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Consortium Investigates Warpage, Die Shift in Large-Format Reconfigured Panels
BERLIN – The second incarnation of a panel level packaging consortium, PLC 2.0, investigated warpage and die shift in large-format reconfigured panels (18″ x 24″), and considerable progress has been made toward understanding the root causes.
Figure 1. First results of PLC 2.0: Detailed view of a fully populated panel with embedded chips.
Figure 1. First results of PLC 2.0: Detailed view of a fully populated panel with embedded chips.
The first incarnation of Panel Level Packaging Consortium (2016-19) consisted of 17 international partners from industry and focused on the entire process chain in panel-level packaging: assembly, molding, wiring, cost modeling and standardization.

With the second consortium, the focus has shifted to die placement and embedding technology for ultra-fine-line wiring down to 2µm lines and space with a potential move to 1µm. As such, migration effects and ways to exploit the migration limits of fine line wiring have become areas of interest for the consortium, whose members include Amkor, ASM, AT&S, Atotech, Corning, DuPont, Schmoll, and Showa Denko, among others.

One major focus of the project has been the investigation of warpage and die shift in large-format reconfigured panels, and the group reports “considerable progress” has been made toward understanding root causes. With these insights, the relevant parameters can now be controlled better to enable large-area fine-line RDL processes. The analytical effort has paid off, as RDL could be scaled down considerably on the panel level, making the most of the advantages of both wafer and panel-level technologies and paving the way for an entirely new process chain with new equipment and materials.

Figure 2. FIB cut of an ultrafine line wiring layer on panel size (pitch: 5µm).
Figure 2. FIB cut of an ultrafine line wiring layer on panel size (pitch: 5µm).
The partners are now expecting 12 months of agile progress, developing and managing viable process options on the road to a complete high-yield process chain. Test vehicles for electrochemical migration tests were designed in accordance with IPC standards; the design of the test vehicles was guided by the standard’s description of the IPC multi-purpose test board, but with the structure sizes matched to the geometries reflecting the goals of the PLC 2.0 project as interdigital structures. Researching a combination of economic and environmental assessments to promote more sustainable production approaches is another strong part of the PLC 2.0. A first model to estimate the carbon footprint of the PLP technology has already been established. This first calculation will help all members identify the most energy-intensive stages and further improve the data quality in the most relevant steps.