Sensor Package Structure Embedding Wire Bonds in Adhesive
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Solution Overview
Problem
Conventional sensor package structures in the wire bonding manner face issues of increased thickness and reduced reliability, particularly in reverse bond configurations.
Innovation Solution
A sensor package structure incorporating a substrate, sensor chip, electrical connection members, a supporting adhesive layer, and a light-permeable sheet, where the electrical connection members' head solder and wire bending portions are embedded in the adhesive layer, optimizing wire placement to minimize thickness and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is performed in normal bond manner, then reliability is improved, but package thickness increases
Solution Approach 1:
The wire bonding structure transitions from a planar configuration to a three-dimensional configuration by routing wires through vertical vias and embedding them in adhesive layers. The wire path includes segments in different spatial planes (horizontal bonding, vertical via, horizontal connection), effectively using the Z-dimension to reduce the horizontal footprint and overall package thickness while maintaining bonding reliability.
Solution Approach 2:
The wire and its bonding structure are embedded within the adhesive layer, which itself is part of the package structure. The wire path is nested within the adhesive layer thickness, and the adhesive layer is nested within the overall package assembly, creating a compact hierarchical structure that reduces total package thickness.
2Length of stationary object
If wire bonding is performed in reverse bond manner, then package thickness is reduced, but reliability deteriorates
Solution Approach 1:
Different segments of the wire path have different functions and quality requirements. The bonding endpoints use traditional wire bonding for reliable electrical connection, while the intermediate path segments are embedded in adhesive for mechanical support and positioning. This local differentiation allows the wire to achieve both low profile (reduced thickness) and high reliability at critical connection points.
Solution Approach 2:
The adhesive layer serves as an intermediary medium that provides mechanical support, positioning, and protection to the wire path. Rather than relying solely on wire bonding for both electrical connection and mechanical support, the adhesive acts as a mediator that enhances wire stability and positioning accuracy, thereby improving overall reliability while enabling reduced package thickness.
3Length of stationary object
If wires are routed close to sensing region, then connection length is reduced, but risk of wire contact with light-permeable sheet increases
Solution Approach 1:
The adhesive layer is applied beforehand to define the wire path and provide a cushioning effect that prevents wire contact with the light-permeable sheet. The adhesive acts as a pre-established protective barrier that cushions the wire from potential contact points, ensuring optical performance reliability even when wires are routed close to the sensing region.
Solution Approach 2:
The adhesive layer serves as an intermediary barrier between the wire and the light-permeable sheet. When wires need to be routed close to the sensing region for minimal connection length, the adhesive mediates the spatial relationship, preventing direct contact between the wire and optical components while maintaining the short wire path for electrical performance.
Data Source
AI summary
A sensor package structure is provided. The sensor package structure includes a substrate, a sensor chip disposed on the substrate, a plurality of electrical connection members electrically connecting the sensor chip to the substrate, a supporting adhesive layer formed on the sensor chip, and a light-permeable sheet disposed on the supporting adhesive layer. Each of the electrical connection members includes a head solder disposed on a connecting pad of the sensor chip, a wire having a first end and a second end, and a tail solder. The first end of the wire extends from the head solder so as to connect the second end onto a soldering pad of the substrate, and the wire has a first bending portion arranged adjacent to the head solder. The head solder and the first bending portion of each of the electrical connection members are embedded in the supporting adhesive layer.