Its flux system is optimized for SAC alloys, and the broad process window is not minimized by long preheating procedures with higher temperatures. Its consistency in the print process itself is stable, even with high print (ambient) temperatures up to 32°C. The material can be printed in short cycles due to high squeegee and lift-off speed. Once printed, the paste remains tacky for about 8 hours in order to place the components into the wet paste. The actual time span for tackiness is of course depending on the individual environment conditions. Heraeus said that they have gained very good results with this paste on many different board surfaces, whereby the no-clean residues are clear in their color. Reportedly, intensive testing by users revealed optimum print results in demanding assembly applications. Within the wide range of different pastes types in the F640 series, there are formulations available for virtually all lead-free board assembly applications, for touch-up procedures and solder wires as well. There are also paste types offered for dispensing operations delivered in various syringe sizes. As W.C. Heraeus’ Circuit Materials Division (CMD), Business Unit Assembly Materials is responsible for the development of leading materials for high-specification circuit assembly and semiconductor packaging tasks. The materials are designed and tested against the stringent demands of automotive, telecom, high reliability, semiconductor packaging and consumer electronics applications.
The Heraeus’ PCB test board Benchmarker II has been used in this demo as the standard print substrate for all machines used, applying the above mentioned solder paste from this supplier in order to allow a direct comparison with each machine. Heraeus has been using the Benchmarker II for the verification of the entire process from paste print up to the final reflow soldering, for example controlling solder ball generation or the tombstoning effect of 2-pole components. There is an abundance of different circuit-like structures and pad geometries on its golden contact surface, representing the footprint of passive (resistors, capacitors, etc.) and active components such as ICs, QFPs, BGAs/flip chips, etc. in all variations and pitches of today’s manufacturing requirements. The following parameters can be verified with this board: line resolution, the volume of solder joints for many different component packages, bridges, short circuits, voids, wetting of different pad areas and the printing behavior after a stop in the process. Together with the appropriate software package a model-based, statistical planning of the experiment and its analysis is possible. (gbw)
SMT, booth 9-537, 7-404, 7-639
EPP Europe 407
