Overcome high density substrate shortage by using Fan Out Chip Module

High performing computing, artificial intelligent and networking are growing significantly. But, getting high density substrate is difficult. Particularly high layer counts substrate, its cycle-times normally take a year, the yield is particularly low; cost of the substrate is high.In this paper, we are converting a high-density substrate from 9-2-9 layers to 3-2-3 layers. This could be accomplished by transferring some substrate layers to Fan-Out redistribution layers (RDL). The overall structure of this Fan-Out Multi-Chip-Module (FOMCM) consists of two chips; 5-RDL layers with Cu line/space (L/S) of 2/2 μm; and flip overed on a 3-2-3 substrate. This FOMCM package is equivalent to a FOMCM with 3-RDL layers; Cu L/S of 4/4 μm and 9-2-9 layers substrate. By using this approach, we reduced the overall cycle time by half, and improved total package cost by 30%. This FOMCM package is achieved by using RDL first. Thus, the fabrication of RDL layers and IC chips could be done in parallel. By using this approach, we could attain higher fabrication yield. Upon completion of assembly, this package is undergone the similar reliability tests. And demonstrated equivalent reliability performances, without any RDL damage. Details of the assembly package structures results are presented and discussed. The successful of this demonstration enables the supply chain issue by using the mainstream 3-2-3 substrate supply.