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All You Need to Know About SMD Soldering

by:Caodahai     2020-05-16
Hello!
Welding is easy. . . .
Apply some flux, heat the surface, apply welding.
However, a little bit of skill and some tools and accessories are required when soldering SMD components.
In this note I will show you 3 of my SMD welding techniques that are re-welded using hot air
Welding station, hot plate, ordinary soldering iron.
Checkout video for easy understanding!
63/37 soldering tin Pap 26 gauge core soldering tin wire 30 W soldering iron soldering tin repair station (
For hot air welding)/Hot Plate (Roti Maker)(
For hot plate welding)
IPA solutions and cotton (for cleaning)De-solder Pump De-
Tin core SMD steel mesh (order online)
If you don\'t know what the SMD template is, it\'s a laser-cut stainless steel sheet used to distribute the solder paste to the PCB very efficiently.
Large production lines in the industry use advanced machines and SMD templates to distribute solder paste.
First I will show you how to do hot plate welding.
I will use an electric cooker in India that is also known as the Roti manufacturer for welding.
Of course, this does not have any temperature control, but I will handle the process manually.
So there must be no problem.
Industry use re-
Flow oven with temperature distribution control can produce circuit boards in bulk. Re-
Flow ovens accurately controls the heating and cooling profiles according to welding materials and component data sheets.
I stick the PCB to my desk with clear tape and place the SMD template right above the board.
Align the template with the PCB pad and it is best to fix the template in place using a magnet.
I use 63% tin.
37% lead solder paste.
Apply some solder paste on the template and then use something flat like a PCB or credit card to spread the solder paste evenly across the PCB.
Carefully remove the template and you can see that the solder paste is evenly applied to the pads of the PCB.
Place all surface mounting components on the hot plate.
Open the hot plate, wait for the solder paste to melt, remove the plate immediately after melting
Under the tin cream.
The solder paste melts at about 180 degrees Celsius to 220 degrees Celsius, and the process took me about three minutes to finish the welding.
If you are working on a temperature sensitive part, the previous method cannot be used because there is no temperature control.
So I will re-use the hot air
Flow welding station.
This is a reliable tool with Re-flow ovens.
Follow the same procedure to apply the solder paste to the PCB as shown in the precious steps.
After placing the elements on the board, set the rework station to the desired temperature and wind speed.
Close the blower nozzle to the circuit board and wait for the solder paste to melt and fuse with the IC pin.
Please note that if you use this method to weld the LED, do not blow the hot air directly on the LED, blow the hot air behind the PCB to the hot pad, and the solder paste will be fused with the LED.
There is no need to place the component completely on the PCB.
Due to the surface tension of the molten solder paste, a small amount of placement offset will be automatically corrected.
If you do not wish to use hot plates or rework stations, this method uses soldering iron, flux and solder wires.
It\'s convenient to use sharp iron, but it doesn\'t matter.
I put the board on the PCB stand that I made at home.
I have attached a link to the video at the end of this note.
Apply some flux on the pad, heat the surface to clean the pad and remove the oxide layer.
For two terminal components, such as resistors, capacitors and diodes, first apply some solder on any pad by keeping the soldering iron at about 45 degrees, then heat the solder with tweezers and place the assembly.
Then on the other end.
I used the No. 26 core solder wire.
Similarly, for soldering SMD ICs, clean the surface using flux and cotton.
Then apply some flux in the corner, keep the IC in the proper position, weld the corner first, then weld the other pads.
Sometimes there is an opportunity to form a welding bridge between the IC pins.
There are two ways to correct this situation.
One is to heat the welding Bridge and use de-
The solder pump that absorbs excess solder.
Another way is to use de-solder wick.
Place the Wick on the welded bridge and heat the surface. De-
Solder core is just a stranded copper wire coated with flux to increase the affinity of solder to copper.
Once you have completed the welding process, it is important to remove the flux from the PCB.
Spray a small amount of IPA (iso-propyl alcohol)
Solve and clean it with cotton.
If you have any questions or suggestions, please leave them in the comments section below.
Thank you for visiting my guide!
H. S. sandsh. hs1234@gmail.
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