Overmolded Encapsulation Cover with Optical Element Positioning

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Solution Overview

Problem

Existing electronic packages with encapsulation covers struggle to precisely control the distance between optical elements and electronic chips, limiting the effectiveness of light radiation emission and detection.

Innovation Solution

The encapsulation cover design features a cover body with a frontal wall and optical elements that are inserted by overmolding, allowing for adjustable positioning and the use of sacrificial spacers to determine the distance between optical elements and chips, along with a process involving wafer-scale overmolding and removal of spacers to achieve precise placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If optical elements are attached to shoulders using adhesive layers, then the assembly process is simplified, but the distance between optical elements and electronic chips cannot be precisely controlled

Engineering Contradiction:

Improvedistance control between optical elements and chipsVSAvoidencapsulation cover structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The optical elements are positioned at predetermined locations within the encapsulation cover body before the final assembly step. The overmolding process pre-positions optical elements at precise locations, and the sacrificial spacers are removed after molding but before final assembly, ensuring the distance is determined by the molded structure itself rather than by adhesive layer thickness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Sacrificial spacers are used as temporary intermediaries during the molding process to define the precise distance between optical elements and the chip mounting surface. These spacers are positioned during molding, support the optical elements at the correct height, and are subsequently removed to leave the precise spacing permanently established in the molded structure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If sacrificial spacers are used to determine distance, then positioning precision is improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improveoptical element positioningVSAvoidfabrication process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent combines multiple operations into a single overmolding step: positioning sacrificial spacers, placing optical elements, molding the encapsulation cover body around them, and creating the precise geometric relationships all occur in one manufacturing cycle. This integration reduces the number of separate manufacturing steps despite the added complexity of using sacrificial materials

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Sacrificial spacers are designed as temporary, disposable components that serve their purpose during molding and are then removed. These spacers can be made from inexpensive materials that are easy to remove (such as water-soluble or heat-soluble materials), and their temporary nature allows them to be discarded after serving their positioning function, reducing the need for expensive precision fixtures that would need to be reused

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If optical elements are inserted by overmolding, then integration is improved, but the mold design becomes more complex

Engineering Contradiction:

Improveoptical element integrationVSAvoidmold structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The mold is designed with separate, modular components including a first mold portion, a second mold portion, and removable sacrificial spacer components. This segmentation allows the complex overmolding process to be broken into manageable steps: positioning spacers and optical elements, closing the mold, molding the cover body, and then removing the mold and spacers. Each mold component has a specific function, making the overall complex process more controllable

Inventive Principle:

Principle #1Segmentation

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 solution enables precise control over the distance between optical elements and chips, enhancing light radiation emission and detection capabilities, such as proximity sensing, while allowing for efficient fabrication and assembly of electronic packages.

Implementation Method 1

at least one optical element allowing light to pass through

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 2

a face of the sacrificial spacer and a face of the optical element make contact with the faces of the cavity of the mold, respectively

Methodology Applied

Scientific EffectPhysical spacing:

Implementation Method 3

injecting a coating material into said cavity and setting the coating material

Methodology Applied

Scientific EffectSetting:

Data Source

PatentUS10748883B2Encapsulation cover for an electronic package and method of fabrication

Publication Date: 2020.08.18 STMICROELECTRONICS (GRENOBLE 2) SAS

AI summary

An encapsulation cover for an electronic package includes a cover body having a frontal wall provided with at least one optical element allowing light to pass through. The optical element is inserted into the encapsulation cover by overmolding into a through-passage of the frontal wall. A front face of the optical element is set back with respect to a front face of the frontal wall. The process for fabricating the encapsulation cover includes forming a stack of a sacrificial spacer on top of an optical element, with the stack placed into a cavity of a mold.