Chip-on-Glass (CoG)

Finetech’s bonders address the unique challenges associated with Chip on Glass (CoG) bonding.  Chip-On-Glass (COG) is a flip chip bonding technology for direct connection assembly of bare integrated circuits (ICs) on glass substrate by using Anisotropic Conductive Film (ACF). The pitch of the IC bumps (footprint) can be scaled down according to customer requirements (contact pitch of glass substrate). This technology reduces the assembly area to the highest possible packing density, important to applications where space saving is crucial. It allows a cost-effective mounting of driver chips because integrating flex PCB is no longer required. The IC is bonded directly onto the glass substrate and is suitable for handling high-speed or high-frequency signals.

COG is primarily used for source driver ICs within TFT display technologies where they are used for LCD, plasma, e-ink, OLED or 3D technologies. This is essential for consumer electronic products such as notebooks, tablets, cameras or mobile phones with the need for small size and light-weight components.

Chip on Glass Flip Chip

What are the challenges?

  • Sensitive, bare chips with long and extra thin dimensions and high packaging density
  • Requires specialized tooling, fixtures and optics shifting for wide range of chip and substrate sizes
  • Miniaturization of chip footprint (for example pitch of 60 µm (line/gap=25/35[µm]) requires high degree of parallelism and alignment accuracy
  • ACF demands for application of controlled bond-force (for example up to 300 N/cm² needed for specific foils)
  • Flexible solutions for chips, substrates and ACF with different visibility (reflections, transparency)

The Finetech Solution

I. Stable Substrate Handling

  • Heating plate for small substrates
    Heating plate with customized vacuum cavities
  • Heating plate optimized for small substrate sizes up to 100 mm x 100 mm
  • Special support table for larger panel sizes are available
  • Full-area or individual vacuum clamping solutions for glass substrates
  • Flexibly-designed heating plate with cavities for substrate backside assembly

II. Adapted Tooling & Optics

  • Gimbal or non-gimbal tooling according to chip dimensions
  • Quick tool switchover, flexible use for different applications
  • Contact heating tools available if substrate heating is limited
  • Optics shifting allows visual alignment over the complete chip length

III. Flexible Process Technologies

  • ACP dot dispensing
    Precision dispensing of an ACP dot

Anisotropic Conductive Film
ACF module supports application of various ACF materials with flexible force and time parameters

Other adhesives possible (ACP, NCA)
Adhesive dispensing is supported

Low-temperature curing
UV curing

Alternative process technologies
Ultrasonic and thermocompression bonding technologies can be integrated

Integrated Process Management (IPM)

  • Integrated Process Management (IPM)
  • Principle of process gas integration
  • Operating software for bonding

The Integrated Process Management (IPM) is the center piece of a FINEPLACER® system1 - the place where it all comes together. IPM is more than just thermal management. It synchronizes the control of all process modules and their related parameters:

  • Controlled and precisely balanced interaction of top and bottom (pre-)heating and cooling
  • Control of temperature, time, force, power, energy, flow
  • Process-integrated camera and light control
  • Controlled process gas integration for reduced solder contamination, minimized surface tension effects and smooth spherical solder residues

 IPM is very complex, yet easy to access. Via the GUI of the operating software, the user has perfect control of all required adjustments. Just drag 'n drop to define temperature ramps or activate process modules. All settings are represented in only one profile, making for a very intuitive work flow.
 
The operating software provides an ever-growing library of profiles for all kinds of processes. It also offers comprehensive data logging functions essential for statistical process control.

In combination with the system-to-system process transfer capability this is as easy as process development can get.

1 FINEPLACER® core offers co-ordinated top and bottom heating but does not support IPM

FINEPLACER® Bonding Systems

  • FINEPLACER® femto
    Automated sub-micron die bonder
  • FINEPLACER® matrix ma
    Semi-automated die bonder
  • FINEPLACER® lambda
    Flexible sub-micron die bonder
  • FINEPLACER® pico ma
    Multi-purpose die bonder
  • FINEPLACER® pico ama
    Automated flip chip bonder

Due to the modular design approach, FINEPLACER® bonding systems can be configured for virtually any application challenge.

The main distinguishing features between the machines are the

  • degree of automation
  •  optical resolution and
  •  placement accuracy

Browse our product range or get in contact with your sales contact to figure out the best equipment solution for your specific application requirements.

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