AN1902 Freescale Semiconductor / Motorola, AN1902 Datasheet - Page 8

• Manufacturer Part Number: AN1902
• Description: Quad Flat Pack No-Lead (QFN)
• Manufacturer: Freescale Semiconductor / Motorola

AN1902/D
8
The PCB terminal pad should be approximately 0.05mm longer than the length of the
package lead. The extra 0.05mm should extend towards the center of the package.
This provides a slack to accommodate the placement tolerance of the component dur-
ing the pick & place process. Details of the land design for 4x4mm and 9x9mm QFN
are shown in
Notes:
2. In this evaluation, the same land pattern design and process parameters were used for both
1. Since the lead pitch of 9x9mm QFN is much finer than the 4x4mm QFN, the land pad width
3. For other QFNs with pitch and lead dimension different from the styles used in this study,
Version
Number of pins
A - Pitch (mm)
B - Lead pad length (mm)
C - Lead pad width (mm)
D
D
Maximum compent lead length (mm)
Maximum compent lead width (mm)
for 9x9mm is designed to be 0.02 mm less than the maximum lead width so as to avoid
bridging between adjacent leads.
“S” and “E” styles. Since there was no adverse result after the soldering process (before and
after the solder joint continuity test), it is believed that the PCB land design is appropriate.
further evaluation is required to determine the optimal design.
Freescale Semiconductor, Inc.
1
2
- Thermal pad width (mm)
- Thermal pad length (mm)
For More Information On This Product,
Figure 10 (L) QFN 4x4, (R) QFN 9x9mm Land Pattern Design
Quad Flat Pack No-Lead (QFN)
Figure
Go to: www.freescale.com
0.05mm
10.
Component lead
0.37mm
Table 2 Land Dimensions
0.92mm
0.65
0.92
0.37
0.75
0.37
2.0
2.0
16
0.05mm
E
4x4
0.28mm
0.65
0.92
0.37
0.75
0.37
2.0
2.0
16
S
PCB land
0.69mm
0.69
0.28
0.5
7.1
7.1
0.5
0.3
64
E
MOTOROLA
9x9
0.69
0.28
0.5
7.1
7.1
0.5
0.3
64
S