The Grizzly, October 30, 1990

Ursinus Honored at Governor\u27s Mansion • Sam Stretton To Speak • Glassmoyer Retires • Heefner New Board President • The Gender of Speech: A Tri-Lambda Lecture • Career Day November 6th • Forbes to Speak to Clergy • Animal Lovers Unite • Mock DWI A Hit • Student Camp Experience • David is Great!! • Presenting Protheatre: The Changeling • Crutcher Leads Team• Muhlenberg Falls • Swimmers Open Season at Relay Meet • Women Running To MAC\u27s • Men Go for MAC Title • Soccer • Letters: Keep Ursinus Clean; Quad Keys Revoked?; Signs Stolen; Security, Please Hold • Environmentally Concerned? Get Active • Bush\u27s Environmental Lip Service • This Time for Real • Nature Versus Nurture: A Step in Solving the Puzzlehttps://digitalcommons.ursinus.edu/grizzlynews/1262/thumbnail.jp

The Grizzly, December 3, 1990

Wismer Hall to be Renovated by Next Fall • Quad Intruder Returns • Politics Honors Projects • Foreign Policy and the Press • Ursinus Offers St. Joseph\u27s Post-MBA Certificates • Dance Marathon Planned • Crazy Toys • Holiday Messages Encouraged • Exam Schedule • Mixed Up • Jane\u27s Addiction Concert Review • European Old Master Prints • At the Playhouse • Attention Skiers • Edie Brickell Reviewed • In the Spotlight • Swimmers Host Double-Header Weekend • Lady Hoopsters Shoot for Title • Are We Going to War? • Why are We Really There? • Hey! Who\u27s the New Guy? • Brain in Brief • Bonnie and SAM (not Clyde)https://digitalcommons.ursinus.edu/grizzlynews/1266/thumbnail.jp

The Grizzly, October 9, 1990

Student Activities Reorganized • Homecoming 1990: Student and Alumnae Festivities • LaRouche Supporter to Speak • Pledging Rules In Effect • EcBa Club Holds First Meeting • The Path to Opportunities • Ursinus Goes South of the Border • Olin Brick Explained • Esther Remembered • Homecoming Festivities • Comedy Brightens Wismer • Pennsylvania Impressionist • Acting Sports • Presenting ProTheatre • Russian Trumpeter • Soccer Team Gets It Together • Grubb\u27s Fearless Predictions • Football Impresses • Field Hockey Rebounds • Harley\u27s Haven • Letters: RAs Question Editorial; Congrats, Now be Quiet! • Classics: Guaranteed to Improve Your Life • Losing Traditions • Grading Our Food Service • Middleton: Man of Many Projectshttps://digitalcommons.ursinus.edu/grizzlynews/1260/thumbnail.jp

The Grizzly, November 13, 1990

Clergy Assembly Meets Ninth Consecutive Year • Career Day: An Information Session for Students • U.S. Energy Policy Anti-American? • The Ursinus Tutoring Program • Being British Without Being English • Election Results • Students React to Reimert Security Doors • Greeks Sponsor Halloween Party • F.W. Olin Foundation • Wilk 3 Protest • The History of Olin Grant • The Changeling • INXS • Television: Whose Reality is it Anyway? • Swimmers Wash Out Washington • Cross-Country Team Pleased with Regionals • Steimy Starts Club • Men\u27s Basketball Looks for Improvement in 1991 Season • Football Finishes Season with a Loss • Letters: No Defense for Personal Abuse; Zeta Chi Missed the Point! • Uncle Sam Wants Everyone • Pre-Med Prognosis Improving • Ursinus Grad in Sticky Situation • Brownback-Anders Meetinghttps://digitalcommons.ursinus.edu/grizzlynews/1264/thumbnail.jp

The Effect of Reflow Profile on SnPb and SnAgCu Solder Joint Shear Strength

Purpose –The purpose of this work is to study the effect of the reflow peak temperature and time above liquidus on both SnPb and SnAgCu solder joint shear strength. Design/methodology/approach –Nine reflow profiles for Sn3.0Ag0.5Cu and nine reflow profiles for Sn37Pb have been developed with three levels of peak temperature (230°C, 240°C, and 250°C for Sn3.0Ag0.5Cu; and 195°C, 205°C, and 215°C for Sn37Pb) and three levels of time above solder liquidus temperature (30, 60, and 90 s). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear forces for the resistors were measured after assembly. The fracture interfaces were inspected using scanning electron microscopy with energy dispersive spectroscopy in order to determine the failure mode and failure surface morphology. Findings –The results show that the effects of the peak temperature and the time above solder liquidus temperature are not consistent between different component sizes and between Sn37Pb and Sn3.0Ag0.5Cu solder. The shear force of SnPb solder joints is higher than that of Sn3.0Ag0.5Cu solder joints because the wetting of SnPb is better than that of SnAgCu. Research limitations/implications –This study finds that fracture occurred partially in the termination metallization and partially in the bulk solder joint. To eliminate the effect of the termination metallization, future research is recommended to conduct the same study on solder joints without component attachment. Practical implications –The shear strength of both SnPb and SnAgCu solder joints is equal to or higher than that of the termination metallization for the components tested. Originality/value – Fracture was observed to occur partially in the termination metallization (Ag layer) and partially in the bulk solder joint. Therefore, it is essential to inspect the fracture interfaces when comparing solder joint shear strength

Investigation of the Lead-free Solder Joint Shear Performance

Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The purpose of this study is to investigate the effects of reflow profile and thermal shock on the shear performance of eutectic SnPb (SnPb) and Sn3.0Ag0.5Cu (SAC305) solder joints. Test boards were assembled with four different sized surface mount chip resistors (1206, 0805, 0603 and 0402). Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb were developed with three levels of peak temperature (12ºC, 22ºC, and 32ºC above solder liquidus temperature, or 230ºC, 240ºC, and 250ºC for SAC 305; and 195ºC, 205ºC, and 215ºC for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). Half of the test vehicles were then subjected to air-to-air thermal shock conditioning from -40 to 125°C. The shear force data were analyzed using the Analysis of Variance (ANOVA). The fracture surfaces were studied using a Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). It was found that thermal shock degraded both SnPb and SnAgCu joints shear strength, and that the effect of thermal shock on solder joint shear strength is much more significant than that of reflow profile. The SnAgCu solder joints have weaker shear strength than the SnPb solders. The SnAgCu solder joint after thermal shock retains more of its shear strength than that of SnPb for small components and vice versa for larger components

Effects of Reflow Profile and Thermal Conditioning on Intermetallic Compound Thickness for SnAgCu Soldered Joints

Purpose – The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for Sn3.0Ag0.5Cu (SAC305) soldered joints. Design/methodology/approach – A four-factor factorial design with three replications is selected in the experiment. The input variables are the peak temperature, the duration of time above solder liquidus temperature (TAL), solder alloy and thermal shock. The peak temperature has three levels, 12, 22 and 32°C above solder liquidus temperatures (or 230, 240 and 250°C for SAC305 and 195, 205, and 215°C for SnPb). The TAL has two levels, 30 and 90 s. The thermally shocked test vehicles are subjected to air-to-air thermal shock conditioning from -40 to 125°C with 30 min dwell times (or 1 h/cycle) for 500 cycles. Samples both from the initial time zero and after thermal shock are cross-sectioned. The IMC thickness is measured using scanning electron microscopy. Statistical analyses are conducted to compare the difference in IMC thickness growth between SAC305 solder joints and SnPb solder joints, and the difference in IMC thickness growth between after thermal shock and after thermal aging. Findings – The IMC thickness increases with higher reflow peak temperature and longer time above liquidus. The IMC layer of SAC305 soldered joints is statistically significantly thicker than that of SnPb soldered joints when reflowed at comparable peak temperatures above liquidus and the same time above liquidus. Thermal conditioning leads to a smoother and thicker IMC layer. Thermal shock contributes to IMC growth merely through high-temperature conditioning. The IMC thickness increases in SAC305 soldered joints after thermal shock or thermal aging are generally in agreement with prediction models such as that proposed by Hwang. Research limitations/implications – It is still unknown which thickness of IMC layer could result in damage to the solder. Practical implications – The IMC thickness of all samples is below 3 µm for both SnPb and SAC305 solder joints reflowed at the peak temperature ranging from 12 to 32°C above liquidus temperature and at times above liquidus ranging from 30 to 90 s. The IMC thickness is below 4 µm after subjecting to air-to-air thermal shock from -40 to 125°C with 30 min dwell time for 500 cycles or thermal aging at 125°C for 250 h. Originality/value – The paper reports experimental results of IMC thickness at different thermal conditions. The application is useful for understanding the thickness growth of the IMC layer at various thermal conditions

Drop Test Reliability of Lead-free Chip Scale Packages

This paper presents the drop test reliability of 0.5 mm pitch lead-free chip scale packages (CSPs). Fifteen 0.5 mm pitch CSPs were assembled on a standard JEDEC drop reliability test board with Sn3.0Ag0.5Cu lead-free solder. Eight boards were edge-bonded with a UV-cured acrylic; eight boards were edge- bonded with a thermal-cured epoxy; and twelve boards were assembled without edge bonding. Half of the edge-bonded test boards were subjected to drop tests at a peak acceleration of 1500 G with a pulse duration of 0.5 ms, and the other half subjected to drop tests at a peak acceleration of 2900 G with a pulse duration of 0.3 ms. Half of the test boards without edge bonding were subjected to drop tests at a peak acceleration of 900 G with a pulse duration of 0.7 ms, and the other half subjected to drop tests at a peak acceleration of 1500 G with a pulse duration of 0.5 ms. Two drop test failure detection systems were used in this study to monitor the failure of solder joints: a high-speed resistance measurement system and a post-drop static resistance measurement system. The high-speed resistance measurement system, which has a scan frequency of 50 KHz and a 16-bit signal width, is able to detect intermittent failures during the short drop impact duration. Statistics of the number of drops to failure for the 15 component locations on each test board are reported. The effect of component position on drop test reliability is discussed. The test results show that the drop test performance of edge-bonded CSPs is five to eight times better than the CSPs without edge bonding. However, the drop test reliability of edge-bonded CSPs with the thermal-cured epoxy is different from that with edge-bonded CSPs with the UV-cured acrylic. The solder crack location and crack area are characterized with the dye penetrant method. The fracture surfaces are studied using scanning electron microscopy (SEM)