Effective Mitigation of Shock Loads in Embedded Electronic Packaging Using Bilayered Potting Materials

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
S. A. Meguid ◽  
Chen Zhuo ◽  
Fan Yang

Shock loads which are characterized by high intensity, short duration, and vibration at varied frequencies can lead to the failure of embedded electronics typically used to operate/control numerous devices. Failure of electronics renders these devices ineffective, since they cannot carry out their intended function. It is therefore the objective of this work to determine the behavior of a typical electronic board assembly subject to severe shock loads and the means to protect the electronics. Specifically, three aspects of the work were considered using 3D finite element (FE) simulations in supercomputer environment. The first was concerned with the dynamic behavior of selected electronic devices subject to shock loads. The second with the ability of different potting materials to attenuate the considered shock loads. The third was with the use of a new bilayer potting configurations to effectively attenuate the shock load and vibration of the electronic board. The shock loads were delivered to the Joint Electron Device Engineering Council (JEDEC) standard board using simulated drop impact test. The effectiveness of different protective potting designs to attenuate the effect of shock loads was determined by considering the two key factors of electronics reliability: the stress in the interconnection and deformation of the printed circuit board. Our results reveal the remarkable effectiveness of the bilayer potting approach over the commonly adopted single potting attenuation strategy.

1992 ◽  
Vol 59 (2S) ◽  
pp. S253-S259 ◽  
Author(s):  
E. Suhir

Treating a printed circuit board (PCB) as a thin flexible rectangular plate, we evaluate its dynamic response to periodic shock loads applied to the support contour. The effect of the load periodicity on the amplitudes, accelerations, and stresses is analyzed for transient and steady-state damped linear vibrations, as well as for steady-state undamped nonlinear vibrations. It is shown that the transient nonresonant linear response can exceed the steady-state response by up to two times, and that the linear approach can be misleading in the case of a nondeformable support contour and intense loading. The obtained results can be of help when evaluating the accelerations, experienced by surface mounted electronic components and devices, and the dynamic stresses in a PCB of the given type, dimensions, and support conditions.


1992 ◽  
Vol 114 (4) ◽  
pp. 368-377 ◽  
Author(s):  
E. Suhir

We evaluate the nonlinear dynamic response of a flexible printed circuit board (PCB) to the following two types of shock loads acting on its support contour: 1) suddenly applied constant acceleration and 2) periodic instantaneous impacts. The purpose of the analysis is to determine the maximum accelerations experienced by the electronic components and devices surface mounted on the board. We show that when the support contour is immovable (nondeformable) and the deflections are large, it is important to account for the nonlinear effects. These are due to the in-plane (“membrane”) forces in the PCB and can possibly result in substantially higher accelerations than those predicted by a linear theory. The obtained formulas are easy-to-use and enable one to evaluate the maximum displacements (amplitudes), velocities, and accelerations of the surface-mounted devices, as well as the maximum dynamic stresses in the board. These formulas can be helpful when choosing the appropriate PCB type and dimensions, and the most rational lay-out of the components on the board.


2012 ◽  
Vol 132 (6) ◽  
pp. 404-410 ◽  
Author(s):  
Kenichi Nakayama ◽  
Kenichi Kagoshima ◽  
Shigeki Takeda

2014 ◽  
Vol 5 (1) ◽  
pp. 737-741
Author(s):  
Alejandro Dueñas Jiménez ◽  
Francisco Jiménez Hernández

Because of the high volume of processing, transmission, and information storage, electronic systems presently requires faster clock speeds tosynchronizethe integrated circuits. Presently the “speeds” on the connections of a printed circuit board (PCB) are in the order of the GHz. At these frequencies the behavior of the interconnects are more like that of a transmission line, and hence distortion, delay, and phase shift- effects caused by phenomena like cross talk, ringing and over shot are present and may be undesirable for the performance of a circuit or system.Some of these phrases were extracted from the chapter eight of book “2-D Electromagnetic Simulation of Passive Microstrip Circuits” from the corresponding author of this paper.


Author(s):  
Prabjit Singh ◽  
Ying Yu ◽  
Robert E. Davis

Abstract A land-grid array connector, electrically connecting an array of plated contact pads on a ceramic substrate chip carrier to plated contact pads on a printed circuit board (PCB), failed in a year after assembly due to time-delayed fracture of multiple C-shaped spring connectors. The land-grid-array connectors analyzed had arrays of connectors consisting of gold on nickel plated Be-Cu C-shaped springs in compression that made electrical connections between the pads on the ceramic substrates and the PCBs. Metallography, fractography and surface analyses revealed the root cause of the C-spring connector fracture to be plating solutions trapped in deep grain boundary grooves etched into the C-spring connectors during the pre-plating cleaning operation. The stress necessary for the stress corrosion cracking mechanism was provided by the C-spring connectors, in the land-grid array, being compressed between the ceramic substrate and the printed circuit board.


Author(s):  
William Ng ◽  
Kevin Weaver ◽  
Zachary Gemmill ◽  
Herve Deslandes ◽  
Rudolf Schlangen

Abstract This paper demonstrates the use of a real time lock-in thermography (LIT) system to non-destructively characterize thermal events prior to the failing of an integrated circuit (IC) device. A case study using a packaged IC mounted on printed circuit board (PCB) is presented. The result validated the failing model by observing the thermal signature on the package. Subsequent analysis from the backside of the IC identified a hot spot in internal circuitry sensitive to varying value of external discrete component (inductor) on PCB.


Author(s):  
Jun-Xian Fu ◽  
Shukri Souri ◽  
James S. Harris

Abstract Temperature and humidity dependent reliability analysis was performed based on a case study involving an indicator printed-circuit board with surface-mounted multiple-die red, green and blue light-emitting diode chips. Reported intermittent failures were investigated and the root cause was attributed to a non-optimized reflow process that resulted in micro-cracks and delaminations within the molding resin of the chips.


Author(s):  
Norman J. Armendariz ◽  
Prawin Paulraj

Abstract The European Union is banning the use of Pb in electronic products starting July 1st, 2006. Printed circuit board assemblies or “motherboards” require that planned CPU sockets and BGA chipsets use lead-free solder ball compositions at the second level interconnections (SLI) to attach to a printed circuit board (PCB) and survive various assembly and reliability test conditions for end-use deployment. Intel is pro-actively preparing for this anticipated Pb ban, by evaluating a new lead free (LF) solder alloy in the ternary Tin- Silver-Copper (Sn4.0Ag0.5Cu) system and developing higher temperature board assembly processes. This will be pursued with a focus on achieving the lowest process temperature required to avoid deleterious higher temperature effects and still achieve a metallurgically compatible solder joint. One primary factor is the elevated peak reflow temperature required for surface mount technology (SMT) LF assembly, which is approximately 250 °C compared to present eutectic tin/lead (Sn37Pb) reflow temperatures of around 220 °C. In addition, extended SMT time-above-liquidus (TAL) and subsequent cooling rates are also a concern not only for the critical BGA chipsets and CPU BGA sockets but to other components similarly attached to the same PCB substrate. PCBs used were conventional FR-4 substrates with organic solder preservative on the copper pads and mechanical daisychanged FCBGA components with direct immersion gold surface finish on their copper pads. However, a materials analysis method and approach is also required to characterize and evaluate the effect of low peak temperature LF SMT processing on the PBA SLI to identify the absolute limits or “cliffs” and determine if the minimum processing temperature and TAL could be further lowered. The SLI system is characterized using various microanalytical techniques, such as, conventional optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and microhardness testing. In addition, the SLI is further characterized using macroanalytical techniques such as dye penetrant testing (DPT) with controlled tensile testing for mechanical strength in addition to disbond and crack area mapping to complete the analysis.


Author(s):  
O. Crépel ◽  
Y. Bouttement ◽  
P. Descamps ◽  
C. Goupil ◽  
P. Perdu ◽  
...  

Abstract We developed a system and a method to characterize the magnetic field induced by circuit board and electronic component, especially integrated inductor, with magnetic sensors. The different magnetic sensors are presented and several applications using this method are discussed. Particularly, in several semiconductor applications (e.g. Mobile phone), active dies are integrated with passive components. To minimize magnetic disturbance, arbitrary margin distances are used. We present a system to characterize precisely the magnetic emission to insure that the margin is sufficient and to reduce the size of the printed circuit board.


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