Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Boards coated in wax?

Jeff Sanchez

#11363

Boards coated in wax? | 23 May, 1999

Hey peoples, We are working with the dairy industry out here and they asked us to start reworking all there boards for them. Of course we said yes, hehe. Only we didn't know what them farmers coated them boards with. It turned out to be wax, hmmmmm? Now I know I have so much to learn here but the wax thing has got me I must say. The farm equipment company (our new customer) told us that it keeps the moisture out. Sounds simple right? He also said it made it easier to rework? Well at face value it does. But here are my questions. 1. Will the wax effect the solder flow?

2. When the wax reaches a temp that makes it sweat will it then become conductive?

3. I dont want to boo hoo the whole wax thing but isn't there a better sealant out there? One that you might know of that will alow us to do the same easy rework ability?

These boards gotta live with the cows. But I think the wax is for the birds. < bad joke! I thought I would run this one past you guys and believe me I am open minded.I just can't seem to find bees wax in my book. So if ya all think wax is ok I will go with it! Thanks alot if you can help................Jeff Sanchez

reply »

Herb Pabes

#11364

Re: Boards coated in wax? | 24 May, 1999

| Hey peoples, | We are working with the dairy industry out here and they asked us to start reworking all there boards for them. Of course we said yes, hehe. Only we didn't know what them farmers coated them boards with. It turned out to be wax, hmmmmm? Now I know I have so much to learn here but the wax thing has got me I must say. The farm equipment company (our new customer) told us that it keeps the moisture out. Sounds simple right? He also said it made it easier to rework? Well at face value it does. But here are my questions. | 1. Will the wax effect the solder flow? | | 2. When the wax reaches a temp that makes it sweat will it then become conductive? | | 3. I dont want to boo hoo the whole wax thing but isn't there a better sealant out there? One that you might know of that will alow us to do the same easy rework ability? | | These boards gotta live with the cows. But I think the wax is for the birds. < bad joke! I thought I would run this one past you guys and believe me I am open minded.I just can't seem to find bees wax in my book. So if ya all think wax is ok I will go with it! | Thanks alot if you can help................Jeff Sanchez |

To anwser your question 3,

Why don't you guys just use Conformal Coating? I would recommend a silicone-based, since it's the easiest to rework - especially the less viscous kind. I used to work with the Dow Corning's 4105 Silicone and you could just literally peel it right off.

Most Conformal Coatings have a very wide temperature range - if I remember correctly i believe it's in the -40 C to 260 C ballpark...i don't really remember since it's been awhile since I've looked at a Conformal Coating data sheet. Conformal Coating is NOT conductive, and its intended use is for Printed Circuit boards. MOst coatings out there act as both a dielectric and for environmental protection. I'd recommend that you get in touch with a conformal coating supplier and get some literature.

However, I would guess that wax is a hell of a lot cheaper.

reply »

Earl Moon

#11365

Re: Boards coated in wax? | 27 May, 1999

| | Hey peoples, | | We are working with the dairy industry out here and they asked us to start reworking all there boards for them. Of course we said yes, hehe. Only we didn't know what them farmers coated them boards with. It turned out to be wax, hmmmmm? Now I know I have so much to learn here but the wax thing has got me I must say. The farm equipment company (our new customer) told us that it keeps the moisture out. Sounds simple right? He also said it made it easier to rework? Well at face value it does. But here are my questions. | | 1. Will the wax effect the solder flow? | | | | 2. When the wax reaches a temp that makes it sweat will it then become conductive? | | | | 3. I dont want to boo hoo the whole wax thing but isn't there a better sealant out there? One that you might know of that will alow us to do the same easy rework ability? | | | | These boards gotta live with the cows. But I think the wax is for the birds. < bad joke! I thought I would run this one past you guys and believe me I am open minded.I just can't seem to find bees wax in my book. So if ya all think wax is ok I will go with it! | | Thanks alot if you can help................Jeff Sanchez | | | | To anwser your question 3, | | Why don't you guys just use Conformal Coating? I would recommend a silicone-based, since it's the easiest to rework - especially the less viscous kind. I used to work with the Dow Corning's 4105 Silicone and you could just literally peel it right off. | | Most Conformal Coatings have a very wide temperature range - if I remember correctly i believe it's in the -40 C to 260 C ballpark...i don't really remember since it's been awhile since I've looked at a Conformal Coating data sheet. Conformal Coating is NOT conductive, and its intended use is for Printed Circuit boards. MOst coatings out there act as both a dielectric and for environmental protection. I'd recommend that you get in touch with a conformal coating supplier and get some literature. | | However, I would guess that wax is a hell of a lot cheaper. | Jeff,

Herb is right, but I will post here the message I sent to your email address before I got brains enough to read your forum posting:

Jeff,

Good to see from you again. I hope everything is going well, except for the wax.

I saw your posting and really didn't pay much attention, but it did concern me. First, what kind of wax as what chemistry? Who applied it and how (supplier and process as coated, draped, dipped, or?). What is the metallized surface as bare copper, gold, or? Is the wax removed during soldering operations? If so, what is the recommended method (wax supplier specifications)? Is the wax compatible with your fluxes and other solder process chemistries (solder paste, wire solder, etc.)?

Beyond all this, have you tried soldering to a sample surface? If so, how did it solder wet?

What I'm getting to is what you know so well. All copper surfaces must be protected to prevent oxidation whether the coating is tin/lead, gold, tin, or organics. No matter the coating, it only is there to protect, not inhibit solder wetting. If this stuff does both these, it is fine. If one or the other is not done effectively, the coating is unacceptable.

I hope this helps and best regards,

Earl Moon

Now that I understand the wax is designed to be a post process protective coating, I must say most of the same questions above must be asked. My biggest concern now is whether the wax really protects as do so many other conformals as Herb mentioned. Again, I get back to what works and how well.

Enjoy,

Earl Moon

reply »

Jens-H.

#17440

Boards coated in wax? | 31 August, 2001

> Hey peoples, We are working with the dairy > industry out here and they asked us to start > reworking all there boards for them. Of course we > said yes, hehe. Only we didn't know what them > farmers coated them boards with. It turned out to > be wax, hmmmmm? Now I know I have so much to > learn here but the wax thing has got me I must > say. The farm equipment company (our new > customer) told us that it keeps the moisture out. > Sounds simple right? He also said it made it > easier to rework? Well at face value it does. But > here are my questions. 1. Will the wax effect > the solder flow? > > 2. When the wax reaches a > temp that makes it sweat will it then become > conductive? > > 3. I dont want to boo hoo the > whole wax thing but isn't there a better sealant > out there? One that you might know of that will > alow us to do the same easy rework > ability? > > These boards gotta live with the > cows. But I think the wax is for the birds. _ bad > joke! I thought I would run this one past you > guys and believe me I am open minded.I just can't > seem to find bees wax in my book. So if ya all > think wax is ok I will go with it! Thanks alot > if you can help................Jeff Sanchez

Hi Jeff,

sorry I read about your wax problem so late but there is good news for you. We are a small producer of conformal coatings in Germany and we also have a "wax" for the protection of electronics. In my opinion it is a very good product because it is a kind of barrier to moisture. Furthermore it is 1-k, solvent-free and we also deliver a manual for repairing it. This makes it ideal for certain uses in harsh environments and I understand your dairy farm's need. If you want further information feel free to mail to info@kc-produkte.com or look at http://www.kc-produkte.com

reply »

#17445

Boards coated in wax? | 31 August, 2001

hi The parafin wax should not be a problem. We have used it for very high impedance circuits for some numbers of years as a moisture barrier. In fact it is basically an indsutry standard for that type of specialized circuit. It is very non conductive under all conditions, including its liquid form. The low leakage properties far exceed any polymer or alkyd conformal coating that we have been able to find. Basically you can melt the rework area with a heat gun and do the rework with an iron. It will make a lot of smoke when you touch it with the iron but thats about it. Once you touch it the wax boils off leaving no residue. There are different grades of manmade waxes (parafins) but all are about the same for most applications unless high voltages are involved (>700 V). If you need more wax to patch up the rework area just to the grocery store and get some parafin that is used for canning. Its cheap and non toxic but it is combustable if there is there is sustaiing flame. Plus you can make candles out of what ever you have left.

reply »

Boundary Scan

Used PCB Equipment - ECM