The FanOut process generally represents the redistribution of the electrical interconnections located inside and outside of the die envelope. FanOut can also fall in the category of eWLP (embedded Wafer Level Package), eWLB (embedded Wafer Level Ball Grid Array), FOWLP (FanOut Wafer Level Package), WLSiP (Wafer Level System in Package), etc. The FanOut process can also embed chip capacitors and inductors. The FanOut process is also being considered for 3D die stacking as well.
The FanOut technology is basically a process of reconstituting a new wafer based on all KGD (known good die). KGD are accurately placed and temporarily held on to an interposer with double sided sticky tape or an adhesive. Then, EMC (Embedded Mold Compound) is applied to create a new wafer or panel. Once the new wafer or panel is created then the frontend lithography steppers apply the RDL (Redistribution Layer) connecting and relocating the interconnections. The RDL process demands that all die be placed with micron accuracy over the entire wafer. One of the major challenges is finding a die attach machine that can place all die with micron accuracy while maintaining this accuracy over a very large bond area for example, die placement accuracy of ±3μm @ 3σ at 3,000 UPH (Units per Hour) over an area of 600mm x 600mm.
ASMPT AMICRA offers a die attach solution dedicated to the FanOut process and offers additional features and options to support today’s known process and future variations that inevitably evolve as the FanOut process matures. Amicra serves the high volume production segment of the FanOut market.
NOVA FanOut supports:
A wafer cassette is manually loaded into the machine and the first wafer is automatically loaded on to the X-Y table of the pick-up station while an interposer wafer/panel is automatically presented to the X-Y table of the bond station. KGD are removed from the wafer film frame via a chip ejector and vacuum pick-up tool. The die is then transported directly to the bond station where the die is bonded to the interposer using the features of adjacent die as local fiducials. This process is repeated until the interposer is fully populated reconstituting the wafer/panel. It is worth noting that the NOVA FanOut supports a heated bond tool where heat can be efficiently applied to the die to help secure the die to the interposer. The reconstituted wafer/panel can be automatically transported out of the machine on an edge belt conveyor while a new interposer is presented to the bond station.
The NOVA FanOut system also supports an upstream adhesive dispense system where futuristic adhesives or material may be required to be dispensed prior to the bond station. For example, to ensure the bonded die does not move during the mold process other adhesives may need to be dispensed immediately prior to the bonding process.
Note: The ASMPT AMICRA systems are essentially a vision driven die attach machine consisting of 4x automatic vision systems located throughout the machine, all imaging systems (camera, optics and illumination) are fixed to a very rigid structure made of granite. Imaging systems are located: