The date on the Yageo recommended footprint patterns document http://www.yageo.ru/pdf/R_Mount.pdfis November, 26, 2004. This is before IPC-7351 was released.

The Placement Accuracy noted in the document is +/-0.25mm. That’s what it was back in 2004. Today in 2020 the placement accuracy of a0603 resistor is 0.01 mm (10um).

In the 98,000 part Yageo database on POD there are –

• 1,471 RC0603 series resistors
• 329 RE0603 series resistors
• 61 RL0603 series resistors
• 7,868 RT0603 series resistors
• 202 RV0603 series resistors
• 180 SR0603 series resistors

Total = 10,111 0603 Yageo resistors on POD and they alluse the IPC-7351 guidelines.

Here is the difference –

IPC-7351 – L pad length = 0.74, W pad width = 0.93 and Spad gap = 0.85

Yageo Resistor 2004 – L pad length = 0.90, W pad width =0.80 and S pad gap = 0.80

Our conclusion:

• The Yageo Toe is too big for today’s assembly
• Potential for tombstoning
• The IPC Side is too big, but that’s because IPC does not differentiate between chip Resistors, Capacitors and Inductors
• Resistors do not have metal termination on the sides, but capacitors and inductors do
• The pad spacing “S” is close (within 0.05 mm)

As a PCB designer, you need to know what Toe, Heel andSide goals are good for your assembly process.

Build your Chip footprint library using a little from IPCand a little from the component manufacturer.

If I was defining the Yageo 0603 Resistor, I would usethese values:

PCB Libraries, Inc. – L pad length = 0.75, W pad width =0.80 and S pad gap = 0.80

I work with a 0.05 mm PCB design and route grid. I wantall the features of my footprints to be snapped and rounded to a 0.05 mm gridsystem.