Specifications

LM3269

SNVS793D –NOVEMBER 2011 –REVISED MAY 2015

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10.3 DSBGA Package Assembly And Use

Use of the DSBGA package requires specialized board layout, precision mounting, and careful re-flow

techniques, as detailed in Texas Instruments Application Note 1112. Refer to the section Surface Mount

Technology (SMD) Assembly Considerations. For best results in assembly, alignment ordinals on the PC board

should be used to facilitate placement of the device. The pad style used with DSBGA package must be the

NSMD (non-solder mask defined) type. This means that the solder-mask opening is larger than the pad size.

This prevents a lip that otherwise forms if the solder-mask and pad overlap from holding the device off the

surface of the board and interfering with mounting. See Application Note AN-1112 DSBGA Wafer Level Chip

Scale Package (SNVA009) for specific instructions how to do this.

The 12-bump package used for the LM3269 has 300 micron solder balls. The trace to each pad should enter the

pad with a 90° entry angle to prevent debris from being caught in deep corners. Initially, the trace to each pad

should be 9.5 mil wide, for a section approximately 5 mil long, as a thermal relief. Then each trance should neck

up or down to its optimal width. The important criterion is symmetry. This ensures the solder bumps on the

LM3269 re-flow evenly and that the device solders level to the board. In particular, special attention must be paid

to the pads for bumps A3, B3, and D3. Because PVIN and PGND are typically connected to large copper planes,

inadequate thermal relief can result in late or inadequate re-flow of these bumps.

The DSBGA package is optimized for the smallest possible size in applications with red or infrared opaque

cases. Because the DSBGA package lacks the plastic encapsulation characteristic of larger devices, it is

vulnerable to light. Backside metallization and/or epoxy coating, along with front-side shading by the printed

circuit board, reduce this sensitivity. However, the package has exposed die edges. In particular, DSBGA

devices are sensitive to light (in the red and infrared range) shining on the package's exposed die edges.

Product Folder Links: LM3269