Fingerprint Sensor Chip Package with Protection Cap
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Solution Overview
Problem
In manufacturing finger printing sensor chip packages, issues such as flaring, warpage, and pollution of the sensing area occur due to the thickness of dam elements and the exposure of side surfaces, leading to difficulty in handling thin wafers and low product yield.
Innovation Solution
A chip package design incorporating a first adhesive layer, a second adhesive layer, and a protection cap with a bottom board and sidewall to cover the chip's surfaces, enhancing protection and stability, and a manufacturing method involving a carrier to support the wafer and prevent warpage and pollution during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass sheet is used to cover the chip surface for protection, then the sensing area is protected, but the thickness of the dam element increases the gap between the glass sheet and the chip, causing flaring issues
Solution Approach 1:
The patent removes the glass sheet from the chip package structure entirely. Instead of using a glass sheet that creates gap and flaring issues, the invention uses the protection cap with bottom board and sidewall to provide protection without introducing the harmful gap between protective element and chip surface.
Solution Approach 2:
Rather than placing a protective element (glass sheet) on top of the chip that creates distance and flaring, the invention inverts the approach by using a protection cap that encloses the chip from the sides and bottom, with the sidewall directly covering the side surface and bottom board covering the second surface, eliminating the top-gap problem.
2Manufacturing precision
If no glass sheet is used on a thin wafer before cutting, then flaring is avoided, but it becomes very difficult to move the wafer and warpage issues occur due to process limitations
Solution Approach 1:
The patent introduces a carrier as an intermediary substrate that supports the thin wafer during manufacturing processes. The wafer is mounted on the carrier before cutting, providing mechanical support that enables easy handling and movement without causing warpage, while still allowing the sensing area to remain exposed and free from flaring issues.
Solution Approach 2:
The wafer is preliminarily mounted on the carrier before the cutting process. This preliminary action of attaching the thin wafer to a rigid carrier provides the necessary mechanical support for subsequent handling, dicing, and assembly operations, preventing warpage while maintaining the ability to avoid flaring by not using a glass sheet at this stage.
3Manufacturing precision
If the sensing area is exposed during manufacturing, then flaring is avoided, but the sensing area is easily polluted during manufacturing processes, reducing product yield
Solution Approach 1:
The sensing area is preliminarily protected by the sidewall of the protection cap after chip separation. The sidewall is positioned to cover the side surface of the chip, creating a protective barrier that prevents pollution during subsequent assembly and packaging operations, while the sensing area on the first surface remains accessible for its intended function.
Solution Approach 2:
The protection cap is segmented into distinct functional parts: the sidewall that protects the side surface and prevents pollution, and the bottom board that covers the second surface. This segmentation allows the sensing area on the first surface to remain exposed and functional while providing targeted protection against pollution from manufacturing processes.
4Ease of manufacture
If a typical chip package is disposed on a printed circuit board, then the chip is mounted, but the side surface of the chip package is exposed and may easily be damaged by external force
Solution Approach 1:
The patent uses a rigid protection cap with sidewall that acts as a protective shell enclosing the side surface of the chip. This shell structure provides mechanical strength and protection against external forces, while being compatible with the chip mounting process on the printed circuit board through the use of adhesive layers and carrier removal.
Data Source
AI summary
A chip package includes a chip, a first adhesive layer, a second adhesive layer, and a protection cap. The chip has a sensing area, a first surface, a second surface that is opposite to the first surface, and a side surface adjacent to the first and second surfaces. The sensing area is located on the first surface. The first adhesive layer covers the first surface of the chip. The second adhesive layer is located on the first adhesive layer, such that the first adhesive layer is between the first surface and the second adhesive layer. The protection cap has a bottom board and a sidewall that surrounds the bottom board. The bottom board covers the second adhesive layer, and the sidewall covers the side surface of the chip.