Display Module Test Pad Layout for Bonding Resistance Inspection
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Solution Overview
Problem
In display devices, improper bonding between the display panel and the driver, as well as between the display panel and the circuit board, leads to high contact resistance, negatively affecting device performance.
Innovation Solution
A display module with a second circuit board bonded to a first circuit board to measure contact resistance between the display panel and the driver, and between the display panel and the circuit board, allowing for proper bonding and reducing the area of the first circuit board by removing the second circuit board after inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact resistance measurement is performed, then bonding quality is ensured, but device complexity increases
Solution Approach 1:
The patent divides the measurement function into separate test pads and test terminals, isolating the measurement capability from the main circuit board structure. This allows contact resistance measurement without integrating complex measurement circuitry into the primary device architecture.
Solution Approach 2:
The patent introduces test pads as intermediary elements between the display panel and the driver/circuit board. These test pads serve as mediators that enable contact resistance measurement without requiring direct integration of measurement equipment into the main bonding interface.
2Measurement precision
If second circuit board is bonded to first circuit board for measurement, then contact resistance can be measured, but area of first circuit board increases
Solution Approach 1:
The patent extends the measurement capability to a separate second circuit board that bonds to the first circuit board. This dimensional extension allows measurement functions to be performed outside the footprint of the main circuit board, preserving its area while enabling precise contact resistance measurement through the additional board layer.
3Area of stationary object
If second circuit board is removed after inspection, then area of first circuit board is reduced, but manufacturing time increases
Solution Approach 1:
The patent performs contact resistance measurement using the second circuit board during the manufacturing process before final assembly. This preliminary measurement action allows the second circuit board to be removed afterward, reducing the final device area while ensuring bonding quality was verified during production.
Solution Approach 2:
The second circuit board serves as a temporary measurement tool that is discarded after its inspection function is fulfilled. This approach allows the measurement capability to be present during manufacturing but absent in the final product, optimizing both area and functionality.
Data Source
AI summary
A display module includes: a display panel including a plurality of pixels located in a display area, a plurality of first test pads located in a first pad area, a plurality of second-first test pads located in a second pad area spaced apart from the first pad area and electrically connected to the first test pads, and a plurality of second-second test pads located in the second pad area; a driving integrated circuit bonded to the first test pads, the driving integrated circuit configured to provide driving signals to the pixels; a first circuit board bonded to the second-first test pads and the second-second test pads; and a second circuit board bonded to one end of the first circuit board, the second circuit board including a first test terminal group electrically connected to the second-first test pads and a second test terminal group electrically connected to the second-second test pads.