Active Optical Cable (AOC)

The acronym AOC represents Active Optical Cable and can also fall in the category of a Transceiver, SFP (Small Form-factor Pluggable) or QSFP (Quad Small Form-factor Pluggable) modules, TOSA (Transmit Optical Sub-assembly, ROSA (Receive Optical Sub-assembly), etc.

The AOC typically has 3x components that require placement accuracies that are critical to the performance of the connector: Laser/VCSEL, PIN, Lens. 3x bonding processes are commonly used to assemble various types of AOC products: Epoxy, AuSn Eutectic and UV curable adhesive.

There are 3x basic categories of laser assemblies that utilize the bonding materials mentioned above, Single mode, multi-mode and VCSEL (Vertical Cavity Surface Emitting Laser). Single mode and Multi-mode configurations use edge-emitting lasers where VCSEL are vertical emitting lasers.

Generally speaking, single mode and multi-mode laser configurations use an AuSn eutectic bonding process and VCSEL use an Ag-filled epoxy bonding process. Edge-emitting lasers dissipate lots of power therefore requiring a eutectic bonding process where VCSELs dissipate much less power therefore requiring a conductive epoxy. It is interesting to note that single mode laser configurations require 0.5μm to 1.0μm die placement accuracy where multi-mode and VCSEL assemblies require 2.0μm placement accuracy and up. Likewise, single mode generally produces a much higher bandwidth followed by multi-mode then VCSEL applications. Refer to SiPh/PIC application write-up to learn more about the importance of placement accuracy for single mode lasers supporting SiPh and PIC applications.

Product Offering

ASMPT AMICRA offers two die attach solutions to address the AOC market segment. We primarily serve the high volume production segment of the AOC market.

AFC Plus supports:

  • Die placement accuracies down to ±0.5μm @ 3σ with cycle times down to 20 seconds/bond or 180 UPH

NOVA Plus supports:

  • Die placement accuracies down to ±2.5μm @ 3σ with cycle times down to 3 seconds/bond or 1,200 UPH

Our AMICRA Systems support the following bonding processes:

  • Bonding Die (VCSEL and PIN) with Silver Filled Epoxy Process
  • Bonding Die (VCSEL and PIN) with a AuSn Eutectic Process
  • Bonding a Lens with UV Curable Adhesive Process
  • Bonding Edge Emitting Laser Die with a AuSn Eutectic Process

Process Overview

A capacity/bulk of materials like die or lenses and substrates can be manually loaded or automatically presented to the AMICRA system. The die or lens can be presented to the machine in waffle packs, gel packs or wafers (film frames or grip rings). The substrates can be presented to the machine one at
a time or in custom trays, or the AMICRA system can load each substrate to the bonding stage automatically, provided the substrates are presented in waffle packs or gel packs.

Epoxy or UV adhesive can be applied to the die via die dipping or applied via pin transfer (epoxy stamping) or via through a variety of standard dispensing systems, located at the bond station or located upstream prior to the bond station:

  • Time Pressure Vacuum Dispenser
  • Volumetric/Auger Dispenser
  • Jet Dispenser

Note: The AMICRA systems are essentially a vision driven die attach machine consisting of 4x automatic vision systems located throughout the machine, all imaging systems (camera, optics and illumination) are fixed to a very rigid structure made of granite. Imaging systems are located:

  • Pick-up Station with a precision X-Y Table
  • Mapping/Alignment Station consisting of an upward looking camera and a downward looking camera
  • Bond Station with a precision X-Y Table

A single or dual pick and place bondhead(s) are mounted to a linear motor where either a die, lens or flip chip die are picked up, via a vacuum tool, from the Pick-up Station and either the:

  • Die are transported to the Mapping/Alignment Station for alignment then moved to the Bond Station where the die is bonded to epoxy
  • Lenses are transferred to the Bond Station where they are placed into the UV adhesive while UV light is projected on to the Lens until the adhesive is cured and bonded.
  • Flip chip die is transferred to the Mapping/Alignment Station where the bumps of the die are mapped to a feature on the backside of the die, i.e. the die corner for alignment and finally, the die is transferred to the Bond Station where laser heat is applied to the substrate while the die is being eutectically bonded.

Additional Key Features, Options and Capabilities

  • Dynamic Alignment with 3x levels of Post Bond Inspection
  • Flip Chip System
  • HEPA Filter with Ionizer
  • Heated Bond Tool
  • Laser Heater
  • Pulse Heater
  • Wafer Heater
  • Wafer Substrate Loader & FOUP Loader
  • Substrate Magazine Loader
  • Active Bond Force
  • Supports 300mm Wafers and Large Substrates up to 600mm x 600mm
  • Bonding Resolutions <0.1μm
  • Autocollimator for Parallelism Calibration

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