The Raspberry Pi Pico is a fantastic controller board for your electronic creations. When you unpack Raspberry Pi Pico, you’ll see that it’s totally smooth, with no metal pins protruding from the sides as on the Raspberry Pi’s GPIO header. It does not come with any pins to attach to the 40 GPIO pinholes. The board can’t attach to circuits, cameras, sensors, or anything else you’d like to make a project without pins. This is in case you decide to solder wires directly to Pico or use the castellations (bumpy edges) to link Pico to another circuit board. More advanced users can directly attach female pin headers as soldering makes it messier and more cluttered.

Soldering is an essential maker art, and the Raspberry Pi Pico is an excellent way to practice it. The Raspberry Pi Pico has 40 GPIO pins that must be soldered before used. The most convenient way to use Pico is to connect it to a breadboard, which necessitates the use of pin headers. The $4 Raspberry Pi Pico is a good place to start if you’ve never soldered before. There are no tight spaces or wide solder joints on this frame, making it easy to solder.

Hardware Components40 Male header pins in a strip
Snips/side cutters
Half-size and full-size breadboards are available.
Soldering iron, as well as a stand.
Solder that is free of lead.
Soldering paste
It’s better to wear eye protection, particularly if you don’t wear glasses.
Desoldering wicks

Points to be noted:

  1. Soldering irons come in a variety of sizes, wattages, and nibs, as well as a wide range of prices. I would advise you to purchase a soldering iron from a reliable maker shop at a price that you can afford.
  2. You’ll also require solder. Leaded solder and lead-free solder are the two forms of solder available. Due to the marginally higher melting point of lead-free solder, some people find it more difficult to deal with. However, since leaded solder contains lead, which is a toxic metal, you must exercise caution when handling it.
  3. Make sure the room is well ventilated. We have an extractor fan here at Pi Towers to remove all of the smoke, but because you are unlikely to have one at home, I recommend soldering in a well-ventilated environment like a garage or by an open window.
  4. If you make a mistake, you might want to have some desoldering wick on hand.
  5. Finally, you’ll need the pieces that you’ll be soldering together. We’ll teach you how to solder a header to a Raspberry Pi Zero in this scenario.

Your Setup preparation

Preparation is the secret to soldering safely. Before you turn on the soldering iron.

  • Make sure your workspace is ready.
  • Sit down and double-check that it is in working order. 
  • Will you be able to get to the solder?
  • Do cross-check that you have everything you need.
  • Make sure you have some eye and respiratory protection.

Soldering is a lot of fun, and once you get the hang of it, take your time and have a good time. You’ll require a soldering iron with a stand, solder, a cleaning sponge, a Raspberry Pi Pico, and two 20-pin 2.54 mm male header strips, as well as two 20-pin 2.54 mm male header strips. You should use a solderless breadboard to make the soldering operation simpler if you already have one.

2.54 mm headers are often sold in strips of more than 20 pins. If yours are longer, count 20 pins in from one end and look at the plastic between the 20th and 21st pins for a little indentation on both sides. Split the strip at this stage by placing your thumbnails in the indentation while holding the headers in both hands.

Invert the Raspberry Pi Pico so that the silkscreen pin numbers and test points on the bottom can be seen. Take one of the two header strips and softly drive it through the pinholes on the Pico’s left side. Take the other header and put it into the right-hand side, making sure it’s correctly inserted in the holes and not only lying in the castellations. When you’re finished, press the pins’ plastic blocks against the circuit board of your Pico.

Steps for working

Pinch the sides of your Pico to hold the circuit board as well as the two-pin headers. Hold on tight because the headers will break out if you let go! If you don’t have a breadboard, you’ll need a way to keep the headers in place when soldering – don’t use your fingers, or they’ll fire. Small alligator clips or a small glob of Blu Tack or another sticky putty may be used to keep the headers in place.

Step 1: Make use of a breadboard

If you have a breadboard, just turn the Raspberry Pi Pico upside down, pinching the headers, and drive both the headers and the Pico into the breadboard’s gaps. Continue pressing until the pin headers’ plastic blocks are sandwiched between your Pico and your breadboard, and your Pico is almost smooth.

If you look at the top of your Pico, you’ll see that a tiny portion of each pin protrudes from the pinholes. This is the element you’ll solder, which entails heating all the pins and pads on Pico and applying a small amount of a special metal called solder to them.

Step 2: Before soldering

Put the soldering iron in its stand and plug it in, making sure the metal tip isn’t resting on something. When you’re waiting for the tip of the iron to heat up, unroll a short length of solder that’s about twice as long as your index finger. Since solder is a very soft metal, you should be able to crack it by pushing and turning it.

If your soldering stand comes with a washing sponge, take it to the sink and soak it in cold water to smooth it. Put the sponge back on the stand after squeezing out the excess water. It should be moist but not leaking. You won’t require any water if you use a cleaner made of coiled brass wire. You can refer this video as well.

WARNING: Soldering irons get really hot and remain that way for a long time after they’ve been turned off. If you’re not using the iron, make sure it’s in the stand and all the metal bits aren’t touched – even though it’s unplugged.

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Step 3: Make header pins

Count the number of pins in a strip of male header pins. There would be 40 pins in a standard strip. Using the side cutters/snips, divide the pins into two strips of 20. Before you make the cut, take your time and double-check everything.

Step 4: Strips to the pico

Attach the two strips to the Raspberry Pi Pico so that the shortest legs pass through the board’s gaps. The Pico’s CPU should be faced up, while the long pins should be facing down. You may also turn the Pico over so that the CPU is facing the breadboard. This displays the GPIO pin names, which is handy if you’re not sure what each pin does.

Step 5: 90-degree angle

Place the long pins into the breadboard, making sure they are at a 90-degree angle to the Raspberry Pi Pico. Make sure all of the pins are in place and that everything is upright.

Step 6: Soldering

  • Make sure you’re wearing eyeglasses.
  • Pick up your soldering iron by the handle and shift it around carefully to avoid hitting the cable on something. Hold it like a pencil, but just cover the plastic or rubber handle surface with your fingers: the metal bits, including the shaft instead of the real iron tip, would be incredibly hot and will easily sear you.
  • Tining: The iron is the process of applying a glob of solder to the tip. The flux in the solder aids in the removal of some dirt from the end of the iron and prepares it for use. Wipe the excess solder off the iron with your sponge or washing wire once more; the tip should be smooth and clear.
  • Return the iron to its stand, where it belongs because you’re consciously using it and place your Pico in front of you. Press the tip of the iron on the pin nearest to you, ensuring that it is in contact with both the vertical metal pin and the gold-colored pad on the Pico.
  • It’s important that both the pin and the pad heat up, so press your iron against both when counting to three. When you’ve hit three, softly press the end of your length of solder against both the pin and pad on the opposite side of your iron tip, while holding the iron in place.
  • The solder can flow across the pin and pad, but not much farther, since Pico’s circuit board is covered with a solder resist coating that keeps the solder where it belongs. Using just a small amount of solder: a little goes a long way.

Step 7: Take out the solder

Pull the leftover solder away from the joint while maintaining the iron’s position. If you touch the iron first, the solder will harden and you won’t be able to remove the piece with your hand; if this occurs, just re-melt it with the iron. Remove the soldering iron until the molten solder has scattered across the pin and pad, it should only take a second or two.

You’ve successfully soldered the first pin!

  • Repeat the Steps as above

Step 8: Soldering check

Make sure your soldering is in good shape! Examine the joint in detail. Is there a decent level of contact? Does it seem to be correct? To ensure a decent bond, we can need to reheat a joint and then flow a little more solder.

Soldering issues

  • The pad will not sufficiently heat if the solder adheres to the pin but not to the copper surface,. Don’t worry, it’s simple to repair. Simply put your soldering iron where the pad and pin touch, ensuring that it presses against all this time. After a few seconds, the solder can reflow to make a nice joint.
  • However, if the solder is so hot, it will not flow properly, resulting in an overheated joint with burnt flux. You can remove it with a toothbrush and a little isopropyl alcohol, or by carefully scratching with the tip of a knife.
  • You used so much solder if it completely covers the screw. Even if it doesn’t look really appealing, it shouldn’t be a problem: as long as none of the solder touches any of the pins surrounding it, it should always function. If it comes into contact with other pins, you’ve built a bridge, which would result in a short circuit.
  • Bridges, once again, are simple to repair. If that doesn’t fit, place your iron against the pin and pad on the other side of the bridge to flow any solder through the joint there.
  • Another typical blunder is using too little solder: If the copper pad can still be seen, or if there is a distance between the pin and the pad that isn’t filled in with solder, you used too little. Replace the iron on the pin and pad, count to three, and apply a small amount of solder. It’s still better to patch too little than too much, so be gentle with the solder!

Desoldering Process

Desoldering is the process of applying heat to a solder joint and then removing the molten solder to separate the joint. To repair a defective part, change an existing circuit, or recycle components for reuse, desoldering may be needed. If there’s already a lot of solder on the board, you’ll need to scrape it before you can use your Pico, you can use the desoldering braid to suck the excess up, or you can use a desoldering pump to manually suck the melted solder out.

Clear the excess solder with the desoldering wick if you make a mistake. Place the desoldering wick on top of the solder you want to strip. Then, with the soldering iron’s tip on the wick, solder it in order.

Simple steps for Desoldering

  1. Header Joints Can Be Sliced: Using flushed clippers, cut where the headers are connected together.
  2. Remove the Black Plastic: After cutting, remove the black plastic with needle-nose pliers.
  3. Take out the silver bobby pins:
  • Make sure the tip of your soldering iron is clear.
  • Tin the soldering iron before using it.
  • Fill the pinholes with a glob of solder, then softly tap the glob to extract the pin.

 (Using this method, you can avoid burning the copper pad on the board.)

STEP 4: Using Solder Wick to Clean Up: Remove some solder blobs by absorbing the excess solder with solder wick.

STEP 5: Check to see if any critical pins have been damaged:

  • Inevitably, certain pins will be de-copped (the copper pad will be burnt off), but none of these pins are critical to the board’s operation.
  • There are 40 GPIO pins on the Raspberry Pi Pico.
  • Thankfully, neither of these pins had been de-copped!

Tips For Soldering GPIO

  1. If it doesn’t stick, it’s either not hot enough or the pieces aren’t tight enough together.
  2. You’ll need to keep the thing mechanically stable while you heat it up enough for the solder to flow, and then you’ll need to wait for it to cool off. For the GPIO header, this will be difficult because there isn’t enough space to loop wires around the pins, so you’ll need to devise some sort of arrangement (“Helping hands” may be a good example.) to keep the wires in place.
  3. When doing difficult soldering jobs, coat both sides in solder first, then re-melt the solder to complete the bond, which is always much easier than having the solder coat the surface in the first place.
  4. Overall, though it would be inconvenient and unreliable, it is preferable to use a proper connector.
  5. Soldering to the other end of the pins on the underside of the board could be smoother. This also has the benefit of keeping the pins unchanged and allowing for the use of a connector in the future if desired.

FOR MORE related PROJECTS VISIT THE RASPBERRY PI-projects section

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