CY7C68000A CYPRESS [Cypress Semiconductor], CY7C68000A Datasheet - Page 13

• Manufacturer Part Number: CY7C68000A
• Manufacturer: CYPRESS [Cypress Semiconductor]

package to the PCB. Hence, special attention is required to the
heat transfer area below the package to provide a good
thermal bond to the circuit board. A Copper (Cu) fill is to be
designed into the PCB as a thermal pad under the package.
Heat is transferred from the MoBL-USB TX2 through the
device’s metal paddle on the bottom side of the package. Heat
from here, is conducted to the PCB at the thermal pad. It is
then conducted from the thermal pad to the PCB inner ground
plane by an array of via. A via is a plated through hole in the
PCB with a finished diameter of 13 mil. The QFN’s metal die
paddle must be soldered to the PCB’s thermal pad. Solder
mask is placed on the board top side over each via to resist
solder flow into the via. The mask on the top side also
minimizes outgassing during the solder reflow process.
For further information on this package design, refer to the
application note “Surface Mount Assembly of AMKOR’s
MoBL-USB TX2 is a trademark of Cypress Semiconductor Corporation. Intel is a registered trademark of Intel Corporation. All
product and company names mentioned in this document are the trademarks of their respective holders.
Document #: 38-08052 Rev. *F
© Cypress Semiconductor Corporation, 2006. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be
used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its
products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Via hole for thermally connecting the
QFN to the circuit board ground plane.
PCB Material
Figure 8. Crosssection of the Area Underneath the QFN Package
Cu Fill
Figure 9. Plot of the Solder Mask (White Area)
Solder Mask
0.013” dia
0.017” dia
This figure only shows the top three layers of the
circuit board: Top Solder, PCB Dielectric, and
the Ground Plane
Cu Fill
PCB Material
MicroLeadFrame (MLF) Technology.” The application note can
be downloaded from AMKOR’s web site from the following
URL http://www.amkor.com/products/notes_papers/MLFApp
Note.pdf. The application note provides detailed information
on board mounting guidelines, soldering flow, rework process,
etc.
Figure 8 displays a cross-sectional area underneath the
package. The cross section is of only one via. The solder paste
template needs to be designed to allow at least 50% solder
coverage. The thickness of the solder paste template should
be 5 mil. It is recommended that ‘No Clean’, type 3 solder
paste be used for mounting the part. Nitrogen purge is recom-
mended during reflow.
Figure 9 is a plot of the solder mask pattern image of the
assembly (darker areas indicate solder).
CY7C68000A
Page 13 of 14