at88rf1354 ATMEL Corporation, at88rf1354 Datasheet - Page 35

• Manufacturer Part Number: at88rf1354
• Description: 13.56 Mhz Type B Rf Reader Specification
• Manufacturer: ATMEL Corporation

Appendix D.
D.1.
D.2.
8547A−RFID−10/08
Introduction
This Appendix provides PCB designers with a set of guidelines for successful board mounting of Atmel’s QFN
MicroLeadFrame ® package. The QFN package is a near chip scale plastic encapsulated package with a copper
leadframe substrate. This is a leadless package where electrical contact to the PCB is made by soldering the lands
on the bottom surface of the package to the PCB, instead of the conventional formed perimeter leads. The ePad
technology enhances the thermal and electrical properties of the package. The exposed die attach paddle on the
bottom efficiently conducts heat to the PCB and provides a stable ground through down bonds and electrical
connections through conductive die attach material.
Surface Mount Considerations for QFN Packages
For devices to perform at their peak, special considerations are needed to properly design the board and to mount
the package. For enhanced thermal, electrical, and board level performance, the exposed pad on the package needs
to be soldered to the board using a corresponding thermal pad on the board. Furthermore, for proper heat conduction
through the board, thermal vias need to be incorporated in the PCB in the thermal pad region. The PCB footprint
design needs to be considered from dimensional tolerances due to the package, PCB, and the assembly factors. A
number of factors may have a significant effect on mounting the QFN package on the board and the quality of the
solder joints.
Some of these factors include: amount of solder paste coverage in the thermal pad region, stencil design for
peripheral and thermal pad region, type of vias, board thickness, copper thickness, lead finish on the package,
surface finish on the board, type of solder paste, and reflow profile. This appendix provides the guidelines for this
purpose. It should be emphasized that this is just a guideline to help the user in developing the proper board design
and surface mount process. Actual studies as well as development effort maybe needed to optimize the process as
per user's surface mount practices and requirements.
Figure D-1. AT88RF1354 6x6 mm QFN package
PIN#1 ID
R0.20
L
2
3
1
QFN Package Mounting Guidelines
N
e
BOTTOM VIEW
b
D2
E2
13.56 MHz Type B RF Reader
A2
SIDE VIEW
A
C
A1
A3
SEATING
PLANE
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