Browse Prior Art Database

SYNTHESIZER LOOP CAPACITOR PCB DESIGN

IP.com Disclosure Number: IPCOM000009136D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-09
Document File: 2 page(s) / 77K

Publishing Venue

Motorola

Related People

Conor Hilliard: AUTHOR

Abstract

A slot can be added to a PCB under d compo- nent in order to stop the solder flux wicking along the bottom of the part during manufacture. This slot prevents solder flux residue from joining both com- ponent pads together, which would increase leakage current and may cause Hum + Noise failures with loop capacitors.

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MOTOROLA Technical Developments

SYNTHESIZER LOOP CAPACITOR PCB DESIGN

by Conor Hilliard

ABSTRACT

  A slot can be added to a PCB under d compo- nent in order to stop the solder flux wicking along the bottom of the part during manufacture. This slot prevents solder flux residue from joining both com- ponent pads together, which would increase leakage current and may cause Hum + Noise failures with loop capacitors.

INTRODUCTION

  This paper describes improvements in printed circuit board (PCB) layout for capacitors and other components which are required to have very low leakage currents. In prior art arrangements, the leakage current for the component can increase due to contamination on the surface of the PCB or on the part itself.

PROBLEM TO BE SOLVED

  One of the problems with the current Surface Mount Technology (SMT) Synthesizer Loop capac- itors and PCB design is that flux residue can be left behind on the PCB after solder re-flow. The flux during solder re-flow is drawn between the under- side of the capacitor and the PCB. This can cause a bridge of flux residue between the pads of the capacitor.

The bridge of flux residue typically contains conductive particles, which lower the insulation

resistance of the capacitor. This lowered insulation resistance increases the leakage current. The effect of this is to cause "Spurs" and "Hum and Noise" performance problems in circuits, which lower fac- tory test yields.

PROPOSED SOLUTIONiT THE PROBLEM

  The solution to the...