This post shares three informative videos about hand soldering applied to Electronics. The first video introduces the basic tools and materials needed to do good solder joints. The second video addresses soldering techniques and tips applied to through-hole components soldering. Finally, the last video discusses techniques useful for surface-mount components. Following each video appears a brief summary of the respective video content. Have fun soldering your boards! After all it's a "piece of cake"! :-)
Summary of the tools and materials mentioned in the video for quick reference.
Main tools:
- Adjustable temperature soldering iron (e.g. Hakko FX-888 | Typical temperature range from 350 to 400 ºC, being 350 ºC a good typical soldering temperature | Lower temperatures for heat-sensitive components)
- Flush side cutter (e.g. 170M Xcelite)
- Solder wire (e.g. Multicore | Top quality brand | Diameter < 0.5 mm | Alloy 60/40 or 63/37 (recommended) or 62/36/2 (Sn/Pb/Ag) | Not recommend lead-free solder, more difficult to use | Multicore flux solder highly recommended)
- Desoldering wick, aka Desoldering braid (e.g. Multicore | Top quality brand)
- Tweezers (e.g. C.K 2343 | Stainless steel | Non-magnetic)
- Different types of tips for soldering iron (Not recommended conical tip | Chisel tip recommended | 2 or 2.5 mm typical diameter tip)
- Magnification loupes (2.5x to 8x magnification range recommended)
- Flux pen (e.g. Electrolube SMF12)
Secondary tools:
- Hot air rework soldering station (e.g. Atten AT858D)
- Safety goggles
- Fume extractor
- Vacuum desoldering pump solder sucker
- PCB holder
- Solder paste
Summary:
- Soldering through-hole technology components
- Soldering iron at 350 ºC (typical soldering temperature)
- Touch the chisel tip simultaneously on the pin and on the pad
- Do not apply solder to the iron tip because the flux will go out and it will result in a cold solder joint
- Flux is important to clean oxidation over pins and pads, allowing the solder melt appropriately and forming a reliable solder joint
- For through-hole components soldering, it is sufficient the flux built-in in the solder itself (do not need to apply external flux)
- Soldering step-by-step: i) clean tip; ii) apply the tip on pad & pin; iii) leave the tip in touch with the pad & pin by about 1 sec. or more; iv) apply a small amount of solder to the opposite side of the joint; and v) remove tip
- High quality solder joint will be very bright, shiny, and smooth (at least for solder containing lead)
- Flux residue left over can be cleaned with a special fluid
- Use specific lead-free iron tips for lead-free solder
- Periodically apply solder on the tip to protect its plating againt aging
- Use a electronic cleaning solvent (e.g. Electrolube IPA) for flux removal
- Spray the solvent on the flux residue & rub with an anti-static brush
- If you apply to much solder, you can use the desoldering wick to suck some solder
- Super-fine (canonical) tips are difficult to use (avoid them)
- It is possible to put a bit of solder on the tip to help heat the joint quicker, but after heating do not forget to apply a bit of additional solder with flux to build a good solder joint
- Thermal reliefs in pads attached to large copper planes help the soldering process (easier to heat the pads)
- If you do not have flux, then soldering does not work at all (hence it is important use multicore flux solder wire)
- In military or aerospace applications, they use better techniques and materials for soldering
- Fine diameter solder wire helps to control the amount of solder applied
- Two ways to solder connectors (see video for details)
- Use a bigger chisel tip (to increase thermal transfer) to solder larger joints (e.g. big components or ground planes) and also a 1 mm or more diameter solder wire
- Basic rules for hand soldering:
+ Good brand temp controlled iron
+ Good brand < 0.5 mm diameter solder
+ Flux is everything (because metals oxidize too easily). In solder itself or separate
+ Use the right tip. Chisel tip is best
+ Don't bring the solder to the joint! Iron one side, solder in the other
+ Use the right temp. 350 ºC tops
Summary:
- Surface-mount device (SMD) typical package sizes: 1206, 0805, 0603, 0402, ... For hand soldering, use 0603 or larger packages. Packages 0402 or smaller require some kind of magnification for soldering
- Current not-advanced pick and place machines are able to deal with package sizes 0603 or bigger only
- Standardized footprints for SMDs come at least, normal and most pad sizes. It's recommended to use the normal or most pad size (easier to solder)
- Soldering step-by-step: i) apply a small amount of solder on one pad; ii) put the SMD in place with a tweezers and reflow the solder of the previous step with the iron tip; iii) solder the other side of the component; iv) check the solder joint with a loupe
Soldering Tutorial Part 1 - Tools & Materials
Summary of the tools and materials mentioned in the video for quick reference.
Main tools:
- Adjustable temperature soldering iron (e.g. Hakko FX-888 | Typical temperature range from 350 to 400 ºC, being 350 ºC a good typical soldering temperature | Lower temperatures for heat-sensitive components)
- Flush side cutter (e.g. 170M Xcelite)
- Solder wire (e.g. Multicore | Top quality brand | Diameter < 0.5 mm | Alloy 60/40 or 63/37 (recommended) or 62/36/2 (Sn/Pb/Ag) | Not recommend lead-free solder, more difficult to use | Multicore flux solder highly recommended)
- Desoldering wick, aka Desoldering braid (e.g. Multicore | Top quality brand)
- Tweezers (e.g. C.K 2343 | Stainless steel | Non-magnetic)
- Different types of tips for soldering iron (Not recommended conical tip | Chisel tip recommended | 2 or 2.5 mm typical diameter tip)
- Magnification loupes (2.5x to 8x magnification range recommended)
- Flux pen (e.g. Electrolube SMF12)
Secondary tools:
- Hot air rework soldering station (e.g. Atten AT858D)
- Safety goggles
- Fume extractor
- Vacuum desoldering pump solder sucker
- PCB holder
- Solder paste
Soldering Tutorial Part 2 - Through Hole Technology Soldering
Summary:
- Soldering through-hole technology components
- Soldering iron at 350 ºC (typical soldering temperature)
- Touch the chisel tip simultaneously on the pin and on the pad
- Do not apply solder to the iron tip because the flux will go out and it will result in a cold solder joint
- Flux is important to clean oxidation over pins and pads, allowing the solder melt appropriately and forming a reliable solder joint
- For through-hole components soldering, it is sufficient the flux built-in in the solder itself (do not need to apply external flux)
- Soldering step-by-step: i) clean tip; ii) apply the tip on pad & pin; iii) leave the tip in touch with the pad & pin by about 1 sec. or more; iv) apply a small amount of solder to the opposite side of the joint; and v) remove tip
- High quality solder joint will be very bright, shiny, and smooth (at least for solder containing lead)
- Flux residue left over can be cleaned with a special fluid
- Use specific lead-free iron tips for lead-free solder
- Periodically apply solder on the tip to protect its plating againt aging
- Use a electronic cleaning solvent (e.g. Electrolube IPA) for flux removal
- Spray the solvent on the flux residue & rub with an anti-static brush
- If you apply to much solder, you can use the desoldering wick to suck some solder
- Super-fine (canonical) tips are difficult to use (avoid them)
- It is possible to put a bit of solder on the tip to help heat the joint quicker, but after heating do not forget to apply a bit of additional solder with flux to build a good solder joint
- Thermal reliefs in pads attached to large copper planes help the soldering process (easier to heat the pads)
- If you do not have flux, then soldering does not work at all (hence it is important use multicore flux solder wire)
- In military or aerospace applications, they use better techniques and materials for soldering
- Fine diameter solder wire helps to control the amount of solder applied
- Two ways to solder connectors (see video for details)
- Use a bigger chisel tip (to increase thermal transfer) to solder larger joints (e.g. big components or ground planes) and also a 1 mm or more diameter solder wire
- Basic rules for hand soldering:
+ Good brand temp controlled iron
+ Good brand < 0.5 mm diameter solder
+ Flux is everything (because metals oxidize too easily). In solder itself or separate
+ Use the right tip. Chisel tip is best
+ Don't bring the solder to the joint! Iron one side, solder in the other
+ Use the right temp. 350 ºC tops
Soldering Tutorial Part 3 - Surface Mount Technology Soldering
Summary:
- Surface-mount device (SMD) typical package sizes: 1206, 0805, 0603, 0402, ... For hand soldering, use 0603 or larger packages. Packages 0402 or smaller require some kind of magnification for soldering
- Current not-advanced pick and place machines are able to deal with package sizes 0603 or bigger only
- Standardized footprints for SMDs come at least, normal and most pad sizes. It's recommended to use the normal or most pad size (easier to solder)
- Soldering step-by-step: i) apply a small amount of solder on one pad; ii) put the SMD in place with a tweezers and reflow the solder of the previous step with the iron tip; iii) solder the other side of the component; iv) check the solder joint with a loupe
- Soldering a 8-pin integrated circuit (IC): i) apply a small amount of solder on a corner pad; ii) place the chip with a tweezers and reflow the solder of the previous step to tack the chip in place; iii) solder the diagonally opposed pin; iv) solder the remaining pins; v) inspect the soldering with a magnification loupe
- Solder mask is vital for SMD soldering because it prevents shorts between adjacent closely-spaced pins
- Soldering a fine-pitch 0.5 mm IC: i) apply a small amount of solder on a corner pad; ii) place the chip in the right position with a tweezers and reflow the solder of the previous step to tack the chip in place; iii) solder the diagonally opposed pin; iii) apply flux to help the soldering process; iv) put some solder in the concave tip (special iron tip); v) drag the concave tip with solder over the pins and pads for soldering the remaining pins all together; vi) use the desoldering wick to remove some short, if needed; vii) verify pin shorts with a loupe
- Another soldering method, which doesn't require a special concave tip, uses a normal chisel tip to drag the solder over the IC pins. Don't forget to apply flux over the pads before dragging the solder
- Even another technique uses solder paste with a hot air gun (typical temperature for hot air is 350 ºC)
- For fine-pitch SMDs it is recommended gold finishing over the pads (flatter & doesn't corrode)
- Small SMDs can be damaged by excessive temperatures. Also excessive heat may lift the pads. Be careful!
UPDATE:
The next video shows a technique to solder SMD packages with a bottom thermal pad using soldering iron.
- Solder mask is vital for SMD soldering because it prevents shorts between adjacent closely-spaced pins
- Soldering a fine-pitch 0.5 mm IC: i) apply a small amount of solder on a corner pad; ii) place the chip in the right position with a tweezers and reflow the solder of the previous step to tack the chip in place; iii) solder the diagonally opposed pin; iii) apply flux to help the soldering process; iv) put some solder in the concave tip (special iron tip); v) drag the concave tip with solder over the pins and pads for soldering the remaining pins all together; vi) use the desoldering wick to remove some short, if needed; vii) verify pin shorts with a loupe
- Another soldering method, which doesn't require a special concave tip, uses a normal chisel tip to drag the solder over the IC pins. Don't forget to apply flux over the pads before dragging the solder
- Even another technique uses solder paste with a hot air gun (typical temperature for hot air is 350 ºC)
- For fine-pitch SMDs it is recommended gold finishing over the pads (flatter & doesn't corrode)
- Small SMDs can be damaged by excessive temperatures. Also excessive heat may lift the pads. Be careful!
UPDATE:
The next video shows a technique to solder SMD packages with a bottom thermal pad using soldering iron.
