PCB Blog - What is stencil of circuit board?

Stencil is an important production tool widely used in the PCB manufacturing process. It is made of a high-strength metal mesh with precise combination and design, used for coating solder paste on PCBs.

In the PCB manufacturing process, the stencil is placed on the solder pads of the PCB board and a special scraper or brush is used to evenly apply solder paste to the steel mesh. Solder paste is composed of solder powder and flux, which can adhere to the metal surface and form a good welding effect. By heating and pressure, the solder paste melts and reacts with the solder pads on the PCB board and the pins of electronic components, forming a good welding connection.

The main role of stencil in PCB manufacturing:

1. Control the deposition amount of solder paste: The voids and openings on the stencil allow as much solder paste as possible to pass through. By controlling the pore size, shape, and distribution of the stencil, the deposition amount of solder paste can be accurately controlled. This is crucial for ensuring the connectivity and reliability between electronic components and printed circuit boards.

2. Accurate placement of circuit components: during the soldering process, electronic components on the PCB need to be placed precisely in the designated position. The design and aperture of the stencil correspond one-to-one with the position of the solder joints on the circuit board, ensuring the correct installation of electronic components by depositing solder paste in the correct position.

3. Improve production efficiency and consistency: Stencils can be coated with a large amount of solder paste in a short period, improving the efficiency of PCB manufacturing. Due to the high repeatability of steel mesh, the use of steel mesh can ensure consistency of solder paste. This is beneficial for the stability of the production line and the control of product quality.

The production process of circuit board stencil:

1. Design: Firstly, it is necessary to determine the size and shape of the stencil based on the design drawings of the circuit board.

2. Create a grid: Then, use metal wire or photoresist film to create a grid pattern on the grid board.

3. Acid etching: Next, place the mesh plate in the acid etching solution to remove any metal that is not covered by the mesh.

4. Cleaning: Clean the acid-etched mesh to remove residual acid solution and metal.

5. Coating: Finally, apply the ink onto the mesh plate and apply pressure to force the ink into the grid pattern.

Advantages and disadvantages of circuit board stencil:

1. High precision: The precision of stencil production is very high, which can accurately coat circuit board printing ink.

2. Durability: The stencil of the circuit board has undergone special treatment, which has high durability and can be reused multiple times.

3. Stability: The stencil has high stability, which can ensure stable printing quality.

The stencil in the circuit board is an important component, which mainly helps to solder electronic components onto the PCB board. Steel mesh is a type of metal mesh, usually made of stainless steel or nickel, with high corrosion resistance and wear resistance.