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I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary? ?In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary? ?I am using good Kester 63/37 solder with flux.
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It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.
Tony AC9QY
On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith= [email protected]> wrote: I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
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Also, as I understand it, simple rubbing alcohol suffices as flux-cleaner, so it's not a big deal. I've been using alcohol-wipe pads I had on hand (being careful not to leave behind fibers from the pad), which I'm sure is not ideal, but seems to clean the board up pretty well.
/m
On Sat, Sep 21, 2024, at 10:28, Tony Scaminaci wrote:
It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.
Tony AC9QY
On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith= [email protected]> wrote: I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
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Isopropyl alcohol works well and I prefer brands containing 99%. I use cotton swabs soaked in alcohol to clean around pads. The wet end does the cleaning and then I use the dry end to wipe up the residue. A toothpick works well to remove any leftover swab fibers.
Tony
On Sat, Sep 21, 2024 at 10:55?AM Michael - WD0OM via <wd0om= [email protected]> wrote: Also, as I understand it, simple rubbing alcohol suffices as flux-cleaner, so it's not a big deal. I've been using alcohol-wipe pads I had on hand (being careful not to leave behind fibers from the pad), which I'm sure is not ideal, but seems to clean the board up pretty well.
/m
On Sat, Sep 21, 2024, at 10:28, Tony Scaminaci wrote:
It’s not absolutely?necessary to remove flux but I be always do for two reasons. First, long term, flux could affect the performance of high-impedance points, most notably at RF frequencies. Second, it makes looking for solder bridges, shorts, and cold solder points much easier.
Tony AC9QY
On Sat, Sep 21, 2024 at 10:15?AM Keith Hamilton via <n8cep.keith= [email protected]> wrote: I am going to start building a QMX+. I was wondering if removing flux with a chemical is necessary?? In all the builds I have done before I never bothered to try to remove the flux after finishing. Is it necessary?? I am using good Kester 63/37 solder with flux.
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'Flux rarely causes a problem during the warranty period - especially the no-clean stuff'
But years-on in certain circumstances of temperature and humidity it can become a problem for RF and power circuitry?
I generally clean it off.? ?The no clean fluxes may require a specific cleaner like ECSP or FLU FluxClene? (both of which can often be ordered with a handy Brush) but many fluxes come off with just Isopropyl Alcohol
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I took Jeff Moore's advice and bought a pint of 99% isopropyl alcohol from Amazon ( about $9). Much better than even 91%.?
A little goes a long way. Really cleans quick and leaves little or no smeary residue.
On Sat, Sep 21, 2024 at 12:40 PM, Bruce Akhurst <bruce@...> wrote: 'Flux rarely causes a problem during the warranty period - especially the no-clean stuff'
But years-on in certain circumstances of temperature and humidity it can become a problem for RF and power circuitry?
I generally clean it off.? ?The no clean fluxes may require a specific cleaner like ECSP or FLU FluxClene? (both of which can often be ordered with a handy Brush) but many fluxes come off with just Isopropyl Alcohol
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On Sat, Sep 21, 2024 at 11:29 AM, Tony Scaminaci wrote:
Second, it makes looking for solder bridges, shorts, and cold solder points much easier.
The cleaning process will direct your attention to each area, kind of like hand-washing your car will allow you to find those little dings and scratches you would never have noticed if using the car wash.
Extra style points for cleaning and inspecting under 8X-10X binocular magnification.
73, Don N2VGU
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I use "acid brushes" with the bristles cut down to about half length to scrub the board while it is wet with solvent.? Saves time and effort when removing flux residue.
73, Don N2VGU?
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Certain solder described as containing "no-clean" flux will leave a residue that even alcohol pads won't touch,? I made the error of purchasing a pound of Kester 63/37 with a non-rosin flux:
I have since purchased
The Kester 44 is a solder I have used for decades.? Activated rosin core, remains clean up just fine with alcohol.
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I use alcohol and a cheap Harbor Freight Ultrasonic cleaner.?? Awesome.
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I use 99.9%? IPA (not the beer!) and an old medium toothbrush to dissolve the flux away. While the area is still wet I lay two layers of kitchen roll over it and rub over the top of that with the same toothbrush. It's a fairly gentle method, doesn't leave and debris and the boards come up minty-fresh every time.
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Ronan
MM0IVR?
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Long ago (1974, oy), I had a summer job at JPL and was sent to NASA soldering school for a week.? The teacher impressed upon us that "flux is hygroscopic" and could not be allowed to remain on any assembly.? Since then I've believed that I should remove residual flux, even when I don't.? (Have fluxes changed in fifty years?? I don't know.)
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Eric
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I've been using no clean flux on my QMX+ and using 91% isopropyl UNSUCCESSFULLY. A friend recommended a product called "flux off" but it costs $30 a can (too much for me). I don't remember my old solder leaving so much gunk behind ?. I do have an ultra-sonic tank I'm willing to try, but I do agree fully that the point-by-point cleaning process is also a good inspection opportunity. The cotton swabs do annoyingly leave a lot of fibers, maybe I need nippers that don't cause burrs??? So I am still looking for a solution (pardon the pun) to get rid of this flux.
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I clear thick areas of flux build up with a careful and gentle scraping with the back edge of the pointy end of a #11 Xacto blade.?
Then a very used, old soft toothbrush to brush way the flux crumbs.
I follow that with frequently changed Q-Tips, one end only soaked in 99% IPA ( yes, ninety nine percent) and swiped clean with the dry end. I look for fiber wisps and take care of those.?
I clean periodically as I go, taking the time to inspect joints and touch up soldering where necessary.?
Then 99% IPA and a new, clean, cut down acid brush in sort of broader areas followed by pressing and wiping gently with cut up pieces of micro fiber cloth; also frequently changed until the IPA flashes off quickly leaving no smears.?
I do all of this over my grounded (1 M ohm) static safe building board,? wearing a proper static control wrist strap that plugs into a barrel ended alligator clip that is joined to the? board. I use that same static control setup while handling ANYTHING at any time, that includes static sensitive components while inspecting, sorting, installing components and calibrating procedures that involve touching any component. And static safe soldering irons too.
GREG
On Sun, Sep 22, 2024 at 9:34 PM, Robert AD6XJ <91710robert@...> wrote: I've been using no clean flux on my QMX+ and using 91% isopropyl UNSUCCESSFULLY. A friend recommended a product called "flux off" but it costs $30 a can (too much for me). I don't remember my old solder leaving so much gunk behind ?. I do have an ultra-sonic tank I'm willing to try, but I do agree fully that the point-by-point cleaning process is also a good inspection opportunity. The cotton swabs do annoyingly leave a lot of fibers, maybe I need nippers that don't cause burrs??? So I am still looking for a solution (pardon the pun) to get rid of this flux.
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Hi All
It is very interesting to see so many recommendations for IPA etc. I have tried this on a kit I built and it attacked the green coating on the rear of the board.?
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John G0UBE
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On Sun, Sep 22, 2024 at 09:34 PM, Robert AD6XJ wrote:
So I am still looking for a solution (pardon the pun) to get rid of this flux.
Fix the problem at the source, get rid of that no-clean fluxed solder and get a roll of 63/37 with RMA flux from Kester or Multicore and clean it off with ordinary isopropanol and a cut-down acid brush..
Life is too short to deal with annoying stuff like crappy solder intended for commercial use.?
Don't get me started on lead-free solder.....
73, Don N2VGU
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Robert,
For board cleaning I am using Isopropyl alcohol brushing the board with a tooth brush.
The solder I use is Kester no clean 63/37 and the flux can be easily removed.
No harm done to the board either.
I tried cotton swabs before and they don't work, like you discovered yourself!
73,
Roelof, pa0rdt
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Some days ago someone posted a Google link to Kester’s no clean solder. Reading that document I learned that their flux was unaffected by IPA, even 99%.
So I agree with others that good old rosin core 63/37 is easiest to solder with, and cleans up nicely with IPA. The 70% works well.
Just don’t eat lunch at the work bench, wash your hands before eating, and clean up the solder splashes on the bench and floor.
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On Sep 23, 2024, at 08:02, Donald S Brant Jr via groups.io <dsbrantjr@...> wrote:
? On Sun, Sep 22, 2024 at 09:34 PM, Robert AD6XJ wrote:
So I am still looking for a solution (pardon the pun) to get rid of this flux.
Fix the problem at the source, get rid of that no-clean fluxed solder and get a roll of 63/37 with RMA flux from Kester or Multicore and clean it off with ordinary isopropanol and a cut-down acid brush..
Life is too short to deal with annoying stuff like crappy solder intended for commercial use.?
Don't get me started on lead-free solder.....
73, Don N2VGU
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I’ve been using water-based flux cored solder (and same in a flux pen) for many years now. ?After assembly, I wash my boards with water, a bit of dishwashing detergent and an old toothbrush. ?Shake off vigorously and follow that up with drying using an old hair dryer. ?My boards look as good or better than machine built boards (if I do say so myself). ?I still have rosin-cored solder but doubt I’ll ever use it again.
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73,
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Robert, WA2T
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Here’s a pic of one of my boards.
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Bruce Akhurst
Donald S Brant Jr
Mark K9TR