The Microstructure and Shear Strength of the BGA Joint Using Cu Cored Sn-3.5Ag Solder.

Kohara, Yasuhiro; Saeki, Toshio; Uenishi, Koji; Kobayashi, Kojiro F.; Shohji, Ikuo; Yamamoto, Masahiro

doi:10.5104/jiep.4.192

Cited by 6 publications

(3 citation statements)

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“…13,14) In addition, SB/SA most all of Bi was in solid form dissolved in Sn. After heat exposure at 423 K, Ag 3 Sn changed morphology and assumed a more equiaxed shape.…”

Section: Melting Behavior Of Solder Ballsmentioning

confidence: 99%

“…In particular, the effect of Cu-core balls on controlling the interaction with Au/Ni plating will be a key issue in obtaining reliable BGA joints since this interaction is reported to be enhanced for Pb-free solders due to its higher reflow temperature and larger molar fraction of Sn. [9][10][11] Cu-core Sn-Pb solder balls are normally prepared by electroplating solder on Cu balls. After the promotion of research to develop Pb-free solders, Sn-Ag based solders were recognized as the most promising candidates due to their superior mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

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Melting and Joining Behavior of Sn/Ag and Sn-Ag/Sn-Bi Plating on Cu Core Ball

et al. 2002

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We fabricated Cu core Sn-Ag solder balls by plating pure Sn and Ag on Cu balls and clarified that Sn/Ag plating began to melt at a rather low temperature, the eutectic temperature of Sn-Ag-Cu. This early melting at the eutectic temperature was ascribed to the diffusion of Cu and Ag into the Sn plating during the heating process. We investigated the solderability of the BGA joint with the Ni/Au coated Cu pad to compare it with that of the commercial Sn-Ag and Sn-Ag-Cu balls. After reflow soldering, we observed a eutectic microstructure composed of β-Sn, Ag 3 Sn, and Cu 6 Sn 5 phases in the solder, and a η -(Au, Cu, Ni) 6 Sn 5 reaction layer was formed at the interface between the solder and the Cu pad. The BGA joint using Cu core solder balls could prevent the degradation of joint strength during aging at 423 K because of the slower growth rate of the η -(Au, Cu, Ni) 6 Sn 5 reaction layer formed at the solder-pad interface. Furthermore, we were able to fabricate Cu-cored, multicomponent Sn-Ag-Bi balls by sequentially coating binary Sn-Ag and Sn-Bi solders onto Cu balls. The coated balls also exhibited almost the same melting and soldering behaviors as those of the previously alloyed Sn-2Ag-0.75Cu-3Bi solders.

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“…13,14) In addition, SB/SA most all of Bi was in solid form dissolved in Sn. After heat exposure at 423 K, Ag 3 Sn changed morphology and assumed a more equiaxed shape.…”

Section: Melting Behavior Of Solder Ballsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Melting and Joining Behavior of Sn/Ag and Sn-Ag/Sn-Bi Plating on Cu Core Ball

et al. 2002

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“…[2] Since the joints are formed with solder balls, many studies of the reliability of the joints made with lead-free solder balls have been performed. [3][4][5][6][7][8][9][10][11][12][13] In most of these studies, the joint strength of the solder ball joint was examined at lower shear speeds using a ball shear tool. Since the increasing popularity of mobile products has made the impact reliability of the solder ball joint a critical issue, [14] impact tests have been used to examine the impact strength of solder ball joints at higher shear speeds.…”

Section: Introductionmentioning

confidence: 99%