Electrochemical migration study of fine pitch lead free micro bump interconnect

Chai, Tai Chong; Thew, Meei Ling; Ong, Yue Ying

doi:10.1109/eptc.2009.5416517

Cited by 3 publications

(1 citation statement)

References 15 publications

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“…With the reduced pitch between leads and repeated soldering, reliability issues can arise, such as the formation of conductive bridges (shorts) leading to non-functional devices. Moreover, a decreased pitch between leads can cause the faster growth of dendrites, which can ultimately result in device failure as was shown in studies [ 1 , 2 , 3 , 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach for Temperature-Induced Ball Grid Array Collapse Observation

Sorokina,

Dušek,

Bušek

2024

Materials

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This study presents a new approach to investigating the impact of repeated reflow on the failure of ball grid array (BGA) packages. The issue with the BGA package collapse is that the repeated reflow can lead to short circuits, particularly for BGAs with a very fine pitch between leads. A novel approach was developed to measure the collapse of BGA solder balls during the melting and solidification process, enabling in situ measurements. The study focused on two types of solders: Sn63Pb37 as a reference, and the commonly used SAC305, with measurements taken at various temperatures. The BGA samples were subjected to three different heating/cooling cycles in a thermomechanical analyzer (TMA) at temperatures of 250 °C, 280 °C, and 300 °C, with a subsequent cooling down to 100 °C. The results obtained from the TMA indicated differences in the collapse behavior of both BGA solder alloys at various temperatures. Short circuits between neighboring leads (later confirmed by an X-ray analysis) were also recognizable on the TMA. The novel approach was successfully developed and applied, yielding clear insights into the behavior of solder balls during repeated reflow.

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Section: Introductionmentioning

confidence: 99%

A Novel Approach for Temperature-Induced Ball Grid Array Collapse Observation

Sorokina,

Dušek,

Bušek

2024

Materials

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Bumping and stacking processes for 3D IC using fluxfree polymer

Choi

Sung

Bae

et al. 2011

2011 IEEE 61st Electronic Components and Technology Conference (ECTC)

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Fine pitch solder-less bonding using ultrasonic technique

Chong

Cereno

et al. 2012

2012 IEEE 14th Electronics Packaging Technology Conference (EPTC)

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Industry is adapting micro-bumps in the device structures in order to having module with multiple functions and capabilities within smaller area. Micro-bumps is coated with Tin (Sn) cap to facilitates solder interconnects formation between the chip and substrate. Electrochemical migration failure is a known issue related to flux residue on the solder joints after the thermal compression of the chip with solder cap micro-bumps on substrate. Electromigration is another issue related to shrinking interconnects. It is related to atomic displacement in a conductor line due to an applied current.In this study, the micro bumps are directly bonded to the substrate without solder cap and thus there is no electro migration failure concern. The chip used in this study is of size 7mm x 7mm x 0.05mm and consists of peripheral microsolder bumps at 40μm pitch with no solder cap.Ultra-sonic process was adopted to form the direct metal to metal joint between the chip and substrate. Ultrasonic process offered several advantages such as lower bonding temperature and shorter bonding duration over thermal compression process. However, the US process demand bumps with good co-planity of less than 0.6μm and good surface finishing.The copper bumps were coated either with TiAu, ENEPIG, and ENEP to prevent oxidation occurring during the bonding process. Detail DOE experiment was conducted to evaluate the bonding quality. Shear test and x-section analysis revealed that chips coated with either TiAu or ENEPIG could form a bond on silicon substrate coated with TiAu with optimized US parameters.The developed US bonding process successfully demonstrated on C2C application.

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Electrochemical migration study of fine pitch lead free micro bump interconnect

Cited by 3 publications

References 15 publications

A Novel Approach for Temperature-Induced Ball Grid Array Collapse Observation

A Novel Approach for Temperature-Induced Ball Grid Array Collapse Observation

Bumping and stacking processes for 3D IC using fluxfree polymer

Fine pitch solder-less bonding using ultrasonic technique

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