Gas Sensor Package Molding with Post-Mold Sensitive Layer Deposition
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Solution Overview
Problem
Existing methods for manufacturing gas sensor packages face challenges in protecting sensitive layers during the molding process, as they require direct access to the environment for gas sensing, which can lead to mechanical damage or interference from molding process particles, and conventional annealing methods may affect the molding compound.
Innovation Solution
A method involving mounting semiconductor chips on a carrier, applying a molding compound with openings for access, applying sensitive material through these openings after molding, and using integrated heaters for local annealing to protect the sensitive layers, while electrically isolating contact pads to manage heating currents safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensitive layer is manufactured prior to the package molding process, then the gas sensor can detect gases through the opening in the molding compound, but the sensitive layer is vulnerable to mechanical damage and contamination from molding process particles
Solution Approach 1:
The patent applies preliminary action by first manufacturing the package structure with the molding compound and opening before applying the sensitive layer. This reverses the conventional sequence, ensuring the sensitive material is deposited after the molding process, thereby avoiding exposure to mechanical damage and contamination during molding while still enabling gas detection through the pre-formed opening.
2Manufacturing precision
If conventional annealing methods are used to treat the sensitive layer, then the sensitive material can be properly activated, but the molding compound may be affected or damaged by the heating process
Solution Approach 1:
The patent applies local quality by implementing localized annealing that targets only the sensitive layer region through the opening in the molding compound, rather than heating the entire package. This allows the sensitive material to be properly activated while the molding compound remains unaffected, as the heating is confined to the specific area where the sensitive layer is located.
3Manufacturing precision
If the entire uncovered portion of the semiconductor chip is filled with sensitive material, then complete coverage is achieved, but material waste increases and processing complexity rises
Solution Approach 1:
The patent applies partial action by depositing sensitive material only in the specific regions where gas sensing is required, rather than covering the entire uncovered portion of the semiconductor chip. This selective deposition reduces sensitive material waste while still achieving complete coverage of the functional areas, and simplifies processing by targeting only necessary regions.
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 approach ensures the sensitive layers are protected during manufacturing, maintains sensing integrity, and allows for efficient handling and annealing without damaging the molding compound, enhancing the reliability and precision of gas sensor packages.
Implementation Method 1
integrated heaters for local annealing
Data Source
Figure 1a~1c
Figure 2a
Figure 2b
AI summary
A method for manufacturing a gas sensor package, comprising the steps of mounting a semiconductor chip (3) on a carrier (2) and applying a mold compound (1) for at least partially enclosing the semiconductor chip (3) thereby generating an opening (11) in the mold compound (1), wherein the opening (11) provides access to a portion of the semiconductor chip (3) being uncovered by the mold compound (1). After molding, a sensitive material is applied through the opening (11) onto the uncovered portion of the semiconductor chip (3) for building a layer (31) sensitive to a gas.