here I present my current step by step practice for soldering smd:
1. solder the PCB pad with low temperature solder, usually silver loaded solder do have lower melting temperature, it doesn't need to be "audiophile stuff" but I have very good result with cardas, which melt and solder very nicely, it didn't clump up like paste while cooling if you know what i mean.
2. use solder wick to get to remove excess solder, so the pad will only have slight solder there, try your best not to do too thin nor too thick.
3. use 99% isopropyl alcohol with some sort no cloth to remove solder flux on the board, you might need to do a few time, some people says 90% alcohol is not good enough and will left some residue, but you might be just fine, 99% is the one you want though.
4.Clean your solder tips thoroughly using wetted sponge.
5.Put the smd component on the spot, with some helping hand of your preference, I use tiny blu-tac blob put on a tip of toothpick, this work reasonably well, make sure the blu-tac is as far away away from the solder heat while doing this.
at stage no 5. do not add extra solder, if you do you will leave excess flux which can left under the component side. Excess flux under the component have various detrimental effect.
as SMD component usually come pre-tinned, no flux while soldering them should not be a problem, the main problem is the PCB which quickly get thin layer of corrosion and cause imperfect joint.
good luck !!
1. solder the PCB pad with low temperature solder, usually silver loaded solder do have lower melting temperature, it doesn't need to be "audiophile stuff" but I have very good result with cardas, which melt and solder very nicely, it didn't clump up like paste while cooling if you know what i mean.
2. use solder wick to get to remove excess solder, so the pad will only have slight solder there, try your best not to do too thin nor too thick.
3. use 99% isopropyl alcohol with some sort no cloth to remove solder flux on the board, you might need to do a few time, some people says 90% alcohol is not good enough and will left some residue, but you might be just fine, 99% is the one you want though.
4.Clean your solder tips thoroughly using wetted sponge.
5.Put the smd component on the spot, with some helping hand of your preference, I use tiny blu-tac blob put on a tip of toothpick, this work reasonably well, make sure the blu-tac is as far away away from the solder heat while doing this.
at stage no 5. do not add extra solder, if you do you will leave excess flux which can left under the component side. Excess flux under the component have various detrimental effect.
as SMD component usually come pre-tinned, no flux while soldering them should not be a problem, the main problem is the PCB which quickly get thin layer of corrosion and cause imperfect joint.
good luck !!
djQUAN said:I also have 0.3mm flux cored solder but there are portions that there aren't any flux in them.
so what I did was run 6 strands of 0.1mm solid core solder together (much like litz wire) and use that along with dipping it in a pot of solder paste before soldering. then I would clean the board after soldering.
if you can get the solder practice kit from Jan, I suggest you do since 0.8mm for SMD parts is not too difficult once you get a bit of experience.
yes I also did the same litz thing with my solder most of the time, it seems to help the fluxing process to spread more effectively than single big solder wire.
how did you clean your board ? any good advice ?
for board cleaning, I use a lot of laquer thinner. put a lot on a tupperware type container, enough to cover the board, then agitate for 10-30min depending on how clean I want the board. do this in a well ventilated area.
if I don't need a very very clean board, a small amount of thinner and a paint brush is enough for most cases.
if I don't need a very very clean board, a small amount of thinner and a paint brush is enough for most cases.
If the ultrasonic cleaning is done properly it shouldn't do any damage.
The key to cleaning with alcohol is to remove the dissolved flux with the lint free wipe/cloth. I've seen a lot of people just use a brush and alcohol but all that does is move the flux residue all over and make the board sticky.
The key to cleaning with alcohol is to remove the dissolved flux with the lint free wipe/cloth. I've seen a lot of people just use a brush and alcohol but all that does is move the flux residue all over and make the board sticky.
BWRX:
"If the ultrasonic cleaning is done properly it shouldn't do any damage."
I'm searching the way to do it properly I read somewhere that the frequency used for cleaning jewelry and PCB is not the same, PCB use lower frequency, that might explain it. I felt the agitation on the jewelry is way too strong and too high frequency, which I'm really worried.
"The key to cleaning with alcohol is to remove the dissolved flux with the lint free wipe/cloth. I've seen a lot of people just use a brush and alcohol but all that does is move the flux residue all over and make the board sticky."
Agree on this one, also did this with various degree of success. I'm just very worried (I should change my nick-name to paranoid
) about the "Ionic Activator" thing left on the board , do you know how to remove this properly ?
djQUAN
Thinner ??
I don't really know if thinner is safe for the PCB and component or not, It can damage some component ?? no ?? or damage the solder mask surface ?
Thinner is pretty strong stuff. Be careful man
For my "nice" warning,you should send me some :
Kalamansi, Bagoong, and Lechon
"If the ultrasonic cleaning is done properly it shouldn't do any damage."
I'm searching the way to do it properly
I read somewhere that the frequency used for cleaning jewelry and PCB is not the same, PCB use lower frequency, that might explain it. I felt the agitation on the jewelry is way too strong and too high frequency, which I'm really worried."The key to cleaning with alcohol is to remove the dissolved flux with the lint free wipe/cloth. I've seen a lot of people just use a brush and alcohol but all that does is move the flux residue all over and make the board sticky."
Agree on this one, also did this with various degree of success. I'm just very worried (I should change my nick-name to paranoid
) about the "Ionic Activator" thing left on the board , do you know how to remove this properly ?djQUAN
Thinner ??
I don't really know if thinner is safe for the PCB and component or not, It can damage some component ?? no ?? or damage the solder mask surface ?
Thinner is pretty strong stuff. Be careful man
For my "nice"
warning,you should send me some :Kalamansi, Bagoong, and Lechon
Hartono said:
yes I also did the same litz thing with my solder most of the time, it seems to help the fluxing process to spread more effectively than single big solder wire.
how did you clean your board ? any good advice ?
wait I make a mistake in my earlier post,
what I mean is : I use a few flux cored solder twisted together, not solid cored ones to make litz, this works very well for larger soldering task ( Non SMD)
I'm sure thinner would remove flux but, like Hartono mentioned, it might also remove other things you don't want it to! I wouldn't recommend using lacquer thinner for cleaning because it is much more aggressive than alcohol and it is not nice stuff to handle and use. Pure Isopropyl alcohol works very well at dissolving flux and has the added advantage of not being toxic and can evaporate very quickly.djQUAN said:I use the thinner and brush method but that doesn't leave my boards sticky. you just need enough thinner.
Most ultrasonic cleaners for electronics work around 40kHz and are lower power (maybe around 10W/liter?). Ultrasonic jewelry cleaners are usually quite a bit more powerful and can do damage to components.Hartono said:I'm searching the way to do it properly
I'm not sure what the "Ionic Activator" is?Hartono said:I'm just very worried (I should change my nick-name to paranoid
Originally posted by Hartono djQUAN
Thinner ??
I don't really know if thinner is safe for the PCB and component or not, It can damage some component ?? no ?? or damage the solder mask surface ?
Thinner is pretty strong stuff. Be careful man
For my "nice"
Kalamansi, Bagoong, and Lechon [/B]
lacquer thinner. yep, the strong stuff that leaves your skin really dry. it basically works like concentrated alcohol. you just need a well ventilated area when working with it. I haven't had any problems with component damage with it (other than some component markings getting erased) but electrical damage, none so far. I used it to clean 41hz Tripath amp kits and no damage. actually, the amps didn't work if I don't use thinner to clean the boards.
lechon is too big to send over. you pay shipping then
BWRX
In Horowitz book, "art of electronics" they mentioned about cleaning solder flux after soldering, and there's this Ionic Activator inside the flux, and it says that if not removed properly(completely ?) might do more damage than not cleaning the flux. That's why I'm very worried about cleaning fluxes.
As for the damage cause by Ionic Activator, I don't know, I've never left PCB for that long yet ( a few years) to see the damage.
djQUAN
I better forget about the Lechon then
In Horowitz book, "art of electronics" they mentioned about cleaning solder flux after soldering, and there's this Ionic Activator inside the flux, and it says that if not removed properly(completely ?) might do more damage than not cleaning the flux. That's why I'm very worried about cleaning fluxes.
As for the damage cause by Ionic Activator, I don't know, I've never left PCB for that long yet ( a few years) to see the damage.
djQUAN
I better forget about the Lechon then
I'm actually building a rather big SMPS module right now, a simple unregulated step up supply for a car amp. 1000wrms, two transformers and a lot of caps. I will be using the methods I mentioned above for board cleaning. if I have the time, I could post pictures after everything is done......
There's very fine solder available for SMT rework. Probably good info on Kester's web site (maybe owned by Litton?). Anyway, the two varieties commonly used are "no-clean", which is a minimal rosin flux and doesn't have to be cleaned. (or so they claim) I think it's #242 flux. The other one is #331 water washable. This is great stuff, but you absolutely have to wash the boards. It's corrosive if you don't, but if you wait a day or so, there's no harm done. That lets you build in multiple sessions. If I'm building a board from scratch, I try to use the 331, as it's so easy to wash. I use a bar of Fel's Naphtha soap and a toothbrush, followed by a hot water rinse and a blow off with compressed air. That's the only way to be sure sockets, nooks & crannies are dry. If I use no-clean, or plain old RMA (rosin, mildly activated), I clean with isopropanol and a toothbrush. You have to get the bulk off, then finish with clean solvent so you don't leave tracks. I follow with the naphtha soap, hot water, and compressed air. IMO, the best solder is good old Kester "44" that my dad used on his ham radio stuff. I also like a solder with 2% Ag, as it won't eat into very fine wires and leaves a bit brighter joint.
Hoffman's Rule- "If you solder at my bench, put the darn roll down with the label facing up, so the printing doesn't get worn off and I can tell what it is six months down the road!"
Hoffman's Rule- "If you solder at my bench, put the darn roll down with the label facing up, so the printing doesn't get worn off and I can tell what it is six months down the road!"
Hi Conrad,
Did you get any board corroded by the 331 ?
it would be very useful to know if you have any board using the 331 with proper and improper cleaning, and what it does.
how long it takes to corrode the board ?
Horowitz book says the water based one turn out to be tricky to wash, and all flux must be removed thoroughly,or corrosion will occur. He recommend rosin based for DIY.
I also fear that the soap perfume or other chemical sticks to the board.
At least now I know solvent works well for rosin based, I would dip the board in a few separate alcohol bath for now.
Cheers
Hartono
Did you get any board corroded by the 331 ?
it would be very useful to know if you have any board using the 331 with proper and improper cleaning, and what it does.
how long it takes to corrode the board ?
Horowitz book says the water based one turn out to be tricky to wash, and all flux must be removed thoroughly,or corrosion will occur. He recommend rosin based for DIY.
I also fear that the soap perfume or other chemical sticks to the board.
At least now I know solvent works well for rosin based, I would dip the board in a few separate alcohol bath for now.
Cheers
Hartono
Hartono said:
I found my copy of that book and read the section you mentioned (on page 840 of the second edition). Generally types of fluxes are described as as active, mildly active, or non-active. The more active a flux is the more aggressive it is at removing oxidation in order for the solder to form a good metal to metal joint.
I use Kester's 186 RMA flux along with their 44 rosin core solder for all of my DIY needs. As is said in the Art of Electronics, the RMA type flux is less active and doesn't necessarily need to be cleaned. I still like to clean my boards as thoroughly as possible though.
You can use organic core solder but most will tell you not to because it can be bad for your health (you think rosin core solder fumes are bad...) and the flux needs to be cleaned well. The advantage is that the organic stuff is water soluble.
In the end, just clean your work the best you can and don't worry about it too much. Poor cleaning of flux residue can cause sensitive and/or high speed circuits to do weird things but circuitry working at audio frequencies is generally much less vulnerable.
Hartono, I've been pretty casual about instantly washing boards after using 331, and haven't had a problem. We use the same stuff at work, and no problems there. I wouldn't go more than a week though. This stuff isn't like acid core flux- it's nowhere near that corrosive. Mostly it will just dull the surface. The real problem is that it's somewhat conductive, but washing it off is easy. We build high voltage equipment with it, so it's just not an issue. The organics have been pretty well developed at this point, but I do agree they smell bad. You shouldn't breath soldering fumes, smoke, vapors, or whatever the correct term is. I set a small muffin fan behind what I'm soldering to direct the smoke away. The organics will also discolor your expensive diagonal cutters, so if you like to keep your tools very shiny, stick with rosin!
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