Supercon SMD Challenge Gets 3D Printed Probes: Build Your Own | Hackaday

This year is the second SMD challenge faced by Supercon, so it can be said that we may have learned something from last year. If you are not familiar with the challenge, you can use some very traditional tools, and you must solder the circuit board with gradually smaller LEDs until you get the 0201 component. Even with the right tools, these tools are challenging, but even with the bulky and large irons we provide, there are a surprising number of people who manage to make them.

In the first challenge, we did find a problem. The LEDs are marked with polarity. However, since we do not provide ultra-high power amplification, it is often difficult to determine the polarity, especially on smaller parts. Last year, [xBeau] produced some fast LED testers to help overcome this problem. This year, we improved it.

As you can see, the 2018 model uses existing technology very cleverly. The probe is powered by the CR2032 holder, and the probe itself is two resistors. If you can use a probe to make the LED glow, you know which lead is the anode and which lead is the cathode. A little red ink makes it more obvious.

One idea is that these surveys worked well in 2018, so we can do more for the challenges of 2019. However, although these tools work well, they are not convenient to use. Small wires are not real springs, and will be fatigued after long-term use.

I want something that can better restrain abuse and have better ergonomics. I thought of 3D printing. Before trying to design something, I did a quick search as always to see if there was something similar.

On Thingiverse, [Tom20170] has

. This is a simple 3D printing for SMD test clip. It has a small flexible plastic coil and a housing for the breadboard cable, which serves as a probe.

Printing is easy, but I don't want to have too many wires or connections, so I ended up making two very simple modifications.

This is my bill of materials:

9 V capture is ideal. I got a better type, which has a molded body instead of the cheaper one, which breaks easily after 9 or 10 snaps. Their prices are indeed higher, but even if you only buy one, they cost less than $1. Saving fifty cents and disconnecting the connector every few months is definitely the wrong economy.

I did some tests with the Molex pins and determined that the bareness of the resistor leads is equally good, so I did not use the remaining pins. When I use them, I use heat shrinking agent on them. If needed, you may also be able to use Thingiverse to design the required wires.

The resistor is my hand. They are not very critical, if I have to do it again, they are one of the few things I want to change.

I used PLA to print a bunch of probe bodies on ANET A8 with a layer height of 0.3 mm. I used 20% padding, but this may not be very important. They don’t take long to print, so I can put them on the bed once, and then run a few times.

The resistor can be inserted well into the cavity on either side, and a little heat shrink will cover the solder joints. Use electrical tape or heat shrink to tie the wires on both sides to relieve all stress. As before, a small amount of red ink can easily see which lead is positive.

If you look closely, you will find that permanent marking is not the best way to mark PLA. It seeps into places you didn't intend to go. However, it is not very important to get positive results. However, if the colored area is clear, I would not use it to color 3D printing.

We really can’t be sure if anyone prefers tricks over bare resistor leads. The battery is removable, which undoubtedly makes the transportation of the probe easier.

The resistor limits the current based on the forward voltage of the LED. Generally, the voltage drop of the LED is between 1.8 V and 3.3 V. Using 100 resistors, its operating range is 13.5 mA to 21 mA. The high end is a bit overheated, you may be able to safely increase the resistance value. Using two 470Ω resistors, the current is approximately between 3 mA and 8 mA. 1kΩ is fine, but it may be a little dark.

Instead of using a higher resistance, I thought of placing the second LED in series so that the tweezers can double as continuity probes. For example, if you short-circuit the probe, a 1.8 V red LED will see about 12 mA of current, but it will still make most of the tested LEDs get 5 or 6 mA with a 100 resistor.

Of course, if your multimeter has a diode setting, it may be the right tool for this job. If the device lights up, the positive probe will indicate the anode of the LED. If it does not light up, switch the probe.

If you look at the LED data sheet, you should find a way to optically identify the polarity. For example, some have green stripes, dots or notches. If the lens is transparent, you can also understand the polarity by paying attention to the connections inside the LED. Sometimes, the shape of the pad will tell you. If the component is on the reel, the reel usually has a way to tell you, but if you only have some scattered parts, it won’t help you.

see this

. You will see that the terminals and pads look a little different. This from

A cut-off angle is clearly shown. You can see many examples here

.

If you want to know more about the SMD challenge, please check

. Maybe you like yours better

. However, if you do make a pair, please post them and send us a link. At the same time, you can start practicing next year's game. It is never too early.

When you perform this operation on DEFCON, a part data sheet will be provided in advance. I use it to optically determine 0201. I can easily see the rest.

Using the same title photo as [Dan] makes me wonder if there are different HaD authors writing the same story on the blog.

(It’s not that it happened before B^)

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