Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

A Split PTH/Via Approach to Achieve Significantly Lower Inductance

IP.com Disclosure Number: IPCOM000124927D
Publication Date: 2005-May-13
Document File: 5 page(s) / 569K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to vertically split the existing conventional PTH/via metallization, to provide significant advantages due to reduced parasitics. Benefits include a higher operating frequency and PTH/via density, and improved signal integrity.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

A

Split

PTH/Via Approach to Achieve Significantly Lower Inductance

Disclosed is a method to vertically split the existing conventional PTH/via metallization, to provide significant advantages due to reduced parasitics. Benefits include a higher operating frequency and PTH/via density, and improved signal integrity.

Background

Current POR Vcc and Vss via pairs (see Figure 2a) are constructed using two fully metallized cylindrical PTH/vias, separated by a minimum pitch. The loop inductance of this arrangement is limited by the via pair pitch dictated by the technology and manufacturing limitations (the POR pitch for PTH is 480 600 mm).

General Description

The disclosed method splits the vertical metallization of the PTH/vias into n number of sections (where n is an even number). Alternate sections are assigned opposite polarities (e.g. Vcc and Vss are opposite polarities in this case). Figure 1a and 1b show the case where n=2 and n=4, respectively. The red shaded segment represents Vcc and the blue shaded segment represents Vss.

Due to the proximity of the Vcc and Vss segments, the loop inductance is significantly reduced (i.e. up to 2.5x). Figure 2b shows two splits (n=2) in a single cylindrical PTH/via. Increasing the number of sections (i.e. more splits) reduces the inductance even further. For four splits (n=4) in a single cylindrical PTH/via (see Figure 2c), the inductance is reduced up to 4.3x.

Simulations performed on the split via arrangement vary the drill diameter (d) and the spacing between the split sections (slot s). The drill diameter d varies from 200 to 500 mm. The slot s varies from 20 to 80 mm (see Figures 3a and 3b). The simulation results are compared with the POR Vcc and Vss via pair, with a drill diameter of 250 mm and a pitch of 550 mm (see Figure 3c). Many current products use a PTH diameter of 250 to 350 mm and a pit...