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Bottom-Mounted Capacitor

IP.com Disclosure Number: IPCOM000011509D
Publication Date: 2003-Feb-26
Document File: 2 page(s) / 59K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to attach capacitors to a substrate with solder joints under the capacitor. Benefits include increased capacitor density and reduced inductance.

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Bottom-Mounted Capacitor

Disclosed is a method to attach capacitors to a substrate with solder joints under the capacitor.  Benefits include increased capacitor density and reduced inductance.

Background

The current state of the art requires that solder fillets extend up the side of the capacitor where substrate lands extend beyond the capacitor’s perimeter (see figure 1).  Solder fillets limit the spacing between adjacent capacitors which minimizes the number of capacitors that can be placed in a given area.  Therefore, increasing capacitance density is restricted to increasing the capacitance value of a given capacitor.

General Description

The disclosed method adds additional capacitors in a given area by (1) increasing the length of the capacitor termination and (2) placing substrate lands under the capacitor rather than extending outside the perimeter of the capacitor. Figure 2 illustrates the disclosed method.

Advantages

The disclosed method decreases inductance by (1) reducing the current path and (2) strengthening the inductance canceling affect of adjacent capacitors.  Additionally, capacitance density is increased by mounting capacitors closer together as shown in figure 2. 

Figs. 1 and 2

Disclosed anonymously