COG Driver IC Bump Redesign for Bonding Resistance Testing
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Solution Overview
Problem
In display devices using the chip-on-glass (COG) method, the need to measure bonding resistance often requires additional bumps, increasing the number of bumps and potentially deteriorating device function due to COG process variations.
Innovation Solution
A display device and bonding test system that reduces the number of dedicated bumps for bonding resistance measurement by using a driver integrated circuit (IC) with input and output bumps connected to internal ground lines, allowing for resistance measurement through existing bumps and lines, and optionally incorporating diodes to prevent data signal transfer during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional dedicated bumps are formed to measure bonding resistance, then bonding resistance measurement capability is improved, but the number of bumps increases and device complexity increases
Solution Approach 1:
The patent makes existing input bumps serve dual functions: both data input and bonding resistance measurement. The bonding test device utilizes the same input bumps that receive data signals to also measure bonding resistance, eliminating the need for separate dedicated measurement bumps. This multi-functional approach resolves the contradiction by maintaining measurement capability while reducing structural complexity.
Solution Approach 2:
The patent merges the bonding resistance measurement function with the existing data input function by using the same physical path (input bumps and internal ground lines) for both purposes. The bonding test device combines data input and resistance measurement into a single testing process, thereby reducing the number of required bumps and simplifying the overall device structure.
2Reliability
If additional dedicated bumps are formed for bonding resistance measurement, then bonding resistance can be measured, but the number of bumps increases which may deteriorate device function due to COG process variations
Solution Approach 1:
By making input bumps multi-functional for both data input and bonding resistance measurement, the patent eliminates the need for additional dedicated measurement bumps. This reduces the total number of bumps that could introduce COG process variations, thereby improving device reliability while maintaining bonding resistance measurement capability.
Solution Approach 2:
The patent extracts the bonding resistance measurement function from the set of additional dedicated bumps and integrates it into the existing input bump structure. By taking out the measurement function and combining it with existing components, the patent reduces the number of potential failure points from COG process variations while maintaining measurement reliability.
3Measurement precision
If three pairs of dedicated bumps are formed for bonding resistance measurement, then bonding resistance can be measured at multiple locations, but the number of bumps and pins increases
Solution Approach 1:
The patent makes existing input bumps serve multiple purposes including bonding resistance measurement at different locations. By utilizing the same input bumps for both data input and resistance measurement across multiple test points, the patent achieves comprehensive measurement capability without increasing the total number of bumps or pins required in the device.
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
Enables automatic bonding resistance measurement without additional dedicated bumps, improving device functionality by reducing COG bonding resistance variations and simplifying the testing process.
Implementation Method 1
measuring a resistance of a path of the test signal including a first bonding resistance between the first input pad and the first input bump and a second bonding resistance between the second input pad and the second input bump
Data Source
AI summary
A display device includes a display panel having a glass substrate, a first input pad formed on the glass substrate and a second input pad formed on the glass substrate, and a driver integrated circuit mounted on the glass substrate of the display panel using a chip-on-glass (COG) method. The driver integrated circuit includes first and second input bumps respectively coupled to the first and second input pads, and an internal ground line coupled to the first and second input bumps. The first input bump of the driver IC receives a test signal through the first input pad when a COG bonding test is performed, and receives a ground voltage when the display device operates.