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Learning to Solder in Pre-Fab Academy Class

Soldering

Materials

Kester Lead-Free Solder is recommended for its ease of use as it has flux within the material.

image1-recommended-solder image1-recommended-solder.png

Equipment: Tweezers, micro cutter, protective goggles, air purifying fan, magnifying glass, helping hands soldering station, soldering iron, recommended solder, brass wool, copper desoldering wick, desoldering pump.

Reminders

  • Soldering tip must be clean before using.
  • Check that the soldering iron is hot by touching it to the soldering wire, then clean off the tip.
  • Wet sponge in the soldering iron holder
  • Turn on air filtering fan, and/or wear a good mask
  • Don't touch the hot iron, but if that happens ice immediately, on and off a few hours
  • Hair back and glasses on

Needle nose pliers are better than tweezers at pulling legs through

Procedure

Set up station:

image2a-soldering-station image2a-soldering-station.png

  • Insert a resistor so that the legs go through to the side without
  • Bend legs outward
  • Hold soldering iron at 45 degrees, and touch to pad and wire
  • Touch solder to iron to melt
  • Form a slope attaching the pad to the wire, not a crater or a ball
  • Clip excess wire close to board although leaving excess may make it easier to remove and reuse
  • Do not bridge any joints with excess solder or wire

I have added Image 2b for easy reference.

image2b-solder-method image2b-solder-method.png

Observations & Thoughts

I practiced on this board with a few resistors using both the thin and thick soldering wires.

image3-soldering-practice image3-soldering-practice.jpeg

At first I was worried I would put too much solder onto the joint, which resulted in not having enough. At home I cut the excess wire off the resistors, and used them as extra practice. This time I tried to put too much solder on to get a feel for the right amount. It took a lot more solder than I expected to make a ball form. I removed the excess solder by reheating it, and scooping some onto the iron which I then scraped off into the brass wool. In the end I liked using the thicker solder.

Soldering feels similar to when I learned welding.

When I was confident, I started the Pixel Game Boy project. The soldering felt different on its board. I'm not sure if the blue colored board acts differently or I was nervous. I switched to the thin soldering wire, and that worked better for me on this project.

Since I have no prior training on circuit boards, I found directions to the project were difficult to follow. I was able to attach the resistor, and capacitors, but I now know to fold the cylindrical capacitor flat to the board before soldering. I soldered it while it was perpendicular to the board, and was unable to fold it flat. That prevented me from being able to install the STC15 MCU chip in Part IV step 3.

image4-cylindrical-capacitor-in-the-way image4-cylindrical-capacitor-in-the-way.png

This gave me the perfect opportunity to practice with the desoldering pump. I was able to remove some solder, but the capacitor was not freed. I eventually folded it down, but I'm not sure if I damaged the capacitor in the process.

Another problem I had was getting the pinned components to stay tight to the board to solder them. I secured the USB port with a rubber band that worked well.

image5-rubber-band-holding-USB image5-rubber-band-holding-USB.jpeg

However, there were very large holes for 2 of the pegs. I worry that I over filled them with solder. When soldering the buttons, I tried to lay the piece flat. This caused the buttons to be slightly tilted, and the top of the case not to fit on properly. My final circuit board is shown below.

image6-final-gameboy-circutboard image6-final-gameboy-circutboard.png

I was not sure how to solder chips into the board. Was I supposed to bend the legs? YouTube video tutorials say to hold it, and get some solder on the iron to solder it one handed.

I tried to power on the game using the USB outlet, but it did not turn on. I believe this was due to overfilling the holes for the USB port, and not that I damaged the capacitor. I put batteries in, and the game worked. So the problem was from the USB outlet.

The case needed to be removed so that the buttons worked right due to my poor soldering.

image7a-final-working-gameboy-no-case image7a-final-working-gameboy-no-case.png

The next day I tried using a different USB outlet after removing the batteries, and the gameboy worked. It was the extension cord, not my soldering.

I bought another kit to practice with, and had no trouble. Pliers helped me to bend the short legs to make it easier to hold in place. I was able to fix the wonky buttons on the first gameboy by reheating the solder while applying pressure with pliers. Once the solder melted, the pressure pushed the button into place.

image7b-final-gameboy-in-case image7b-final-gameboy-in-case.png

Soldering Project 2: Potted Plant

This was a great practice project, because it had a simple circuit that was easy to test which solder joints were working. Having 3 LED plants allowed me to learn from my mistakes without ruining the whole project.

For this project I aligned the resisters, and soldered them.

Image8-resisters-aligned Image8-resisters-aligned.jpeg

Image9-solder-joints Image9-solder-joints.jpeg

Following the directions, I assembled, and soldered the remaining components. One component was bent out of shape, but I carefully bent the legs to fit.

image10-bent-legs image10-bent-legs.jpeg

After the wonky buttons from the first gameboy I came up with a way to hold the solder, and the component in my left hand while using the iron in my right.

image11-hand-hold-grip1 image11-hand-hold-grip1.jpeg

I used the thin solder, and the small conical tip. I really liked using the conical tip until I accidentally touched it to the rubber grip on the alligator clip. Then it stopped working. I remember Tom saying to keep the tip shiny, and it was now dull black. I got out the Tip Tinner, and read the instructions on the back. After scraping off the residue on the iron, I applied the tinner, and removed excess with the brass wool. I repeated this a few times, and the iron started to work again.

image12-tip-tinner-attempt1 image12-tip-tinner-attempt1.jpeg

I then attached the LEDs using the technique in the instructions. I look forward to trying the soldering paste for similar projects in the future. I did not bring my heat gun with me so I could not try it.

image13-soldering-ball-on-pad image13-soldering-ball-on-pad.jpeg

The LEDs are incredibly small, and are easily lost when dropped. After soldering them onto the cactus, I tested my work. It did not light up. The likely mistakes were that my soldering was faulty on either the pot or the cactus. If my mistake was on the cactus I likely got the positive and negative mixed up or damaged the LEDs when soldering. To test if the polarity was reversed I turned the cactus around in the pot. One light came on. Luckily I must have added too much solder, and connected the LED even though it was upside down.

image14-cactus-backwards-in-pot image14-cactus-backwards-in-pot.jpeg

The instructions say there is a "green mark" on the front of the LED on the negative side. This mark is not visible to my eyes even with a magnifying glass. However, there is a very clear green mark on the back side of the LED on the positive side. Having never worked with these LEDs before, I mistook the front and back because of the green mark.

image15-led-negative-on-left image15-led-negative-on-left.jpeg

I did not try to fix the cactus, but moved on to the succulent. It lit up, and changed color.

image16-succulent-lights-up image16-succulent-lights-up.jpeg

I was able to remove the LEDs from the cactus, and re-solder the salvageable LEDs. There were only 3 that could be reused, and the middle one (LED3) color changes color differently than the other 2 (LED6, LED7). See Table 1 for my observations of the color changes. My observations are basic, and do not adequately relay the range of colors displayed.

These RGB LEDs are composed of 3 light emitting diodes, a red, a green, and a blue. As the diodes are given varying voltages they emit more or less light. The lights blend into one color seen by the human eye. The additive color chart below shows how the three primary colors of light, red, blue and green, combine to form the secondary colors of magenta, cyan, yellow, and white. Using the color chart and my observations the possible ratios of light from each diode were inferred.

additive-color-chart additive-color-chart.png

Additive color chart from "What is RGB Lighting? Top 5 RGB LED Strips & Lights" February 8, 2023 by Taylor Scully https://www.ledsupply.com/blog/rgb-lighting-guide-to-the-top-5-rgb-led-strips-lights/

Video 1: color changing lights on cactus

video1-cactus-colors_4x_compressed.mp4

Table 1: Observations of LED colors

table1 table1-observations of LED colors.png

Table 2: Color changing lights ratio on cactus

table2 Table2-color-changing-lights-ratio-on-cactus.png

From table 2 one can see that all observed color combinations can be achieved if LED3 is not producing green light. Either the green diode of LED3 was damaged in the salvaging process or it has a poor connection. As I added more solder, I noticed the LED was slightly raised. I applied pressure to the top of the LED as I worked to quickly melt both solder connections. This made a tighter connection. Image 17 shows LED3, LED6, and LED7 all producing green light. Therefore the problem had been with the soldered joint, and not the LED itself. I am impressed that the LED could withstand being manipulated so much, and still work. If I find the badly damaged LEDs that have been lost in my work area, I would like to see if they could still work.

image17-final-solder-of-cactus image17-final-solder-of-cactus.png

Soldering paste was used with the sunflower circuit board. With the soldering paste it was significantly easier to obtain a good connection. However, the paste left a residue over the board. Soldering paste is made of solder powder in flux, which is rosin in a solvent such as isopropyl alcohol. The paste melted to form a ball of solder, and the flux spread out onto the board. The residue left behind as the solvent evaporated was likely rosin. This was cleaned using ethyl alcohol. Isopropyl may be a better solvent, but I didn't have any on hand.

image18-soldering-paste-on-sunflower image18-soldering-paste-on-sunflower.jpeg

image19-residue-left-from-paste image19-residue-left-from-paste.jpeg

Four out of five LEDs worked as expected, the right eye did not have a blue light being emitted.

image20-righteye-does-not-match-others image20-righteye-does-not-match-others.jpeg

video2-led-color-changes-of-sunflower-videox2_compressed_4x.mp4

The right eye LED was angled, likely causing the issue.

image21-right-eye-led-set-on-angle image21-right-eye-led-set-on-angle.jpeg

I tried to use gravity to my advantage by clipping the board so the LED would slide into place as the solder joints were heated. However, during the repositioning attempt the LED fell, and has been lost. A new LED was used, and the light works. Although it is most likely the solder joint that was at fault it is impossible to know for sure it wasn't the LED.

After I was done with this project, I was trying to remember how to use a multimeter. I had been hoping to see if I could detect the current running through the LEDs. I serendipitously found that if I set the altimeter to the 1.5V battery test, the LED the probes were touching would change color. It always blinked, and reset the pattern of the color change.

image22-reset-lcd-with-multimeter image22-reset-lcd-with-multimeter.jpeg

The LED continued to color in time with the other LEDs after the probes were removed. Turning the system off and on again reset the light to match the others.

Why did the LED remain at a different color setting after the voltage was removed? Could the measurement have broken the circuit, and reset the sequence? Is it possible to set each LED to be slightly different?

As I attempted to make each LED be a different color, I noticed that each time I applied the leads the LED blinked back to red. It seems the program was reset each time. The program outputs red more than the other colors, which made it difficult to get a point where all LEDs were different.

image23-all-leds-different image23-all-leds-different.png