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Re: Gold plating the entire PCB

>>Lately, I've been looking again at gold plating the entire PCB. It >>makes a nice chemically stable layer on top of the copper. With the >>price of copper these days, changes are the copper on the PCB will >>cost more than the small amount of gold involved. >

If you don't care about long term reliability or your selling to audiophools (everybody knows that gold is the best conductor!) gold plate to your heart's content.

Normally, if you want to gold plate your pcb, use "immersion gold" plating. This puts a very thin layer of gold over the pads. I'm told that the solder joint is mechanically good since there is so little gold that gets absorbed into the solder joint. Thick layer of gold will create an intermetallic layer with solder which can cause solder joint failure due to embrittlement. You also want to nickel plate before gold plating. Gold over copper is an unhappy mixture.

Theses days with BGAs and 0402 parts and smaller, immersion gold or silver is recommended. HASL (tin plating) leaves too much material on the pad which messes up the volume of solder on the pad.

Mark

Reply to
qrk
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That has nothing to do with it, dipshit.

Strike two! SILVER is the best conductor. Gold and Platinum have the best oxidation characteristics, hence their use on contacts.

I think you're an idiot. Every circumstance is different, so "normally" doesn't ever apply.

"You're told"? Whom is it handing you this horseshit? There are REAL numbers. We typically measure these things in micro-inches.

Wow. You actually remembered something correctly.

You might have a little experience in this realm, but I still have my doubts.

You just make shit up as you go all the time? EVERY PCB situation is different.

HASL hasn't been used in years. Even solder plated PCB assemblies have SMOBC treatment these days.

Reply to
Hattori Hanzo

HASL is very often used on SMOBC boards.

Hey, are you DampMatter/AlwaysWrong? Sounds like his style.

John

Reply to
John Larkin

Look at the headers and you'll see his IP address, 72.197.139.29 so it is dimmie.

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Reply to
Michael A. Terrell

It is interesting that you say the above and then: [....]

You you are saying that gold is a reliability problem and recomended. What gives?

Reply to
MooseFET

Of course it's Dimbulb.

NNTP-Posting-Host: 72.197.139.29

--
Keith
Reply to
krw

Consider the edge of the solder joint where it meets the rest of the (unsoldered) gold-plated trace. What is the percentage of gold at that thin edge? Hint; the saturation point og gold in solder.

Is that really where you want embrittlement?

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Reply to
Guy Macon

Has anybody figured out who he works for?

John

Reply to
John Larkin

OK, I'm considering it. (........) Done.

Why would one tiny brittle sliver matter?

John

Reply to
John Larkin

FWIW, it looks like his isp is Cox:

$ nslookup 72.197.139.29 Server: 10.0.0.1 Address: 10.0.0.1#53

Non-authoritative answer:

29.139.197.72.in-addr.arpa name = ip72-197-139-29.sd.sd.cox.net.

Authoritative answers can be found from:

Reply to
Rich the Newsgroup Wacko

It's the thickness of the gold layer. Supposedly, immersion gold layer is thin enough (

Reply to
qrk

You forgot to take your meds. Dose up and re-read.

Reply to
qrk

I guess it depends on whether you want to avoid a crack there. Such a crack would be across the trace, and could propagate into the underlying copper, causing an intermittent open.

--
Guy Macon
Reply to
Guy Macon

...but only if the entire gold surface is wetted by solder. This is not the case if you gold plating the entire PCB. Also, after the gold is dissolved, the solder has to wet tin, not copper.

--
Guy Macon
Reply to
Guy Macon

Doesn't sound frightening to me. The brittle area will be not very many microinches in extent. If it does fracture - very unlikely, given the big soft pad and soft copper all around - it's no worse than a tiny scratch on a trace. I've never heard of a small scratch propagating. Copper is nice soft stuff.

Anyhow, I've never heard of this happening. Have you?

John

Reply to
John Larkin

Why do you care, LarkinTard?

Reply to
Hattori Hanzo

You obviously have no clue what terms like "mission critical" refer to.

Would you not be upset if the failure of such a connection was the cause of a catastrophic failure of a system that caused the death of the person it failed on?

Reply to
Hattori Hanzo

It is also a problem for gold plated terminals that have solder cups on the wiring side. The cups are plated just as thick as the terminal contact is, and that is far too much gold, as you indicated earlier.

For mil solder cups that are gold plated (most), we have to add solder, and then evacuate it... twice... with copper solder braid, then a proper solder joint can be constructed. Otherwise, one gets a bad solder joint, due to Gold Intermetallic Embrittlement.

Reply to
GoldIntermetallicEmbrittlement

Just curious. Whoever it is seems to be 10 or 20 years behind current technology.

John

Reply to
John Larkin

Hahahahaha... That's damn funny.

More like industry leaders.

Reply to
Hattori Hanzo

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