SMD Part Test Jig

This is a spring loaded test jig that will hold SMD parts so they can be easily attached to test equipment or circuits for a prolonged time.

Bill of materials:

• 2 pcs Gold plated contacts (buy additional spares though), Digikey part number: 54-3004-0-00-15-00-00-03-0-ND
• 2 pcs Banana jack, Digikey part number: 501-1928-ND
• 1 pc Dowel pin, 5mm x 60mm 
• 20cm silver plated wire, 24AWG
• 20cm flexible wire
• 2 pcs spring, 7x12,5mm

Tools required:

• 5mm drill bit or reamer.
• round file, diameter <5mm
• flat file
• temperature controlled soldering station
• hammer
• punch, diameter <5mm
• wire cutters
• 3D printer
• flat nose plyers
• small vice

Print all parts. The jig base with 45% infill, and both jaws with 100% infill. Only print supports structures that touch the build plate.

Use a 5mm drill (or preferably, a 5mm reamer) on both side holes to get them to 5mm diameter. The dowel pin should be sitting firmly, requiring light taps with a hammer to be inserted. You may need to use a file to gradually make the hole larger.

Do the same for both holes in the jaws, but here, keep opening it up with the file until the dowel pin barely falls through the hole using its own weight. There should be very little play between the jaw and the dowel pin.

solder a 0,5mm wire into the contact pin. The solder should not spill over. If it does, sand the pin down to its original diameter or scrape off the excess solder with a knife.

Clean the tip of your soldering iron and set it to a temperature that will barely start melting the material that you used for printing. Feed the wire through the hole. Note: this may need drilling open with a 1mm drill depending on the quality of your print.

Now, pull on the wire and gently heat the contact. Pull it into the block for about 3mm. It should go in straight, but you can adjust it if necessary with some plyers while the material is still soft.

Cut off the wire, leaving about 4cm of it sticking out. Coil the wire around a small screwdriver or drill bit, forming a solder eye. This should point to what later is going to be up.

Assemble the unit and drive the dowel pin through. All parts should move freely.

They probably won't at first. Check where parts are touching and file down the parts that cause friction. Rinse and repeat until it works smoothly.

Once everything is moving freely, mount the banana jacks in their slots, and connect them with a flexible wire to the eyelets. Neaten up with shrink sleeve at your discretion.