Laser separation technique: Multiple Laser Beam Technology (MLBT)
The two main requirements for any separation process are a superior cutting quality – in terms of visual appearance and structural integrity of the cut – and a low throughput time. The latter depends to a great extend on the dicing speed thus the material removal rate of the process. In the case of laser dicing both requirements are generally speaking diametrical opposed to each other. The material removal rate scales with increasing laser power, the dicing quality deteriorates accordingly. Typically a fast laser separation process comes along with a wide cut, rough edges, increased volumes of recast and burr as well as a pronounced heat affected zone (HAZ).
Process parameters such as intensity (= power / irradiated surface), focus size, pulse duration, pulse repetition frequency and feed rate may influence the processing result. By choosing the combination of these parameters which is best suited for a certain application, dicing speed and quality can be optimized. However key to a good dicing quality is a limited local energy input. This means only a fraction of the power, that most lasers that are developed for material processing generate, can thus be used. External beam attenuation significantly decreases the efficiency of single spot laser dicing tools. Moreover the number of low energy pulses per unit of length which are necessary to dice though the target material is comparably high which results in an unfavorable throughput time. This is where ALSI’s proprietary multiple laser beam technology (MLBT) comes into play.
By splitting up a single laser beam in numerous components – depending on the application, the number of beams can reach up to about 100 – the local energy input is limited provided sufficient spacing between adjacent spots is guaranteed. At the same time the total energy available for material removal is considerable. Compared to a single beam a number of n beams remove more than n times as much material per time provided the energy content per laser spot is kept constant. This way ALSI’s MLBT combines the dicing quality of a low power single spot process with the process speed of a high power process. A low throughput time can be combined with a high quality separation.