SMD IC soldering techniques and steps using electric soldering iron
With the development of technology, chip integration is getting higher and higher, and packages are getting smaller and smaller, which has also caused many beginners to sigh when they look at SMD ICs. Holding a soldering iron to an IC whose pin spacing does not exceed 0.5mm, do you feel that you have no way to start? This article will explain in detail the welding methods of discrete components with pinned SMD ICs, ordinary pitch SMD ICs, and small packages (0805, 0603 or even smaller).
Tools/Materials
Tools: tweezers, rosin, soldering iron, solder
Material: PCB circuit board
1. Welding of dense pin IC (D12)
First, use tweezers to hold the chip and align it with the pads:
Then hold the chip with your thumb:
Before proceeding to the next step, be sure to confirm that the chip has been aligned with the pads, otherwise it will be more troublesome to find that the chip is not aligned after the next step.
Next, use tweezers to pick up a small piece of rosin and place it next to the D12 chip pin. Note that the rosin used here is not the thick flux (this flux cannot fix the chip):
The next step is to use a soldering iron to melt the rosin. Rosin has two functions here: one is to fix the chip on the PCB board, and the other is to help solder, haha. When melting rosin, melt the rosin as much as possible and distribute it evenly on a row of pads.
Then also use rosin to fix the pin on the other side of D12. After this step, D12 will be firmly fixed on the PCB, so you need to check whether the chip is accurately aligned with the pad before, otherwise, wait until the rosin on both sides is applied. It's not that easy to get after it's ready.
Next, cut a small piece of solder and place it on the left pad (if you use your left hand to use the soldering iron, put it on the right. This example is based on right-handers, haha). The diameter of the solder in the picture is 0.5mm. In fact, The diameter doesn't matter, the important thing is how much you choose. If you are not sure how much to put, it is recommended to put less solder first, and if it is not enough, add more solder.
If you accidentally put too much tin at once, there is no solution. If it is just a little more, you can drag it left and right as in the video tutorial to distribute the excess tin evenly to each pad; if there is a lot more, you can drag it left and right as shown in the video tutorial. , you need to use other methods. It is recommended to use soldering tape to get out the excess solder.
Use a soldering iron to melt the solder, and then drag the soldering iron to the right along the contact point between the pin and the pad, all the way to the rightmost pin:
In this way, the pins on one side of D12 have been soldered, and the other side can be soldered using the same method.
2. Welding of rare-pin IC (MAX232)
The above introduction is the welding method of dense pin IC, but do not use this welding method on all chip ICs. The above welding method feels that the denser the pins, the better. Basically, the pin spacing is less than or equal to This is the only way to weld 0.5mm films, and the specific operation depends on your feeling. Let's take a look at how to solder an IC with a slightly larger pin spacing, taking the MAX232 on the USB board as an example.
First, put some solder on the pad next to the chip pad:
Then use tweezers to align the chip with the pad. At this time, the pin with tin on the pad will be lifted up a little. Find a good feeling and align the chip.
Then use a soldering iron to melt the solder on the pad, and apply a little force with your fingers pressing the chip so that the chip can be tightly attached to the PCB, and the pin is now soldered. Don't press too hard, especially before the solder is completely melted, otherwise the pins will be bent off.
Next, solder the pin on the other diagonal end of the chip to hold the chip in place:
The next thing to do is to solder the remaining pins of the MAX232 one by one. In this way, MAX232 has been soldered. There is no need to wash the board this time because we did not use rosin (in fact, the soldering wire contains a certain amount of flux, which may be rosin, haha).
3. Welding of small package discrete components
Small package discrete components, that is, resistors and capacitors. Demonstrated here is soldering a capacitor in a 0603 package. First apply a little solder to one of the pads where the component is to be soldered:
Then use tweezers to hold the capacitor, and use the soldering iron in your right hand to melt the solder just touched. At this time, use tweezers to "send" the capacitor onto the pad a little, and then solder it:
The next step is to solder another pin, so that the small package component can be soldered to the board beautifully.
