The study of OSP as reliable surface finish of BGA substrate

Chang, David; Bai, Fengsong; Wang, Y.P.; Hsiao, C.S.

doi:10.1109/eptc.2004.1396594

Cited by 19 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…OSP vaporization during the reflow process caused a direct contact between the copper pillar and the solder, thus expediting the dissolution of Cu. It is reported that quick dissolution of Cu causes the formation of thick IMCs [7]. Moreover, the nickel layer was relatively thick and remained intact In the TS test , as shown in Fig.…”

Section: Osp-capped Copper Pillar Interconnection Fcommentioning

confidence: 94%

“…For instance, an ENIG surface finish provides an oxidation and diffusion barrier layer between the Sn-based solders and copper conductor [5], [6]. Inexpensive OSP surface finishes can be easily removed during the reflow process, enhancing the solderability of the joint [7], while a lead-free SnAg surface finish exhibits good wetting/solderability behavior on copper and is resistant to microstructural coarsening [8]. Because the reliability of the joint is significantly affected by the property of the surface finish, it is important to understand the influence of different surface finishes on the reliability of copper pillar interconnections.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Intermetallic Formation of Copper Pillar With Sn–Ag–Cu for Flip-Chip-On-Module Packaging

Huang

Yeow

Poo

et al. 2008

IEEE Trans. Comp. Packag. Technol.

View full text Add to dashboard Cite

Copper pillar interconnects are a popular interposing option due to the advantages of small pillar size and good thermal and electrical performance, making copper pillar interconnects very useful for high-frequency and high-density flip-chip-on-module (FCOM) packages. However, the challenges associated with the technology include controlling the formation of brittle intermetallic compounds (IMC) and weak interfaces during heat-related processes, and preventing copper migration during bonding and reliability testing. As the reliability of the joint is significantly affected by the property of the surface finish, it is important to understand the influence of different surface finishes on the reliability of copper pillar interconnections. This paper focuses on Ni/Au-capped, Sn-capped, Sn-2.5Ag-capped, and organic solderability preservative (OSP)-capped copper pillar interconnections with lead-free Sn-3.0Ag-0.5Cu solder paste in FCOM packages. The types, morphology, and distribution of IMC formed in the bulk solder, the copper pillar/SAC, and copper pad/ENIG/SAC interfaces during multiple reflows (265 C) and reliability testing [thermal cycle (TC), autoclave (AC), high-temperature storage (HTS), and thermal shock ([TS)] were investigated using a scanning electron microscope with energy dispersive X-ray (SEM-EDX). The feasibility and reliability of these copper-pillar FCOM systems were also compared and evaluated. The reliability results show that OSP-capped copper pillar interconnects are the best interposing option in terms of reliability and performance.

show abstract

Section: Osp-capped Copper Pillar Interconnection Fcommentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Intermetallic Formation of Copper Pillar With Sn–Ag–Cu for Flip-Chip-On-Module Packaging

Huang

Yeow

Poo

et al. 2008

IEEE Trans. Comp. Packag. Technol.

View full text Add to dashboard Cite

show abstract

“…So it is foreseen that CuOSP pad will continue to be the surface finish pad of choice not just for reliability improvement but also for cost savings and simpler more environmentally friendly manufacturing process (5). There are drawbacks to CuOSP in that it is sensitive to thermal, humidity, and physical effects resulting to poor wetting (6).…”

Section: Surface Finish Issuesmentioning

confidence: 99%

Dippable Paste: A Robust Assembly Material and Enabling Technology

Lathrop

2009

ECS Trans.

View full text Add to dashboard Cite

Despite the tackiness offered by ball attach fluxes, they have failed to prevent ball movement on Solder on Pad (SoP) finishes when the solder protrudes above the solder mask. Dippable solder paste provides the tackiness needed for these adverse situations as well as small solder particles that inhibit ball rolling due to mechanical or convective forces downstream. Also, other pad finishes like OSP has issues with oxidation with partial pad wetting as a common defect. The use of dippable paste has also demonstrated relief with these wetting related issues. The most current application of dippable pastes is in the assembly of stacked BGA's also known as Package on Package (PoP). Although water clean formulations are typical in BGA assembly, PoP assembly typically utilizes no clean formulations. Although tacky flux has been successful in many PoP applications, issues such as coplanarity and package tolerances that require increasing the sphere size during assembly have found benefit from dippable solder paste.

show abstract

“…However, many shortages have limited the use of it, such as the weak of high temperature shock resistant and the brittle of the intermatellic compounds (IMCs). OSP pad treatment has high strength solder joints and is environment friendly, so it is widely used in electronic assembly industry [2][3]. The ENIG finish is less expensive than electrolytic Ni/Au but the former may cause"black-pad" phenomenon [4][5], so resulting in soldering joint reliability decreasing.…”

Section: Introductionmentioning

confidence: 99%

Influence of multiple reflows and thermal shock on interfacial IMC of solder joints between Sn0.3Ag0.7Cu solder/pads(HASL, OSP, electrolytic Ni/Au and ENIG PCB finishes)

Wei

Luo

Shi

et al. 2011

2011 International Symposium on Advanced Packaging Materials (APM)

View full text Add to dashboard Cite

The effects of multiple reflows and thermal shock on interfacial reaction of the solder joints between Sn-0.3Ag-0.7Cu solder/pads (HASL, OSP, electrolytic Ni/Au and ENIG PCB finishes) were systematically investigated in this work. The results showed that the scallop Cu 6 Sn 5 phase were formed in HASL and OSP finish pads during reflows, whereas the cylinder-type (Cu,Ni) 6 Sn 5 near the solder and needle-type (Ni,Cu) 3 Sn 4 adjacent to the Ni layer were formed in electrolytic Ni/Au and ENIG finish pads. For all the four kinds of finishes, the thickness of IMCs increased with reflow times increasing, and the interfacial IMCs growth was controlled by grain boundary diffusion; the growth rate at Cu surface was faster than at Ni surface. Furthermore, it was also indicated that the interfacial IMCs growth were not notable with thermal shock cycle numbers increasing, but Kirkendall voids could be observed in the Sn-Cu-Ni intermetallic compounds layer for electrolytic Ni/Au and ENIG Finish Under thermal shock tests.

show abstract

The study of OSP as reliable surface finish of BGA substrate

Cited by 19 publications

References 0 publications

Intermetallic Formation of Copper Pillar With Sn–Ag–Cu for Flip-Chip-On-Module Packaging

Intermetallic Formation of Copper Pillar With Sn–Ag–Cu for Flip-Chip-On-Module Packaging

Dippable Paste: A Robust Assembly Material and Enabling Technology

Influence of multiple reflows and thermal shock on interfacial IMC of solder joints between Sn0.3Ag0.7Cu solder/pads(HASL, OSP, electrolytic Ni/Au and ENIG PCB finishes)

Contact Info

Product

Resources

About