[SOLVED] Thiners = clelaning alcohol?

Hi Folks

Im just starting to look at building a run of prototypes using solder paste and stencils myself for the first time and am looking for a suitable agent for cleaning the solder paste from the stencil.

I am looking to use a lead-free no-clean paste probably multicore LF318 as it seems up to the job and not too expensive and is available from farnell in my region.
I also looked on farnell to find a cleaning agent and it comes up with a non-acrylic thinner....
(ELECTROLUBE|DCT01L|THINNER, NON ACRYLIC, 1L | Farnell Ireland)
Is this the same thing as the alcohol normally used to clean rework debris on PCBs?
Is it suitable for what I want it to do?
If not what is the actual terms I should be searching but? (I tried just alcohol but got compressed cans, not what I want).

Many thanks

I use this product from RS for cleaning Flux residue etc from PCB's:
Buy Precision (EEM) Cleaning Fluids Fluxclene fast dry cleaner,400ml Electrolube ERFLU400DB online from RS for next day delivery.
Most likely available from other suppliers as well

hope this assists
Mik

Hi
Thanks for your reply
Ive never used this type of stuff before is it a spray on type use? will it break up large amounts of sticky stuff? or just films?
Many thanks

I actually have some sodium Hydroxide solution available from another lab that is used as a solvent there, though I think this may be way to strong...?

---------- Post added at 11:10 ---------- Previous post was at 11:07 ----------

Have just found and searched on the term IPA cleaner (isopropyl alcohol) would this fit the bill?

---------- Post added at 11:17 ---------- Previous post was at 11:10 ----------

Another question in the same vein: what are the square white microfibre pcb wipes normally made from, are they cotton or polyester?

Many thanks

Here is a response I drafted before my Internet connection went down. It may still have some relevance:

Wolf99 said:

I also looked on farnell to find a cleaning agent and it comes up with a non-acrylic thinner....
(ELECTROLUBE|DCT01L|THINNER, NON ACRYLIC, 1L | Farnell Ireland)
Is this the same thing as the alcohol normally used to clean rework debris on PCBs?

Click to expand...

No, it is not the same as alcohol. According to its safety datasheet (MSDS in the USA), it is mostly xylene and has less than 0.5% of a ketone oxime (an oxime can be viewed as changing the =O in a ketone to a =NOH). I suspect the oxime is added to increase solvent polarity or maybe just to give it a different odor.

Which alcohol do you normally use? Isopropyl alcohol (IPA) (>70%) or ethyl alcohol (absolute or denatured) will work. I personally use ethyl alcohol with about 20 to 30% acetone added. Alcohol by itself works fine, though.

Is it suitable for what I want it to do?
If not what is the actual terms I should be searching but? (I tried just alcohol but got compressed cans, not what I want).

Click to expand...

That's a bit harder to answer. The Farnell solvent is sold for that purpose, but note that it will attack acrylic coatings. Acrylic coatings may be used as solder masks or conformal coatings, but not all solder masks and conformal coatings are acrylic based.

John

Edit: The Farnell material also contains a little bit of a silane. That may be to leave a light protective coating after cleaning.

The spray I linked to certainly removes 'lumps' of flux. Think Electrolube also do a non spray cleaner the same as well but I don't make enough PCB's these days to need it in quantity.
There is a pdf in the link to RS for full product info
Wouldn't use Sodium Hydroxide solution, although it is used as a 'developer' for some types of photo resist, but washing after is a pain!

Isopropanol - works sometimes depending on what you are trying to dissolve - seems a bit selective but easily available in 500ml bottles from pharmacies as well as RS, Farnell etc and also in spray cans.

Don't actually know what the microfibre wipes are actually made from as I just use lint free cloths for a number of different things.

hope this assists
Mik

Edit: just seen jpanhalt's post, best to try different solvents on test samples first perhaps?

@John
Many thanks for your reply, very informative
Im not using conformal coating for this but solder mask effects would be of importance... IPA looks like what Iv seen used in industry before. At the moment I just intend to use it for cleaning metal foil stencils so it will probably fit the bill.

Is there any advantage to Ethyl? and why do you add the acetone?

@Mik
Many thanks for your reply, again very informative
The sodium hydroxide was just something I thought of, as its the only other solvent I know I have freely available, but is used for a much different process!!

Many thanks for bearing with me

i think Isopropyl alcohol (IPA) would be better choice...

Yup, definitely avoid Sodium Hydroxide if your metal foil stencils are Aluminium as it will dissolve them!
Mik

Thanks Raksha, I think I will go with the IPA and Mik also, the stencils are stainless though, nut I'll be staying away from the NaOH as I jus tfound the cost of getting it!!
Cheers all

yeah IPA s basically for this kind of application ....

Wolf99 said:

@John

Is there any advantage to Ethyl? and why do you add the acetone?

Click to expand...

I typically use 63/37 leaded solder with mildly activated rosin flux. A principle component in rosin flux is abietic acid (Abietic acid - Wikipedia, the free encyclopedia). I use ethanol, because I have many gallons of absolute ethanol from when we closed a histology laboratory. I add acetone to improve its non-polar solvency. Note that xylene in the Farnell stuff is relatively non-polar, compared to ethanol. I have had mixed results with IPA and sometimes it did not seem to remove the flux completely.

As for testing on various components, yes, you must be cautious if using the acetone mixture, and your board contains styrene, ABS/AES, or other susceptible plastics. I don't know what the windows are on IR detectors and transmitters, so I keep them away from the acetone too (I use just pure alcohol). Be careful with denatured alcohol too, as some of the denaturants used in the various formulas will also attack plastics. As an added note, acrylic plastics (e.g., Plexiglas) often do not show an immediate affect from xylene, but months or years later, they may show crazing as a result of exposure to it.

Finally, while driving around this morning, it occurred to me that the real reason for the oximes in the Farnell stuff is probably related more to the silane brew that is added than to any effect on the solvent properties.

If IPA works for you, then that is what I would recommend using.

John

Wolf99 said:

Another question in the same vein: what are the square white microfibre pcb wipes normally made from, are they cotton or polyester?

Click to expand...

Do you mean Kimwipes? They are made from virgin wood pulp, and are fantastic for everything from cleaning optics to soaking up flux/flux remover residue from PCB's. They are lint free, which makes them much better than paper towels, napkins, etc.

**broken link removed**

@John
Again many thanks for your reply, very helpful and I have saved the email from the reply for future reference.
Im not much on chemistry so a good explanation on parts of it that apply to electronics are like gold to me , generally trawling through paths of wikipedia articles gives me only half the story on WHY a certain chemical would be used with others for certain purposes, so thanks again.

@Nick
They're the kind of "papery-ish" wipes? I think I found something on that front after the "lint-free" mention, I had been searching on micro-fibre. I found some polyester & cellulose wipes that look good (and cheaper) in about the right size pack so they'll do.
Im still not sure if they're the one's I used before in my days as a factory tech but its hard to get a good picture on the net of the wipes/cloths without them just looking like squares of white, so its hard to tell.
I'll see When they get here I suppose!! Thanks