By Dr. Phil Garrou, Contributing Editor

Finishing up our look at the 2018 SMI ISS meeting, let’s take a look what John Hunt, ASE, had to say about the “Transformative Power of Fan-Out.”

Without question so called “fan-out packaging” has become the new packaging buzz word having replaced 3D-IC a few years ago. Focus on this technology has quickly (vs 3DIC) produced significant technical advances and led to broad commercialization. Although IFTLE has covered this technology in detail since its inception by Infineon, it is always good to review it one more time, which is what John Hunt did for the mostly front end folks assembled at Half Moon Bay.

Hunt’s slide shown below is an extension of the well worn slide showing why wafer level packaging developed with a low cost structure, i.e. the packaging was done on the wafer before dicing. Hunt contends, correctly, that the same is true for the WL FO WLP, though I would add that this also shows why the early eWLB structures from Infineon couldn’t get down low enough in cost for major market penetrations, i.e. the extra steps involved with creating the reconstituted wafer.

Fan Out Enables Multi Die Packages

• Advanced technology nodes increase wafer cost
• Fan out allows partitioning into different nodes
  • See DARPA CHIPS concepts in IFTLE 367 “DARPA CHIPS Headlines 14th 3D-ASIP Conf “
• Fan out allows partitioning of functionality
  • Digital, Analog, Components, MEMS, and IPDs

Fan out can be done either chips first or chips last as shown below. The newer chips first, face up (followed by planarization) and chips last options have resulted in much higher density interconnect which has allowed competition with some of the silicon 2.5D applications.

The high density fan out chip on substrate (FOCoS) is capable of 2/2.5um L/S and 4 metal layers as shown below:

Significantly thinner PoP can now be fabricated I much thinner formats:

In addition, they are still looking at moving FOWLP technology to large panel format in an attempt to continue to lower costs even further.

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