Hot bar reflow soldering

Hot bar reflow soldering (or pulse heat soldering) is a selective soldering process that uses a heated element (thermode) to apply localized heat and pressure, enabling precise component attachment to PCBs. Pre-fluxed, solder-coated parts are aligned and heated until the solder reflows; the joint is then cooled to solidify, forming a durable electro-mechanical bond.

This method offers high positional accuracy, minimal thermal stress on adjacent components, and consistent joint quality—ideal for applications like FPC bonding, display module assembly, and fine-pitch connectors.

In mobile and automotive electronics, increasing circuit density necessitates multilayer designs. These layers are commonly interconnected using flexible circuit carriers or foil connectors, typically joined via hot bar reflow soldering. This method is also suitable for attaching display drivers on flex to rigid PCBs, as well as connecting flat or foil cables to components like connectors and boards.

Hot Bar Reflow Soldering is ideal for components requiring high-precision alignment. Unlike conventional methods, it uses a thermode to heat and cool each joint, applying constant pressure throughout the cycle—from heating to solidification. This ensures stability during cooling, reducing the risk of misalignment. Additionally, it allows for simultaneous soldering of multiple connections (over 100 mm in length), minimizing mechanical disturbance between adjacent joints.