SMTs | IN REVIEW
Solder Paste for SMT Exhibits High Void Reduction Effect
With high void reduction, KOKI’s S3X58-G803 solder paste promotes stable performance of automotive and power semiconductor devices.
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OKI Co., Ltd. has been expanding its global business by offering unique solder products. As part of its efforts, the company has released the S3X58-G803 solder paste, which exhibits high void reduction effect for various mounting materials and components, for surface-mounting technology (SMT).

Voids are air bubbles that remain in solder after mounting. They affect bonding quality such that they contribute to impaired heat dissipation of components and to the progress of cracks. Further reduction of voids is required for power semiconductor components that are widely used in automotive devices and power supply devices.

Significant Void Reduction
KOKI’s S3X58-G803 solder paste enables drastic reduction of voids with the removal of metal oxide film at the early stage of preheating. It also achieves swift wetting to the electrode section and discharge of flux components outside the solder.

As flux remains less in the solder, the growth of voids is suppressed. S3X58-G803 exhibits excellent level of continuous printing and intermittent printing performance that ensures stable low voids, and supports the mounting of 0603 chips as well.

Various kinds of components, including power transistors, quad flat no lead packages (QFNs), small-outline packages (SOPs), and ball grid arrays (BGAs) are used for surface mounting. Surface finishes of substrates on which these components are mounted, such as organic solderability preservative (OSP), immersion tin (ImSn), and electroless nickel/immersion gold (ENIG), also vary.

S3X58-G803 solder paste for SMT
S3X58-G803 solder paste for SMT
S3X58-G803’s flux is designed to suppress the generation of air bubbles, insufficient wetting of solder, and discharge failure of air bubbles and flux, which are the factors for the occurrence of voids. Thus, it achieves low voids in all types of mounting materials and components.

As the flux deteriorates less in high temperatures and sustains high active force, S3X58-G803 exhibits excellent wettability. With improved heat resistance, it does not only achieve low voids, but also suppress the occurrence of head-on-pillow. Stable transfer rate and securing of printing shape were confirmed in 0.25mmΦ chip scale package (CSP) and 0.4mm-pitch quad flat package (QFP).

Furthermore, as the drop of transfer amount during the halt of printing is small, consistent transfer quality is maintained. The solder paste exhibits good meltability for fine patterns and supports mounting of 0603-size components.