Investigation of Transfer Mold Process Effects on Semiconductor Package Warpage

2009 ◽  
Author(s):  
Jason M. Brand ◽  
Myung J. Yim ◽  
Ravi Kumar
Keyword(s):  
Solder Joint ◽  
Material Property ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Filler Concentration ◽  
Packaging System ◽  
Property Variation ◽  
Molding Compound ◽  
Fea Model ◽  
Die Attach

In recent years, Package on Package (PoP) is increasingly used for high density package solutions. Generally the top package is a stacked memory packaging system connected to a bottom logic packaging system via solder joint: this is representative of PoP configurations. To guarantee the assembly yield and reliability of the solder joint between the top package and bottom package, mechanical compliance between these two packages is crucial during package stacking. Henceforth package warpage needs to be understood and controlled to meet the assembly yield targets. The complexity of the package configuration increases by thinner package thickness, higher number of stacking dies and large package size. Controlling the warpage within the target requirement is very challenging, especially when the material behaviors of substrate, die, molding compound and die attach film are different and also changing as a function of temperature. Certainly, the material properties of key components in top PoP package plays a crucial role in warpage performance. Among various material properties, the chemical cure shrinkage, coefficient of thermal expansion and storage modulus for the molding compounds are determining factors on the temperature dependant warpage control of top PoP package. Warpage variation still exists within parts processed at the same time mainly due to slight material property variation. In this paper, the cause of the warpage variation is investigated. The main cause was found to be filler migration effect in narrow gaps with in the stacked die package during the mold process, which resulted in different filler concentration and distribution, and finally different local molding compound material property among the package unit location in the substrate strip. The findings indicate that mold pressure is not a major modulator of warpage, while filler distribution can dramatically alter the warpage behavior. FEA model results and warpage data are presented to validate the filler migration phenomena and warpage behavior impact. The findings and results provide some clues and design/process guideline for warpage control in Top PoP package, which influence the PoP assembly yield and reliability.

Effects of material property variation in composite panels

2017 ◽  
Vol 89 (2) ◽  
pp. 274-279
Author(s):  
Thomas Wright ◽  
Imran Hyder ◽  
Mitchell Daniels ◽  
David Kim ◽  
John P. Parmigiani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Property ◽  
Material Properties ◽  
Damage Model ◽  
Element Model ◽  
Maximum Load ◽  
Content Type ◽  
Property Variation ◽  
Load Carrying

Purpose The purpose of this paper is to determine which of the ten material properties of the Hashin progressive damage model significantly affect the maximum load-carrying ability of center-notched carbon fiber panels under in-plane tension and out-of-plane bending. Design/methodology/approach The approach used is to calculate the maximum load using a finite element model for a range of material property values as specified by a fraction factorial design. The finite element model used has been experimentally validated in prior work. Findings Results showed that for the laminates considered, at most three and as few as one of the ten Hashin material properties significantly affected the magnitude of the maximum load. Practical implications While the results of this paper only specifically apply to the laminates included in the study, the results suggest that, in general, only a small number of the Hashin material properties affect laminate load-carrying ability. Originality/value Knowing which properties are significant is of value in selecting materials to optimize performance and also in determining which properties need to be known to a high accuracy.

MEMS Die Warpage During Curing of Die Attach Material

2015 ◽  
Author(s):  
Hohyung Lee ◽  
Ruiyang Liu ◽  
Seungbae Park ◽  
Xiaojie Xue
Keyword(s):  
Material Properties ◽  
Residual Strain ◽  
Critical Role ◽  
Measurement Data ◽  
Curing Process ◽  
Assembly Process ◽  
Structural Elements ◽  
Mems Sensor ◽  
Fea Model ◽  
Die Attach

Microelectromechanical system (MEMS) packages are vulnerable to stresses due to its functional structure. During the assembly process of the package, stresses stemming out of CTE mismatches of the structural elements and curing of the die attach material can cause warpage of the MEMS die [1]. Even though die attach material takes relatively small volumetric portion of the package, it plays a critical role in warpage of the die due to its location and sensitivity of a MEMS sensor. Most of virgin die attach adhesives are in a state of viscous liquid and, as it is cured the material properties such as modulus and CTE change. Accordingly, residual strain is cumulated on MEMS die after curing process and signal trim process is required. Therefore, the material properties changes depending on the curing profile is valuable information for assembly process of the MEMS package. To monitor the material properties changes and shrinkage during curing process, strain and modulus of a die attach material are measured in each curing step. Also, to investigate the material property change depending on the curing profile, two different curing profiles are used. Experimental data show that die attach materials are gradually cured after each thermal cycling, which cause the increment of the modulus and glass transition temperature (Tg) with shrinkage at elevated temperature. Using the measurement data, FEA model is built to predict the warpage of the MEMS die. In the FEA model, residual strain on MEMS die is calculated by inputting material properties of die attach in each curing step. Also, die warpage of the package during the curing process is monitored using an optical profiler for the validation of the simulation results.

Effect of Material Properties and Thickness of Die Attach on Delamination of Die Attach/Die Paddle Interface in Electronic Package

2010 ◽  
Author(s):  
Chia-Lung Chang ◽  
Po-Hsien Li
Keyword(s):  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Damage Parameter ◽  
Stress And Strain ◽  
Thermal Expansion Mismatch ◽  
The Finite Element Method ◽  
Electronic Package ◽  
Die Attach ◽  
Encapsulation Process ◽  
Die Bonding

The electronic package is a multi-layered structure that is consisted of several materials. Under the temperature loadings, the interfacial stresses between layered components are generated due to the CTE (coefficient of thermal expansion) mismatch between different materials. In die bonding process, the void or defect might exist at the die attach/die paddle interface. The void cause further delamination on the interface during the encapsulation process. In this study, the finite element method is used to construct the model of electronic package with a void on the die attach/die paddle interface. The energy release rate based on J integration, which is calculated by the stress and strain around the tip of crack, is used as a damage parameter to predict the tendency of further delamination during encapsulation. Effect of material properties (Young’s modulus and CTE) and die attach thickness on delamination of die attach/die paddle interface in package during encapsulation is studied.

Correlation of Warpage Distribution With the Material Property Scattering for Warpage Range Prediction of PBGA Components

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Qiming Zhang ◽  
Jeffery C. C. Lo ◽  
S. W. Ricky Lee ◽  
Wei Xu
Keyword(s):  
Material Property ◽  
Material Properties ◽  
Printed Circuit Boards ◽  
Coefficient Of Thermal Expansion ◽  
Academic Research ◽  
Sensitivity Study ◽  
Industrial Applications ◽  
Surface Mount Technology ◽  
Surface Mount ◽  
Distribution Ranges

In recent years, due to the increased size of ball grid array (BGA) devices, the assembly of BGAs on printed circuit boards through surface mount technology has encountered unprecedented challenges from thermal warpage. The excessive warpage of BGAs in the reflow process may cause manufacture problems and even the risk of failure. Thus, it is essential to acquire warpage values and corresponding distribution ranges of BGAs before the surface mount technology process. In order to avoid assembly failure, theoretically, it is necessary to guarantee that all BGA devices meet the acceptance requirement of relevant standards. Generally, a large number of samples should be measured to obtain a relatively reliable warpage data distribution in the reflow temperature range, which makes this test quite costly and extremely time consuming. This study proposes another method to estimate the BGA warpage value and its possible corresponding range from the material property point of view. Because the mechanism of BGA warpage is related to the coefficient of thermal expansion (CTE) mismatch between the different materials, the warpage data scattering can be correlated with the scattering of material properties through finite element method (FEM) analysis. With a known mean value and range of material properties, the warpage value and corresponding distribution range can be solved. A sensitivity study is also presented in this paper. The accuracy of the proposed method is evaluated and the corresponding warpage data fluctuation range is estimated. From the comparison of the simulation and experiment results, determining the material properties could lead to a reasonable prediction of warpage in both the qualitative and quantitative sense. The proposed methodology for BGA warpage estimation can be used for academic research and industrial applications.

Warpage Analysis of FBGA (Fine Ball Grid Array) Package by the Altered EMC (Epoxy Molding Compound) Filler Contents

2006 ◽  
Vol 306-308 ◽  
pp. 625-630 ◽  
Author(s):  
Yong Tae Park ◽  
Yoo Kyoung Whang ◽  
Joon Ki Hong ◽  
Kwang Yoo Byeon
Keyword(s):  
Numerical Analysis ◽  
Material Properties ◽  
Filler Content ◽  
Coefficient Of Thermal Expansion ◽  
Ball Grid Array ◽  
Structure Design ◽  
Actual Measurement ◽  
Molding Compound ◽  
Semiconductor Packaging ◽  
Adhesive Materials

In a semiconductor packaging process, the warpage greatly has influenced the reliability of the package as well as the workability. The strip warpage in FBGA package result from the structure of constitutes and the thermal mismatch by the mechanical or thermal properties such as CTE (Coefficient of Thermal Expansion) and Modulus of EMC, substrate, chip and adhesive materials. Therefore, the optimization of material properties and the package structure design has been needed by the numerical analysis. EMC used as one of the package constituents has a decisive effect on the trend of warpage, and the filler content is dominant in the EMC property. In this research, firstly the effect of the filler contents is evaluated in the warpage of FBGA package and the numerical analysis is performed with the high temperature – material properties to deal with the warpage under the actual measurement value.

Temperature Dependence of the Mechanical Properties of GaAs Wafers

1991 ◽  
Vol 113 (4) ◽  
pp. 331-336 ◽  
Author(s):  
Jun Ming Hu ◽  
Michael Pecht
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Critical Value ◽  
Modulus Of Rupture ◽  
Gaas Wafer ◽  
Photovoltaic Conversion Efficiency ◽  
Die Attach ◽  
Different Temperatures ◽  
Fracture Assessment

GaAs is known to have superior electronic properties and greater photovoltaic conversion efficiency compared to elemental semiconductors such as silicon and germaniumn. Mechanical properties of GaAs at different temperatures are now necessary to incorporate into the design models for the GaAs die attach and substrate architecture for microelectronic packages. These properties are also required to aid in defining reliability and screening specifications. This paper presents the experiment results on various material properties of GaAs wafer over the temperature range of − 75°C to 200°C. Material properties determined from testing include the modulus of elasticity, the modulus of rupture, the critical value of stress intensity factor, and the coefficient of thermal expansion. The importance of fracture assessment in semiconductor devices is also discussed.

Spontaneous Crack Propagation Along Functionally Graded Bimaterial Interfaces

2006 ◽  
Author(s):  
Dhirendra V. Kubair ◽  
B. Bhanu-Chandar
Keyword(s):  
Crack Propagation ◽  
Material Property ◽  
Material Properties ◽  
Propagation Speed ◽  
Functionally Graded ◽  
Hardening Material ◽  
Property Variation ◽  
Material Inhomogeneity ◽  
Crack Propagation Speed ◽  
Mode 3

The effects of spatially varying the material properties on the mode-3 planar crack propagation characteristics are numerically investigated. The spectral scheme that is available for homogeneous materials is modified to account for the asymmetrically varying material properties. Crack propagation along the interface of a functionally graded bimaterial system has been simulated. A parametric study was performed by systematically varying the material inhomogeneity length scale independently in the two half-spaces. Our study indicated that softening type graded materials reduce the resistance to fracture, while a hardening material offers higher fracture resistance with increase in inhomogeneity. Only the transient phase of crack propagation speed was affected by the material property variation, irrespective of whether the material was hardening, softening or an asymmetric type. The crack always reached a quasi-steady-state velocity, which remained unaffected by the material property inhomogeneity.

Numerical and Experimental Study of Interface Delamination in Flip Chip BGA Package

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Hu Guojun ◽  
Andrew A. O. Tay ◽  
Luan Jing-En ◽  
Ma Yiyi
Keyword(s):  
Thermal Expansion ◽  
Material Properties ◽  
Flip Chip ◽  
Coefficient Of Thermal Expansion ◽  
Element Analysis ◽  
Epoxy Molding Compound ◽  
Molding Compound ◽  
Interface Delamination ◽  
Underfill Material ◽  
Die Thickness

The reliability of the flip chip package is strongly influenced by underfill, which has a much higher coefficient of thermal expansion (CTE) compared with other packaging materials and leads to large thermomechanical stresses developed during the assembly processes. Thermal expansion mismatch between different materials causes interface delamination between epoxy molding compound and silicon die as well as interface delamination between underfill and silicon die. The main objective of this study is to investigate the effects of underfill material properties, fillet height, and silicon die thickness on the interface delamination between epoxy molding compound and silicon die during a lead-free solder reflow process based on the modified virtual crack closure method. Based on finite element analysis and experiment study, it can be concluded that the energy release rates at reflow temperature are the suitable criteria for the estimation of interface delamination. Furthermore, it is found that underfill material properties (elastic modulus, CTE, and chemical cure shrinkage), fillet height, and silicon die thickness can be optimized to reduce the risk of interface delamination between epoxy molding compound and silicon die in the flip chip ball grid array package.

Predicted Bow of Plastic Packages Due to the Nonuniform Through-Thickness Distribution of Temperature

1992 ◽  
Vol 114 (3) ◽  
pp. 329-335 ◽  
Author(s):  
E. Suhir ◽  
L. T. Manzione
Keyword(s):  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Thickness Distribution ◽  
Edge Length ◽  
Nonuniform Distribution ◽  
Temperature Gradients ◽  
Molding Compound ◽  
Thermally Induced ◽  
Plastic Packages ◽  
Selection Of

Warpage of molded plastic packages becomes a more serious consideration as their size increases. In this analysis we develop an analytical stress model for the evaluation of the thermally induced bow of large plastic packages due to the nonuniform distribution of temperature in the through-thickness direction after the molding cycle. This model enables one to determine the effects of the package geometry and material properties on the induced warpage. We show that the bow of the package is proportional to the edge length squared, and is inversely proportional to the package thickness. We show also that the coefficient of thermal expansion (contraction) of the molding compound has a strong effect on the bow, while its Young’s modulus has a small effect. The performed experimental work has indicated that different procedures for handling the packages after molding result in different temperature gradients leading to different bows. The obtained results are useful in the selection of the appropriate molding compound and rational physical design of thick plastic packages, as well as in the optimization of the handling procedures after molding and post-curing.

Effects of Material Properties and Thickness of Die Attach on Warpage and Stresses of TSOP

2011 ◽  
Vol 264-265 ◽  
pp. 542-547
Author(s):  
Chia Lung Chang ◽  
P.Y. Chen ◽  
M.H. Huang
Keyword(s):  
Nonlinear Model ◽  
Material Properties ◽  
Residual Deformation ◽  
Primary Factor ◽  
Chemical Shrinkage ◽  
Process Step ◽  
Electronic Package ◽  
Molding Compound ◽  
Die Attach ◽  
Plastic Package

The assembly of plastic electronic package requires a sequence of process steps. Every process step induces thermal residual deformation and stresses on the assembled components, which cause mechanical effects on the subsequent process step. Processing model with considering the effect of chemical shrinkage on molding compound is built to simulate the package warpage and stresses in assembly. The processing model, a nonlinear model with element birth and death used to activate and deactivate the processing materials, can more realistically simulate a series of assembly processes in a plastic package. The stresses in package components are primary factor for the damage of package. The induced package stresses can cause the delamination between die/die attach interface or die attach/die pad interface. In this study, effects of material properties as well thickness of die attach on warpage and stresses of TSOP (Thin Small Outline Package) during assembly are discussed.

Sign in / Sign up

Export Citation Format

Share Document