Poll: Do you tin/laquer/etc..your PCBs?

[KORGULL]

I have read up on this in the archives but would like to get a feel for just how many people tin or otherwise coat their PCBs after etching. I'm mainly wondering about preventing corrosion (oxidation?). Not enhancing solderability.
A couple guys talked about leaving the etch resist on the traces - except for the pads. This sounds like the simplest, most practical method -  but it doesn't seem like many people do it. I wonder why - Is it because you can't check for problem traces? Or is it because you never get to see all the nice shiny copper traces you worked so hard to make.
I'd rather not use Tinnit since some have said it is pretty toxic and has bad fumes.
Laquer sounds like a problem if you ever want to solder on your board again after you coat it.
I saw a spray that is like laquer and you can still easily solder on your board after coating with it, but it's sold in Australia and I can't have it shipped to the U.S. or find anything like it around here. Can someone point me to a similar product available here?
-Just trying to figure out how neccessary this step is in PCB making, and the best way(s) to do it.

[Fret Wire]

I've been tinning my boards for  awhile with Liquid Tin. I remove the resist with Acetone, buff the traces lightly with 0000 steel wool, degrease, then a couple minutes in the Liquid Tin, and it's done. No heating, fumes, long term storage spoilage, or chemical disposal problems like you have with Tinnit. Liquid Tin is fast and easy.

http://www.mgchemicals.com/products/421.html

[sir_modulus]

Well, for all my comercial pedals, I just quickly spray them with spray paint on the backside! It protects the board, and I do put a schmo in the back anyways, so it's not like I'm copy-protecting it etc..

Cheers,

Nish

[KORGULL]

Fret Wire wrote:

I've been tinning my boards for a awhile with Liquid Tin.

Yeah, I've heard good things about liquid tin. I couldn't get it from any of my usual suppliers though.
...I just located someone near me that carries it through the MG chem link you provided and requested a catalog (Allied Electronics). Maybe they'll have some other good stuff too. Thanks.

[markusw]

Just take care when using Liquid Tin. It contains thiourea which is supposed to be carcinogenic, terrratogenic and to cause reproductive deffects. So I would'nt say it's not toxic. Have a look at the MSDS.

Markus

[KORGULL]

Thanks, I will. After reading it I will probably be voting for: "I leave the copper bare" in this poll :wink:

[Fret Wire]

Just take care when using Liquid Tin. It contains thiourea which is supposed to be carcinogenic, terrratogenic and to cause reproductive deffects. So I would'nt say it's not toxic. Have a look at the MSDS.
Markus

True, but nowhere near the same league as etching chemicals. And since it uses no heating, mixing, and has no fumes, all you need is gloves to submerge the pcb, and gloves to remove and rinse. You use far nastier chemicals routinely. Don't let that deter you. A good solder (63/37), and tinned board make assembly so much nicer.

[markusw]

Although etching chemicals are nasty too they do not cause cancer. Neither they terratogenic. So I would'nt say it's nowhere near the same league.

Ferric chloride:

Inhalation:
Extremely destructive to tissues of the mucous membranes and upper respiratory tract. Symptoms may include burning sensation, coughing, wheezing, laryngitis, shortness of breath, headache, nausea and vomiting.
Ingestion:
Corrosive. Swallowing can cause severe burns of the mouth, throat, and stomach. Can cause sore throat, vomiting, diarrhea. Low toxicity in small quantities but larger doses (30 mg/kg) may cause nausea, vomiting and diarrhea. Pink urine discoloration is a strong indicator of iron poisoning. Liver damage, coma and death may follow, sometimes delayed as long as three days.
Skin Contact:
Corrosive. Symptoms of redness, pain, and severe burn can occur.
Eye Contact:
Corrosive. Contact can cause blurred vision, redness, pain and severe tissue burns.
Chronic Exposure:
Repeated ingestion may cause liver damage. Prolonged exposure of the eyes may cause discoloration.

Ammonium persulate

EYE EFFECTS: Minimally irritating (rabbit) [FMC I87-0968]
SKIN EFFECTS: Non-irritating (rabbit) [FMC Study I87-0970]
DERMAL LD50: > 2,000 mg/kg (rabbit) [FMC I91-1200]
ORAL LD50: 742 mg/kg (male rat) [FMC I2001-2331]
700 mg/kg (female rat) [FMC I2001-2331]
INHALATION LC50: > 2.95 mg/l (4 h) (rat) Maximum attainable concentration [FMC I87-0969]
SENSITIZATION: May be sensitizing to allergic persons. [FMC Study I87-0970]
TARGET ORGANS: Sensory irritation - eyes, nose, throat and lungs
ACUTE EFFECTS FROM OVEREXPOSURE: Dust may be harmful and irritating.
Ammonium persulfate has low dermal toxicity and is moderately toxic when ingested. Product is minimally
irritating to the eyes and non-irritating to the skin.
CHRONIC EFFECTS FROM OVEREXPOSURE: Sensitive persons may develop
dermatitis and asthma [Respiration 38:144, 1979].
CARCINOGENICITY:
NTP: Not listed
IARC: Not listed
OSHA: Not listed
OTHER: ACGIH: Not listed

Anyway, take care when using liquid tin, be sure to ware gloves and keep it away from food.



Markus

[Fret Wire]

After awhile it gets a little academic comparing all the hazards. I guess the bottom line is that if you can't use any of these products properly (near food?), you should buy your boards pre-made, do perf, or vero.

And since Liquid Tin doesn't require heating, mixing,  has no fumes, and can be used indoors no problem, in all reality, it isn't in the same league as Tinnit and the etching chemicals. Regardless of the MSDS sheets, people will still use the other chemicals without proper ventilation, and probably will stain their hands and clothes. Unfortunately, people rarely head safety precautions for most products. Most people don't use any ventilation when soldering. Constant soldering fumes whether you use pcb or perf is far worse than Liquid Tin, don't you agree? So in manner that most people are actually going to use these products, Liquid Tin is probably the least worriesome.

[rubberlips]

I always coat my boards with PCB laquer. I bought a tin about 10 years ago from Dickies and still haven't had to buy another tin.
I don't have any problems with it not soldering, keeps the boards looking new as the day I made them.

Pete

[markusw]

After awhile it gets a little academic comparing all the hazards. I guess the bottom line is that if you can't use any of these products properly (near food?), you should buy your boards pre-made, do perf, or vero.

And since Liquid Tin doesn't require heating, mixing,  has no fumes, and can be used indoors no problem, in all reality, it isn't in the same league as Tinnit and the etching chemicals. Regardless of the MSDS sheets, people will still use the other chemicals without proper ventilation, and probably will stain their hands and clothes. Unfortunately, people rarely head safety precautions for most products. Most people don't use any ventilation when soldering. Constant soldering fumes whether you use pcb or perf is far worse than Liquid Tin, don't you agree? So in manner that most people are actually going to use these products, Liquid Tin is probably the least worriesome.

I totally agree, it gets academic. I also agree that using Liquid tin is less worse than constantly soldering w/o ventilation provided one takes the proper safety precautions. However, Tinnit and Liquid tin both contain thiourea so they are in pretty the same league, but since Liquid Tin does not require mixing and equally important heating I also would go with it. Up to now I just used some PCB laquer and it worked out fine. If I can find Liquid Tin somewhere here in Austria I definitely will try it.  
To sum it up, I really did'nt want to convince someone here not to use tinning solutions, I just wanted to point to the fact that one should take care when using that stuff. By the way, this discussion again reminded me to use ventilation when soldering. Thanks!

Markus

Edit: For me there is huge difference between corrosive stuff like etchant chemicals and cancerogens: if you spoil yourself or even worse swollow some corrosive stuff you most likely will realise it immediately because your skin or eyes or whatever start burning. Therefore you would take more care the next time. With cancerogens it's quite different because you may well contaminate yourself continuosly over a long period of time without even noticing it. Once some of your cells have aquired a suffienct number of mutations in their genome a tumor may develop. I've never used tinning solutions but I could imagine you could dip your PCBs in tinning solutions with bare hands and probably the only thing you'd feel would be a slight itching. Therfore, you probably would just wash your hands but you would'nt think about waring gloves. Just my personal point of view.

[Connoisseur of Distortion]

gloves are useful for everything! i bought about 400 surgical gloves when i got into the whole etching scene... didn't want to make THAT mistake.

if you are etching your own boards, you should be wearing gloves while cleaning board, ironing, etching, and while cleaning it off. if you tin, wear them then, too.

when i am prepping boards, i go through probably 5 pairs of gloves each time i etch. buy gloves in bulk!

[KORGULL]

Korgull wrote:

I saw a spray that is like laquer and you can still easily solder on your board after coating with it, but it's sold in Australia and I can't have it shipped to the U.S. or find anything like it around here. Can someone point me to a similar product available here?

While looking through a bunch of DIY PCB sites last night, I saw where one guy uses Testor #1256 transparent green enamel from a hobby shop to coat his boards. He said this particular enamel vaporizes from the heat when you solder your components, leaving the board masked right up to the solder joints. Probably releases some bad fumes in the process, but if you have a good ventilation system for soldering it's probably not a big deal. I may try it if I can't locate any spray coat products made for PCBs.
-Thought you guys might be interested.

[Paul Marossy]

I have used a coating made by GC Electronics on a few things that I have built, but I mostly leave them bare. I have tinned a couple of things, too.  

[formerMember1]

Hi,

I have been just tinning my boards, by using a soldering iron, electronics paste flux, and some solder, isn't that fine, or should i use this MG Chemicals liquid tin, you guys talk about?

thanks 

[spudulike]

I use "Tinnit" from ESR Electronics.

(and how come I dont get a voting option ?)

[troubledtom]

I have used a coating made by GC Electronics on a few things that I have built, but I mostly leave them bare. I have tinned a couple of things, too.  

yep,
   
         -tom

[KORGULL]

Hey formerMember1, how's that tinning method working out for you?
Is it pretty quick and easy?
I tried doing it like that once, but I didn't have the flux paste and it wasn't so easy.
I've been meaning to get some flux and try it again to see if it works out better.

*Edit*...Oh yeah, and I was using lead-free solder, so maybe that added to the difficulty I had getting it to flow easily.

[formerMember1]

well,  when i made my first board, a month or so ago, i was getting help from mark hammer, you and others,  well someone told me to tin the traces with liquid flux, but i couldn't find any, so i tried to tin it, without and it didn't work good,  So i went to a electronics surplus store and they had paste flux, so i took a cotton swap, and barely got some paste flux on it, i then when over the whole board, i then wiped as much off with a paper towel, (not on traces though, only around it), then i used a screwdriver iron tip, and heated the trace, and applied a little solder, i then just moved the iron tip along the trace, and it went on pretty good, then add more solder and so on,  Then what i did,(becuase the solder tends to end up being too much), i took desoldering braid and heated it and tried to remove the solder off the board, enough comes off to make it thin, but you can't get enough off to expose the copper trace, i then wipe it down with a paper towel, and then reheat the traces with a well tinned soldering iron tip,(not adding any more solder!!), and now when i heat the traces, the solder flows evenly and thin, and looks shiny.   Then when i am done, i let the board cool, and i spray this contact cleaner i have on it, and then rub it down with a dry paper towel,  then i am done.

I only did this too small boards though, like fuzzface, wah, i don't know if this would be a pain to do on more delicate traces, where the spacing is small or not.  BUt it works for me!!  It takes all of a minute or two for me. I actually found out that it is easier to use a well tinned flat head screwdriver tip, and as i drag it along the trace, i go right behind it with the solder(i am using 60/40, never used 63/47), and that works best for me.

I did want to try another method, like that  MG Chemicals liquid tin, but think i might stay with my method, since i am doing simple circuits, with not too close circuit pads,...