si2439-a-gm Silicon Laboratories, si2439-a-gm Datasheet - Page 65

• Manufacturer Part Number: si2439-a-gm
• Description: V.92 And V.34 Isomodem With Global Daa
• Manufacturer: Silicon Laboratories

12. 38-Pin QFN Land Pattern
Figure 17 shows the recommended land pattern for the Si2494/39 QFN-38 package. Table 19 lists the values for
the dimensions shown in the illustration.
Notes:
General
Solder Mask Design
Stencil Design
Card Assembly
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
1. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is
1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder
2. The stencil thickness should be 0.125 mm (5 mils).
3. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads
4. A 3x5 array of 0.90 mm square openings on 1.10 mm pitch should be used for the center ground pad.
1. A No-Clean, Type-3 solder paste is recommended.
2. The recommended card reflow profile is per the JEDEC/IPEC J-STD-020 specification for Small Body Components.
Dimension
to be 60 m minimum, all the way around the pad.
paste release.
C1
C2
X1
X2
Y1
Y2
E
Table 19. QFN-38 PCB Land Pattern Dimensions
Pad column spacing
Thermal pad length
Thermal pad width
Pad row spacing
Pin pad width
Pin pad width
Figure 17. QFN-38 Land Pattern Drawing
Pad pitch
Feature
Rev. 1.0
4.70
6.70
0.20
3.20
0.80
5.20
Min
0.50 BSC
Si2494/39
Max
4.80
6.80
0.30
3.30
0.90
5.30
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