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Thermal Design of Semiconductor Components in Electronic EquipmentPrecautions Regarding Mounting by Hand Soldering

2023.07.05

Points of this article

・When using hand soldering to mount components on the surface of an evaluation board, thermal resistance may be high.

・When mounting components on a board where heat-related evaluations are necessary, as a rule reflow mounting is used for surface-mounted components.

When mounting ICs on an evaluation board for use in evaluating thermal resistance or the like, there may be cases in which a heat gun or hot plate is used in mounting by hand soldering of surface-mounted package components. When soldering by hand, solder does not extend over the entirety of the exposed pads on a package rear surface, particularly when the area is greater, and insufficient solder wettability may occur. An IC chip is mounted on the exposed pads on the package rear surface, and the pads are important for heat dissipation. If the package is not mounted properly on the mounting board via solder, the expected heat dissipation may not occur–that is, thermal resistance may be increased.

Below are an X-ray image showing the solder wettability for hand-soldered mounting and reflow mounting, and a graph of a structure function showing the thermal resistance. As the X-ray images indicate, hand-soldered mounting results in insufficient solder wettability of the exposed pads on the rear surface, and the thermal resistance is high as a result. When evaluations relating to heat are needed, as a rule surface-mounted components should be mounted using reflow soldering.

【Download Documents】 Thermal Design of Semiconductor Components in Electronics

Thermal design has become a new issue in the design of electronic equipment in recent years, as thermal countermeasures have been the focus of attention. Although heat has been an important consideration for some time, the requirements for electronic equipment have changed in recent years, making it necessary to review conventional thermal countermeasures. This handbook describes thermal design based on the assumption that ICs and transistors are basically used in electronic equipment.

Precautions Regarding Mounting by Hand Soldering

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