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SMT Test probe point in Reference Designs

September 23rd, 2015

One of the things I like to do in the prototype and evaluation boards design is to add capability to hook up the ground clip of the oscilloscope. You can do this using Keystone part number 5016 - that looks something similar to

Keystone 5016 test probe

The digikey price for this is $0.26 each in quantity of 100. If you are doing a small production run, you do not need to do it on all boards. Just populate it one few boards that you would like probe with an oscilloscope. You may also hook this test point that you expect to debug a lot.

If you have not included this point, you can still use your imagination to use this test probe point. Find a place, like a big capacitor, on end of which is ground. Use the exposed ground pad of the Capacitor to partially hook this test probe point.

If you want an even smaller foot print, you can use Keystone part 5019. It uses an SMT pad size of only 150 mils x 80 mils ( compared to 185 mils x 135 for 5016). The 5019 is also less expensive at $0.21 in quantity of 100.

test-probe-5019

The Keystone 5017 part uses even smaller 135 mils x 70 mils pad.

This test point may not be very suitable for high speed probes. You will need to use a ground pin very close to the high speed testing pin.

It turns out that Harwin Incorporations' part number S2761-46R is another similar product ( Pad size is only 40 mils x 80 mils). For slightly larger size look for Harwin's part numbers S2751-46R and S1751-46R).

It is easy to damage these test points during tests, as extra force can knock off these test points. But this should not be very serious issue, since test points are not part of the actual circuit.

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