LIFT for die-attachment and assembly of ICs and PICs
LIFT for die-attachment and assembly of microelectronic components
The capability of LIFT to print die-attach materials on substrates relevant to the microelectronic packaging and assembly technologies, with digital control over the resulting form factors, has been demonstrated in the project “SYN-LASER”. Novel results by NTUA show that LIFT offers control over both the lateral and vertical dimensions of deposited solder paste bumps [1]. This control can facilitate the soldering process of heterogeneous components, whose pads have significant height and pitch dissimilarities. To this end, the optimized process parameters are first identified, such as the donor/receiver gap, laser spot size and laser fluence. Next, the actual printing process is described, followed by the selective sintering of the printed patterns employing laser sintering, using the same laser source as in the LIFT process. Therefore, two digital processes are subsequently applied for microfabrication of bumps and linear patterns, interesting for die-attachment, PCB assembly and soldering applications.
In the following Figure, an example of the vertical stacking of Ag paste bumps utilizing LIFT is presented.
The laser printing of solder bumps on a Au/Ni/Cu pad was investigated towards the direction of demonstrating that the reported process is fully compatible with the widely used pad materials in PCB technology [2]. The following figure comprises a schematic of LIFT printing of solder paste on PCB pads, (b) resulting printed solder paste circular pattern at 2 m/s (c) resulting printed solder square micro-pattern at 2 m/s.
Finally the last figure demonstrates the capability of LIFT for interconnecting components on microelectrodes: (a) Image of laser-printed and sintered linear patterns each connected to their respective pads; (b) Image of laser-printed solder paste stacked micropatterns on pads; (c) Image of the deposited pin connectors on the solder micropatterns prior to thermal treatment; Insets: Profilometry measurements of the LIFT printed and sintered pad (top left) and linear pattern (top middle) and of the LIFT printed solder paste micro-pattern (top right); (d) Operating a commercial LED by applying 3 V on LIFT printed and laser sintered silver pads.
[1] “Laser-Induced Forward Transfer (LIFT) technique as an alternative for assembly and packaging of electronic components”, F. Zacharatos, M. Makrygianni and I. Zergioti, in IEEE Journal of Selected Topics in Quantum Electronics, 27(6), 1-8, (2021). 10.1109/JSTQE.2021.3084443
[2] “Eco-Friendly Lead-Free Solder Paste Printing via Laser-Induced Forward Transfer for the Assembly of Ultra-Fine Pitch Electronic Components”, M. Makrygianni, F. Zacharatos, K. Andritsos, I. Theodorakos, D. Reppas, N. Oikonomidis, C. Spandonidis, I. Zergioti, Materials, 14, 3353, (2021). DOI: 10.3390/ma14123353
Nowadays, the wide adoption of hybrid and complex integration schemes have introduced new challenges in the field of microelectronic component assembly. NTUA, within MatEl project will address most of the integration challenges, by introducing an integration scheme, where laser-based processes (LIFT and laser soldering) are utilized for the integration of optoelectronic components. The overall process chain is outlined below:
Figure 1. Schematic with LIFT, pick and place, Laser soldering
MatEl’s innovative solution, enhanced by the monolithic integration of advanced materials – graphene and high-quality PZT, will thus be demonstrated for two selected next-gen devices at TRL5:
AR display featuring a 2D light source for light-field with on-chip RGB lasers and OEIC-based demultiplexer.
Bio-photonic sensors for reliable and low-cost detection of Covid-19 featuring integrated on-chip VCSEL at 850 nm and Graphene-based photodetector.
This project has received funding from the European Union: Horizon Europe Project (Grant n. 101091774)
research and innovation program under grant agreement No 101058079.