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Abstract
One of the most common causes of failure for portable electronic products is from drop impact. Impact and shock to such products can cause significant functional and physical damage. They can cause external housing, internal electronic component or package-to-board interconnection failure. This paper examines the drop impact response of portable electronic products at different impact orientations and drop heights. A method whereby actual drop test using a cellular phone as an example is proposed. Of interest is the measurement of the level of shock experienced by the electronic components on the printed circuit board (PCB) during impact. A patent pending drop tester which allows drop impact of the cellular phone at any orientation and drop height is used. A high-speed video camera is also utilized to verify the impact orientation. The drop impact responses examined are the impact force and the strains and level of shock induced at the PCB. A better understanding of the shock induced at the electronic components and packages in the products can assist manufacturers not only in designing better components and electronic packages but also products which are more robust and reliable, to handle shock and impact loading.
... Standard protocol for flat and side drop tests is given in IS standard IS: 11052-1984 [3]. Lim and Low [4] investigated the drop impact analysis of portable electronic products. It was observed that the components were badly damaged under impact loading. ...
Hearing disability is commonly observed in old age person. It is observed that for the age limit 55 to 80 years around 40% of individuals are facing age related hearing loss. Light weight hearing aid made of composites are being used very frequently. There are two types of hearing aids canal: In-the-ear (ITE), Behind-the-ear (BTE); out of which BTE is commonly preferred. Around 38% of BTE aids fail in their operation due to the impact generated by mishandling. Drop test measures the impact and fragility of the component. It particularly determines how the component performs under external the impact of the load. In the present study, drop impact numerical analysis has been carried out using ANSYS workbench explicit dynamic module for hearing aid casing. Three different polymer materials namely Acrylonitrile butadiene styrene (ABS), Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) have been used. The main purpose of the analysis is to determine the maximum deformation and critical area when it falls on the ground. Load conditions like impact velocity and height have been considered as per the IS standard IS: 11052–1984 for the flat and side drop test. It is observed that maximum deformations were observed in TPU as compared to PLA and ABS irrespective of velocity. In addition, contact force was observed maximum in PLA and minimum in ABS irrespective of velocity which leads to minimum internal energy for PLA. TPU and ABS could be the second choice of material after PLA for the hearing aid casing.
... Reference [2] proved the role of rigidity of the housing in determining the impact tolerance of a cellular phone and indicated that the thin-walled clamshell structure may not have sufficient rigidity to withstand impact induced loads. Some experiments on portable electronic products were conducted from different impact orientations and drop heights using drop tester and verified the impact orientation for various impact orientations PDAs by using a high-speed camera [3,4]. It is concluded that horizontal drop orientations generally give the largest impact responses and impact responses will differ for various products with different dimensions and material compositions. ...
Finite element analysis (FEA) provides numerical modeling and testing methods of stress analysis for products. The time of products development cycle can be shorten and the cost for products physical testing can be reduced with FEA. Drop test is one of the important tools uses for the impact behaviour study of cell phones, which identifies weak design points during the impact behaviour of cell phone. With the development of technology and growing of people’s demand, the screen of cell phone is getting bigger and bigger. Full-screen smartphones have become a trend. It is necessary that modeling and analyzing for full-screen smartphones are considered. This study conducts free-drop simulation and analysis on full-screen smartphones based on ABAQUS/CAE.
Packaging reliability and materials failure mechanisms in memory device packaging are very important topics in semiconductor manufacturing. Reliability engineering is a fundamental part of all good electrical and mechanical engineering product designs. In this chapter, the concept of reliability, some backend packaging reliability models and first-level, second level wearout reliability of memory packaging are discussed. Key literature reviews of interconnect materials (bonding wires, solder alloys, solder bumping), mitigation strategies of prevention of those associated wearout failure modes are revealed in this chapter. The reliability of lead-free solder joints such as reliability testing and data analyses, design for reliability, and failure analyses of lead-free solder joints will be discussed in this chapter. First ball bond wearout reliability, solder bump reliability, solder joint reliability included board level drop and bending reliability are presented. At the end of this chapter, summary and key recommendation of future works have been provided for better clarity and reference purposes.
Owing to the complex stress condition of the on-board devices in a mobile phone under drop impact condition, high test cost and long validation period are usually spent on product-level drop test for product design. Most of the standardized test protocols including the JEDEC standard for handheld electronic products are essentially based on board level tests, not taking into account the interaction between the PCB and other internal components, so the accurate experimental validation of product-level drop reliability remains time-consuming. This paper established a finite element model of a whole mobile phone for the simulation of its product-level drop tests. By conducting simulation of 6-side and 4-corner drop postures, it is found that the risk of overstress failure of the critical large chips and solder joints on the printed circuit board (PCB) are relatively higher in the case of back drop and front drop. The bending of the printed circuit board (PCB) and the collision between the shielding frame and the front frame of the mobile phone are the decisive factors that bring the overstress failure risk of the chip and solder joint. Finally, a series of product-level drop tests were conducted and compared with the simulations, with a variance of stress value within 20%, which proves that the simulation model could provide useful insights for the reliability design and validation phase during the development of new products.
A Manufatura Aditiva (Additive Manufacturing– AM), contribui para o design de produtos ao materializar ideias e projetos, se caracterizando como uma ferramenta importante no processo criativo. Nesse sentido, este artigo discute a influência da utilização da AM no processo de design de embalagens, sendo descritos os momentos nos quais foram tomadas ações para a concretização das ideias e como a AM contribuiu para o refinamento da embalagem. Para tal, a AM foi aplicada no projeto de redesign das embalagens de Memórias de Resultado (MRs), que são dispositivos que armazenam informações para o funcionamento das urnas eletrônicas. A pesquisa é de natureza aplicada, objetivo exploratório e teve como procedimento um estudo de caso. A AM foi incorporada como uma ferramenta dentro de uma metodologia específica para o design de embalagens, o Guia de Orientação para o Desenvolvimento de Embalagens (GODE). O uso da tecnologia perpassou diversas etapas do processo de design, com a construção de modelos (representações tridimensionais) específicos para melhor compreensão e análise das especificações. Foram incorporadas ainda técnicas para obtenção de auxílio de profissionais e usuários para avaliação a partir das peças desenvolvidas por AM, como a técnica Delphi e a ferramenta Thinking Out Loud. A AM demonstrou a eficácia das configurações da embalagem de uma forma que a descrição verbal ou a imagem bidimensional seria incapaz de comunicar. Auxiliou ainda na melhor compreensão do projeto pela equipe de design e por indivíduos externo ao grupo de projetação, contribuindo para as discussões de melhorias de forma dinâmica e contínua. Os testes com os protótipos geraram feedbacks que resultaram em refinamentos, como a ampliação das medidas da área de acondicionamento para que a remoção da MR não demandasse do usuário força maior que o ideal. Em suma, pode-se afirmar que a AM contribuiu para o êxito do projeto da embalagem, tendo auxiliado na checagem das proposições, numa maior aproximação com os usuários finais, na obtenção de maior precisão durante o processo de design, na incorporação de melhorias de usabilidade, e na identificação de fragilidades estruturais, alcançando maior proximidade das configurações da embalagem final antes da produção.
Since drop-impact is the most frequent cause of failure of mobile devices and the display is the major channel for users to interact with mobile devices, the reliability of the display module by drop-impact is one of the most important concerns for both manufacturers and customers. In this paper, we propose- a drop-impact reliability assessment method for the mobile display module using a statistical modeling approach. First, the general likelihood functions that consider various censored data are proposed to obtain accurate estimates. Second, under the constraints of the test budget and the sample size, the optimization problem for minimizing the mean squared error of the target of interest with the decision variables was proposed. The proposed method was applied to the real application example to determine the most reliable mobile display module design.
Dropping a tablet (or mobile phone) can be extremely costly, as loss of functionality, visible body damage, screen delamination and failure are all too familiar outcomes. This paper discusses the analysis led design of a novel passive protection concept, capable of isolating a device from the primary impact, and is also insensitive to impact angle and device dependent features.
A high fidelity finite element model of an iPad Air was used to develop the BLOKTM protection concept, which utilises different grades of elastomer, optimised internal castellation geometry and a high stiffness backplate. Sensitivity studies include the influence of glass properties, screen bonding and impact angle on the robustness of the numerical predictions, whereby quantitative comparisons with experimental data in terms of metal body damage (location, size) and accelerometer data were used.
Explicit finite element analysis verifies the effectiveness of decoupling the tablet from the impact loads, as resultant acceleration for unprotected versus protected was reduced by ∼76% (2152g vs 509g), and consistent with ∼74% reduction observed through testing (1723g vs 447g). For the protected tablet, simulation predicted displacements within 6%, with peak acceleration overestimated by 14%, and attributed to overestimating elastomer stiffness at full compression and its subsequent unloading.
Final validation demonstrated device independence by protecting an iPad Air 2TM (with significantly different internal structure to AirTM), against corner and short edge impacts. The concept developed resulted in a product to market with a mass of 165g (∼36% tablet mass), providing protection from a 1.8m drop onto concrete, far exceeding MIL-STD-810G requirements.
Recent work has shown that due to the multiple impacts that result during an accidental drop of a portable electronic product, the propensity for damage to the product can be significantly higher than in a single impact. When viewed in light of these findings, conventional methods for drop-testing of portable products, either constrained or free, suffer from drawbacks. In the former, the object being tested is not allowed to move naturally during impact, and in the latter, it is difficult to control the orientation of the object at impact and to instrument it. In this paper, a new method of drop-testing is introduced, that combines the advantages of the constrained and free methods, without their drawbacks. It is proposed that the object being tested be suspended onto a guided drop-table in the precise desired impact-orientation. The drop-table hits the ground first, but just before impact, the test object is released from suspension so it can move unrestrained thereafter. The main advantages of this method are that the object is free to move naturally during impact which provides for more realistic drop-testing. At the same time, the product can be instrumented reliably, the tests are repeatable, and can be automated. A simple machine built to illustrate this novel drop-testing scheme is presented. Results of drop-tests performed using this machine are compared to similar free-drops and they show good agreement.
This paper uses analysis and high-speed photography to study the impact tolerance of cellular phones. Thin-walled clamshell case construction, which is currently favored for portable products due to its size and weight advantages, may not provide sufficient rigidity to impact-induced loads, which can cause the housing to separate when dropped. A simple method for increasing case rigidity—castellation of the housing interface to prevent slipping of the case halves—that can substantially improve the product's drop tolerance is presented. Implementation of variations of this technique in existing cellular phone designs allows the phones to surpass their drop survivability requirements. In addition, it is shown that the traditional construction method for cellular phone battery packs could lead to fracturing of the battery housing in a drop due to the multiple impacts that result. The authors describe a simple remedy—immobilization of the battery cells within the housing—that dramatically improves the battery pack's drop performance.
The authorse examine the dynamic response of an element having a
shape of a rectangular plate (e.g. liquid crystal display) and packaged
in a “double box” system (e.g. a “chassis” and a
“cabinet”). The analysis is carried out, assuming that the
outer box (“cabinet”) does not rebound. The purpose of the
analysis is to evaluate the effect of the masses (weights) of the
element itself and the inner box (“chassis”), as well as the
effect of the spring constants of the cushionings, on the maximum
displacement and the maximum acceleration of the plate's support
contour. On the basis of the performed analysis, they developed
engineering guidelines for the preliminary selection of the spring
constants of the cushionings, so that not to compromise the dynamic
stability of the package (e.g. to keep the induced displacements and
accelerations at a sufficiently low level). They show that this
stability can be ensured by designing the package in such a way that the
lower natural frequency of vibrations of the two-degree-of-freedom
dynamic system in question (plate/chassis assembly) differs considerably
from its higher frequency
The ability to predict and possibly minimize the adverse
consequences of dynamic loading on electronic equipment is especially
important for portable electronic products, both because they can be
easily dropped and because the minimum displacement (stopping distance)
in such products, when subjected to shock loads, has to be made very
short. This leads to high accelerations and, as a consequence of that,
to elevated dynamic stresses, and can possibly result in failures of
vulnerable elements. In this analysis, we examine the dynamic response
of an element having a shape of a rectangular plate (e.g., liquid
crystal display), and packaged in a “double box” system,
(e.g., a chassis and a cabinet). The analysis is carried out, assuming
that the outer box (cabinet) does not rebound. The purpose of the
analysis is to evaluate the effect of the masses (weights) of the
element itself and the inner box (chassis), as wed as the effect of the
spring constants of the cushionings, on the maximum displacement and the
maximum acceleration of the plate's support contour. On the basis of the
performed analysis, we developed engineering guidelines for the
preliminary selection of the spring constants of the cushionings, so
that not to compromise the dynamic stability of the package, e.g., to
keep the induced displacements and accelerations at a sufficiently low
level. We show that this stability can be ensured by designing the
package in such a way that the lower natural frequency of vibrations of
the two-degree-of-freedom dynamic system in question (plate/chassis
assembly) differs considerably from its higher frequency. For the given
masses of the plate element and the inner box (chassis), this can be
achieved by making the inner cushioning (gasket) substantially stiffer
than the outer one (grommet). We show also that the strength of the
plate element can be improved, if it is made thick enough and is clamped
by the support contour. Finally, we demonstrate that a probabilistic
approach can be successfully applied to design a package with a low
probability of failure