Abutment Issues During I/O Row Creation

During IO row creation, certain scenarios may lead to abutment issues.

Scenarios

• Generating Two Rows Using the IO Planner
  When two rows are created on each side of the top-level boundary, some rows are not abutted based on the PR dimensions and siteDefs as shown in the following figure.
  
  
  Consider a scenario of IO pads with the following site definitions.

  scalarSiteDefs(

  ;(siteDefName    type width  height symInX symInY symInR0)

  ;(-----------    ---- -----  ------ ------ ------ -------)

  (corner          pad  40.015 40.015 nil    nil    nil)

  (it_pad_1        pad  1.0    40.015 nil    nil    nil)

  (it_pad_2        pad  1.0    60     nil    nil    nil)

  );scalarSiteDefs

  )

  ;siteDefs

  • it_pad_1 is the inner row (Row2). The inner row consists of pads, filler, and corner cells.
  • it_pad_2 is the outer row (Row1). The outer row consists of wirebond cells only.
  • The PR boundary is set to 500 x 500.
    
    
  To resolve this issue, you can adjust the PR boundary and have some overlap of rows to ensure that the pad placements are abutted. Depending on the PR boundary and the number of pads you want to keep, you can also make the width of the site definitions smaller and change it to 0.1 instead of 1.0 and re-create the rows. In case of adjacent rows, IO pads can be placed with a common PR boundary.
• Pad Placement with Two Rows
  During IO planning, some gaps are identified between the IO pads when two rows are created on each side and wirebond is placed such that its height matches the exact height of row cells.
  
  

In this case, the wirebond cells in the outer row are exactly same as on the boundary of the inner row. Therefore, the tool does not place fillers and leaves empty spaces.

To place fillers and to complete the row, increase the width of the site definition for the outer row and manually add some spaces between the two rows to ensure a DRC-correct design.

Related Topics

Create I/O Row Form

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