m28333-3x Mindspeed Technologies, m28333-3x Datasheet - Page 61

• Manufacturer Part Number: m28333-3x
• Description: Single/dual/triple E3/ds3/sts-1 Line Interface Unit
• Manufacturer: Mindspeed Technologies

M28331/M28332/M28333 (–3x)
Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit
B.2.3 PCB Design
Figure B-3. Internal Structure for a Two-Layer PCB
Figure B-4. Internal Structure For a Six-Layer PCB
28333-DSH-003-A
Thermal Via
Electrical Isolation
Core Laminate Layer
Thermal Via
Thermal vias are the primary method of heat transfer from the PCB thermal land
to the internal copper planes or to other heat removal sinks. The number, size, and
construction of the vias is important in obtaining the best package thermal
performance and package/PCB assembly. Thermal performance analysis
indicates there is a point of diminishing returns where additional vias will not
improve heat transfer through the board.
performance.
six-layer design, respectively. PCB designs with more than two layers should
have all thermal vias connected to the ground plane.
The PCB internal structure plays a very important role in package thermal
Mindspeed Technologies
Figures B-3
60 Micron Solder Mask Layer
1/2 Oz Copper Layer
Core Laminate Layer
1/2 Oz Copper Layer
60 Micron Solder Mask Layer
60 Micron Solder Mask Layer
1/2 Oz Copper Layer
1 Oz
1 Oz
1 Oz
1 Oz
1/2 Oz Copper Layer
60 Micron Solder Mask Layer
and
B-4
Copper Layer
Copper Layer
Copper Layer
Copper Layer
Appendix B: Exposed Thin Quad Flat (ETQFP) Pack
illustrate the PCB structure for a two- and
™
B.2 Package Thermal Characterization
1.50 mm
1.50 mm
100998_029
100998_028
B-5