By Dr. Phil Garrou, Contributing Editor
Continuing our look at the GaTech Global Interposer Technology Workshop.
Krause of LPKF detailed their laser formation of through glass vias (TGV). They claim to be capable of forming 5000 TGV/sec. Their two step process is shown below.
They are reporting that their prototype tool will be available in 2Q 2015 and available on the market in 4Q2015.
Seki of NTK described their work on glass core substrates which can be used as both interposer substrates and cores for high density laminate substrates.
The fabrication process is shown below:
Because of the high modulus, glass core has less warpage than laminate with or without dies.
With CO2 laser drilling cracks were observed in the polymer laminated glass, reportedly due to the CTE mismatch between the polymer and glass and the stresses induced by the laser drilling. The thicker the polymer coating the higher the induced stress.
2um L/S and 10um TGV appear possible for this system.
DC Hu of Unimicron reviewed their perspective on the “Glass as a Substrate Material for High Density Interconnects”.
Their process flow for using glass sheet to replace woven glass core for PCB laminate is shown below. It has been run on a 508mm x 508mm panel size.
Techniques for L/S reduction are shown below:
The embedded interposer carrier is an option to eliminate the solder joints between the interposer and organic substrate.
Abe Yee of Nvidia described their program with TSMC and Hynix for their future gen graphics modules.
Nvidias GPU roadmap shows the 2016 entry of Pascal with 3D memory:
Yee comments that “Memory to GPU requires 2.5D with TSV”.
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