These boards are named "double-layer" because they have circuitry on both the top and bottom sides, separated by an insulating layer in the middle. The proper electrical connection between the two sides is achieved through small metal-coated holes called vias. Vias act as "bridges" that allow electrical signals to pass through and connect circuits on both sides of the PCB. This via technology enables efficient signal transmission and connectivity, making double-sided PCBs a popular choice for a wide range of electronic devices and systems.

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Planning and Pre-production

During the planning and pre-production phase of PCB manufacturing, the manufacturer carefully reviews the CAD data and other relevant information, such as films, mechanical drawings, and specifications.

One important decision made during this stage is determining the number of boards per motherboard. This decision is influenced by factors like cost-effectiveness and production efficiency, as manufacturers aim to maximize the yield while minimizing waste.

Another consideration is the selection of the panel size, which is optimized for economical reasons. Panelization involves arranging multiple PCBs on a single larger panel to streamline the production process, reducing material waste and manufacturing time.

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In addition to the main circuitry, the pre-production phase includes planning for adding essential information and functionality during panelization. This may include incorporating the UL symbol for compliance, attaching test sheets, specifying the number of layers in each board, and creating a frame for added support and protection.

Choosing the appropriate layer material is also critical at this stage. The selection depends on the specific application, environmental conditions, and desired performance characteristics of the PCB. Different materials offer varying levels of insulation, thermal conductivity, and mechanical strength, catering to diverse project requirements.

Another important consideration during the pre-production phase is determining the drilling size. The choice of drilling size is influenced by the components used and the complexity of the circuit design.

2 layer PCB manufacturing process distribution guide

In the initial stages of 2-layer PCB manufacturing, the necessary materials are carefully prepared based on the traveler's information. The PCB itself is made of copper-clad epoxy glass, and there are various material options available for users and manufacturers, each with unique characteristics and benefits. For instance, FR4, a widely used flame-retardant material, is economical and offers stability and safety in extreme temperature conditions. However, for high-frequency and high-speed PCBs, high-frequency materials like Rogers' RO4000 series or Tacanic's TLX series are preferred. In certain industries like LED lighting, aluminum or metal substrates are utilized for improved thermal management.

Next, the cutting process commences to obtain the desired size for the PCB. The original boards are larger, and cutting them to the appropriate size optimizes the manufacturing process and cost efficiency. Vias, small metal-coated holes, are essential to provide electrical connections between the two sides of the double-sided PCB.

Subsequently, the drilling process occurs, creating holes on the PCB through an automated drilling machine. Deburring follows to remove any copper burrs and ensure a smooth finish. Electroless copper plating is a crucial step, depositing copper through the holes to enable connections between different layers.

In the photo imaging stage, the negative circuit pattern is transferred onto the PCB panel using photoresist. Pattern plating is then employed, adding copper and tin or tin/lead solder to form the desired circuit pattern. The panel undergoes development and etching to remove imaging material and exposed copper, revealing the circuit pattern.

Applying solder mask in various colors such as green, white, or blue, ensures insulation between wires and prevents short circuits. Surface treatment options like HASL, OSP, ENIG, and more are chosen to protect the copper from oxidation. Gold and nickel plating may be used to enhance corrosion resistance and provide a durable finish.

Labels and component legends are added using screen printing, and the PCBs are separated into individual parts. Finally, the electrical test, performed with flying probe test technology, verifies the functionality of the circuits.

Throughout the 2-layer PCB manufacturing process, careful selection of materials and adherence to various steps ensure the production of high-quality PCBs tailored to specific application requirements.