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Introduction

Plastic Mold Compound

Exposed Thermal Pad Located

Underneath the Package

Die Attach (Epoxy)

IC (Silicon)

Leadframe (Copper Alloy)

Application Report

SLOA122 – July 2006

QFN Layout Guidelines

Yang Boon Quek

........................................................................................

HPL Audio Power Amplifiers

Board layout and stencil information for most Texas Instruments (TI) Quad Flat No-Lead (QFN) devices is
provided in their data sheets. This document helps printed-circuit board (PCB) designers understand and
better use this information for optimal designs.

The QFN package is a thermally enhanced standard size IC package designed to eliminate the use of
bulky heat sinks and slugs. This package can be easily mounted using standard PCB assembly
techniques and can be removed and replaced using standard repair procedures.

The QFN package is designed so that the lead frame die pad (or thermal pad) is exposed on the bottom
of the IC (see

Figure 1

). This provides an extremely low thermal resistance (

θ

JC

) path between the die and

the exterior of the package.

Figure 1. Section View of a QFN Package

SLOA122 – July 2006

QFN Layout Guidelines

1

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Summary of Contents for QFN Layout

Page 1: ...r use this information for optimal designs The QFN package is a thermally enhanced standard size IC package designed to eliminate the use of bulky heat sinks and slugs This package can be easily mount...

Page 2: ...der mask The recommended dimensions are shown in Figure 3 Figure 3 Finger Pads Layout The solder mask defined thermal pad is the exposed copper area not covered by solder mask It must be soldered dire...

Page 3: ...top copper layer of the PCB to the inner or bottom copper layers TI provides the recommended layout of the thermal vias in most data sheets The recommended via diameter is 0 3 mm or less and the recom...

Page 4: ...thermal pad to help dissipate heat through bottom or inner planes If thin PCBs or vias larger than 0 3 mm are used designers may use only external vias to prevent solder loss and protrusions see Figur...

Page 5: ...gs and thickness recommended to ensure that the right amount of solder paste is used Figure 9 Recommended Stencil Openings and Thickness for RGZ Package Use cross hatching in the thermal pad stencil o...

Page 6: ...ional Information Board Layout Figure 10 Thermal Pad Stencil Opening TI recommends the use of type 3 or finer solder paste when mounting a QFN For detailed information on the QFN package including the...

Page 7: ...m TI to use such products or services or a warranty or endorsement thereof Use of such information may require a license from a third party under the patents or other intellectual property of the thir...

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