Display Circuit Test Pad Placement for Driver Testing

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Solution Overview

Problem

In liquid crystal display devices, the existing Chip-On-Film (COF) and Chip-On-Glass (COG) bonding methods require lengthy test operations due to the need to turn over flexible printed circuit boards (FPCs) for testing, and COG bonding damages wires on glass substrates with probe stations, increasing analysis time.

Innovation Solution

Incorporating test pads on either the printed circuit board or glass substrate, allowing drivers' output signals to be measured without turning over the FPC, thereby reducing test time and preventing wire damage through flexible printed circuit boards acting as intermediaries between the drivers and the substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If COF bonding is used with test pads on the bottom surface of the FPC, then drivers can be tested, but the FPC must be turned over during test operations increasing test time

Engineering Contradiction:

Improvedriver testing capabilityVSAvoidtest time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

Instead of placing test pads on the bottom surface of the FPC requiring turnover, the invention inverts the approach by forming test pads on the top surface of the FPC where the driver is located. This allows testing without turning over the FPC, directly reducing test time while maintaining testing capability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If COG bonding is used with drivers directly bonded on the glass substrate, then no test pad is formed on the glass substrate, but a probe station is required to measure output waveforms causing wire damage and longer analysis time

Engineering Contradiction:

Improvedriver bonding processVSAvoidwire damage

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The FPC serves as an intermediary component between the driver and the test pad. By forming test pads on the FPC rather than directly on the glass substrate, the invention eliminates the need for probe stations to directly contact wires on the glass substrate, thereby preventing wire damage while maintaining the COG bonding process.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If COG bonding is used with drivers directly bonded on the glass substrate, then drivers can be integrated directly, but probe station measurement causes damaged wires and increased analysis time

Engineering Contradiction:

Improvedriver integration efficiencyVSAvoidanalysis time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The FPC acts as an intermediary that provides accessible test pads for the driver outputs. This allows standard test equipment to measure driver waveforms without requiring probe stations to access wires on the glass substrate, thereby reducing analysis time while maintaining direct driver integration on the glass substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7834972B2Display circuits

Publication Date: 2010.11.16 AU OPTRONICS CORP

AI summary

A display circuit for a display panel is disclosed. The display circuit comprises a circuit board, a flexible printed circuit board (FPC), and a driver. The circuit board has at least one test pad. The flexible printed circuit board is electrically connected and disposed between the circuit board and the display panel. The driver is disposed on the flexible printed circuit board and has at least one test pin. The at least one test pin is electrically connected to the at least one test pad.