Ceramic Ball Grid Array Package Research Articles

Numerical and Experimental Investigations of the Thermal Fatigue Lifetime of CBGA Packages

A thermal fatigue lifetime prediction model of ceramic ball grid array (CBGA) packages is proposed based on the Darveaux model. A finite element model of the CBGA packages is established, and the Anand model is used to describe the viscoplasticity of the CBGA solder. The average viscoplastic strain energy density increment ΔWave of the CBGA packages is obtained using a finite element simulation, and the influence of different structural parameters on the ΔWave is analyzed. A simplified analytical model of the ΔWave is established using the simulation data. The thermal fatigue lifetime of CBGA packages is obtained from a thermal cycling test. The Darveaux lifetime prediction model is modified based on the thermal fatigue lifetime obtained from the experiment and the corresponding ΔWave. A validation test is conducted to verify the accuracy of the thermal fatigue lifetime prediction model of the CBGA packages. This proposed model can be used in engineering to evaluate the lifetime of CBGA packages.

Influence of ceramic substrate quality on CBGA assembly reliability

The highly air-sealed ceramic ball grid array (CBGA) package is more and more popular in the aerospace and other military industries, the quality of its ceramic substrate can largely determine the CBGA package reliability and further product performance. Thus, two kinds of high temperature co-fired ceramic (HTCC) substrates from A and B suppliers were employed to assess different CBGA assembly performances in this work. The results were found that the pads of A and B substrates owned similar morphology feature and mean size. After re-balling process, comparing to that of B substrate, the mean deviation from coplanarity of A substrate was higher, but the shear strength of solder balls on A substrate was better and more stable. Through analyzing shear fracture faces, the dimples were discovered and ductile fracture mode was verified. Additionally, the microstructure of CBGA package was observed after soldering process, the metallurgical reactions at solder joints occurred and the interfacial intermetallic compound (IMC) layers formed. When 100 cycles test from −55 to 85 °C finished, the metallographic analysis was obtained that the solder joint in the corner of CBGA package produced deformation and microcracks due to high thermal stress, the microcrack result was better with the usage of A substrate. The series of detection methods and means might provide the effective help for CBGA engineering application.

Influence of Y2O3 Addition on Crystallization, Thermal, Mechanical, and Electrical Properties of BaO-Al2O3-B2O3-SiO2 Glass–Ceramic for Ceramic Ball Grid Array Package

Y2O3 addition has a significant influence on the crystallization, thermal, mechanical, and electrical properties of BaO-Al2O3 -B2O3 -SiO2 (BABS) glass–ceramics. Semi-quantitative calculation based on x-ray diffraction demonstrated that with increasing Y2O3 content, both the crystallinity and the phase content of cristobalite gradually decreased. It is effective for the additive Y2O3 to inhibit the formation of cristobalite phase with a large coefficient of thermal expansion value. The flexural strength and the Young’s modulus, thus, are remarkably increased from 140 MPa to 200 MPa and 56.5 GPa to 63.7 GPa, respectively. Also, the sintering kinetics of BABS glass–ceramics with various Y2O3 were investigated using the isothermal sintering shrinkage curve at different sintering temperatures. The sintering activation energy Q sharply decreased from 99.8 kJ/mol to 81.5 kJ/mol when 0.2% Y2O3 was added, which indicated that a small amount of Y2O3 could effectively promote the sintering procedure of BABS glass–ceramics.

Shear strengths of CBGA/PBGA solder ball joints with lead-free solder pastes

The present study is carried out to characterise the ball shear strengths of ceramic ball grid array (CBGA) and plastic ball grid array (PBGA) packages with lead-free solder pastes. Three commercially available Sn/Ag/Cu (SAC) solder pastes such as Sn 96.5/Ag3.0/Cu0.5 and 95.5/Ag3.8/Cu0.7 with a no-clean flux are employed. The effects of temperature profiles during reflow on the strength of solder joints are studied. Their printing abilities are also observed. Of particular concern for ceramic ball grid array packages is the interaction between 90/10 Pb/Sn compound solder balls and SAC solder pastes. The composition of the solder paste region between the I/O pad and the solder ball is analysed using the energy dispersive X-ray (EDX) machine.

Norris–Landzberg Acceleration Factors and Goldmann Constants for SAC305 Lead-Free Electronics

Goldmann constants and Norris–Landzberg acceleration factors for SAC305 lead-free solders have been developed based on principal component regression models (PCR) for reliability prediction and part selection of area-array packaging architectures under thermo-mechanical loads. Models have been developed in conjunction with stepwise regression methods for identification of the main effects. Package architectures studied include ball-grid array (BGA) packages mounted on copper-core and no-core printed circuit assemblies in harsh environments. The models have been developed based on thermomechanical reliability data acquired on copper-core and no-core assemblies in four different thermal cycling conditions. Packages with Sn3Ag0.5Cu solder alloy interconnects have been examined. The models have been developed based on perturbation of accelerated test thermomechanical failure data. Data have been gathered on nine different thermal cycle conditions with SAC305 alloys. The thermal cycle conditions differ in temperature range, dwell times, maximum temperature, and minimum temperature to enable development of constants needed for the life prediction and assessment of acceleration factors. Goldmann constants and the Norris–Landzberg acceleration factors have been benchmarked against previously published values. In addition, model predictions have been validated against validation datasets which have not been used for model development. Convergence of statistical models with experimental data has been demonstrated using a single factor design of experimental study for individual factors including temperature cycle magnitude, relative coefficient of thermal expansion, and diagonal length of the chip. The predicted and measured acceleration factors have also been computed and correlated. Good correlations have been achieved for parameters examined. Previously, the feasibility of using multiple linear regression models for reliability prediction has been demonstrated for flex-substrate BGA packages (Lall et al., 2004, “Thermal Reliability Considerations for Deployment of Area Array Packages in Harsh Environments,” Proceedings of the ITherm 2004, 9th Intersociety Conference on Thermal and Thermo-mechanical Phenomena, Las Vegas, Nevada, Jun. 1–4, pp. 259–267, Lall et al., 2005, “Thermal Reliability Considerations for Deployment of Area Array Packages in Harsh Environments,” IEEE Trans. Compon. Packag. Technol., 28(3), pp. 457–466., flip-chip packages (Lall et al., 2005, “Decision-Support Models for Thermo-Mechanical Reliability of Leadfree Flip-Chip Electronics in Extreme Environments,” Proceedings of the 55th IEEE Electronic Components and Technology Conference, Orlando, FL, Jun. 1–3, pp. 127–136) and ceramic BGA packages (Lall et al., 2007, “Thermo-Mechanical Reliability Based Part Selection Models for Addressing Part Obsolescence in CBGA, CCGA, FLEXBGA, and Flip-Chip Packages,” ASME InterPACK Conference, Vancouver, British Columbia, Canada, Jul. 8–12, Paper No. IPACK2007-33832, pp. 1–18). The presented methodology is valuable in the development of fatigue damage constants for the application specific accelerated test datasets and provides a method to develop institutional learning based on prior accelerated test data.

A COMPACT PACKAGE WITH INTEGRATED PATCH ANTENNA FOR SINGLE-CHIP 60-GHz RADIOS

This paper presents the development of a standard surface mountable ceramic ball grid array (CBGA) package with an integrated patch antenna in low temperature coflred ceramic (LTCC) technology for emerging single-chip 60-GHz radios. It addresses the challenges of low-loss wire bonding interconnections required between the chip and the antenna as well as the package to allow e-cient utilization of available space for miniaturization. The compact package of size 12:5£8£1:265mm 3 achieves good electrical performance. For instance, the package part exhibits insertion loss 22dB, and attenuation rate < 0:2dB/cm below 5GHz; while the antenna part demonstrates 8-GHz impedance bandwidth and 8 § 2dBi peak realized gain at 60GHz. Simulated and measured results are compared. They agree reasonably well, indicating the feasibility of designing and manufacturing the integrated antenna package in LTCC for millimeter- wave applications.

The Effect of Underfill Fillet Geometry to Die Edge Stress for Flip Chip Packaging

The possible source of die edge cracking for Flip Chip Ceramic Ball Grid Array (FC-CBGA) package due to thermal cycling have been investigated in this study. Finite Element Analysis (FEA) models were used to analyze the effect of underfill fillet geometry on interfacial stresses between die edge and the underfill fillet. The input parameters of FC-CBGA from industry was used for simulation and the properties of commercial underfill were extracted by using Thermal Mechanical Analyzer (TMA) and Dynamic Mechanical Analyzer (DMA). Die stress distribution for different fillet height were generated to depict variation of stress due thermal loading. The variation of tensile stress due different fillet height and width were discussed for parameters optimization.

Ball Grid Array Lead-Free Solder Joint Strength under Monotonic Flexural Load

Abstract This work compared ball grid array (BGA) lead-free solder joint strengths to eutectic lead (Sn–Pb) solder joint strengths under monotonic bend load at room temperature. Flexural test methodologies for evaluating solder joint strength are presented. Various effects on solder joint strength were summarized systematically into three parts. The first part focused on the effect of solder joint geometries. BGAs with Sn-4Ag-0.5Cu and 63Sn-37Pb solders were tested, respectively. The effects of package side solder resist opening sizes, solder ball diameters, and board side metal defined/solder mask defined pads were investigated with 0.062 in printed circuit board (PCB). The results showed that the solder joint strength of Sn–Ag–Cu solder is lower than that of the traditional Sn–Pb solder under room temperature board flexural load and similar dynamic load. The second part investigated the effects of type of package (plastic BGA (PBGA) versus ceramic BGA (CBGA)), board thickness (0.093 in. versus 0.135 in.), and the effect of rework (reworked versus non-reworked) with Sn-3.9Ag-0.7Cu and 63Sn-37Pb solders. The joint strength of Sn–Ag–Cu solder is consistently lower than that of eutectic Sn–Pb solder for both board thicknesses, both CBGA and PBGA packages, and both non-reworked and reworked packages. The third part explored the feasibility of alternative low temperature solders as board-level interconnects. In addition to the traditional 63Sn-37Pb solder and the lead-free Sn-4Ag-0.5Cu solder, four other lead-free solders (Sn-52In, Sn-58Bi, Sn-57Bi-1Ag, and Sn-9Zn-0.006Al) were tested with 0.044 in PCB. Effects of board surface finishes with immersion silver (ImAg) or organic solderability preservatives, and pads with via-in-pad (VIP) or non-VIP pads were investigated. Test results showed that most of the BGAs with non-VIP pads performed better than those with VIP pads, except Sn–In solder with ImAg surface finish. The Sn–In solder showed the lowest performance, while Sn–Bi and Sn–Bi–Ag solder compositions showed better performance. Sn–Zn–Al solder joint strength performs better than others.

An Optimization of Two-Steps Curing Profile to Eliminate Voids Formation in Underfill Epoxy for Hi-CTE Flip Chip Packaging

Underfilling is the preferred process to reduce the impact of the thermal stress that results from the mismatch in the coefficient of thermal expansion (CTE) between the silicon chip and the substrate in Flip Chip Packaging. Voids formation in underfill is considered as failure in flip chip manufacturing process. Voids formation possibly caused by several factors such as poor soldering and flux residue during die attach process, voids entrapment due moisture contamination, dispense pattern process and setting up the curing process. This paper presents the optimization of two steps curing profile in order to reduce voids formation in underfill for Hi-CTE Flip Chip Ceramic Ball Grid Array Package (FC-CBGA). A C-Mode Scanning Aqoustic Microscopy (C-SAM) was used to scan the total count of voids after curing process. Statistic analysis was conducted to analyze the suitable curing profile in order to minimize or eliminate the voids formation. It was shown that the two steps curing profile provided solution for void elimination.

Comparative Study of Different Underfill Material on Flip Chip Ceramic Ball Grid Array Based on Accelerated Thermal Cycling

Problem statement: This study mainly to study the effect of several commercial underfill materials to the reliability of HiCTE Flip Chip Ceramic Ball Grid Array (FC-CBGA) package due to Accelerated Thermal Cycling (ATC) effect. Approach: The warpage condition of package, die back stress, interfacial die shear stress, and solder bump fatigue for different commercial underfills were assessed and compared via a commercial Finite Element Analysis (FEA) under JEDEC Standard of ATC. The thermo-mechanical properties of underfills for simulation were obtained by using Thermal Mechanical Analyzer (TMA) and Dynamic Mechanical Analyzer (DMA). The actual package of HiCTE FC-CBGA were assembled with those underfill materials and underwent ATC to be compared with FEA result. Results: The results from FEA and experimental were discussed to characterize the performance of each underfill material. The results of this study indicate that the underfill materials investigated, those with a glass transition temperature (Tg) and a Young’s modulus of approximately above 105°C and 8-9 GPa, respectively, were appropriate for HiCTE FC-CBGA with high lead solder bumps. Conclusion: The result from FEA analysis and ATC reliability test found that the underfill materials with high and medium low Young’s modulus has high reliability in FC-CBGA package.

Antenna-in-Package Design for Wirebond Interconnection to Highly Integrated 60-GHz Radios

This paper first presents a quasi-cavity-backed, guard-ring-directed, substrate-material-modulated slot antenna. The antenna, intended for use in highly integrated 60-GHz radios, is deliberately designed to exhibit capacitive input impedance to suit low-cost wire-bonding packaging and assembly technique. The antenna implemented in a thin cavity-down ceramic ball grid array (CBGA) package in low-temperature cofired ceramic (LTCC) technology has achieved an acceptable impedance bandwidth from 59 to 65 GHz with an estimated efficiency of 94%. At millimeter-wave (mm-wave) frequency 60 GHz, one of key challenges is how to realize low-loss interconnection between a radio chip and an antenna using wire-bonding technique. This paper then addresses this issue in the framework of antenna-in-package (AiP) design at 60 GHz and proposes a new solution to the challenge. Detailed wirebond design method and results are given. A major concern with AiP is the risk of the antenna coupling to the radio chip. This paper also evaluates this unwanted coupling and shows that the coupling from the in-package antenna to the on-chip inductor is lower than 30 dB for the worst case. These results clearly demonstrate the feasibility and promise of the elegant AiP technology for emerging high-speed short-range 60-GHz wireless communications.

Integration of Grid Array Antenna in Chip Package for Highly Integrated 60-GHz Radios

A grid array antenna integrated in a thin cavity-down ceramic ball grid array (CBGA) package in low-temperature cofired ceramic (LTCC) technology is reported. The grid array antenna, intended for use in highly integrated 60-GHz radios, has achieved good matching (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | ¿ -10 dB) and directional patterns from 57 to 64 GHz as well as high gain with the peak value of 13.5 dBi at 60 GHz.

Comparative Studies on Solder Joint Reliability of Plastic and Ceramic Ball Grid Array Packages of the Same Form Factor Under Power and Accelerated Thermal Cycling

Experimental and numerical techniques are employed to assess the thermomechanical behavior of ceramic and organic flip chip packages under power cycling (PC) and accelerated thermal cycling (ATC). In PC, nonuniform temperature distribution and different coefficients of thermal expansion of each component make the package deform differently compared to the case of ATC. Traditionally, reliability assessment is conducted by ATC because ATC is believed to have a more severe thermal loading condition compared to PC, which is similar to the actual field condition. In this work, the comparative study of PC and ATC was conducted for the reliability of board level interconnects. The comparison was made using both ceramic and organic flip chip ball grid array packages. Moiré interferometry was adopted for the experimental stress analysis. In PC simulation, computational fluid dynamics analysis and finite element analysis are performed. The assembly deformations in numerical simulation are compared with those obtained by Moiré images. It is confirmed that for a certain organic package PC can be a more severe condition that causes solder interconnects to fail earlier than in ATC while the ceramic package fails earlier in ATC always.

Integration of Yagi Antenna in LTCC Package for Differential 60-GHz Radio

A Yagi antenna implemented in a thin cavity-down ceramic ball grid array package in low temperature cofired ceramic (LTCC) technology is reported. The antenna, intended for use in highly integrated differential 60-GHz radios, has achieved a 10-dB impedance bandwidth of 2.3 GHz from 60.6 to 62.9 GHz and a peak gain of 6 dBi at 62 GHz.

Using Carrier Fringes to Study the High Temperature Deformation Behavior of a BGA Package Under Extended Dwell Times

There is a compelling need to experimentally understand solder joint deformation behavior at high temperatures over an extended period of time. Accordingly, the deformation behavior of solder joints in a Ceramic Ball Grid Array (CBGA) package mounted on an organic FR4 board under extended dwell time at a high temperature has been studied using laser moire interferometry. The warpage and the in-plane horizontal deformation of the ceramic substrate and the organic board as a function of time were determined. The variation of the normal strains and shear strains in the solder joints with time were also investigated. It was found that increased sensitivity was necessary to accurately determine the strains in the small sized solder joints. A new method utilizing carrier fringes to increase the sensitivity of the moire interferometry system is proposed and has been used to determine the strains in the small sized solder joints. Increased sensitivity can be obtained merely by changing the incident angle of the laser light on the surface of the specimen, thereby making it unnecessary to use expensive phase shifting apparatus with the traditional laser moire system.

Integration of slot antenna in LTCC package for 60 GHz radios

A slot antenna implemented in a thin cavity-down ceramic ball grid array (CBGA) package in low-temperature cofired ceramic (LTCC) technology is reported. The antenna, intended for use in highly integrated 60 GHz radios, has achieved an acceptable impedance bandwidth from 59 to 65 GHz and a peak gain of 11 dBi at 61.5 GHz with an estimated efficiency of 94%.

Thermal analysis of a flip chip ceramic ball grid array (CBGA) package

The function of an electronic cooling package is to dissipate heat to ensure proper operation and reliability. The flip chip ball grid array package is probably the most suitable package for high-level thermal performance applications. A high thermal performance flip chip ceramic ball grid array (FC-CBGA) package with an aluminum silicon carbide (AlSiC) lid and one without lid were evaluated using the computational fluid dynamics (CFD) technique. This paper compares the thermal performance of a 35 × 35 mm FC-CBGA package with three different die sizes of 5 × 5 mm, 15 × 15 mm and 20 × 20 mm. The performance of a lid fitted with different heat sinks was investigated in standard JEDEC defined natural and in forced convection environments. Thermal measurements were performed using a functional application specific integrated circuit (ASIC) chip, in compliance with the JEDEC standards. Excellent agreement was found between the numerical results and the measured data. Improved thermal performance was observed with a lidded package as compared to the unlidded one. However, no significant improvement was observed between lidded and unlidded packages when fitted with a heat sink subjected to forced convection. This paper also discusses the package thermal budget estimate with and without heat sinks. Printed circuit board and package top surface temperature patterns were measured using an infrared thermal camera. The usefulness of the thermal characterization parameter is demonstrated in system level applications. Parametric studies were carried out to understand the effect of die size, radiation effect, gird size variations and airflow rate on die junction temperature and package thermal resistance. This study also incorporates the effects of substrate, lid, die and PCB temperatures for different die sizes in natural and forced convection environments.

Universal fatigue life prediction equation for ceramic ball grid array (CBGA) packages

A traditional approach to predicting solder joint fatigue life involves finite-element simulations in combination with experimental data to develop a Coffin–Manson type predictive equation. The finite-element simulations often require good understanding of finite-element modeling, physics-based failure models, and time-, temperature-, and direction-dependent material constitutive behavior. Also, such simulations are computationally expensive and time-consuming. Microelectronic package designers often do not have the time and the expertise to perform such simulations. The traditional solder joint fatigue predictive equations fall short of ideal because: (1) they are not applicable to others due to numerical modeling issues, (2) they require a mature understanding of mechanics, numerical modeling, and reliability theory, and (3) they are difficult to implement into the design process. This includes both design of an individual electronic component and selecting which type of existing component to include in an application. Therefore, this work develops universal predictive equations that are: (1) simple, quick, and accurate, (2) require only a basic understanding of reliability and mechanics, (3) require no special software; easy to implement in a spreadsheet or current reliability tools, (4) information rich in regards to design parameters, and (5) maximize available information from experimental tests and numerical models. Using experimental data and finite-element simulations as a basis, this work has developed a predictive equation for solder joint fatigue life in lead-containing ceramic ball grid array (CBGA) package. The developed equation has been validated with other experimental data with good success. Efforts are underway to develop similar equations for other packages and Pb-free CBGAs.

An Expedient Experimental Technique for the Determination of Thermal Cycling Fatigue Life for BGA Package Solder Balls

Although accelerated thermal cycling has been widely used in electronics industry to qualify electronic packages, efforts to reduce the time and cost associated with such qualification techniques are continuously being sought. This paper outlines a laser-moiré based experimental technique to quickly assess the thermal cycling reliability of microelectronic packages. Unlike accelerated thermal cycling that takes several months to complete, the proposed technique takes one to two weeks to complete and does not suffer from various modeling assumptions used in finite-element simulations. The developed technique has been used to determine the thermomechanical reliability of organic and ceramic ball grid array packages, and it is shown that the number of cycles determined by the proposed technique is comparable to the number of cycles determined through accelerated thermal cycling.

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB, S11 of -29 and -40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die