INTRODUCTION

Today’s requirements for professional repair and rework of QFN components (Quad Flat No leads), have SMD repair systems facing tough challenges. On one hand, QFN components are generally delivered without a solder ball / deposit and, on the other, the leads are located on the underside of the chip (fig. 1). Furthermore, QFN’s often have a large ground pad for their thermal management. Because of these specific features, the Rework-system has to have certain characteristics to ensure professional repair of the device.

PROCESS

During the repair you have to make sure that the neighbouring components will be not affected by the thermal stress. The placement accuracy of the new component is also a key feature. These main characteristics are combined in the R-System for a professional and efficient way of rework. Tresky’s R-System provides the operator with precise positioning of the components using its innovative Beamsplitter optic (fig. 2) in combination with a video camera to display it on a monitor. For the soldering process, the R-System uses a combined hot air (top heater) and IR ceramic (bottom heater) system. The hot air top heater provides, with an optimized design of the nozzle, the possibility of a soldering profile (IPC/JEDEC) which ensures not to damage any neighbouring components (fig. 3). The IR bottom heater support uniform heating of the PCB to avoid twisting and warping. The bottom heater can be provided in different power rating and sizes.

Conclusion

With 30 years of experience, Tresky AG offers its customers a repair system that makes a comprehensive and repeatable process for rework and repair possible. From over desoldering, solder removal, applying new solder paste, and soldering of a new component, the flexible platform combines modularity with all process steps.

Recommended Tresky equipment

• R-System 1200

• Beam Splitter Optics

• Solder removal module