth's magnetic field, Galactic Cosmic Rays and Solar Particle Events. The space radiation may be a source of cumulative effects (such as total ionizing dose (TID) or displacement damage) and single event effects (SEE), and in general may lead to decreased performance of specific functions, temporal malfunctions or critical failure and loss of mission. In this context, the goal of RHA is to ensure that all the potentially radiation-sensitive units of a space system (including the space system itself) will meet their design specifications up to the end of the targeted mission [1]. The core part of the RHA is defining the target environment, defining the requirements and evaluating the design and components for the mission [2]. The standard RHA approach requires component-level testing of all the potentially sensitive components, which is time- and money-consuming. Therefore, simplified approaches are searched for, including testing of the reduced number of components in the system (e.g., the most critical components only) and system-level testing [3]. In this paper, the system-level radiation tests are discussed from the point of view of potential electronic system radiation qualification. The main goal of this paper is to present opportunities and limitations related to the radiation qualification of the System-in-Package (SiP) modules (and systems in general) using system-level tests. While discussing the system-level radiation testing of electronics, it is essential to define what is understood as an electronic system and what is not. It was proposed in [4] todefine a component as any device that cannot be physically partitioned without damaging it; therefore, anything manufactured on a chip falls into this category. Furthermore, a \"system\" would be something at a higher integration level than a component (PCB (printed circuit board), assembly of PCB boards, SiP module, satellite subsystem or even whole satellite). Definitions proposed in [4] were found helpful in the context of radiation testing and RHA and will also be used within this description and this project. SiP is often used as a commercial name for a product, the electronic system developed in 3D PLUS on-demand of a client, based on provided part list, block diagram, required functionality/features list, etc., enclosed in a single, miniaturized package (typically not bigger than 3 \(\times\) 3 \(\times\) 2 cm\({}^{3}\)). In this work, SiP will refer to a more general meaning of the electronic system consisting of a number of dissimilar integrated circuits and passive components, enclosed in a single, miniaturized package. However, the SiP mostly discussed in this paper is the Point-of-Load converter (PoL) from 3D PLUS [5], as all the radiation test experiments performed within this study had the PoL as the test vehicle.