Those two well-established technologies used that way, result in the generation of so-called Lasercavities, where Flip Chips are being integrated. The Lasercavity technique offers stable and reliable joints between components and bare board of highest precision in short processing times, thus quite a cost- saving technology.

The increasing integration level in multilayer boards poses a challenge for electronic designers, component experts as well as for PCB manufacturers. Innovative and practicable solutions are in demand right now. By Lasercavity, Würth Elektronik offers the suitable concept that meets those demands. "Integrated instead of superimposed ", is the principle of integrating active components, as simple as ingenious.

A Lasercavity of up to 300 μm depth is being carved out in a printed circuit board’s inner layers. There, laser technology allows for highest precision both in dimensions and depth of the emerging notch and its position. A stable cavity is made, coated with a special adhesive. Afterwards, Flip Chips are being placed by means of a so called „Die Bonder". The adhesive is being cured within a few seconds under specific pressure. At the same time, the chips’ stud bumps are being solder-joint with the PCB by targeted exposure to pressure and temperature. That provides for additional stability of the Lasercavity and enhances the system’s reliability.



Based on many years of experience in micro via technology, a cooperation with the Fraunhofer Institute and an expert of die bonding, we managed to create a technique with so called Lasercavities which is impressing by its simplicity and efficiency. Those are ideal conditions for making that new technique soon coming out on top, explains Roland Schönholz, product manager HDI-microvia at Würth Elektronik and creator of the Lasercavity-idea.

Reliability tests exceeding expectations
Numerous production cycles showed that laser cavities with bonded Flip Chips can be processed in the multilayer production in standard processes without any restriction. Reliability tests with Lasercavity-PCBs were completed successfully and are outranging expectations to that new technique. Neither thermal shocks nor long-term temperature exposure had an impact on the bonding joint between PCB and Flip Chip.