This learning guide aims to help you review and consolidate your knowledge of Flexible Printed Circuits (FPC) and their applications in display panels. The focus covers the following topics:
- Structure and Composition of Flexible Circuit Boards: Understand the functions and interrelationships of key components such as the main body, auxiliary test part, gold fingers, test pads, test points, and separation parts.
- Principle of Bonding Impedance Detection: Master the method of detecting the impedance at the gold finger junction through test points, as well as the binding processes of other flexible circuit boards or integrated circuit chips.
- Applications in Display Panels: Understand how flexible circuit boards are integrated into display panels and their impact on the thickness and internal space of the display panels.
- Technical Advantages and Innovations: Identify improvements in detection accuracy, space utilization, and product thinness proposed by the invention of flexible circuit boards and display panels.
Q&A
Please briefly answer the following questions in 2-3 sentences:
- What are the two main components of a flexible circuit board? How are they connected?
- What role does the gold finger play on a flexible circuit board? Which key area does it extend into?
- What is the function of test pads and test points in a flexible circuit board? How are they electrically connected?
- Why do the ends of test pads far from the auxiliary test part need to be insulated from each other?
- How can a multimeter be used to detect bonding impedance?
- What is the main function of the separation part? When does it play a role during the lifecycle of the flexible circuit board?
- What are the benefits of separating the auxiliary test part from the flexible circuit board or display panel?
- In a display panel, how do the first gold finger of the main flexible circuit board and the second gold finger of the auxiliary flexible circuit board interact?
- Why does the second test pad on the auxiliary flexible circuit board need to be shorted away from the edge of the display panel?
- Besides test pads, what other types of pads can gold fingers include? What are the characteristics of their arrangement?
Answers to Q&A
- A flexible circuit board mainly consists of the main body and the auxiliary test part. They are connected by the separation part.
- The gold finger is a conductive contact on the flexible circuit board used to connect to other components. It extends into the separation part where the main body connects to the auxiliary test part.
- Test pads and test points are used to detect the impedance at the gold finger junction. The test points are electrically connected to the corresponding test pads through copper traces.
- The ends of test pads far from the auxiliary test part are insulated from each other to ensure that an independent resistance detection loop can be formed during bonding impedance detection, allowing for accurate measurement of specific junction impedances.
- When detecting bonding impedance, a multimeter can be used in resistance mode, connecting the probes to each pair of test points to directly read the multimeter’s value, which represents the bonding impedance.
- The main function of the separation part is to separate the auxiliary test part from the flexible circuit board or display panel after testing is completed. It plays a role after the internal testing phase before the product is shipped.
- The benefit of separating the auxiliary test part from the flexible circuit board or display panel is that it reduces the thickness of the display panel, saves internal space, and meets the design requirements for thinner display devices.
- In a display panel, the first gold finger of the main flexible circuit board and the second gold finger of the auxiliary flexible circuit board are positioned opposite each other and achieve electrical connection through compression.
- The second test pad on the auxiliary flexible circuit board needs to be shorted away from the edge of the display panel to form a complete resistance detection loop with the test pad on the main flexible circuit board during bonding, allowing the multimeter to accurately measure the bonding impedance.
- Besides test pads, gold fingers can also include signal transmission pads. The test pads in a pair can be arranged adjacent to each other or spaced apart from the signal transmission pads.
Thesis Topics
Here are five thesis topics that can be explored in depth; please choose one to write about:
- Detail how the innovative structure of the flexible circuit board in this invention addresses the issues of space occupation and thickness increase faced in traditional display panels during bonding impedance detection.
- Compare the advantages and disadvantages of the bonding impedance detection method proposed in this invention with existing technologies (such as setting additional test pads or test boards) and analyze its potential impact on product reliability improvement.
- Discuss the importance of the design of the “separation part” in this invention, and the convenience of micro-connection points as components of the separation part during the disassembly of the auxiliary test part.
- Analyze how the design of placing two pairs of test pads on either side of a gold finger in a display panel enhances the accuracy of bonding quality detection.
- From the perspective of materials science and manufacturing processes, discuss the technical challenges and solutions that may arise in realizing the structures of the flexible circuit board and display panel in this invention (such as copper traces, vias, etc.).
Glossary of Terms
- Flexible Printed Circuit Board (FPC): A circuit board made from flexible insulating materials that can bend and fold.
- Main Body: The core functional area of the flexible circuit board that carries the main circuits and gold fingers.
- Auxiliary Test Part: A temporary part on the flexible circuit board used for auxiliary detection of bonding impedance, which can be separated after testing is completed.
- Gold Finger: Gold-plated contacts on the edge of a flexible or rigid circuit board, typically used for connector insertion or electrical connection with other circuit boards.
- Test Pad: The area on the gold finger specifically designated for electrical testing.
- Test Point: The contact on the auxiliary test part that is electrically connected to the test pad, used for connecting testing equipment (such as a multimeter).
- Separation Part: The area connecting the main body and auxiliary test part, designed to be easily broken for removing the auxiliary test part after testing.
- Micro-connection Point: A specific form of the separation part, similar to the perforations of a stamp, facilitating manual tearing.
- Bonding Impedance: The resistance value of the electrical connection between two components (such as the main flexible circuit board and the auxiliary flexible circuit board or integrated circuit chip), reflecting the quality of the bond.
- Signal Transmission Pad: A pad on the gold finger used for signal transmission.
- Auxiliary Flexible Circuit Board: Another flexible circuit board that bonds with the main flexible circuit board in a display panel.
- Integrated Circuit Chip (IC Chip): A miniaturized electronic circuit, typically connected to a flexible circuit board via gold fingers and other means.
- Peripheral Circuit Area: The area in the display panel that contains driver circuits and connectors.
- Shorting Line: A wire used to connect two or more test pads under specific conditions.
- Via: A hole in a multilayer circuit board that connects conductive patterns on different layers.