Method for a split PTH structure for enhanced power delivery in multi-power processor systems

Method for a split PTH structure for enhanced power delivery in multi-power processor systems

Disclosed is a method for a split plated through-hole (PTH) structure for enhanced power delivery in multi-power processor systems. Benefits include improved inductance, improved power performance, and improved design flexibility.

Background

        � � � � � CPU operation at multiple voltage domains enables power saving features.

        � � � � � The substrate core lies in the path between the die and the first level of decoupling capacitors in a typical pin-side cap package. The core is very thick to ensure mechanical stability. However, the core typically contributes higher inductance and resistance in the path to the decoupling capacitors and directly impacts their effectiveness. Higher inductance and resistance increases the voltage fluctuations at the die bumps, resulting in lower frequency of operation.

        � � � � � A CPU that operates at multiple voltage domains requires a robust power delivery network. Conventional solutions (see Figure 1) include PTHs arranged in a face-centered rectangle (FCR) pattern at a pitch that is the minimum possible for the package technology. This solution provides the lowest possible inductance and resistance within the scope of the substrate design rules.
        � � � � � For CPUs operating at multiple voltage domains, the conventional method of PTH placement results in higher perforations decreasing the effectiveness of the power delivery connection between the package caps and the die.

        � � � � � The conventional PTH can be implemented using the following steps:

1.        � � Through-hole drilling

2.        � � PTH plating

3.        � � PTH plugging/grinding

4.        � � Lid plating and patterning

General description

        � � � � � The disclosed method is a split PTH structure of alternating polarity that replaces the conventional PTHs through a substrate core.

        � � � � � The key elements of the method include:
•        � � � � Split PTH structure that alternates with V_CC-V_SS-V_CC-V_SS polarity with respect to the orientation of the neighboring split PTH structure
•        � � � � Confinement of current near the sidewalls, resulting in substantial reduction in skin effect resistance

•        � � � � Arrangement of every V_SS split PTH so that they are surrounded by three V_CC split PTHs, resulting in a substantial reduction in...