How to calculate the hole and pad diameter sizes for dual inline package

How to calculate the hole and pad diameter sizes for dual inline package

How to calculate the hole and pad diameter sizes for dual inline package

Calculating PTH (plated-through hole) and pad diameter sizes for a Dual Inline Package (DIP) can be a bit tricky, but it is a crucial step in the design process of any electronic circuit board. PTH and pad sizes are critical to ensuring that the components fit properly  dual inline package meaning on the board, have good electrical connections, and do not damage the board during assembly or operation. In this article, we will explain the process of calculating PTH and pad diameter sizes for a DIP.

Step 1: Determine the Lead Diameter and Spacing

The first step in calculating PTH and pad diameter sizes for a DIP is to determine the lead diameter and spacing. This information can be found in the manufacturer’s datasheet for the component. For example, the lead diameter for a DIP package may be 0.508mm, and the lead spacing may be 2.54mm.

Step 2: Calculate the Pad Diameter

The next step is to calculate the pad diameter, which should be slightly larger than the diameter of the PTH. A good rule of thumb is to make the pad diameter 0.1mm larger than the PTH diameter. For example, if the PTH diameter is 0.508mm, the pad diameter should be 0.608mm. The formula for calculating the pad diameter is:

Pad Diameter = PTH Diameter + 0.1mm

Step 3: Calculate the PTH Diameter

The PTH diameter is calculated based on the lead diameter, and should be slightly larger than the lead diameter to ensure a good fit. A good rule of thumb is to make the PTH diameter 0.2mm larger than the lead diameter. For example, if the lead diameter is 0.508mm, the PTH diameter should be 0.708mm. The formula for calculating the PTH diameter is:

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PTH Diameter = Lead Diameter + 0.2mm

Step 4: Add Annular Rings

The annular ring is the area between the PTH and the pad, which is used for electrical connections. The annular ring should be at least 0.15mm wide to ensure good electrical connections. The formula for calculating the annular ring is:

Annular Ring = (Pad Diameter – PTH Diameter) / 2

For example, if the pad diameter is 0.608mm and the PTH diameter is 0.508mm, the annular ring would be (0.608mm – 0.508mm) / 2 = 0.05mm.

Step 5: Check Clearance

Finally, it is important to check the clearance between adjacent PTHs and pads to ensure that they do not touch each other. The clearance should be at least 0.15mm to ensure that there is no short-circuiting. The formula for calculating the clearance is:

Clearance = (Lead Spacing – PTH Diameter) / 2

For example, if the lead spacing is 2.54mm and the PTH diameter is 0.508mm, the clearance would be (2.54mm – 0.508mm) / 2 = 1.016mm.

Final words

calculating PTH and pad diameter sizes for a DIP is an important step in the design process of any electronic circuit board. The process involves determining the lead details diameter and spacing, calculating the pad and PTH diameters, adding annular rings, and checking clearance. By following these steps, you can ensure that your electronic circuit board is properly designed, and will function correctly during assembly and operation. It is always recommended to double-check the calculations before proceeding with the design process to ensure accuracy

How to calculate the hole and pad diameter sizes for dual inline package
How to calculate the hole and pad diameter sizes for dual inline package
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