HDI Via-In-Pad (VIP)

HDI Via-In-Pad (VIP)

When designing HDI boards, one question that needs to be resolved up-front is whether or not to use VIP, and if so, what type?  Happy Holden’s book “HDI Handbook” (available at www.hdihandbook.com) has quite a few references in the Index that describe the use of VIP.  I wrote an article recently in CircuiTree called  “A Fresh Look at MicroVias”, in which a few paragraphs describe the various forms of VIP and their advantages in the context of routing.  The full article, which expands upon this blog, can be found here:  http://www.circuitree.com/Articles/Feature_Article/BNP_GUID_9-5-2006_A_10000000000000953428

The different forms of VIP include:

• VIP – The microvia in the center of the ball pad.  Great for very fine pitch BGAs.
• Offset VIP – Via inside the ball pad, but allows for fanout patterns that increase route density.
• Partial VIP – Here the center of the via is on the edge of the ball pad.  Also increases route density.
• Near VIP – The via hole is located outside the ball pad which enables fanout patterns using columns and rows, which maximizes route density.

If using VIP is new to you, the CircuiTree article and the HDI Handbook provides good information about the advantages of different patterns and the effects on fabrication and assembly of the board.  Are you using VIP and do you have some information about them that you would like to share?

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