Sensor Glob-Top Resin Positioning via Auxiliary Layer Edges
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Solution Overview
Problem
Existing glob-top technology faces challenges in applying a protective resin layer to sensors that need to be in contact with their environment, as the resin must not cover sensitive areas such as humidity or substance sensors.
Innovation Solution
An auxiliary layer is structured on the substrate to form edges that prevent the resin from covering the sensor device, utilizing surface tension and wetting properties to position and stop the resin expansion, allowing it to be hardened without obstructing the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glob of resin is applied to cover the bond wires and substrate, then the mechanical connection and protection are improved, but the sensor device becomes covered and cannot contact the environment
Solution Approach 1:
The substrate surface is divided into a first section (for sensor device) and a second section (for glob application). The auxiliary layer is structured to form edges that define this segmentation, allowing the glob to be applied only to the second section while leaving the first section exposed for environmental contact.
Solution Approach 2:
Different regions of the substrate receive different treatments: the first section remains exposed for sensor functionality, while the second section receives the protective glob. The auxiliary layer is selectively structured to create this local differentiation, ensuring protection only where needed.
2Reliability
If the glob is applied to cover the entire substrate, then complete protection is achieved, but the sensor device is obstructed
Solution Approach 1:
The auxiliary layer is applied and structured before the glob is applied. This preliminary structuring creates predefined edges that will automatically stop the glob's lateral expansion, ensuring precise positioning without requiring complex control mechanisms during glob application.
Solution Approach 2:
The glob material's own lateral expansion and surface tension properties are utilized to achieve self-positioning. The glob automatically expands until it meets the edge of the auxiliary layer, where surface tension causes it to stop, eliminating the need for external positioning mechanisms.
3Ease of manufacture
If the auxiliary layer is not structured, then the manufacturing process is simpler, but the glob cannot be positioned accurately
Solution Approach 1:
The auxiliary layer's physical-chemical parameters are changed through structuring (creating edges with specific geometries and surface properties). These parameter changes create regions with different wetting properties that guide and stop the glob's lateral expansion, achieving precise positioning while maintaining a relatively simple overall process.
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 method effectively applies a protective resin layer to the substrate while keeping the sensor device exposed, suitable for various types of sensors including humidity, optical, and flow sensors, even on small substrates, by leveraging surface tension and material properties.
Implementation Method 1
utilizing surface tension and wetting properties to position and stop the resin expansion
Implementation Method 2
utilizing surface tension and wetting properties to position and stop the resin expansion
Data Source
Figure 1~5
Figure 6~8
AI summary
The substrate (1) carries a sensor device (3) as well as bond pads (5) integrated on a first surface (2) thereof. A structured auxiliary layer (10) forms a plurality of edges (11a, 11b) traversing the first surface (2) between the bond pads (5) and the sensor device (3). A glob (8) of hardening material is applied over the bond pads (5) for protecting the bond wires (6). The horizontal expansion of the glob (8) is stopped at one of the edges (11a, 11b) formed by the auxiliary layer, which makes applying the glob (8) easier.