Mechanical, thermal and electrical analysis of a compliant interconnect

Galloway, Jesse; Syed, Ahmer; Kang, WonJoon; Khim, Jin Young; Cannis, J.; Ka, YunHyeon; Kim, Seung Mo; Kim, TaeSeong; Lee, GiSong; Ryu, SangHyun

doi:10.1109/itherm.2004.1319233

Cited by 4 publications

(5 citation statements)

References 4 publications

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“…RF insertion losses up to microwave frequencies have also been shown to not be significantly effected e.g. by Movva and Aguirre [3], Galloway et al [4] and Kangasvieri et al [5].…”

Section: Introductionmentioning

confidence: 99%

“…Several experimental studies have demonstrated the potential fatigue life benefits under iso-thermal temperature cycling conditions. For example, Okinaga et al [1] showed a 4 fold increase in fatigue life, Schwanke et al [2] showed a 2 times increase, Movva and Aguirre [3] showed a 2-3 times improvement, Galloway et al [4] showed a 60% improvement and Kangasvieri et al [5] showed a 50% to 75% improvement, as compared to that for conventional solder balls. Simulation based studies have indicated even greater thermal fatigue lifetime improvements may be possible through optimization of the interconnection geometry and materials selection e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Again a number of studies have examined this issue and have concluded that although the thermal [4], [8], [9] and DC electrical resistances [1], [9] of the individual interconnects will be significantly increased, the overall impact on system performance will generally be acceptable. RF insertion losses up to microwave frequencies have also been shown to not be significantly effected e.g.…”

Section: Introductionmentioning

confidence: 99%

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Current density simulations for polymer cored CSP interconnects

Whalley

Kristiansen

2010

3rd Electronics System Integration Technology Conference ESTC

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Polymer cored spheres have been proposed as a more flexible and therefore more reliable alternative to solid solder balls for use in ball grid array (BGA) and chip scale package (CSP) interconnects. However the use of such polymer cored interconnects will result in a significant increase in the average current density within the individual interconnects, due to the much smaller cross sectional area of metal through which conduction may take place. High current densities in metals are well known to lead to electro-migration and this may lead to reductions in their mechanical performance. The soft solders used in electronics manufacturing operate at high homologous temperatures and are therefore particularly vulnerable to electro-migration damage, particularly as miniaturization also leads to increasing current densities.This paper presents results of electrical current density simulations for geometries typical of a polymer cored sphere based CSP interconnect, in comparison with a conventional solder ball based CSP interconnect, and explores the electrical stress raising effects of the presence of tracks feeding into the solder pads on the allowable maximum current before electro-migration becomes a risk.The results show that for a structure where there are no tracks, i.e. for a via in pad design, the allowable current for a polymer cored interconnect may be only half that for a solid solder ball, but where there are surface tracks the polymer cored interconnects may result in a significantly lower stress concentration effect and therefore allow a higher current than for a solder ball.

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“…RF insertion losses up to microwave frequencies have also been shown to not be significantly effected e.g. by Movva and Aguirre [3], Galloway et al [4] and Kangasvieri et al [5].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Current density simulations for polymer cored CSP interconnects

Whalley

Kristiansen

2010

3rd Electronics System Integration Technology Conference ESTC

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“…Polymer core solder balls (PCSBs) are promising solder materials because their polymer cores keep standoff height and absorb generated stress over the solder joint interface, which may help ensure sufficiently high reliability without using underfill. Several studies have been investigated [3][4][5][6][7][8][9]; however, the performance of PCSBs for CBGAs has not yet been proven sufficiently, and their capabilities are still not well understood.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of ceramic BGA using polymer core solder balls

Ishida

Matsushita

2014

2014 IEEE 64th Electronic Components and Technology Conference (ECTC)

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The thermal reliability of lead-free solder joints between ceramic substrates and FR4 printed circuit boards (PCBs) is a major concern when designing ceramic ball grid arrays (CBGAs), particularly for thicker or larger substrates, since their CTE is much smaller than that of PCB. In order to achieve high reliability for critical applications, polymer core solder balls (PCSBs) are a promising solution. PCSBs enable high reliability without the need for other materials such as underfill resin or modification of package design to ensure reliability. In this study, the characteristics of PCSBs were evaluated using a variety of techniques in order to assess their adaptability to CBGA applications. The solder joint condition and the presence of intermetallic compounds (IMCs) were investigated, and the board-level reliability and electrical performance were compared to those of conventional SAC305 solid solder balls. Thermal cycling tests from −40 to +125 °C were carried out using an alumina CBGA with a 25 × 25 mm 2 package size and a 1.0 mm ball pitch. As a result of a larger solder bump height and a finer IMC microstructure, PCSBs exhibited a board-level reliability more than three times higher than that for SAC305 solder balls. PCSBs also exhibited stable electrical performance, with a similar initial resistance to that for SAC305 solder balls. Electromigration tests were carried out at a temperature of 150 °C and a current of 1.8 A, and lifetimes of more than 700 hours were found for both types of solder balls. The PCSB failure mode was fatigue cracking in the solder at the interface with IMCs on the ceramic side, which is similar to the case for SAC305. The use of PCSBs in large-sized HITCE CBGAs was also investigated to assess their potential for increasing the demand for larger package applications. IntroductionCeramic ball grid arrays (CBGAs) are often chosen for high-end products because their multi-layer ceramic substrate has better heat resistance and higher electric performance than organic substrate. They have been used for various applications such as aerospace technologies, communication modules, radio frequency modules, field-programmable gate arrays, CMOS image sensors (CISs), high-end computer servers, and industry equipment. Both their usage and functionality are increasing. For instance, CISs are being in various demands for smartphones, industry equipment, inspection apparatuses, medical and automotive devices, and other applications that require highly sensitive sensors and highly reliable packages. For example, CISs are increasingly used for automotive safety applications, often being mounted on the car body outside. Therefore, a very high level of reliability is required for automotive CISs. Another example of increasing functionalities for CBGAs is server. As a large-

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“…Another more attractive potential characteristic of metallized polymer pillars is that dual-mode (electrical and optical) I/O interconnection can be simultaneously realized in one metallized polymer pillar by creating a slanted end as a mirror for optical signal transmission. In another representation of metallized polymer structure [22], plastic spheres are sequentially coated by copper and solder materials. The slight increase of thermal resistance (5% 8%) of metallized polymer spheres are offset by large gains in the thermal fatigue life (2 3 times) compared to pure solder interconnections.…”

Section: Introductionmentioning

confidence: 99%

Planar Microspring—A Novel Compliant Chip-to-Package Interconnect for Wafer-Level Packaging

Liao

Tay

Ang

et al. 2009

IEEE Trans. Adv. Packag.

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In this paper, a novel compliant chip-to-package interconnect, planar microspring, is presented in terms of design consideration, wafer-level fabrication process and mechanical characterization. Several spring designs have been evaluated, and results indicate that a -shaped spring design produces a combination of high 3-D compliances and acceptable electrical parasitics. Further, numerical analyses on the -shaped microspring interconnect examined the dependence of mechanical and electrical performance upon geometry parameters. A wafer-level fabrication flow combining complementary metal oxide semiconductor (CMOS) back-end-of-line (BEOL) process and 3-D surface micromachining technique has been successfully implemented to create planar microspring interconnect prototypes with a fine pitch (100 m). The mechanical robustness of the prototype interconnects have been evaluated by nanoindentation. Finally, high-frequency electrical simulation suggested that the interconnect application can be extended up to 35 GHz without significant power loss.

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Mechanical, thermal and electrical analysis of a compliant interconnect

Cited by 4 publications

References 4 publications

Current density simulations for polymer cored CSP interconnects

Current density simulations for polymer cored CSP interconnects

Characteristics of ceramic BGA using polymer core solder balls

Planar Microspring—A Novel Compliant Chip-to-Package Interconnect for Wafer-Level Packaging

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