1.Alternative solution to 2.5D

2. Substrate for Chiplets*:

RDL 1: 0.5 µm Dielectric 1: SiO2, SiNx
RDL 2: 2 ~ 10µm Dielectric 2: Polyimide
RDL 3: 15~50µm Dielectric 3: Laminate Materials

*: Proposed by DC Hu in
“An Innovative System Intergration Technology beyond BEOL”
DC Hu, IEEE International Interconnection Technology conference, June 2018

Cost Savings in eHDF Structure Saving 1: No Core in Interposer and Substrate

  1. Save silicon and Substrate core materials cost.
  2. Save TSV and TLV via forming and via filling process cost.

Cost Savings in eHDF Structure Saving 2: No Solder between the Interposer and Substrate

  1. Cost saving on surface finishing, Solder mask, solders and underfill material.
  2. No interposer to substrate assembly process cost.
  3. Less materials used and environmentally friendly solution.

Compare 2.5D and eHDF Solution

Z Height Comparison

  1. Thickness reduction
  2. No intra-solder reliability issues.

Chips on eHDF Substrate

eHDF Savings:
  1. No Silicon(TSV) and laminated cores.
  2. Need only half of the the interposer and substrate surface finishing.
  3. No need of solders between the Interposer and the substrate.
  4. No interposer to substrate assembly cost.
  5. Better electrical performance and simplify the logistic.

Compare HPC Substrate Solutions in the Market

✤: Can be mechanically enhanced by eHDF-OCS or eHDF-eST structure.

eHDF Technology Passed the Substrate Companies Reliability Evaluation

eHDF-OCS and eHDF-eST substrate have passed the substrate company reliability evaluation, respectively.


eHDF structure on Cored Substrate


eHDF structure with embedded Stiffener

*: Picture Curtesy of Nanya PCB.
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