July 2013

DocID024463 Rev 2

1/21

TN0991

Technical note

Description of WLCSP for STMicroelectronics EEPROMs and

recommendations for use

Introduction

This document describes the 5 and 8-bump WLCSPs (wafer level chip size package) used

for STMicroelectronics EEPROM products, and provides recommendation on how to use

them.

The competitive market of portable equipment, in particular the mobile phone market, is

driven by the challenging development of highly integrated devices. To allow manufacturers

of portable equipment to minimize the dimension of their devices, STMicroelectronics has

developed WLCSP with reduced size, thickness and weight. The electrical performance of

such components is improved by using shorter connections than in standard plastic

packages such as TSSOP, SSOP or QFN.

The WLCSP family has been designed to fulfill the same quality levels and same reliability

performance as standard semiconductor plastic packages. As a consequence these new

WLCSP can be considered as new surface mount devices which are assembled on a printed

circuit board (PCB) without any special or additional process steps. In particular these

packages do not require any extra underfill to increase reliability performance or to protect

the device. These packages are compatible with existing pick-and-place equipment for

board mounting. Only Lead-free RoHS compliant WLCSP are available in mass production.

This document addresses the following topics:

• Package description

• Device marking

• Packing specifications and labelling

• Storage and shipping recommendations

• Soldering assembly recommendations

• Package changes

• Package quality

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