Thermo-Mechanical Reliability of Double-Sided IGBT Assembly...

194 IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 14, NO. 1, MARCH 2014

Thermo-Mechanical Reliability of Double-SidedIGBT Assembly Bonded by Sintered Nanosilver

Yun-Hui Mei, Member, IEEE, Jiao-Yuan Lian, Xu Chen, Gang Chen, Member, IEEE,Xin Li, and Guo-Quan Lu, Member, IEEE

Abstract—Double-sided insulated gate bipolar transistor(IGBT) assemblies bonded by sintered nanosilver are fabricatedin this paper. Die-shear tests reveal that the lowest bondingstrength between the chip and the substrate of the assemblies isabout 20 MPa. Furthermore, temperature cycling tests (−40 ◦Cto 150 ◦C) indicate that the shear strength declines as thenumber of cycles increases. In addition, X-ray photographs showincreasing number and size of voids. The bonding area decreaseswith increasing number of cycles, as indicated by scanningacoustic microscopy. Finally, we study both the steady state andthe transient thermal performance of the double-sided IGBTassembly by the finite-element method using the commercial codeANSYS to better understand the superiority of the assembly inthermal management.

Index Terms—Electronic packaging, insulated gate bipolartransistor (IGBT), reliability, temperature cycling, thermal stress.

I. INTRODUCTION

NOWADAYS, the development of power semiconductortechnology is toward high power applications with high

packaging density and high reliability. At the same time, highpower and density packaging of power semiconductor devicesalso present some of the greatest thermal dissipation challengesbecause of the high loss density and interconnection require-ments. As temperature has a huge influence on the aging ofpower modules, thermal management is a critical issue concern-ing the reliability and performance of power modules [1].

Ways to increase the thermal dissipation of power semi-conductor devices include the use of new materials that havehigh thermal conductivities, and advanced cooling techniquessuch as jet impingement, spray cooling, microchannels, andmultiphase flow [2]. However, previous efforts to enhancethe thermal dissipation of power semiconductor devices were

Manuscript received May 20, 2013; revised July 7, 2013, August 6, 2013, andAugust 18, 2013; accepted August 19, 2013. Date of publication September 5,2013; date of current version March 4, 2014. This work was supported in partby the National Natural Science Foundation of China under Grant 51101112and in part by the Tianjin Municipal Natural Science Foundation under Grants13JCQNJC06600 and 13JCZDJC33600. (Corresponding author: X. Chen.)

Y.-H. Mei and X. Li are with the Tianjin Key Laboratory of Advanced Join-ing Technology, and also with the School of Materials Science and Engineering,Tianjin University, Tianjin, Tianjin 300072, China.

J.-Y. Lian, X. Chen, and G. Chen are with the School of Chemical Engineer-ing and Technology, Tianjin University, Tianjin, Tianjin 300072, China (e-mail:[email protected]).

G.-Q. Lu is with the Department of Materials Science and Engineeringand the Bradley Department of Electrical and Computer Engineering, VirginiaPolytechnic Institute and State University, Blacksburg, VA 24061 USA.

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TDMR.2013.2280668

TABLE IPROPERTIES OF SINTERED SILVER [13]

primarily driven by standard device packaging, in which the topand bottom sides of the module were devoted to electrical inter-connections and thermal management, respectively. The use ofnew materials or advanced cooling techniques is not sufficientfor the removal of heat through one side of an insulated gatebipolar transistor (IGBT) package because of the large appliedpower. As a consequence, double-sided cooling has emergedsince planar interconnection was achieved [3].

In 1999, Gillot et al. [4] proposed a double-sided coolingconcept for the first time. Other researchers studied double-sided cooling assembly and found that the static thermal resis-tance of double-sided assembly could be reduced by 40% belowthat of single-sided cooling assembly because of the additionalthermal dissipation through the top surface [5]. Double-sidedcooling has been proven to increase the power dissipation of achip and to improve module reliability by lowering the junctionoperating temperature [6].

However, the availability of semiconductors for solder re-flowing and curing anisotropic conductive film [7] from bothsides and the reliability of die-attachment afterward become themain challenges of double-sided cooling technology [8]. Thus,it is essential to study the properties of the joint in double-sidedcooling assembly. Recently, nanosilver paste has been used asan alternative lead-free die-attach material. Lu et al. [9]–[12]proposed a strategy of replacing the high mechanical pressurewith a chemical driving force by using nanoscale silver powderto lower the sintering temperature. The nanoscale silver powderhas since been made into the paste form to offer a one-to-onereplacement to solder or epoxy. The introduction of the nanosil-ver paste significantly simplifies the low-temperature joining orsintering technology and has paved the way for the widespreadadaptation of nanosilver paste by power electronics manufac-turers. Low-temperature sintered silver has superior properties,as shown in Table I [13]. Previous studies on nanosilver pastewere mainly focused on the sintering process [14]–[16] andthe evaluation of mechanical properties [17], [18] and relia-bility [19]–[21]. Chen et al. discussed the sintering processof nanosilver paste and mechanical properties such as tensilebehavior [22], ratcheting behavior [23], and high-temperaturecreep [24] of the sintered nanosilver. They also studied thethermal performance of the sintered nanosilver for power

1530-4388 © 2013 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

MEI et al.: RELIABILITY OF IGBT ASSEMBLY BONDED BY SINTERED NANOSILVER 195

Fig. 1. (a) Picture and (b) cross-sectional image of a typical specimen sinteredIGBT assembly.

electronic packaging [25], [26]. Other investigators [27]–[30]also studied nanosilver paste and its applications. However,there are few studies on nanosilver paste for joining double-sided cooling assembly.

In this paper, we used nanosilver paste to join a double-sided IGBT assembly. The temperature cycling test was per-formed to evaluate the reliability of the double-sided sinteredIGBT assembly. The shear strength of the double-sided sinteredIGBT assembly was measured. Scanning electronic microscopy(SEM), scanning acoustic microscopy (SAM), and X-ray de-tection were employed to evaluate the bonding quality of thesintered silver joint. Finally, the finite-element method (FEM)was used to evaluate the thermal performance of the double-sided sintered assembly.

II. SAMPLE PREPARATION

A. Materials and Preparation

The IGBT chips were made of silicon, plated with gold onboth sides. The gold plating was 0.3 μm thick. The nanosil-ver paste was obtained from NBE, LLC (Blacksburg, VA,USA). Direct-bond-copper (DBC) substrates were coated withsilver. Fig. 1 shows a typical specimen of a sintered IGBTassembly. The thicknesses of all the materials in the assemblyare listed in Table II.

Both the IGBT chip and the DBC substrates were firstcleaned by an ultrasonic cleaner in an alcohol bath and followed

TABLE IITHICKNESSES OF MATERIALS IN SINTERED IGBT ASSEMBLY

by a plasma cleaner. Fig. 2 shows the sample fabricationprocess. First, the paste was stencil printed to both substrates.Then, the chip was sandwiched by the two DBC substrates withthe printed paste. Finally, the sample was joined by sinterednanosilver.

B. Sintering Process

Based on thermogravimetric analysis and differential scan-ning calorimetry (DSC), the temperature profile for sinteringis generally divided into three stages [14], [27], [31], namely,drying stage, hot-pressing stage, and sintering stage [31]. Inthis paper, an extra cooling stage was added for sintering thedoubled-sided IGBT assembly to minimize the thermal residualstress during cooling to ambient temperature. Fig. 3 shows thetemperature profile for sintering nanosilver. First, the substrateswith printed nanosilver paste were dried at 70◦ for 10 min toensure the wettability of as-dried silver paste and good contactbetween the dried silver paste and the chip. Second, the samplewas hot-pressed at 225 ◦C for 15 min under a pressure of3 MPa to burn out the binder in the paste. Third, the samplewas sintered at 300 ◦C for 10 min to remove all the organics inthe paste. The thermal stress was reduced at the cooling stageconsisting of three steps, namely, the sample was first cooled to200 ◦C and held for 15 min, then cooled to 100 ◦C and held for15 min, and finally, cooled to room temperature.

During sintering, the two substrates of the double-sidedIGBT assembly were staggered for easy shearing. Fig. 4 showsthe as-sintered IGBT assembly before any aging test.

III. TEMPERATURE CYCLING

A. Machine and Tester

Thermal cycling tests were carried out according to the stan-dard of JESD22-A104C. The temperature ranges from −40 ◦Cto +150 ◦C. The soaking time at the extreme temperatures is10 min. Fig. 5 shows that each cycle lasts 70 min.

Samples were divided into six groups for the zeroth, fifth,tenth, 20th, 50th, and 100th cycles. Each group included at leastsix samples. Usually, the reliability requirement for temperaturecycling is 1000 cycles. However, all the samples in this paperwere tested up to only 100 cycles because the Al2O3-DBCsubstrates may not survive after 100 cycles; i.e., cracks weregenerated between the copper and alumina after 100 thermal cy-cles with extremely large temperature variations, e.g., −40 ◦Cto 150 ◦C [32].

In this paper, die-shear strength was chosen as the criterion toevaluate the mechanical performance of both single and double-sided IGBT assemblies. The die-shearing strength at roomtemperature was measured by a die-shearing tester (XYZTEC,CONDOR 150). However, the silicon chip of the single-sided


Fig. 2. Fabrication of double-sided sintered assembly.

Fig. 3. Temperature profile for sintering nanosilver paste.

Fig. 4. Double-sided IGBT assembly joined by sintered nanosilver.

assembly was too fragile to be sheared after thermal cycling.Fig. 6 shows a schematic of the die-shearing tester for double-sided IGBT assembly. Fig. 7 shows SEM micrographs of thefracture surface of a sintered silver joint after shearing test. Thesintered nanosilver joint is uniform and compact. Significantplastic flow is observed on the sheared surface.

B. Experimental Results

Fig. 8 shows that the die-shear strength of the as-sintereddouble-sided IGBT assembly is over 20 MPa on average. Theshear strength quickly decreases with the number of cycles,

Fig. 5. Thermal cycling profile.

Fig. 6. Schematic of die-shearing tester.

particularly within the first ten cycles. Then the rate of decreasein the shear strength becomes smaller and smaller betweenthe 10th cycle and the 100th cycle. There is a tendency forthe rate of decrease to reduce to zero if the number of cyclesis large enough. Thermal residual stresses may be releasedduring thermal cycling because of the growth of microcracksand voids in the sintered joint. As a result, the shear strength de-creases. Moreover, the accumulation of plastic deformation inthe joint because of thermal cycling also helps reduce the shearstrength [30].

The microstructures of the sintered joints of both single- anddouble-sided IGBT assemblies were analyzed at the zeroth,


Fig. 7. SEM micrographs of fracture surface of sintered nanosilver joint ofdouble-sided IGBT assembly.

Fig. 8. Shear strength and void percent versus number of thermal cycles forsingle-sided and double-sided IGBT assemblies.

fifth, tenth, 20th, and 50th cycles by X-ray detection (Modelnumber of Y-Cougar SMT).

For the thermal cycling tests performed at Infineon, which isa leading company in power electronics, the temperature swingwas 80 ◦C (from 20 ◦C to 100 ◦C). The failure criterion ofpower module was assumed to be a 20% increase in thermalresistance. The lifetime varied from 3000 to 30,000 cyclesbecause of the different substrates or packaging architecturesused.

Moreover, for the power cycling tests performed at Infineon,the temperature swing was 50 ◦C (from 75 ◦C to 125 ◦C). Thefailure criterion of power module was assumed to be a 5%increase in saturation voltage. The lifetime was measured asabout 300,000 cycles [33].

It is worth noting that the failure of power module should bemore complicated than that of our assembly because there is noheat sink, wire-bonding, and base-plate for our assembly. It isknown that wire-bonding usually fails before a joint failure forpower cycling tests. Furthermore, the lifetime also decreasesvery fast with increasing temperature swing. The lifetime of apower module would usually reduce by at least half for every9 ◦C increase in junction temperature.

Fig. 9. Voids of sintered silver joint in double-sided IGBT assembly.

Fig. 10. SAM micrographs of double-sided IGBT assemblies at differentcycles [C stands for cycle(s)].

Therefore, with such large temperature swings, we assumedthat 50 cycles should be long enough to evaluate the reliabilityof our assemblies without any heat sink and base-plate for thethermal cycling test.

Fig. 9 shows photographs of void growth of double-sidedIGBT assembly. “C” of “5 C” in Fig. 9 stands for cycle(s).The number of voids increases with the thermal cycles. Sincethe sintered silver was a porous joint, internal pores couldincrease with the number of thermal cycles and grow as voids,as detected by X-ray. Fig. 9 shows that the voids first appearat the edge of the sintered silver joint and gradually spread tothe middle of the silver joint as the number of thermal cyclesincreases. At the 50th thermal cycle, the voids are distributedalmost uniformly in the silver joint. Since joint delaminationhas occurred in the samples, as shown in Fig. 10, the voidcontent at 100 cycles of 40% is much higher than that at50 cycles. As a result, the void content at 100 cycles is notincluded in Fig. 8.


Fig. 8 shows that the calculated void content of the sinteredsilver joint increases with the number of thermal cycles in bothsingle- and double-sided assemblies. The failure criterion ofthe power module for thermal cycling is assumed to be a 20%increase in thermal resistance. Once the voids in a solder jointtook up more than 10% of the joint area, a 28.6 ◦C increase(i.e., about 20% increase in thermal resistance) in junctiontemperature could be obtained [34]. The void contents in oursintered joints were lower than the failure criterion of 10%.Therefore, the sintered joint is reliable even after 50 cyclesin both single- and double-sided assemblies. Additionally, thevoid content is directly proportional to the logarithm of thermalcycle number. Fig. 8 shows that the voids reduce the bondingarea as well as the shear strength of the sintered joint.

The rate of increase in void content and the void contentafter the fifth cycle in the sintered silver joint are higherfor the double-sided IGBT assembly than for the single-sidedassembly because the thermal residual stress is higher for thedouble-sided assembly than for the single-sided one.

The void growth in the sintered nanosilver joint duringthermal cycling was analyzed by SAM. The assemblies wereevaluated at the zeroth, fifth, tenth, 20th, 50th, and 100th cyclesseparately. Fig. 10 shows that the bonding area decreases withincreasing number of cycles in the double-sided IGBT assem-blies, particularly after 50 cycles. However, there is no crackor delamination in the single-sided IGBT assemblies under thesame temperature swing, and an indication that the double-sided IGBT sintered assembly is subject to higher thermal stressand strain by temperature cycling than the single-sided one.

Fig. 10 shows that there is no change in the microstructureof the joint in the first 20 cycles. We may conclude that nocrack initiated before the 20th cycle, after which cracks startedto emerge at the corners right beneath the IGBT chip. After100 cycles, the effective bonding area shows apparent shrink-age. The shrinkage in the effective bonding area contributed tothe decrease in shear strength. The joint was finally delaminatedby thermal stress.

IV. SIMULATION OF THERMO-MECHANICAL

PERFORMANCE OF DOUBLE-SIDED IGBT ASSEMBLY

A. Model and Loads

Since the reliability of IGBT module greatly depends onpackaging architecture, ANSYS was employed to simulatethe temperature and stress distributions of the double-sidedIGBT assembly. The single-sided case was also simulated forcomparison. Because of the symmetry of the assembly, a halfmodel was built for the double-sided IGBT assembly, as shownin Fig. 11. Table III summarizes the material properties [35].The sintered nanosilver was treated as a nonlinear material bythe Anand model. Table IV lists the parameters of the Anandmodel [36]. Fig. 5 shows the cyclic temperature profile for thesimulation.

B. Results and Discussion

Temperature Analysis: The power generation of the IGBTchip was set at 100 W. The substrate was set at 298 K on the

Fig. 11. Solid model of double-sided IGBT assembly (1/2 model).

TABLE IIIMATERIAL PROPERTIES FOR FEM ANALYSIS [34]

TABLE IVPARAMETERS OF ANAND MODEL FOR SINTERED NANOSILVER [25]

bottom side. The heat transfer coefficient was assumed to be10 W/(m2 · K) [37].

The junction temperatures of the single-sided assembly andthe double-sided assembly were compared. The junction tem-peratures were 72 ◦C and 51 ◦C for the single-sided assemblyand the double-sided assembly, respectively. About 30% moreheat was dissipated by the top DBC than by the bottom DBCof the double-sided assembly. The double-sided assembly issuperior to the single-sided assembly in thermal managementcapability mainly because of the additional cooling path [38].

Thermo-Mechanical Analysis: Because of the CTE mis-match between the chip and substrates, thermal residual stresseswere calculated from the maximum temperature of the thermalcycling tests (423 K) to room temperature (298 K) for boththe single-sided IGBT assembly and the double-sided one.All materials except the sintered silver were assumed to belinear and isotropic with respect to mechanical properties. Thesintered nanosilver was still treated as a nonlinear material bythe Anand model [36]. The reference temperature was set tobe 298 K.

Fig. 12(a)–(c) show the von Mises stress distributions ofthe single-sided assembly, the double-sided assembly, and thesintered joint of the assembly, respectively. The maximumvon Mises stresses of the single-sided and the double-sidedIGBT assemblies are 75.9 MPa) and 119 MPa, respectively.The maximum stresses of both assemblies are located at theinterface between the silicon chip and the joint. Since the tensilestrength of silicon is 660 MPa and the compressive strength isabout 120 MPa [39], [40], the IGBT chips should be preferable


Fig. 12. Von Mises stress distributions of (a) single-sided IGBT assembly,(b) double-sided IGBT assembly (1/2 model result), and (c) sintered silver jointin double-sided IGBT assembly.

to bear tensile stresses. The stress distributions show that thechips of both the single-sided and the double-sided assemblyare stretched. However, the IGBT chip of the double-sidedassembly bears higher thermal residual stresses than that of thesingle-sided assembly.

Fig. 13. Stress and strain path of sintered silver.

Fig. 12(b) shows that the maximum von Mises stress ofthe sintered joint in the double-sided IGBT assembly of about29.3 MPa is presented at the corner. This result explains whythe crack initiates at the corner, as shown in Fig. 10.

Temperature Cycling Analysis: We conducted the combinedthermo-mechanical and temperature cycling simulation forboth the single-sided assembly and the double-sided assembly.Room temperature (298 K) was set as the temperature at whichboth assemblies are stress-free.

Fig. 14(a) and (b) show the accumulation of von Misesstress and total von Mises strain along the path shown inFig. 13. Fig. 14(a) indicates that the maximum stress occursat the corner of the as-sintered silver joint in both the single-sided and the double-sided case. Meanwhile, the maximumvon Mises stress has decreased and the minimum von Misesstress has decreased after five cycles. The stress distributionexplains the growth of voids in the sintered silver. The voids areinitiated from the location of highest stress, i.e., the corner ofthe assembly. Therefore, many voids are present at the corner,as shown in Fig. 9. Cyclic thermal stress plays an important rolein the mechanism for void formation [41]. The maximum vonMises stress is higher in double-sided assembly than in single-sided assembly. The variations in the maximum and minimumvon Mises stresses, which were caused by temperature cycling,were also more significant for the double-sided assembly thanfor the single-sided one.

Fig. 14(b) shows that thermal cycling greatly affects thevon Mises strain of the sintered joints of both the single-sided assembly and the double-sided IGBT one. The maximumvon Mises strain increases with the number of cycles. As thenumber of cycles increases to 5, the maximum von Mises strainof the double-sided IGBT assembly increases by 1.06 timescompared with that of the as-sintered double-sided IGBT as-sembly, whereas the maximum von Mises strain of the single-sided assembly increases only by 0.096 times. The maximumvon Mises strain of the double-sided IGBT assembly is 2.55%at the fifth cycle. Because the ultimate fracture strain of sinterednanosilver is usually 3%–5% [30], [36], cracks may be initiatedat the corners of the sintered joint of the double-sided IGBT


Fig. 14. Variations of (a) von Mises stress and (b) total von Mises strain ofsintered silver in single- and double-sided assemblies.

Fig. 15. Plastic von Mises strain for first five cycles.

assembly in agreement with the SAM observations as shown inFig. 10.

Fig. 15 shows that the mean von Mises strain at the cornersof the sintered joint increases with the number of cycles withinthe first five cycles for the double-sided IGBT assembly buthardly changes for the single-sided assembly. Meanwhile, thestrain range is almost unchanged in either cyclic curve, but the

strain range is smaller in the curve for the double-sided IGBTassembly than in the curve for the single-sided assembly. Boththe mean strain and strain range contribute to the fatigue ofmaterials [42]. The lifetime of the double-sided assembly isprolonged by minimizing the strain range and mean strain insintered silver. Hence, in future work, we aim to find a way toreduce the maximum mean strain of sintered silver in double-sided assembly.

V. CONCLUSION

An IGBT chip was attached double-sided with DBC sub-strates by sintered nanosilver paste. Both metallograph andSEM images show that the bondline of the sintered silver jointof the double-sided IGBT assembly had a uniform thickness ofabout 50 μm. Die-shear tests revealed that the die-shear strengthof the as-sintered double-sided IGBT assembly was over20 MPa. Thermal cycling tests revealed that the die-shearstrength of the double-sided IGBT assembly decreased, butthe fraction ratio of the voids in the silver joint increasedwith the number of cycles because of cyclic thermal stress.SAM images showed that the effective bonding area decreasedwith the number of cycles. The decrease was due to cracks ordelamination in the silver joint with the accumulation of plasticstrain as the cyclic thermal stress exceeded the fracture strain ofthe sintered silver joint.

FEM simulation showed that the double-sided IGBT assem-bly had superior thermal performance over a single-sided onebecause the junction temperature could be reduced by 21 ◦Cand about 30% more heat was dissipated from the top DBC.However, the maximum von Mises stress and strain of thesintered silver of the double-sided IGBT assembly were higherthan those of the single-sided one. Thus, the maximum stressand strain during thermal cycling increased.

Finally, the strain range for fixed temperature swing wassmaller in the double-sided IGBT assembly than in the single-sided one. The result indicates that if the mean strain can bewell controlled, a double-sided assembly can have advantagesover a single-sided one in both reliability and lifetime.

REFERENCES

[1] M. Al Sakka, H. Gualous, J. Van Mierlo, and H. Culcu, “Thermal model-ing and heat management of super capacitor modules for vehicle applica-tions,” J. Power Sources, vol. 194, no. 2, pp. 581–587, Dec. 2009.

[2] J. D. Van Wyk and F. C. Lee, “Power electronics technology at the dawnof the new millenium-status and future,” in Proc. 30th Annu. IEEE PowerElectron. Spec. Conf., Aug. 1999, vol. 1, pp. 3–12.

[3] X. Liu, S. Haque, J. Wang, and G.-Q. Lu, “Packaging of integrated powerelectronics modules using flip-chip technology,” in Proc. 15th Annu. IEEEAppl. Power Electron. Conf. Expo., 2000, vol. 1, pp. 290–296.

[4] C. Gillot, L. Meysenc, C. Schaeffer, and A. Bricard, “Integrated singleand two-phase micro heat sinks under IGBT chips,” IEEE Trans. Compon.Packag. Technol., vol. 22, no. 3, pp. 384–389, Sep. 1999.

[5] M. Schneider-Ramelow, T. Baumann, and E. Hoene, “Design and assem-bly of power semiconductors with double-sided water cooling,” in Proc.5th Int. Conf. Integr. Power Syst., Mar. 2008, pp. 1–7.

[6] T. J. Martens, G. F. Nellis, J. M. Pfotenhauer, and T. M. Jahns, “Double-sided IPEM cooling using miniature heat pipes,” IEEE Trans. Compon.Packag. Technol., vol. 28, no. 4, pp. 852–861, Dec. 2005.

[7] Y. Mei, X. Chen, and H. Gao, “Hygrothermal effects on the tensile prop-erties of anisotropic conductive films,” J. Electron. Mater., vol. 38, no. 11,pp. 2415–2426, Nov. 2009.


[8] C. Buttay, J. Rashid, C. Mark Johnson, P. Ireland, F. Udrea,G. Amaratunga, and R. K. Malhan, “High performance cooling systemfor automotive inverters,” in Proc. Eur. Conf. Power Electron. Appl.,Sep. 2007, pp. 1–9.

[9] G.-Q. Lu, J. N. Calata, Z. Zhiye, and J. G. Bai, “A lead-free, low-temperature sintering die-attach technique for high-performance and high-temperature packaging,” in Proc. 6th IEEE CPMT Conf. High DensityMicrosyst. Des. Packag. Compon. Failure Anal., 2004, pp. 42–46.

[10] J. G. Bai, J. N. Calata, Z. Z. Zhang, and G.-Q. Lu, “Low-temperaturesintering of nanoscale silver pastes for high-performance and highly-reliable device interconnection,” in Proc. ASME Int. Mech. Eng. Congr.Expo., 2005, pp. 415–424.

[11] J. G. Bai, T. G. Lei, J. N. Calata, and G.-Q. Lu, “Control of nanosilversintering attained through organic binder burnout,” J. Mater. Res., vol. 22,no. 12, pp. 3494–3500, Dec. 2007.

[12] G.-Q. Lu, J. N. Calata, G. Lei, and X. Chen, “Low-temperature and pres-sureless sintering technology for high-performance and high-temperatureinterconnection of semiconductor devices,” in Proc. EuroSime: Int. Conf.Therm., Mech. Multi-Phys. Simul. Exper. Microelectron. Micro-Syst.,Apr. 16–18, 2007, pp. 1–5.

[13] J. G. Bai and G.-Q. Lu, “Thermomechanical reliability of low-temperaturesintered silver die attached SiC power device assembly,” IEEE Trans.Device Mater. Rel., vol. 6, no. 3, pp. 436–441, Sep. 2006.

[14] Y. Mei, Y. Cao, G. Chen, X. Chen, G.-Q. Lu, and X. Chen, “Rapid sin-tering nanosilver joint by pulse current for power electronics packaging,”IEEE Trans. Device Mater. Rel., vol. 13, no. 1, pp. 258–265, Mar. 2013.

[15] G. Chen, Y. Cao, Y. Mei, X. Li, D. Han, and X. Chen, “Simplification oflow-temperature sintering nanosilver for power electronics packaging,”J. Electron. Mater., vol. 42, no. 6, pp. 1209–1218, Jun. 2013.

[16] G. Chen, Y. Cao, Y. Mei, X. Li, D. Han, G.-Q. Lu, and X. Chen, “Pressure-assisted low-temperature sintering of nanosilver paste for 5 ∗ 5 mm2 chipattachment,” IEEE Trans. Compon., Packag. Manuf. Technol., vol. 2,no. 11, pp. 1759–1767, Nov. 2012.

[17] Y. Mei, G. Chen, G.-Q. Lu, and X. Chen, “Effect of joint sizes of low-temperature sintered nano-silver on thermal residual curvature of sand-wiched assembly,” Int. J. Adhes. Adhes., vol. 35, pp. 88–93, Jun. 2012.

[18] Y. Mei, G. Chen, X. Li, G.-Q. Lu, and X. Chen, “Evolution of curvatureunder thermal-cycling in sandwich assembly bonded by sintered nano-silver paste,” Soldering Surface Mount Technol., vol. 25, no. 2, pp. 107–116, 2013.

[19] Y. Mei, G.-Q. Lu, X. Chen, G. Chen, S. Luo, and D. Ibitayo, “Investigationof post-etch copper residue on direct bonded copper (DBC) substrates,”J. Electron. Mater., vol. 40, no. 10, pp. 2119–2125, Oct. 2011.

[20] Y. Mei, G.-Q. Lu, X. Chen, G. Chen, S. Luo, and D. Ibitayo, “Migrationof sintered nanosilver die-attach material on alumina substrate between250 ◦C and 400 ◦C in dry air,” IEEE Trans. Device Mater. Rel., vol. 11,no. 2, pp. 316–322, Jun. 2011.

[21] Y. Mei, G.-Q. Lu, X. Chen, G. Chen, S. Luo, and D. Ibitayo, “Effect ofoxygen partial pressure on silver migration of low-temperature sinterednanosilver die-attach material,” IEEE Trans. Device Mater. Rel., vol. 11,no. 2, pp. 312–315, Jun. 2011.

[22] T. Wang, X. Chen, G.-Q. Lu, and G. Y. Lei, “Low-temperature sinter-ing with nano-silver paste in die-attached interconnection,” J. Electron.Mater., vol. 36, no. 10, pp. 1333–1340, Oct. 2007.

[23] X. Chen, R. Li, K. Qi, and G.-Q. Lu, “Tensile behaviors and ratchetingeffects of partially sintered chip-attachment films of a nanoscale silverpaste,” J. Electron. Mater., vol. 37, no. 10, pp. 1574–1579, Oct. 2008.

[24] G. Chen, X. H. Sun, P. Nie, Y. H. Mei, G.-Q. Lu, and X. Chen, “High-temperature creep behavior of low-temperature-sintered nano-silver pastefilms,” J. Electron. Mater., vol. 41, no. 4, pp. 782–790, Apr. 2012.

[25] G. Chen, D. Han, Y. H. Mei, X. Cao, T. Wang, X. Chen, and G.-Q. Lu,“Transient thermal performance of IGBT power modules attached by low-temperature sintered nanosilver,” IEEE Trans. Device Mater. Rel., vol. 12,no. 1, pp. 124–132, Mar. 2012.

[26] Y. Mei, T. Wang, X. Cao, G. Chen, G.-Q. Lu, and X. Chen, “Transientthermal impedance measurements on low-temperature-sintered nanoscalesilver joints,” J. Electron. Mater., vol. 41, no. 11, pp. 3152–3160,Nov. 2012.

[27] Y. Yan, X. Chen, X. Liu, Y. Mei, and G.-Q. Lu, “Die bonding of highpower 808 nm laser diodes with nanosilver paste,” Trans. ASME J. Elec-tron. Packag., vol. 134, no. 4, pp. 041003-1–041003-7, Aug. 2012.

[28] Z. Zhang and G.-Q. Lu, “Pressure-assisted low-temperature sintering ofsilver paste as an alternative die-attach solution to solder reflow,” IEEETrans. Electron. Packag. Manuf., vol. 25, no. 4, pp. 279–283, Oct. 2002.

[29] X. Cao, T. Wang, G.-Q. Lu, and K. D. T. Ngo, “Characterization oflead-free solder and sintered nano-silver die-attach layers using thermalimpedance,” in Proc. Int. Power Electron. Conf., 2010, pp. 546–552.

[30] T. Wang, G. Chen, Y. Wang, X. Chen, and G.-Q. Lu, “Uniaxial ratchetingand fatigue behaviors of low-temperature sintered nano-scale silver pasteat room and high temperatures,” Mater. Sci. Eng.: A, vol. 527, no. 24,pp. 6714–6722, 2010.

[31] T. G. Lei, J. N. Calata, G.-Q. Lu, X. Chen, and S. Luo, “Low-temperaturesintering of nanoscale silver paste for attaching large-area (100 mm2)chips,” IEEE Trans. Compon. Packag. Technol., vol. 33, no. 1, pp. 98–104, Mar. 2010.

[32] G. C. Dong, X. Chen, X. Zhang, K. D. Ngo, and G.-Q. Lu, “Thermal fa-tigue behaviour of Al2O3-DBC substrates under high temperature cyclicloading,” Soldering Surface Mount Technol., vol. 22, no. 2, pp. 43–48,2010.

[33] G. Coquery and R. Lallemand, “Failure criteria for long term acceleratedpower cycling test linked to electrical turn off SOA on IGBT module:a 4000 hours test on 1200A–3300V module with AlSiC base plate,”Microelectron. Rel., vol. 40, no. 8-10, pp. 1665–1670, Aug.–Oct. 2000.

[34] J. Shi, W. Sun, W. Jing, H. Sun, and G. Gao, “Failure analysis of voidsin automotive IGBT die attach process,” Electron. Packag., vol. 10, no. 2,pp. 23–27, 2010.

[35] J. G. Bai, J. N. Calata, and G.-Q. Lu, “Comparative thermal and ther-momechanical analyses of solder-bump and direct-solder bonded powerdevice packages having double-sided cooling capability,” in Proc. Appl.Power Electron. Conf. Expo., 2004, vol. 2, pp. 1240–1246.

[36] D. J. Yu, X. Chen, G. Chen, G.-Q. Lu, and Z. Q. Wang, “ApplyingAnand model to low-temperature sintered nanoscale silver paste chipattachment,” Mater. Des., vol. 30, no. 10, pp. 4574–4579, Dec. 2009.

[37] A. Christensen, M. Ha, and S. Graham, “Thermal management methodsfor compact high power LED arrays,” in Proc. 7th Int. Conf. Solid StateLighting, 2007, p. 66690Z.

[38] J. Lian, Y. Mei, X. Chen, X. Li, G. Chen, and K. Zhou, “Low-temperaturesintering of nanoscale silver paste for double-sided attaching 9 × 9 mm2

chip,” in Proc. 13th Int. Conf. Electron. Packag. Technol. High DensityPackag., 2012, pp. 232–237.

[39] C. Gillot, C. Schaeffer, C. Massit, and L. Meysenc, “Double-sided coolingfor high power IGBT modules using flip chip technology,” IEEE Trans.Compon. Packag. Technol., vol. 24, no. 4, pp. 698–704, Dec. 2001.

[40] T. Yi, L. Li, and C.-J. Kim, “Microscale material testing of singlecrystalline silicon: process effects on surface morphology and tensilestrength,” Sens. Actuators A: Phys., vol. 83, no. 1-3, pp. 172–178,May 2000.

[41] L. T. Shi and K. N. Tu, “Finite-element stress analysis of failure mecha-nisms in a multilevel metallization structure,” J. Appl. Phys., vol. 77, no. 7,pp. 3037–3041, Apr. 1995.

[42] S. Vaynman and S. A. McKeown, “Energy-based methodology for the fa-tigue life prediction of solder materials,” IEEE Trans. Compon., Hybrids,Manuf. Technol., vol. 16, pp. 317–322, May 1993.

Yun-Hui Mei (M’13) received the B.S. and Ph.D.degrees in process equipment and controlling engi-neering from Tianjin University, Tianjin, China, in2006 and 2010, respectively.

He studied at the Center for Power ElectronicsSystems, Virginia Polytechnic Institute and StateUniversity, Blacksburg, VA, USA. He is currentlya Faculty Member of the Tianjin Key Laboratoryof Advanced Joining Technology and the Schoolof Materials Science and Engineering, Tianjin Uni-versity. His current research interests include high-

temperature packaging for high-power-density applications. He has publishedmore than 20 papers on power electronic packaging.

Jiao-Yuan Lian received the B.S. degree in processequipment and controlling engineering from TianjinUniversity, Tianjin, China, in 2010. She is currentlyworking toward the M.S. degree in chemical processequipment from Tianjin University.

Her current research interests include processingand characterization of nanosilver paste for double-sided attaching high power electronic device.


Xu Chen received the B.S., M.S., and Ph.D. degreesin applied mechanics from Southwest Jiaotong Uni-versity, Chengdu, China, in 1982, 1986, and 1992,respectively.

He is currently a Professor with the School ofChemical Engineering and Technology, Tianjin Uni-versity, Tianjin, China, where he is the Head of theDepartment of Process Equipment and ControllingEngineering. He has authored or coauthored over100 papers in international journals and conferences.His current research interests include mechanical

properties of newly developed materials, creep-fatigue and constitutive model-ing for electronic and conventional structural materials, thermal management,and reliability of die attachment in electronic packaging.

Prof. Chen was the recipient of the Teaching and Research Program Awardfor Outstanding Young Teachers in Higher Education Institutions of the Min-istry of Education, China, in 2002, and the Thomson Scientific Research FrontsAward in China in 2008.

Gang Chen (M’08) received the Ph.D. degree inprocess equipment and machinery from Tianjin Uni-versity, Tianjin, China, in 2006.

He was a Teacher with the School of Chemical En-gineering and Technology, Tianjin University, wherehe became an Associate Professor in 2008. In 2009,he was a Visiting Professor with the Department ofMaterials Science and Engineering, Virginia Poly-technic Institute and State University, Blacksburg,VA, USA. He has authored or coauthored over30 papers in journals and international conferences.

His current research interests include reliability of microelectronics, finite-element analysis, creep-fatigue of solders, and constitutive modeling for elec-tronic and conventional structural materials.

Xin Li received the Master and Ph.D. degrees inmaterials processing engineering from Tianjin Uni-versity, Tianjin, China, in 2012.

Since April 2012, she has been employed as aLecturer for the School of Materials Science andEngineering, Tianjin University. She is currently en-gaged in research work on high power electronicpackaging technology and reliability.

Guo-Quan Lu (M’97) received the B.S. degreesin physics and in materials science and engineer-ing from Carnegie Mellon University, Pittsburgh,PA, USA, in 1984 and the Ph.D. degree in appliedphysics and materials science from Harvard Univer-sity, Cambridge, MA, USA, in 1990.

He is currently a Professor with the Department ofMaterials Science and Engineering and the BradleyDepartment of Electrical and Computer Engineer-ing, Virginia Polytechnic Institute and State Univer-sity, Blacksburg. He was with the Alcoa Technical

Center, Alcoa Center, PA, USA. He has held a Cheung Kong Guest Profes-sorship with the Tianjin Key Laboratory of Advanced Joining Technologyand the School of Materials Science and Engineering, Tianjin University,Tianjin, China, since 2007. His current research interests include materials andprocessing development for electronic packaging of microelectronics, powerelectronics, and optoelectronics.

Prof. Lu was the recipient of the National Science Foundation Career Awardand the Research and Development 100 Award in 2007.

本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。

学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，

提供一站式文献检索和下载服务”的24 小时在线不限IP

图书馆。

图书馆致力于便利、促进学习与科研，提供最强文献下载服务。

图书馆导航：

图书馆首页文献云下载图书馆入口外文数据库大全疑难文献辅助工具

http://www.xuebalib.com/cloud/

http://www.xuebalib.com/

http://www.xuebalib.com/cloud/


http://www.xuebalib.com/vip.html

http://www.xuebalib.com/db.php

http://www.xuebalib.com/zixun/2014-08-15/44.html


Thermo-Mechanical Reliability of Double-Sided IGBT Assembly...

Documents

Transcript of Thermo-Mechanical Reliability of Double-Sided IGBT Assembly...