Fan-Out Sensing Chip Structure for Crack-Resistant Joint Faces
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Solution Overview
Problem
The joint face between the sensing chip and the dielectric layer in sensing devices is prone to separation or cracking, leading to potential short circuits and bending deformations due to stress, thermal expansion, and etching solution erosion, especially in the positive pole area with a smaller thickness.
Innovation Solution
A sensing device design that includes a dielectric layer with an elevated first surface and conductive wire layers, along with conductive pillars and circuits, ensuring tight integration with the sensing chip to prevent cracking and short circuits by using an adhesive layer and conductive pillars to support the connection points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dielectric layer is made flush with the sensing chip surface to minimize overall thickness, then the device thickness is reduced, but the joint face becomes prone to cracking and separation under stress and thermal expansion
Solution Approach 1:
The patent applies preliminary anti-action by designing the dielectric layer to extend beyond the sensing chip periphery before bonding occurs. This pre-positioning creates an overlapping structure that prevents cracking and separation at the joint face by distributing stress away from the critical bonding interface, thereby preventing the harmful effect before it can occur during thermal expansion or mechanical stress.
Solution Approach 2:
The patent resolves the thickness contradiction by transitioning from a two-dimensional flush surface arrangement to a three-dimensional overlapping structure. The dielectric layer extends in the lateral dimension beyond the chip edges, creating a stepped configuration that maintains compact overall thickness while providing enhanced mechanical support and stress distribution at the joint interface.
2Ease of manufacture
If the conductive layer is placed directly across the joint face to simplify wiring, then the manufacturing process is simplified, but conductive material penetrates into cracks forming electrical connection paths causing short circuits
Solution Approach 1:
The patent introduces the extended dielectric layer as an intermediary barrier between the conductive layer and the joint face. This dielectric extension prevents conductive material from penetrating into cracks at the joint interface, maintaining electrical insulation while still allowing simplified conductive layer formation on the dielectric surface.
Solution Approach 2:
The patent segments the dielectric layer into two functional zones: an extended portion that covers the joint face and prevents conductive material penetration, and a recessed portion that allows normal conductive layer formation. This segmentation enables the conductive layer to be formed simply while preventing it from creating harmful electrical paths through the joint interface.
3Stability of the object's composition
If the sensing chip is embedded deeply in the dielectric layer to improve mechanical support, then structural stability is improved, but the sensing region becomes harder to access and the device thickness increases
Solution Approach 1:
The patent provides mechanical support not by increasing vertical embedding depth, but by extending the dielectric layer laterally beyond the chip periphery. This dimensional shift creates a stepped structure where the extended dielectric flange provides mechanical anchoring and stability without increasing the overall device thickness, as the support comes from the lateral extension rather than vertical embedding.
Data Source
AI summary
A sensing device includes a sensing chip, which has an active face with a sensing region and a metal pad region having at least a metal pad thereon; a dielectric layer, which covers a periphery, back surface and a part of the active surface of the sensing chip, and the first face of the dielectric layer has an elevation higher than the active face of the sensing chip and exposes the sensing region of the sensing chip; a first conductive wire layer and a second conductive wire layer, which are disposed on the first and second faces of the dielectric layer respectively; a conductive pillar, which is disposed within the dielectric layer and connected to the first and second conductive wire layers; and a front-face fan-out circuit, which is connected to the first conductive wire layer and the metal pad of the sensing chip.