TO-220 Failures due to lead bending?

On Wed, 7 Jun 2006 23:25:19 -0500, "Brian" Gave us:

No conformally coated assemblies or encapsulated HV assemblies can use it, however. At least not correctly. It WILL fail.

Just like you have.

On Wed, 7 Jun 2006 23:27:03 -0500, "Brian" Gave us:

You're an idiot. As well as being a wussy.

Some of our mil customers require silicone coating, since most of the other things are fungus nutrients.

I think we'll stick to RMA flux and solvent cleaning, but it's hard to find assemblers that still do this.

John

Even harder to find assemblers that use it and do it well!!

Stick to stupid comments, cuz you are just wrong.

There are PLENTY of water based conformal coatings that work very well, along with potting compounds. I have manufactured HV boards that are potted and they work very well, using 100% no-clean compatible processes. You are just wrong, Roy.

And there are silicone

The irony is that our little internal operation does it very well, and that the contract assemblers are the ones that mess up.

John

What's the downside for them vs. for you?

Best regards, Spehro Pefhany

On Thu, 08 Jun 2006 06:50:43 -0700, John Larkin Gave us:

Since conformal coating is meant to be a moisture barrier as well as an electrically insulative shield, I doubt that a water based version can even actually be qualified by a mil contractor or any real commercial contractor with any brains.

It even sounds stupid... "Water based conformal coating".

Hahahahaah... yeah... sure... :-]

If this guy is so smart lets see if he can tell us what the ONLY encapsulant approved by NASA for HV circuitry is.

One clue... It is NOT water based, and it will not pass muster if "no clean" fluxes are used. The PCB assembly has to be VERY clean, totally free of VOCs, and vacuum and heat baked first.

On Thu, 8 Jun 2006 12:31:03 -0500, "Brian" Gave us:

You must be hiring dipshits as retarded as you are.

Get some HR screening in your life, boy. Stop trying to hire zero experience crapsters just to save a couple bucks an hour, and deliver a poorer product to your customers.

On Thu, 8 Jun 2006 12:52:47 -0500, "Brian" Gave us:

cuz? You aren't a business owner with CRAP lingo like that. You are an inspector, at best. And a poor one at that.

That is aside from the FACT that you don't know what the f*ck you are talking about.

That's NOT what I said, you retarded twit. I SAID that NO CLEAN fluxes leave residues that cause the desired effect of a conformal coating or encapsulant to give rise to failure modes.

One cannot attach to a liquidous media, ducmbfuck. The ENTIRE key of an encapsulant or coating is INTIMATE contact, and adhesion.

You cannot achieve that with liquid all over the f****ng assembly, you retarded twit!

I doubt very seriously that you have done any HV work other than a smoke puffer supply for room freshener. I was talking about REAL HV supplies, dipshit.

Also, you likely do not even know where the break point is for declaring a circuit "HV".

Nope. I did work for NASA and mil contractors, and I know what is and is not acceptable methodology. You do not.

THAT is NOT water based, dipshit.

Also, it doesn't matter what you use if there is flux on the board.

Adhesion is REQUIRED.

YOU ARE AN IDIOT!

On Thu, 08 Jun 2006 13:58:52 -0700, John Larkin Gave us:

Cleaning steps, and cleanliness is your friend.

We do most of our assembly in-house. We have pneumatic solder stencils, reflow oven, and a cleaner, but our bottleneck is the two semi-auto p-n-p machines. Some boards, with as many as 1000 parts, can take 4 hours or so to place. So when we get a big order, as sometimes happens, it helps to be able to send out a kit of, say, 50 or 100 boards for assembly. It usually works OK, but since our stuff is usually analog, we're very sensitive to contamination, and most assemblers are using water-soluble fluxes these days. We occasionally have other problems, but at least most of those are obvious, whereas the killers are the time bombs, the things that may pass test but fail in the field. I don't have a very good feeling about this tin whisker thing.

I guess we're just an awkward size, sometimes too big for the in-house p-n-p but too small to go automatic, and our batches aren't big enough to get any assembler really excited about our business.

John

Redundancy ? Chapter 11 ? Etc.

Graham

He's bad-mouthing the competition.

I doubt he can find really cheap or really experienced assembly labor out there in hobby-farm country. That's what subway lines are there to deliver.

Best regards, Spehro Pefhany

Roy, you are bad at insults and electronics. Study up a bit. Plenty of conformal coatings and potting compounds out there that work with no-clean. Done by many assembly houses everyday. Just go ahead though, you can be wrong. Obviously, you have no clue as to how no-clean flux actually works. If you believe it leaves a wet residue all over the board and dripping of like snail slime, hey, so be it. You have a right to be uninformed. But start with Humiseal, learn something.

So, I guess these tests were all lies....

I would bet the corona treaters I have designed boards for have a tad more voltage than the toasters you tweak for a living (60kV 1020kV plus). The noncontact printer HV modules we potted are less, but enough so that fr-4 had to have cutouts in it. They potted very well in no clean processes.

You are just dreadfully out of date and just ignorant, too, Roy.

And my sentence that got cut-off was that even some silicones have been successfully used with no-clean, although we have not tried them here. We have used Humiseal and other products with no coating related failures.

They probably cannot afford to do it like you do, to be honest. A few boards is a lot different than EVERY board a contract house would make.

Hobby farm country? Not here. 500 head of milking cows is a minimum to be even a hobby farm around here. The whole area is intensive agriculture, why I chose it. I hate cities. Funny thing, though, is Plexus is a stones throw away! Its a great area to live.

Roy, read the statement again (or have someone read it for you). It says that there are few ASSEMBLY HOUSES that do it well, not employees. King of misinterpretation and nonesense. I notice how you like to wander around uttering nonsense, looking for just one little tiny thing you say that might finally be correct. Then you are just proud as a peacock. Weird. But basically, you just aren't understanding the topic, its over your head.

Honestly RMA processes and the cleaning involved for truly contaminant free boards are a niche. It isn't served by many because not many customers need it. As John knows, its hard to get someone to even consider building low volumes of such boards. The money isn't there.

And I would bet, if I wanted to know what coating NASA likes for HV, I could find it just as easy as anyone on QPL-46058

On Fri, 9 Jun 2006 01:32:07 -0500, "Brian" Gave us:

You're an idiot, and you cannot even read. It isn't about whether YOU think they will work or not, it IS about whether they will work PROPERLY or not.

YES, you can use a coating or potting material with it, HOWEVER, it will NOT pass ANY mil or space approval, and it will technically not do the job it was meant to do.

YOU study a bit. Ask a few REAL engineers.

On Fri, 9 Jun 2006 01:32:07 -0500, "Brian" Gave us:

"Humiseal" is NOT a water based conformal coating. I HAVE used it. The name refers to what it is a barrier against, dumbass.