Display Pad Layout for Accurate IC Connection Resistance Testing
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Solution Overview
Problem
Existing display devices face challenges in accurately measuring the connection resistance of integrated circuits due to resistance noise from adhesive films, which is exacerbated by misalignment during chip-on-plastic (COP) or chip-on-glass (COG) mounting methods.
Innovation Solution
The display device incorporates a detection pad with opposing contact points for ground and voltage connections, allowing test current to flow only to the ground contact point, thereby isolating the adhesive film's resistance and reducing noise, ensuring accurate resistance measurement regardless of integrated circuit alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-point contact pads are used for testing, then the test structure is simple, but resistance noise from adhesive films cannot be effectively reduced
Solution Approach 1:
The detection pad is divided into multiple contact points (first contact point and second contact point) instead of using a single contact point. This segmentation allows the test current to be directed specifically to the first contact point while the second contact point serves as a reference, thereby isolating and reducing the influence of adhesive film resistance on the measurement.
Solution Approach 2:
The second contact point acts as an intermediary reference point that helps eliminate the noise from adhesive film resistance. By having both contact points on the detection pad, the system can differentiate between the resistance of the integrated circuit connection and the resistance of the adhesive film, thereby improving measurement accuracy.
2Reliability
If chip-on-plastic or chip-on-glass mounting methods are used, then the integrated circuit can be mounted on the display device, but misalignment during mounting causes increased resistance noise
Solution Approach 1:
The detection pad is designed with multiple contact points before the actual mounting process. This preliminary design ensures that even if misalignment occurs during COP or COG mounting, the test current can still reach the first contact point effectively, and the second contact point provides a reference to compensate for the misalignment, thereby maintaining measurement reliability.
Solution Approach 2:
The pad structure parameters are changed from a single contact point to multiple contact points with specific spatial relationships. This parameter change makes the measurement system more robust to alignment variations, as the multiple contact points provide redundancy and reference points that compensate for positioning errors during mounting.
3Ease of manufacture
If adhesive film is used to connect the integrated circuit, then the mounting is simplified, but the adhesive film introduces resistance noise that degrades measurement accuracy
Solution Approach 1:
The invention extracts and isolates the adhesive film resistance from the total measured resistance by using multiple contact points. The first contact point measures the total resistance (IC connection + adhesive film), while the second contact point provides a reference that helps separate out the adhesive film component, allowing the IC connection resistance to be measured accurately despite the presence of the adhesive film.
Data Source
AI summary
A display device including: a first test pad disposed on a substrate; a detection pad disposed on the substrate; a first voltage pad disposed on the substrate and electrically connected to the first test pad; a ground pad disposed on the substrate and electrically connected to the detection pad through a first contact point of the detection pad; and a second voltage pad disposed on the substrate and electrically connected to the detection pad through a second contact point of the detection pad, wherein the second contact point is opposite to the first contact point in a first direction.