            Commercial Electronic components are increasingly being used in Defense and Aerospace applications, where they’re being exposed to high G forces than their original destined usage in commercial electronics. Reinforced surface mount electronic components with epoxy potting and underfills, has shown improved survivability under harsh extreme environments like thermomechanical shock loading. In addition to that, potting of electronics components offers structural support, shock damping and protection for the components from environmental conditions like moisture. Potting is one of the cost-effective and viable way to improve the survivability of the electronic components. Most of the component failure under mechanical shock occurs at the solder joint interconnects as they undergo tremendous strain during mechanical shocks. Mostly Potting and encapsulation resins are a two part systems, which form a solid on mixing and curing without any by products. On dynamic shock loading, Interfacial delamination occurs between the potting material and the PCB, which further propagates to solder interconnect failures. Due to which it becomes a necessity to the study, understand interfacial fracture resistance in PCB/epoxy potting systems under dynamic shock loading, to mitigate the system failures in mission critical applications. Mechanics of interface delamination of the epoxy potted PCB samples is a primary focus on this paper. Determination of fracture parameters such as fracture toughness and strain energy release rate at steady state stress is important in selection of the potting material and the reliability study of the supplemental restraint systems. Samples of PCB/Epoxy specimens are prepared and fracture behavior is observed under quasi-static three-point bend loading. A comparison has been made on fracture toughness and crack initiation of the PCB/Epoxy systems based on curing schedule and temperature. Under three point bent loading, it is assumed the damage occurs at the interface. A cohesive zone model of the specimen was developed for Mode-I delamination and interface is modeled using cohesive zone elements and at the same time the epoxy which is the bulk material is assumed as linear elastic. The experimental results of fracture parameters is used as input in the model to compare with the fracture characteristics of the cohesive zone law and damage accumulation prediction on the specimen.


Twist Reliability Assessment of Flexible Battery In Wearable Applications

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

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