Internal Bandgap Voltage Error Reduction in High Gradient Layouts
Internal bandgap voltage errors in high gradient layouts are reduced by common-centroid matching, thermal isolation trenching, and package stress mitigation.
WLCSP-8
Package Profile
Ultra-small semiconductor packages route the internal integrated circuit connections directly to an array of eight solder bumps on the active surface of the die. Utilizing a wlcsp-8 configuration provides the smallest possible footprint and thinnest profile for compact mobile and wearable electronic devices.
Thermal Performance
The direct connection to the printed circuit board through the solder bumps provides low thermal resistance, allowing heat to dissipate quickly from the silicon. However, because the package lacks a protective plastic mold compound, the silicon die is exposed to ambient light and physical damage. This requires careful handling during system assembly.
Assembly Challenge
Soldering these tiny devices requires high-precision stencil printing and pick-and-place equipment to avoid misaligning the eight bumps on the board pads. The small distance between the bumps increases the risk of solder bridging, which would cause short circuits. Furthermore, the absence of a leadframe means that any board warpage translates directly to mechanical stress on the silicon.
This stress can cause the solder joints to crack over time if the thermal expansion is not matched.
Reliability Validation
Packaged units are qualified by subjecting them to drop testing and thermal shock cycles to verify the mechanical integrity of the solder bumps. Optical and acoustic microscopy are used to inspect the internal joints for micro-cracks. These tests ensure the design is robust enough for consumer electronics.