CASE STUDY - MICROELECTRONICS
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How ESCATEC are pioneering precision alignment at scale for Microelectronics assembly

As industries push the boundaries of miniaturisation to deliver high-performance, cost-efficient sensor solutions, precision alignment in Micro-Opto-Electro-Mechanical Systems (MOEMS) has emerged as a critical challenge.

 

The need for smaller and more energy-efficient systems demands cutting-edge manufacturing techniques and innovative design approaches.

 

In 2024 ESCATEC Switzerland AG, our MOEMS team were tasked with developing a groundbreaking solution to address this challenge.

 

Their mission was to enable the precise assembly of high-end Time-of-Flight (ToF) LiDAR sensors, a cornerstone technology in applications ranging from autonomous vehicles to medical devices, while ensuring cost-efficiency and scalability for mass production.

 

Micro-Opto-Electro-Mechanical Systems (MOEMS) combine optical, electronic, and mechanical components at microscopic scales. These systems are fundamental in advanced applications, including:

  • Automotive LiDAR systems for autonomous driving

  • Medical imaging devices for precise diagnostics

  • Telecommunication components for high-speed data transfer

ESCATEC sought to design and implement a reliable, cost-effective process for assembling MOEMS components, with a specific focus on:

  • Achieving sub-10 µm alignment precision.

  • Reducing errors and deviations caused by manufacturing tolerances.

  • Optimising assembly for scalability and cost-efficiency.

The Challenge

At the heart of the LiDAR sensor lies its optical assembly, consisting of a Vertical-Cavity Surface-Emitting Laser (VCSEL), photodetectors, signal processing electronics, and a mechanical housing that shields these components from environmental stress.

lens stack with three lenses and VCSEL chip

The sensor's ability to measure distance with pinpoint accuracy hinges on the precise alignment of its optical components, particularly its lens-stack. This stack contains three micro-lenses and must align concentrically with the VCSEL chip.

 

Achieving such precision in assembly is no small feat. Even microscopic deviations in alignment can lead to imaging errors and inaccurate measurements, rendering the sensor unreliable. 

 

The challenge was compounded by the need to scale production cost-effectively while maintaining stringent quality standards, ensuring every unit performed consistently.

lens design and microlens

VCSEL array and photodiode from LiDAR scanner

A common approach in optics assembly is active alignment, where the system is fine-tuned during assembly using real-time optical feedback. However, this process can be too labour-intensive and expensive for a mass-production approach.

 

ESCATEC needed a solution that maintained or exceeded the precision of active alignment but with the speed and scalability of an automated process.

The Solution

 

Automated passive alignment for high-performance systems

 

Instead of actively adjusting components during assembly (a time-intensive process), this approach relies on precision-designed parts and advanced imaging to position lenses perfectly using a robotic system. Think of it as snapping together parts with ultra-high precision based on a pre-engineered design.

 

Smart material and design choices

 

Reflective and darkened surfaces are used strategically during assembly to make the lenses visible to the system. This ensures that every component is placed exactly where it should be.

 

Specialised adhesive process

 

Special adhesives are used that shrink slightly as they harden, pulling lenses into their perfect positions. A quick UV light cure locks everything in place in real-time, ensuring accuracy.

 

Automation-driven precision

 

A fully automated assembly process achieves positioning accuracies within 10 microns—about one-tenth the width of a human hair.

Transformative Results

 

  • Better performance: This new production process ensures that our sensors are highly accurate, avoiding errors that could cause safety or functionality issues.

  • Scalability: The automated process can handle high volumes, making mass production feasible without sacrificing quality.

  • Cost-effectiveness: Eliminates the need for manual adjustments, cutting down costs while still achieving premium results.

  • Energy efficiency: By perfecting alignment, the sensors need less power to work accurately, which is a big deal for energy-sensitive applications like electric vehicles.