1. FPC (Flexible Printed Circuit) refers to flexible circuit boards, commonly known as flexible printed circuit boards, flexible circuits, or soft boards. These circuit boards offer advantages such as high wiring density, lightweight, and thin profiles.

2. FPCs are extensively used in devices like mobile phones, laptops, PDAs, digital camcorders, LCMs, and various other products. Recently, advancements in PCB manufacturing technology have rapidly evolved, and the industry has raised its standards for FPCs.

3. Precision PITCH represents a significant breakthrough direction for the future of FPCs. The demand for stability and precision in dimensions has also resulted in increased costs for FPCs.

4. Addressing the challenge of balancing these factors has become a key focus, particularly in controlling the expansion and contraction of FPC materials during production. Below, we provide a brief overview of the main points on how to effectively manage this control.

5. FPC design

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1. Wiring considerations: As FPCs expand due to temperature and pressure during ACF crimping, the expansion rate of the crimping finger must be factored into the circuit’s initial design, and pre-compensation should be implemented.

2. Layout design: The products should be distributed as evenly and symmetrically as possible throughout the layout. Maintain a minimum distance of 2MM between each PCS product, and stagger the copper-free areas with dense via holes. These considerations are critical as they influence material expansion and contraction during subsequent manufacturing.

3. Material selection: The adhesive for the cover film should not be significantly thinner than the copper foil thickness to prevent inadequate glue filling during pressing, which can lead to product deformation. Both the thickness and even distribution of the adhesive are key factors in the expansion and contraction of FPC materials.

4. Process design: The cover film should cover all copper foil areas whenever possible. It is advisable to avoid direct attachment of the cover film to ensure uniform pressure during pressing. For PI reinforcement bonding with glue thicker than 5MIL, minimize the adhesive area; if necessary, apply PI reinforcement after pressing and baking the cover film.

5. Material storage: The significance of proper material storage is undeniable and must strictly adhere to the conditions specified by the material supplier.

6. FPC manufacturing:

1. Drilling: Pre-baking before drilling is recommended to minimize substrate expansion and shrinkage due to moisture content during subsequent processing.

2. Electroplating: Utilize short-side splints to reduce deformation from water stress caused by movement. Minimize swing amplitude during electroplating, and ensure an appropriate number of asymmetrical splints; additionally, enter the tank with a controlled current to avoid sudden high-current impacts that could adversely affect electroplating.

3. Pressing: Traditional presses operate with constant temperature curing, while fast presses use heat curing. Control of the glue in traditional presses must be stabilized, and laminated boards are also critical components.

4. Baking: For fast-pressed products, baking is essential. Ensure baking conditions fully cure the adhesive to avoid future production or usage issues; the baking temperature should gradually increase to the adhesive melting point, maintain this temperature until solidification, then cool gradually.

5. Throughout the FPC production process, it’s vital to maintain stable temperature and humidity across all stations, particularly during transfers and in storage conditions.