This entry is a review and report on my findings trying out a new flux as well as mentioning a lead-free solder that is very similar to 68/37 Si/Pb solder. So here we go.
Flux.
A few day's ago I returned to investigate how to make my own RMA - Rosin Mildly Activated - found some nice pine harts (rosin or kolofonium) and was looking for an acid. At that point I stumbled upon citric acid which some use when making their own RMA flux and everything was good. But it got me thinking. The reason we use flux is mostly two folded: 1. chemically clean the PCB traces. 2. Better wetting / flow of the solder.
So did some further research / reading and found that one can make a flux which use other carriers / wetting agents than kolofonium and that is what its all about.
Vehicle: It turns out that Glycerol is an excellent vehicle.- Glycerol also called glycerine or glycerin: is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in many lipids which are known as glycerides. It is widely used in the food industry as a sweetener and humectant in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature.
Activator: Citric acid. Citric acid is a weak organic acid that has the chemical formula C6H8O7. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms and least but not last, its an excellent oxidizer and used in many natural cleaning products.
Solvent: This one is plain old water or H2O. This is the primary solvent for the citric acid. I used deionized.
***
The formula is fairly straight forward:
2 parts Glycerol. (300ml = ca $6)
2 parts Citric Acid (crystals) (100g = ca $1)
1 part Water. (Free or cheap)
1. Mix the glycerol and water to a homogeneous mixture. 2. Heat the liquid but don't boil, this will make step 3 go faster since heat act as a catalyst. 3 Add the citric acid and stir / mix until dissolved. That's it, you are now done.
Findings.
So I sat down with an empty experiment board to try out this flux. Using Sn60/Pb38/Cu2 solder. The reference flux was Weller Lötwasser (WS flux). The reference flux behave as a flux should, produce normal amount of smoke and has a "normal" smell during use. Cost $7.54 for 25 ml so not cheap.
The Citric Acid Flux (or CAF) has a nice viscosity, similar to warm maple syrup. Virtually odorless and is clear. I spread it using a cotton swab, it stays put thanks to the glycerin. Was using the KSGER V2.1S T12 Digital Temperature Controller Soldering Station which has a fast temperature ramping and recovery and the reason I am mentioning the recovery is that as the water in the CAF is brought to a boiling point, it will take with it some of the heat. The boiling water is what I would say the main difference between the CAF and Weller Lötwasser. Other than this, it is on par with WS or RME with the difference of being super easy to clean with either water or Isopropanol or a 50/50 blend. What a noticed after cleaning the board was that the CAF side did not have any dimples (due to shrinkage) in the solder while the Lötwasser side had. This could be due to the difference in how it cools or solidifies since the CAF has the water that is removing some of the heat, and hence transition from liquid to solid has a different profile compared to Lötwasser.
Cleaning the board from both fluxes was a very simple job, no residue to talk about and compared to RMA flux, a dream to work with.
Solder.
Now its time for some solder info. If you are inexperienced with solder, leaded vs lead-free (RoHS) SAC305 groups which most of the time is a Tin-Silver-Copper blend, watch this video:
Solder Alloys Test - Lead and Lead Free Solder.
Solder Alloys Test - Lead and Lead Free Solder : 60/40 - 63/37 (Eutectic) - 99.3/Cu0.7 - 99/Ag0.3/Cu0.7 (SAC) - 96.5/Ag3/Cu0.5 (SAC305)
YouTube
PS: Going forward, I want to make you aware of the fact that I have not tested the next solder myself, but plan to in the near future.
***
One of the best solders on the market due to less risk of cold joints is the 63/37 Si/Pb version. Lead-Free solder containing silver and is more or less a nightmare to work with, so I never felt content with how it behaves compared to 63/37. But this is going to change.
Kester K100LD
The Only Lead-Free Alloy that Diminishes the 5 D’s
1. Lowest Dissolution of Copper Prevents Copper Erosion, Reduces Pot Maintenance and Increases Reliability
2. Low Dullness. Produces Shiny, Smooth Solder Joints
3. Low Defects. Bridge-Free with Excellent Top-Side Fillets
4. Low Dross. Anti-Drossing Additive Results in 20% Less Dross than Untreated Sn63Pb37
5. Low Dollars. Silver-Free Alloy is Approximately 50% Lower Cost than SAC305
- K100LD is a new patent-pending lead-free solder alloy that can be used in wave soldering, selective soldering systems and dip tinning operations. K100LD has the Lowest Dissolution of Copper amongst all common solder alloys, including Sn63, SAC305, and other lead-free options.
- K100LD has been designed to give users optimal performance with minimal defects and maintenance costs. By preventing the Copper level from increasing in the solder pot, the alloy remains eutectic and the solder performs consistently over time. Other lead-free alloys dissolve Copper much more quickly, causing the alloy to become sluggish and create additional defects, such as poor hole-fill.
- The low rate of Copper dissolution makes K100LD an ideal product for applications such as fountain rework, where contact times are longer and other lead-free alloys completely erode Copper terminals.
I have attached several documents covering basic info and evaluation of Kester K100LD as well as tracked down the K100LD solders in the available 275, 311 and 48 series which use different fluxes. The series contains SOC305 solder as well, so make sure to match what you are looking for compared to which are the K100LD versions.
One info sheets was to large to attach as a file, so please use the provided links for download.
1. www.amtest.bg/products/Kester/Flux/K100LD_brochure.pdf
Depending on where you live in the world, it can be easy or difficult to get hold of K100LD, Mouser sell them among others, look for distributors on Kester's homepage. One version that is frequently available is the 275 series 0,037" / 0.8mm - 1lb spool which has has part number 2495747618, but you can find other sizes in the Info and Parts Number.pdf I have attached.
And that's it really, not much ells to say. I hope the info was useful, no matter if you are new to this or an experienced solderer.
Oneminde
Flux.
A few day's ago I returned to investigate how to make my own RMA - Rosin Mildly Activated - found some nice pine harts (rosin or kolofonium) and was looking for an acid. At that point I stumbled upon citric acid which some use when making their own RMA flux and everything was good. But it got me thinking. The reason we use flux is mostly two folded: 1. chemically clean the PCB traces. 2. Better wetting / flow of the solder.
So did some further research / reading and found that one can make a flux which use other carriers / wetting agents than kolofonium and that is what its all about.
Vehicle: It turns out that Glycerol is an excellent vehicle.- Glycerol also called glycerine or glycerin: is a simple polyol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in many lipids which are known as glycerides. It is widely used in the food industry as a sweetener and humectant in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature.
Activator: Citric acid. Citric acid is a weak organic acid that has the chemical formula C6H8O7. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms and least but not last, its an excellent oxidizer and used in many natural cleaning products.
Solvent: This one is plain old water or H2O. This is the primary solvent for the citric acid. I used deionized.
***
The formula is fairly straight forward:
2 parts Glycerol. (300ml = ca $6)
2 parts Citric Acid (crystals) (100g = ca $1)
1 part Water. (Free or cheap)
1. Mix the glycerol and water to a homogeneous mixture. 2. Heat the liquid but don't boil, this will make step 3 go faster since heat act as a catalyst. 3 Add the citric acid and stir / mix until dissolved. That's it, you are now done.
Findings.
So I sat down with an empty experiment board to try out this flux. Using Sn60/Pb38/Cu2 solder. The reference flux was Weller Lötwasser (WS flux). The reference flux behave as a flux should, produce normal amount of smoke and has a "normal" smell during use. Cost $7.54 for 25 ml so not cheap.
The Citric Acid Flux (or CAF) has a nice viscosity, similar to warm maple syrup. Virtually odorless and is clear. I spread it using a cotton swab, it stays put thanks to the glycerin. Was using the KSGER V2.1S T12 Digital Temperature Controller Soldering Station which has a fast temperature ramping and recovery and the reason I am mentioning the recovery is that as the water in the CAF is brought to a boiling point, it will take with it some of the heat. The boiling water is what I would say the main difference between the CAF and Weller Lötwasser. Other than this, it is on par with WS or RME with the difference of being super easy to clean with either water or Isopropanol or a 50/50 blend. What a noticed after cleaning the board was that the CAF side did not have any dimples (due to shrinkage) in the solder while the Lötwasser side had. This could be due to the difference in how it cools or solidifies since the CAF has the water that is removing some of the heat, and hence transition from liquid to solid has a different profile compared to Lötwasser.
Cleaning the board from both fluxes was a very simple job, no residue to talk about and compared to RMA flux, a dream to work with.
Solder.
Now its time for some solder info. If you are inexperienced with solder, leaded vs lead-free (RoHS) SAC305 groups which most of the time is a Tin-Silver-Copper blend, watch this video:
Solder Alloys Test - Lead and Lead Free Solder.
Solder Alloys Test - Lead and Lead Free Solder : 60/40 - 63/37 (Eutectic) - 99.3/Cu0.7 - 99/Ag0.3/Cu0.7 (SAC) - 96.5/Ag3/Cu0.5 (SAC305)
YouTube
PS: Going forward, I want to make you aware of the fact that I have not tested the next solder myself, but plan to in the near future.
***
One of the best solders on the market due to less risk of cold joints is the 63/37 Si/Pb version. Lead-Free solder containing silver and is more or less a nightmare to work with, so I never felt content with how it behaves compared to 63/37. But this is going to change.
Kester K100LD
The Only Lead-Free Alloy that Diminishes the 5 D’s
1. Lowest Dissolution of Copper Prevents Copper Erosion, Reduces Pot Maintenance and Increases Reliability
2. Low Dullness. Produces Shiny, Smooth Solder Joints
3. Low Defects. Bridge-Free with Excellent Top-Side Fillets
4. Low Dross. Anti-Drossing Additive Results in 20% Less Dross than Untreated Sn63Pb37
5. Low Dollars. Silver-Free Alloy is Approximately 50% Lower Cost than SAC305
- K100LD is a new patent-pending lead-free solder alloy that can be used in wave soldering, selective soldering systems and dip tinning operations. K100LD has the Lowest Dissolution of Copper amongst all common solder alloys, including Sn63, SAC305, and other lead-free options.
- K100LD has been designed to give users optimal performance with minimal defects and maintenance costs. By preventing the Copper level from increasing in the solder pot, the alloy remains eutectic and the solder performs consistently over time. Other lead-free alloys dissolve Copper much more quickly, causing the alloy to become sluggish and create additional defects, such as poor hole-fill.
- The low rate of Copper dissolution makes K100LD an ideal product for applications such as fountain rework, where contact times are longer and other lead-free alloys completely erode Copper terminals.
I have attached several documents covering basic info and evaluation of Kester K100LD as well as tracked down the K100LD solders in the available 275, 311 and 48 series which use different fluxes. The series contains SOC305 solder as well, so make sure to match what you are looking for compared to which are the K100LD versions.
One info sheets was to large to attach as a file, so please use the provided links for download.
1. www.amtest.bg/products/Kester/Flux/K100LD_brochure.pdf
Depending on where you live in the world, it can be easy or difficult to get hold of K100LD, Mouser sell them among others, look for distributors on Kester's homepage. One version that is frequently available is the 275 series 0,037" / 0.8mm - 1lb spool which has has part number 2495747618, but you can find other sizes in the Info and Parts Number.pdf I have attached.
And that's it really, not much ells to say. I hope the info was useful, no matter if you are new to this or an experienced solderer.
Oneminde
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For fun, I tried glycerol and citric acid only but the glycerin does not dissolve the citric acid meaning we need water. On another note, I will experiment with Xanthan gum as the thickening agent instead of corn- and potato starch. They are both sugar variants and I want to stay away from potential caramelization.
Lead free soldering is minefield for the uninitiated, there are many different alloy compositions some of which are covered by patents.
The poor hobbyist will just be confused by all the different types and marketing and I'd be wary of promoting one particular product without understanding the complexity of soldering alloys.
Notwithstanding of this, leadfree has been the way of the future for over 10 years and it will be inevitable that we will all be using leadfree solder at some point in the near future once all the exemptions expire.
The poor hobbyist will just be confused by all the different types and marketing and I'd be wary of promoting one particular product without understanding the complexity of soldering alloys.
Notwithstanding of this, leadfree has been the way of the future for over 10 years and it will be inevitable that we will all be using leadfree solder at some point in the near future once all the exemptions expire.
Did you even bother reading the tech notes before your mind uttered NOPE ?. Probably not. Which is a fascinating way humans (don't) move forward. Its okay, hoard as much as you want. Me on the other hand, I have read tech notes and reports on solder, which metal does what and in the end, what blends are the the optimum to use. The only good thing about lead in Si/Pb solder is the lower melting temperature.
60/40 melts at 180°C/356°F
63/37 melts at 183°C/361°F
K100LD melts at ~227°C/441°F
On another note, this thread was created for everyone to enjoy. Some will find the CAF flux and K100LD interesting, maybe even give it a try, while probably the majority will utter nope before getting their hands dirty, its just how things are.
Anyway, enjoy your day, I will return to my more normal stuff and have fun
It's now at the stage where the leadfree alloys are as good as the leaded blended stuff.
In any case leaded solder is being phased out and that can only be a good thing from a health perspective, its time to move on.
With RoHS exemptions expiring in the next couple of years this will only provide an incentive to further improve leadfree solder alloys. Some Technical Articles from AIM Solder Solutions.
In any case leaded solder is being phased out and that can only be a good thing from a health perspective, its time to move on.
With RoHS exemptions expiring in the next couple of years this will only provide an incentive to further improve leadfree solder alloys. Some Technical Articles from AIM Solder Solutions.
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Now here is someone - you - who address a real problem, which was one of the reasons SAC305 and similar have issues. But, if you spend some time looking through K100LD tech notes you will find that this issue, much thank to the added nickel and bismuth (lead substitute) prevent this issue. In one of the several tech notes on K100LD, this very thing - crystallization - is investigated. It wasn't for no reason I created this thread
Its not actual crystalisation but Tin Whiskers, adding silver to leadfree solders exacerbates the problem:
Tin Whiskers Revelations: Part III.
Tin Whiskers Revelations: Part III.
Thanks for the link Indiglo. Both AIM and Kester have figured out the issues with lead-free solder and the common dominator seem to be silver. Few if non of the silver-less solders have whiskers, also the transition from liquid to solid is slower for Pb and Bi solders, meaning less violent than SAC305 which one could see in the video I included in the first post.
All this "environmental talk" pushing for lead-free is just another "fear" campaign for the most part.
The hyped up horrors of lead-based solder continue to annoy me, as I've spent most all of my growing up years using it, and will continue to use it.
So yes, I too stock up on traditional rosen-core 60/40 solder.
For decacdes, since the beginnings of electronics, lead solder was used to wire up chassis.
I've performed service on such things as 1920's vintage radios, phonos, etc.
Through the 1950's and up, and these chassis were holding up perfectly with that connection method.
So time, decades, prove that it's reliable.
Of course, an occasional "bad solder joint" happened, due to poor assembly, not a fault of the solder.
So when you've got a solid century of high reliability for something, and then go and create that lead-free crap which in short order causes issues, why go against something that works, always worked, and works well.
The bottom line is because of "mandates", environment blabber, political crap.
I remember the old germanium transistors from the 50's-60's, and they being prone to "tin whiskers" causing malfunctioning equipment and damage.
Those tiny whiskers would grow inside the transistor case, shorting the BCE terminals.
There are some photos online somewhere of the effects of this.
Audio systems soldered with lead free solder are much better sounding, good riddance to lead soldered toxic junk.
Now THAT is an utterly idiotic statement, obviously showing human bias and not facts.
It is still debatable if tin whiskers are crystals or something else. The scientists are not yet fully sure.
The whiskers in old transistor cans are straight like crystals and the ones in the link in post#13 look a bit more curved and wiggly.
The alloys are vastly different in modern unleaded solder.
There are other metals that get whiskers.
I once read about a data center where plated steel ducting produced whiskers. These may have been zinc.
When cabling work was done some years after the center opened the whiskers got loose and floated about in the air and found there way into power supplies and caused them to blow up.
The whiskers in old transistor cans are straight like crystals and the ones in the link in post#13 look a bit more curved and wiggly.
The alloys are vastly different in modern unleaded solder.
There are other metals that get whiskers.
I once read about a data center where plated steel ducting produced whiskers. These may have been zinc.
When cabling work was done some years after the center opened the whiskers got loose and floated about in the air and found there way into power supplies and caused them to blow up.
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