Sensor Die Package With Through-Silicon Vias for Low-Noise Stacking
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Solution Overview
Problem
Conventional WLCSPs with light sensors have electrical connections that are lengthy, leading to increased electrical resistance, impedance, and parasitic inductance, which cause noise and power integrity issues, and they cannot be stacked on both sides due to lack of electrical contacts.
Innovation Solution
The WLCSPs feature electrical connections extending through the package from one side to the other, utilizing through silicon vias and conductive structures, reducing connection length and eliminating the need for lengthy wires, with a transparent material covering the sensor to allow light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If electrical wires and traces are increased in length to connect external power sources to the sensor die, then the coverage area and mounting flexibility are improved, but the electrical resistance, impedance, and parasitic inductance increase causing noise and power integrity issues
Solution Approach 1:
The patent transitions from planar electrical connections (wires and traces on the same layer) to three-dimensional vertical connections using through-silicon vias (TSVs) that penetrate the substrate. This dimensional change allows electrical contacts to be positioned on both the top and bottom surfaces of the package, enabling shorter connection paths while maintaining flexible mounting options and reducing the harmful effects of long electrical paths.
2Ease of manufacture
If solder balls are placed only on a single side of the conventional WLCSP, then the manufacturing process is simplified, but the package cannot be stacked and requires larger space within the electronic device
Solution Approach 1:
The patent utilizes the vertical dimension by placing electrical contacts (solder balls or pads) on both the top and bottom surfaces of the package. This enables stackable configurations where multiple packages can be vertically arranged, significantly improving space utilization within electronic devices while maintaining manufacturing feasibility through established TSV and dual-sided bonding technologies.
3Strength
If the transparent material covers the entire second side of the package, then the light sensor is fully protected, but light transmission to the sensor is blocked
Solution Approach 1:
The patent applies different material properties to different regions of the package: the first side (opposite the light sensor) uses transparent material for optimal light transmission, while the second side (containing the light sensor) uses opaque molding compound for mechanical protection and environmental sealing. This localized differentiation of material properties simultaneously achieves both full sensor protection and unrestricted light transmission.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces electrical resistance, impedance, and parasitic inductance, minimizing noise and power integrity issues, and allows for a thinner package profile while enabling stacking on both sides with electrical connections.
Implementation Method 1
a transparent material covers the light sensor and exposes the light sensor to an external environment such that light passes through the transparent material and reaches the light sensor
Data Source
AI summary
The present disclosure is directed to a package that includes a transparent layer that is on and covers a sensor of a die as well as a plurality of electrical connections that extend from a first surface of the package to the second surface of the package opposite to the first surface. In at least one embodiment of a package, the electrical connections each include a conductive structure that extends through the transparent layer to a first side of a corresponding contact pad of the die, and at least one electrical that extends into the second surface of the die to a second side of the corresponding contact pad that is opposite to the first side. In at least another embodiment of a package, the electrical connections include a conductive structure that extends through a molding compound to a first side of a corresponding contact pad of the die, and at least one electrical via that extends into the second surface of the die to a second side of the corresponding contact pad opposite to the first side.