The PCBA coating thickness standard mandates a typical range of 25 to 127 microns for most circuit board products, with variations for specific products that may have thinner coatings. To measure the coating thickness of PCBA three-resistant paint, specialized tools are employed:
1. Wet Film Thickness Meter:
- Description: A dedicated instrument designed for direct measurement of the wet film on a circuit board.
- Method: The meter features grooves with known calibration lengths. Placed on the wet film, the depth of the groove is measured. This measurement, multiplied by the coating’s solid percentage, yields an approximate dry coating thickness.
2. Micrometer:
- Description: A micrometer assesses thickness at various points on the board before and after coating.
- Method: Measure the cured coating thickness, subtract the initial thickness without coating, and divide by 2 to determine the coating thickness on one side. Calculating the standard deviation enhances insights into coating uniformity. Ideal for use with harder coatings resistant to deformation under pressure.
3. Ultrasonic Thickness Gauge:
- Description: This tool utilizes ultrasonic technology to measure coating thickness.
- Method: Unlike eddy current probes, it doesn’t require a metal back. The gauge calculates coating thickness by measuring the time sound takes to travel from the transducer through the coating, reflecting back off the PCB surface. This method is non-destructive, ensuring the safety of the PCB.
Understanding these measurement methods empowers practitioners in adhering to PCBA coating thickness standards and ensures the integrity and performance of circuit board products.
