PCB type: FPC flexible circuit board
Number of layers: 4 layers
PCB thickness: 0.2mm
Surface treatment: Electro gold plating
Minimum line width/spacing: 0.065mm/0.065mm

Introduction to 4-layer LCD display FPC flexible printed circuit board

Definition and characteristics

FPC (Flexible Printed Circuit) is a highly reliable and excellently flexible printed circuit board made of polyimide or polyester film as the base material, simply referred to as the flexible board. The 4-layer LCD display FPC flexible circuit board is a flexible circuit board with a 4-layer circuit structure and is used for LCD displays. Its features are as follows:

• Good flexibility: It has excellent bending and folding performance, which can meet various complex assembly requirements and ensure that the LCD display can work properly in various forms.

• Lightweight and portable: Compared with traditional rigid circuit boards, FPCs are thinner and lighter, which helps to make LCD displays lighter and more portable.

• High conductivity: Made of highly conductive materials to ensure the efficiency and stability of signal transmission, meeting the requirements of LCD displays for high-definition display.

• High reliability: Through special design and manufacturing processes, it has good weather resistance, corrosion resistance, and fatigue resistance, ensuring stable performance in complex electromagnetic environments and various usage conditions.

Technical parameters

Regular parameters

• Insulation resistance: 18μ (1/2 OZ), 35μ (1 OZ), 70μ (2 OZ) Ω.

• Thermal shock resistance: 30°C, 45°C, 60°C, depth 1 – 3 mm.

• Plate thickness: Common plate thicknesses include 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, etc.

• Maximum processing size: For single-sided and double-sided boards, it can reach 450mm * 600mm. For multi-layer boards (including 4-layer boards), it can reach 400mm * 600mm.

Process capability parameters

• Drilling: The minimum finished hole diameter is 0.25mm.

• PTH (Plated Through Hole): Minimum hole diameter is 0.25mm, and the ratio of board thickness to hole diameter is 4:1.

• Conductor width: The minimum line width of the gold-plated board is 0.10mm, and that of the tin-plated board is 0.125mm.

• Conductor spacing: The minimum spacing of gold-plated boards is 0.10 mm, and that of tin-plated boards is 0.125 mm.

• Gold-plated board: The thickness of the nickel layer is ≥2.5μm, and the thickness of the gold layer is 0.05 – 0.1μm or as required by the customer.

• Hot air solder leveling (HASL) board: Tin layer thickness ≥ 2.5 – 5 μm.

• Milling the board: The minimum distance from the line to the edge is 0.15mm, the minimum distance from the hole to the edge is 0.2mm, and the minimum contour tolerance is ±0.15mm.

• Chamfer of the socket: The angles are 30 degrees, 45 degrees, and 60 degrees, and the depth is 1 – 3 mm.

• V-cut: The angles are 30 degrees, 35 degrees, and 45 degrees. The depth is two-thirds of the plate thickness, and the minimum size is 100mm * 150mm.

• Continuity test: The maximum test area is 400mm * 500mm, and the maximum insulation resistance is 100M ohms.

Application fields

The 4-layer LCD display FPC flexible printed circuit board is widely used in various electronic products that require the use of LCD displays, such as:

• Consumer electronics: Smartphones, tablets, wearables, etc. Their features of being thin, light, portable, and highly flexible can meet the requirements of these devices for space utilization and appearance design.

• Industrial control: The LCD display control board in industrial equipment needs to work stably in a complex industrial environment. The high reliability of FPC can meet this requirement.

• Automobile field: For automotive dashboards, central control displays, etc., there are high requirements for the weather resistance and vibration resistance of circuit boards. The 4 – layer FPC flexible circuit board can adapt to these harsh conditions.

Development trend

Performance improvement

• Thinner: In the future, the 4 – layer LCD display FPC flexible circuit boards will pay more attention to the flexibility of thickness and be made thinner to adapt to the development trend of electronic products becoming increasingly thinner and lighter.

• Enhanced folding resistance: The ability to be bent is a characteristic of FPC. In the future, its folding resistance must be stronger, exceeding 10,000 times. This requires better base materials.

Cost reduction

At present, the price of FPC is much higher than that of PCB. If the price of the 4 – layer LCD display FPC flexible circuit board can be reduced, the market will surely be broader.

Process upgrade

To meet various requirements, its process must be upgraded, and smaller aperture sizes, smaller line widths/line spacings must meet higher requirements.