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What Is The Production Process For FR4 Printed Circuit Boards?

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FR-4 material is widely used for its high mechanical strength, excellent thermal stability and electrical properties. In the production process of FR-4 printed circuit boards, FR-4 sheets are cut, copper foils are pressed, graphic storming, etching, drilling, plating, and other process steps to make printed circuit boards with specific circuit patterns.

The production process for FR-4 printed circuit boards typically involves a number of key steps, which are outlined in detail below:

Raw Material Preparation: FR-4 sheet is the main substrate for producing PCBs, which is made of glass fibre impregnated with epoxy resin. It is also necessary to prepare the copper foil, which is usually used for the conductive layer of the board.

Drawing and Design: Using professional computer-aided design software, the circuit board graphics are created and routed according to the circuit requirements. This step generates the Gerber file, which is an important reference for the subsequent production process.

Sheet Cutting: According to the circuit board graphics and Gerber file, use cutting machinery to accurately cut large sheets of FR-4 sheet to obtain small pieces of sheet material that meet the design requirements.

Pressing of Copper Foils: The cut FR-4 sheets are placed in a press machine, where the copper foils are tightly fitted to the sheets by means of hot pressing. This step ensures a good bond between the copper foil and the substrate.

Graphic Stamping and Etching: The Gerber file is imported into a photolithography machine and the sheet is graphically stamped. Then, using acid etching or other etching techniques, the unwanted parts of the copper foil are etched away, leaving the desired circuit shape.

Laminating and pressing (for multilayer boards): If a multilayer board is being produced, the layers need to be tightly bonded together by laminating and pressing to ensure electrical connections and stability between the layers.


Drilling of Holes and Slot Openings: A drilling machine is used to drill the required apertures in the circuit board for the subsequent mounting of components. At the same time, slot openings are created as needed to facilitate wiring or the installation of special components.

Plating: In order to enhance the conductivity and corrosion resistance of the circuit board, the exposed copper skin or hole walls are usually plated with a layer of copper or other metals.

Green Oil Coating: Green oil coating is used to protect the circuitry and prevent tinning of the circuitry during soldering. The graphics of the green film are transferred to the circuit board through a specific process.

Character Printing: Printing of logos, component numbers and other information on the circuit boards to facilitate subsequent assembly and maintenance.

Quality Inspection: Strict quality inspection is carried out on the produced circuit boards, including appearance inspection, electrical performance test, etc., to ensure that the products meet the design requirements and quality standards.

Packaging and Shipping: Qualified circuit boards are properly packaged and delivered to customers or to the next stage of the assembly process.

It should be noted that the production process of FR-4 printed circuit boards may vary depending on the manufacturer, equipment and technology level. However, the above steps usually cover the major aspects of FR-4 printed circuit board production. Strict control of process parameters and quality standards at each step in the production process is the key to ensuring the quality of the final product.

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