Solder Paste Characteristics and Uses

Solder paste printing is a key step in the SMT placement process, the quality of which directly affects the component placement accuracy and reliability of welding. The following is IntelliTech will analyze several key technical points of solder paste printing in detail:

1. Solder paste selection and storage methods

Type of solder paste: according to the specific needs of the product (including melting point, conductivity, environmental standards, etc.) to select the appropriate type of solder paste.

Storage requirements: solder paste needs to be placed in the specified temperature range (usually 5 ° C to 10 ° C) and low humidity environment, and avoid direct sunlight, in order to protect the stability and reliability of its performance.

2. Stencil design and manufacturing process

Design accuracy requirements: stencil holes, aperture and shape must be accurate correspondence with the pads on the PCB board, so as to ensure that the solder paste can be accurately and uniformly printed to the pads above.

Material Selection and Thickness Determination: The appropriate stencil material (e.g., stainless steel, nickel alloy) should be selected based on the density of the PCB and the pad spacing, and the thickness should be appropriate to ensure that the stencil has the right amount of thickness in order to balance the strength and accuracy of printing.

3. Printing machine configuration and adjustment

Ensure accurate graphic alignment: Use visual or laser alignment technology to accurately align the stencil with the datum point on the PCB board.

Squeegee Setting Parameters: Optimize the squeegee angle (recommended range is 45° to 60°), applied pressure, hardness and squeegee speed to ensure the best solder paste scraping and filling effect.

Printing gap adjustment: Reasonable setting of the spacing between the stencil and the PCB to ensure that the solder paste can evenly cover the pad to avoid adhesion or overflow.

4. Printing process management

Paste Rolling Diameter Adjustment: Through precise control of the rolling diameter of the paste on the stencil, to ensure the stability and adequacy of the supply of paste during the printing process.

Printing speed adjustment: according to the specific size of the PCB board and pad density to set the appropriate printing speed to ensure that the paste can be evenly distributed and ensure the quality of printing.

When the PCB is separated from the stencil, the risk of solder paste pulling and collapsing is effectively minimized by applying multi-stage mold release technology.

5. Please carry out inspection after printing

Visual Inspection: A magnifying glass or microscope is used to carefully observe the completed printed PCB to assess the quality of solder paste printing, including whether it is evenly distributed and whether there are potential defects such as leakage and continuous tin.

Optical Inspection Technology: Through the application of advanced equipment such as Automatic Optical Inspection (AOI), the quality of printed materials is inspected with high precision, which significantly improves the efficiency and accuracy of inspection operations.

6. Cleaning and Maintenance

Stencil Cleaning: The stencil must be cleaned immediately after the completion of each round of printing operation in order to remove the residual solder paste and impurities, so as to avoid them from causing clogging of the openings.

Equipment Maintenance Management: Comprehensive maintenance and upkeep of the printing equipment should be carried out on a regular basis, with special attention paid to the wear and tear status of the squeegee, stencil clamping device and other key components, and to ensure that when wear and tear is detected, timely replacement or necessary adjustments should be made.

7. Environmental regulation

In order to ensure the environmental stability of the printing shop, need to strictly control the temperature and humidity, to prevent environmental fluctuations on the performance of the solder paste and printing quality has an adverse effect.

Static protection measures: To ensure that the PCB and components are not damaged by static electricity, it is necessary to take appropriate protective measures, including, but not limited to, wearing anti-static clothing, the use of anti-static workstations.

Taken together, the key elements of solder paste printing technology covers the selection and preservation of solder paste, stencil layout and manufacturing, configuration and adjustment of the printing machine, the fine control of the printing process, quality inspection after the completion of printing, cleaning and maintenance, as well as environmental conditions and other levels of maintenance. Only a comprehensive understanding of the above points and strictly follow the operating procedures, in order to ensure the quality and continuity of the solder paste printing operations. Return to Sohu for more details.