🔍 Identifying Pin 1 on ICs Without a Part Number

Even if the printed part number is faded, you can still identify Pin 1 using these physical markers:

🟡 1. Dot or Dimple

• A small circular indentation near one corner of the chip.
• Pin 1 is directly adjacent to the dot.
• Common on DIP, SOIC, and QFP packages.

🟪 2. Notch or Half-Moon

• A groove or notch on one end of the IC.
• When facing the notch, Pin 1 is at the lower-left corner.
• Standard for DIP and some QFP packages.

🔺 3. Beveled or Chamfered Edge

• One edge of the chip is angled or slanted.
• When the bevel is at the bottom, Pin 1 is at the lower-left corner.

🟥 4. Stripe or Band

• A colored or molded stripe across one end of the chip.
• Pin 1 is at the bottom-left corner when the stripe is on the left.

🔳 5. Square Pad (on PCB or QFN/BGA)

• On surface-mount packages, Pin 1 may be marked by a square pad or larger solder ball.
• Especially useful for QFN and BGA packages.

🔤 6. Text Orientation

• If the part number is still readable:
  • Orient the chip so the text is upright.
  • Pin 1 is usually at the lower-left corner of the text block.

📐 7. Triangle or Arrow

• Some chips have a small triangle pointing to Pin 1.
• Found on opto-isolators and some analog ICs.

✅ Summary