Out-of-tolerance zero ohm resistors

On Tue, 02 Jun 2015 15:34:51 +0100, John Devereux Gave us:

15 years ago? Even easier to pontificate about their lack of knowledge or expertise in the field.

I don't, I like gold on my boards. It was just a process screwup of some sort.

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John Devereux

It could have been, although I would have expected the pads to look black then instead of gold? (After reflow).

My theory was it might be incomplete processing of the solder resist removal stage. So there was an invisible layer of very thin resist. But it was just a guess, I did not get the exact details (just replacements).

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John Devereux

Seems like they are black where they separate after the part falls off.

Was it LPI mask? That would make sense.

--
Best regards,  
Spehro Pefhany 
Amazon link for AoE 3rd Edition:            http://tinyurl.com/ntrpwu8 
Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48

On my board the pads were covered with paste before reflow, so the solder should have wetted the gold (I would think). But it didn't.

Yes LPI solder resist.

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John Devereux

No, AlwaysWrong, you have that market cornered.

I understand and don't blame you a bit. For your run rates it's a no-brainer. At a few hundred thousand a month, it matters though.

;-)

That _is_ praying - to the god of hop.

--
Reinhardt

On Wed, 03 Jun 2015 12:59:06 +0800, Reinhardt Behm Gave us:

They do not make beer. They make ale!

When you see the bubbles both rising and falling in the glass, you know you are partaking in a blessed liquid. Ale-ion motion.

That obviously depends on the solder thickness.

However, you carefully missed the point. You originally claimed that: "...if you want to sell in Europe, you have to use lead-free, and that means gold on nickel."

This is simply not true. Many other board finishes are suitable for lead-free. I gave an example.

Both tin-lead and lead-free solders can be affected by excessive dissolved gold, so that can't be the reason for the military having their RoHS exemption. Maybe other factors like tin whiskers are involved.

John

On a sunny day (Sat, 30 May 2015 17:30:49 +1000) it happened Clifford Heath wrote in :

Use Opamps :-)

1 micro-inch = 45 mg Au per ft^2.

(Not sure how many stone that is per acre.)

Cheers, James Arthur

Do whatever steps you want, if You have cleared them with the Pontiff... (Tom Lehrer)

Cheers, James Arthur

On Tue, 2 Jun 2015 23:05:46 -0700 (PDT), snipped-for-privacy@gmail.com Gave us:

It is not the sole reason, but it is one of the reasons.

Lots of cycling over extreme ranges of temperature and humidity is a good way of growing whiskers. Lead-free solder is also mechanically harder than Sn63Pb, which makes the fatigue problems in pad metal and board traces worse.

Also there's some residual vague sense of proportion someplace--the lead prohibition was originally intended to protect people involved in recycling electronics, iirc, and maybe (just perhaps, you know?) people being shot at are in a bit more danger than they are.

Cheers

Phil Hobbs

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

We use to drink Krait, which was a champagne beer. It was champagne, made by the classic process, but they started with beer instead of wine. It was great. But we haven't seen it around lately.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

There are a lot of nice "Belgian style" Abbey Ales around. They add more sugar (or something) and do a second (or third) fermentation in the bottle. That gives it a lot of CO2 bubbles. And a "pop" when you release the cork. My wife and I always have one on New Year's Eve.. we don't like champagne.

George H.

On Wed, 03 Jun 2015 07:09:03 -0700, John Larkin Gave us:

I have been drinking a really good Virginia brewed tripel:

Very nice stuff.

The labels are even those expensive, "fuzzy feel" jobs :-)

Teddy was a drunk and made no qualms about it.

Apparently Hillary is a drunk and won't admit it.

I wouldn't put that lying, dishonest twit in office if you paid me.

None of you should attempt to either. She is farther from being ready for prime time than any candidate I have ever seen.

Except that her hubby likely exposed US secrets to her on a regular basis. How quaint... NOT!

if my math is right that is roughly $1.70

but since only the pads are covered with gold there is no where near that much on a normal ft^2 of pcb

-Lasse