Designing Electronic Card Packages Against Shipping Shock

In optimizing packaging design, the product’s fragility is qualified by a protype undergoing quantitative and qualitative tests that rely heavily on past knowledge and experiments. By the addition of finite element analysis (FEA), the product’s fragility can be obtained in the initial stages of product design with material characterization and simulation. FEA can predict Gs on the product as well as examine the strains, which interpret product failure more easily in the design stage. To incorporate FEA, first the foam material was measured at various strain rates under compression. Next a shipping package containing an Al block with consistent density was dropped at different heights—610 mm (24”), 915 mm (36”), and 1067 mm (42”)—to confirm the methodology. An I/O book was packaged for the final demonstration incorporating FEA with an electronic card package. In an electronic card package, the electronic assemblies are sensitive to strains on the system board. If the strains on the board are high, the assemblies’ solder connections to the board could be damaged and result in a defect during shipment. The simulations’ predicted Gs and board strains were compared to experimental drop testing results at 610 mm (24”) and 915 mm (36”). The simulation results for each sensor location were within reasonable approximation of the experimental results, verifying that FEA could be used in the initial design stages to predict the accelerations and strains for packaging development in parallel to the product design.

Atomic layer deposition (ALD) for environmental protection and whisker mitigation of electronic assemblies

In this study, we demonstrate how metal-oxide thin-film conformal coatings grown by atomic layer deposition (ALD) can be exploited as an effective approach to mitigate tin whisker growth on printed circuit boards. First, we study the effect of different ALD coatings and process parameters on Sn–Cu-electroplated test coupons, by combining optical imaging and scanning electron microscopy and evaluating whisker distribution on the surface. On these samples, we found that one important parameter in mitigating whisker growth is the time interval between electroplating and the ALD coating process (pre-coat time), which should be kept of the order of few days (2, based on our results). Atomic layer-deposited coatings were also found to be effective toward whisker formation in different storage conditions. Furthermore, we show that ALD coating is also effective in limiting the need for outgassing of electronic assemblies (PCBAs), which is an additional stringent requirement for applications in space industry. Our experimental results thus demonstrated that atomic layer deposition is a suitable technique for aerospace applications, both in terms of degassing and whisker mitigation.

Universal single-board computer based control unit for biomedical test benches

Continuous adaptation of international standards for medical devices requires recurrent modification of test benches. A universal control unit using an open software environment is presented to simplify the maintenance of various test benches. Our developed control unit is equipped with a Raspberry Pi 4, with standard communication interfaces and application-specific electronic assemblies. The software is based on Node-RED, a browser-based editor. A measuring setup was adapted for a flow perfusion system. Our control unit simplifies the handling of the flow perfusion system by controlling a hydraulic pump and all required valves. A software programmed PID algorithm adapts the speed of the pump to adjust the pressure automatically. Actuators like proportional pinch valves are handled to control volumetric flow and pressure within the circulation. Consequently, the user directly observes changes inside the system. The measured data are stored and are available for documentation.

Reliability modeling and assessment of solder joints of electronic assemblies under mixed exposure to mechanical loads

Purpose In this paper, a lifetime estimation model for the solder joint is proposed which is capable of considering both severe and running mechanical shocks which is the real case in electric converters in the automotive and aerospace applications. This paper aims to asses the reliability of the solder joint under mixed exposure of mechanical loads. Design/methodology/approach Mechanical failure process may put at risk the perfect performance of any kinds of electronic systems regardless of the applications they are prepared for. Observation of solder joint health in an electronic assembly under simultaneous exposure of severe and running shocks is an open problem. Three commonly used soldering compositions are considered while the electronic assembly is exposed to three well-known driving cycles. Findings The results show that the best performance is achieved using SAC405 soldering alloy in comparison with Sn63Pb37 and SAC387 solder alloy. Consideration of mixed exposure to the mechanical loads leads to much more accurate lifetime estimation of the solder joint in the electronic assemblies. Originality/value The originality of the paper is confirmed.

Accurate composition dependent thermo mechanical lifetime estimation of hour glass type solder joint in electronic assemblies

Purpose This study aims to present a more accurate lifetime prediction model considering solder chemical composition. Design/methodology/approach Thermal cycling and standard creep tests as well as finite element simulation were used. Findings The study found lower error in the solder joint lifetime evaluation. The higher the Ag content is, the higher the lifetime is achieved. Originality/value It is confirmed.

Reliability of soldered joints for aerospace applications

Known to be highly reliable, Tin-Lead (SnPb) solders have long been used in commercial and aerospace electronic assemblies due to their ability to withstand thermo-mechanical fatigue. A number of constitutive and thermo-mechanical life models for SnPb soldered joints can be used to determine whether a given board design meets the reliability requirements of a system. Known to be highly reliable, Tin-Lead (SnPb) solders have long been used in commercial and aerospace electronic assemblies due to their ability to withstand thermo-mechanical fatigue. A number of constitutive and thermo-mechanical life models for SnPb soldered joints can be used to determine whether a given board design meets the reliability requirements of a system.Due to environmental and toxicological concerns, government legislations worldwide now limit the use of Pb in manufacturing processes. Therefore, the aerospace industry must understand the reliability of proposed Pb-free alternatives prior to using them in the aerospace applications. In order to improve the space-readiness of Pb-free solders, a well-rounded collection of space-specific test results must be compiled and test-verified predictive life models must be developed. Finally, quality control processes associated with manufacturing, handling, and repairing Pb-free solders will have to be created before the space industry can make the transition from SnPb to Pb-free solders.