Surface Mount Test Clips

Any one working with electronics, even at the hobby level, will at some point be forced to work with surface mount components. It is a fact of life these days that more and more integrated circuits are released only in surface mount packages.

This fact should not discourage anyone from working with SMT. Sure, they can be more difficult to handle and solder. However, equipped with the proper tools, which are readily available, the use of SMT can be done by the hobbyist and they do have some advantages. Two such advantages are a more compact circuit board design, and if you make your own circuit boards, fewer holes that have to be drilled for through hole components.

Some tools that are necessary are a good quality 5x magnifying glass, a fine soldering iron tip and some static free tweezers to handle the parts with. A flux pen and some soldering paste are also a good idea to have on hand – both are available in water washable formulas.

A problem that I recently ran into is the ability to connect test equipment such as a oscilloscope to a SMT device.

It started when I made a simple test PCB in order to run some operational tests on a PCA9685 Led driver. This device is only available in SMT. The easiest package to work with is the TSSOP28 with a pin pitch of 0.65mm – yes, quite small.

When I designed the PCB, I neglected to add test points for any of the outputs or the I2C pins. Fortunately, I found that there is a solution for this.

A company called TPI USA makes an excellent line of surface mount test clips – Nano Clips and Micro Clips. The Nano Clips are designed for 0.3mm pitch leads and also work on 0.65mm pitch leads as well. The Micro Clips will work on a 1.27mm pin pitch. Both clips have gold plating for good conductivity, and are available in a number of different colors. They connect using a 0.65mm x 4mm long pin located on the clip body.

I purchased two of the Nano Clips from DigiKey Electronics, and although they are not inexpensive, they do work very well.

I connected them to my oscilloscope using a wire whip I made from some 30 awg stranded wire I had on hand. I soldered a small female connector removed from a transistor socket to one end and a 0.65 mm square pin to the other end. I covered both with some small diameter heat shrink tubing.

Problem solved!

Here is a picture of them in use.



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