11.4 Power Module SMT Guidelines
The recommendations below are for a standard module surface mount assembly
- Land Pattern – Follow the PCB land pattern with either soldermask defined or non-soldermask defined pads
- Stencil Aperture
- For the exposed die attach pad (DAP), adjust the stencil for approximately 80% coverage of the PCB land pattern
- For all other I/O pads use a 1:1 ratio between the aperture and the land pattern recommendation.
- Solder Paste – Use a standard SAC Alloy such as SAC 305, type 3 or higher
- Stencil Thickness – 0.125 to 0.15 mm
- Reflow - Refer to solder paste supplier recommendation and optimized per board size and density
- Maximum number of reflows allowed is one
- Refer to Design Summary LMZ1xxx and LMZ2xxx Power Modules Family (SNAA214) for reflow information.
Table 11. Sample Reflow Profile Table
PROBE |
MAX TEMP (°C) |
REACHED MAX TEMP |
TIME ABOVE 235°C |
REACHED 235°C |
TIME ABOVE 245°C |
REACHED 245°C |
TIME ABOVE 260°C |
REACHED 260°C |
1 |
242.5 |
6.58 |
0.49 |
6.39 |
0.00 |
– |
0.00 |
– |
2 |
242.5 |
7.10 |
0.55 |
6.31 |
0.00 |
7.10 |
0.00 |
– |
3 |
241.0 |
7.09 |
0.42 |
6.44 |
0.00 |
– |
0.00 |
– |