Common Measurement Units Used in the PCB Industry
The PCB industry relies on precise measurement units to ensure electronic components are mounted properly. Let's take a look at the commonly used units in the PCB industry.
Length and Thickness Measurements
One of the fundamental units in the PCB industry is the inch.
- 1 foot = 12 inches
- 1 inch = 1000 mils
The term "mil" is frequently used in the PCB industry to measure thickness and spacing. For instance:
- 1 mil = 25.4 micrometers (µm)
- 1 mil = 1000 microinches (µin)
This means that when you see a specification like 4 mil/4 mil, it translates to a line width and spacing of 0.1 mm/0.1 mm.
Weight and Area Measurements
In terms of weight, the PCB industry uses ounces per square foot to measure the thickness of copper layers:
- 1 oz = 28.35 grams per square foot = 35 µm
Additionally, H = 18 µm represents a common copper thickness used in PCBs.
Electrical Measurements
Electrical measurements are also key in PCB manufacturing. For instance:
- 1 ASD (Ampere per Square Decimeter) = 10.76 Amperes per Square Foot
- 1 AM (Ampere Minute) = 60 Coulombs
These units are particularly important in processes like electroplating, where precise current densities are required to achieve the desired layer thickness and material properties.
Volume Measurements
PCB manufacturing also involves various liquid processes, where volume measurements are critical:
- 1 gallon (UK) = 4.5 liters
- 1 gallon (US) = 3.785 liters
Knowing the difference between UK and US gallons can be crucial for international operations and procurement.
Specific Gravity and Baumé Degree
Specific gravity (SG) is a measure of density that is used in the context of chemical solutions used in PCB processes:
- Baumé Degree = 145 - 145 / Specific Gravity (SG)
- SG (g/cm³) = 145 / (145 - Baumé Degree)
This relationship helps in determining the concentration of solutions, which is vital for maintaining consistency in processes like etching and plating.
Conclusion
Understanding these measurement units and their conversions is essential for anyone involved in PCB manufacturing. Accurate measurements ensure that PCBs meet the stringent requirements of modern electronic devices, leading to better performance and reliability. By familiarizing yourself with these units, you can better communicate specifications, improve quality control, and enhance overall production efficiency.
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