Optical IC Module Assembly With Clear PCB Light Windows

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Solution Overview

Problem

The assembly of optical integrated circuits (ICs) is more expensive than other components, and they face challenges in utilizing wafer level chip scale package (WLCSP) assembly due to the opaque nature of printed-circuit boards (PCBs), which obstruct light transmission from the active surface of optical devices.

Innovation Solution

The implementation of an optically clear PCB that allows optical ICs to be coupled upside down to the PCB, with lenses aligned with clear regions or holes to facilitate light transmission, eliminating the need for external packaging and reducing the size and cost of the module by using WLCSP technology and transparent materials like polyimide for insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If an opaque PCB is used to support the optical IC, then the structural integrity and electrical connectivity are ensured, but light transmission from the active surface of the optical device is blocked

Engineering Contradiction:

Improvelight transmissionVSAvoidPCB manufacturing

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The PCB is designed with localized transparent regions (windows or holes) at specific positions corresponding to the optical devices, while other areas remain opaque to provide structural support and electrical connectivity. This allows light transmission only where needed, resolving the contradiction between light transmission and structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The PCB is segmented into opaque support areas and transparent optical areas. The transparent regions are created as separate features (windows, holes, or clear zones) that are integrated into the overall PCB structure, enabling both light transmission and structural support functions simultaneously.

Inventive Principle:

Principle #1Segmentation

2Reliability

If traditional packaging methods are used for optical ICs, then the devices are protected, but the module size and cost increase

Engineering Contradiction:

Improvedevice protectionVSAvoidmodule structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The PCB serves multiple functions simultaneously: it provides structural support, electrical connectivity, and optical transmission. By merging these functions into a single component, the need for separate protective packaging is eliminated, reducing module complexity and size while maintaining device protection through the PCB structure itself.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The PCB is designed as a multi-functional component that combines mechanical support, electrical routing, and optical transmission capabilities. This universal design eliminates the need for dedicated protective packaging, reducing overall module complexity while ensuring device protection through the integrated PCB structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the optical IC is mounted with the active surface facing up, then light transmission is facilitated, but WLCSP assembly cannot be utilized and cost increases

Engineering Contradiction:

Improveassembly costVSAvoidlight transmission path

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The optical IC is mounted upside down with the active surface facing the transparent regions of the PCB instead of facing up. This inversion allows the device to benefit from WLCSP assembly processes while light transmission is facilitated through the transparent PCB regions positioned between the active surface and the external environment.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables cost-effective and compact integration of optical devices by allowing light to pass through the PCB, reducing optical interference, and providing a direct optical sensor window, thereby enhancing the efficiency and affordability of optical module assembly.

Implementation Method 1

an optically clear PCB that allows optical ICs to be coupled upside down to the PCB, with lenses aligned with clear regions or holes to facilitate light transmission

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 2

lenses aligned with clear regions or holes to facilitate light transmission

Methodology Applied

Scientific EffectOptical focusing: Lens

Data Source

PatentUS11862749B2Integrated module assembly for optical integrated circuits

Publication Date: 2024.01.02 ADESTO TECHNOLOGIES CORP

AI summary

An integrated module assembly can include: an optical integrated circuit having first and second optical devices; a PCB having first and second holes therein, where the optical integrated circuit is coupled upside down to a first side of the PCB; and first and second lenses coupled to a second side of the PCB, where the first and second sides of the PCB are opposite thereto; and where the first lens is in alignment with the first hole and the first optical device, and the second lens is in alignment with the second hole and the second optical device.