Sorting-based I/O connection assignment and non-Manhattan RDL routing for flip-chip designs

Ran Zhang*, Takahiro Watanabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


In modern VLSI designs, a flip-chip package is widely used to meet the higher integration density and the larger I/O counts of circuits. Recently the I/O buffers are mapped onto bump balls without changing the module placement using re-distribution layer (RDL) in flip-chip designs. In this research, a sorting-based I/O connection assignment and non-Manhattan RDL routing method is proposed for area I/O flip-chip designs. The approach initially assigns the I/O buffers to bump balls by sorting the Manhattan distance between them. Three kinds of pair-exchange procedures are then carried out to improve the initial assignment. Then to shorten the wire length, non-Manhattan RDL routing is adopted to connect the I/O buffers and bump balls. Finally some un-routed connections are ripped up and rerouted. The experimental results show that the proposed method is able to obtain the routes with shorter wire length in reasonable CPU times.

Original languageEnglish
Pages (from-to)1535-1544
Number of pages10
JournalIEEJ Transactions on Electronics, Information and Systems
Issue number12
Publication statusPublished - 2015 Dec 1


  • Flip-chip designs
  • I/O connection assignment
  • RDL routing

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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