1. The requirements for test coupons for the single ended and differential wave impedance measurement
  • The Pads for „Signal“ and „GND“ should have a distance of 2.54mm in Y-direction (pic.1).
  • In X-direction, the distance of the GND-Pads to both Signal pads should be minus 1.27mm respectively plus 1.27mm (pic.1).
  • To reach a better distinguish, it is recommend to make the Signal pads round, and the GND-Pads – square (pic.1).
  • Just one GND-Pad is sufficient as Reference for Impedance measuring, for each group of tracks to be measured (pic.1).
  • Just one group of test Pads at the ends of test – tracks is sufficient for Impedance measuring (pic.1).
  • The length of the test tracks should be between 130 mm and 145 mm (pic.2).
  • In the centre of each pad there shall be a hole into which the pins of the test adapter shall be put. The drill – diameter of these hole at test-pads can be between 0.8mm to 1.2mm (pic.4).
  • The outside dimension of the Coupon should be 10.0mm x 160.0mm (pic.3).
  • Several Coupons can be placed besides each other.

2.Number of different Test - pads

The groups of test pads (here: A, B, C) can be located below each other or beside each other.

If we place the test pads besides each other (case of multiple Impedance measuring) than we can use the space more economically (pic.5).

3.You can download an example of Test-Coupon GERBER-Data (Thanks to company Polar Instruments) here (.zip, 168Kb).

Pic.1 (back)

Pic.2 (back)

Pic.3 (back)

Pic.4 (back)

Pic.5 (back)