SMTs | IN REVIEW
KOKI Develops Complete Halogen-Free Solder Paste for Harsh Environments
By employing paste flux technology, KOKI has created a halogen-free solder compatible with air reflow and provides excellent meltability and wettability.
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OKI Co., Ltd. has released a complete halogen-free solder paste with high durability alloy composition in its lineup of soldering products for surface-mount technology (SMT).

In applications that involve harsh-use environments, like on-board equipment, industrial equipment, and motor and engine peripheral components, solder pastes with high thermal durability and maintain good joining quality for a long period of time, are required.

Fully Halogen Free
KOKI has been deploying high durability alloy products with excellent thermal durability to varied customers. This time, the company has commercialized the SB6N58-HF350 complete halogen-free solder paste that adopts high durability alloy, meeting the growing demand for complete halogen-free from the viewpoint of environmental friendliness.
SB6N58-HF350 complete halogen-free solder paste
SB6N58-HF350 complete halogen-free solder paste
The SB6N58-HF350 solder paste with alloy composition excellent in thermal durability is categorized as ROL0 according to IPC J-STD-004B. It is a complete halogen-free product with no intentional addition of halogen substances. It has achieved complete halogen free and improved usability, while retaining the same level of joint reliability, viscosity stability and meltability as the conventional halogen-containing solder paste of the same alloy.

As a result of thermal cycle test at -40 to +150°C, it has been confirmed that SB6N58-HF350 developed no cracks after 1,500 cycles. This shows that the solder joining section has been strengthened by the effect of additive element in the alloy, and the solder paste secures normal electrical conduction without impairing the reliability of the joining section even under harsh use environments.

From the viewpoint of environmental consideration, demand for halogen free has been expanding worldwide. Although it has been technically very difficult to secure wettability and meltability without adding halogen substances to the solder paste, KOKI has employed paste flux development technology, which is the company’s forte. As a result, the company has developed SB6N58-HF350, which is fully halogen free, and is compatible with air reflow and provides excellent meltability and wettability. It has an alloy composition of Sn+3.5Ag+0.5Bi+6.0In, and melting point of 202 to 210°C.

As a variation, KOKI offers SB6NX58-HF350 targeting customers that employ electroless nickel/immersion gold (ENIG) for surface finish of PCBs.