# Radiation Qualification by Means of the System-Level Testing: Opportunities and Limitations
## 1 Introduction
The system-level test might be defined as the one in which parameters and/or functionality of the whole system is monitored at the time of the test, instead of parameters of the specific component only. However, not the whole system has to be irradiated at a given time, to call it a system-level test. For example, during laser test, the laser is focused only on one integrated circuit at a time, but if the component is a part of the working system and parameters of the system are monitored during the test, it is a system-level test [6]. Similarly, irradiation with heavy ions of a single component in the monitored system (such as described, e.g., in [7]) is also a system-level test. Different approaches for system-level testing were already used and discussed in the literature. A summary of these approaches is presented in Table 1: \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Test Type** & **Radiation Source/Test Approach** & **Main Features** \\ \hline \multirow{4}{*}{TID} & Photons—gamma rays (Co-60 & - & high penetration of the source (particularly Co-60) \\  & (\(\approx\)1.2–1.3 MeV), Cs-137 & - & high capabilities in testing big systems (limited for X-ray due to typical geometry of X-ray machines) \\  & X-ray [8; 9; 10] & - & high penetration of particles \\  & & - & broad beams available, suitable for board/system-level \\  & & - & testing \\  & protons [11; 12; 13] & - & well-established test method for 200 MeV protons, with provided formulas to calculate SEE rate for the orbit of International Space Station \\  & & - & limited linear energy transfer (LET) (LET of secondary particles after proton hit at the component die) \\ \cline{2-4}  & heavy ions: & - & limited penetration of particles (opening of the component packages required: only board-level testing possible, not for bigger systems) \\  & standard (\(<\)10 MeV/n) and & - & test in vacuum for standard energy heavy ions \\  & high (10–100 MeV/n) energy & - & high LET, up to 100 MeV\(\cdot\)cm\({}^{2}\)/mg \\ \cline{2-4}  & heavy ions: very high energy & - & moderate penetration, suitable for board-level testing, not for bigger systems \\  & (0.1–5 GeV/n) [14] & - & high LET; however, for board-level testing with homogenous LET limited to 30 MeV\(\cdot\)cm\({}^{2}\)/mg for two-side PCB testing, slightly more than 40 MeV\(\cdot\)cm\({}^{2}\)/mg for one-side PCB testing, \\ \cline{2-4}  & heavy ions: & - & high penetration, possible to test whole systems or even several systems stacked in the beam line \\  & ultrahigh energy & - & limited LET: around 10–15 MeV\(\cdot\)cm\({}^{2}\)/mg \\  & (5–150 GeV/n) [15; 16] & - & an alternative approach for RHA: to test with HEH spectrum equivalent to the one at the target environment \\ \hline \multirow{4}{*}{mixed} & CHARM facility: high energy & - & high penetration of the field, big space for testing of systems \\  & hadrons (HEH, with energies up to 24 GeV) [4; 17; 18; 19; 20] & - & a useful tool for soft error rate estimation, however, LET is limited to around 15–17 MeV\(\cdot\)cm\({}^{2}\)/mg \\ \cline{1-1} \cline{2-4}  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of the system-level test approaches discussed in the literature. The table gives references to documents where different system-level test approaches are discussed. For more detailed information on performing tests in different facilities, or using different approaches, the Reader is encouraged to consult the references provided. Another relevant reference is the first guidelines document for system-level testing for space systems, established last year [21]. Some of the system-level test approaches presented in Table 1 were used to test the PoL. In this paper, selected results from these experiments will be presented, with the main goal to discuss opportunities and limitations related to the radiation qualification of the SiP modules using system-level tests.