Out-of-tolerance zero ohm resistors - Page 5

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Re: Out-of-tolerance zero ohm resistors
On Tue, 02 Jun 2015 16:38:46 +0100, John Devereux

Quoted text here. Click to load it

Don't blame gold; it's just an element. Blame the board house.

Every PCB house seems to screw up sooner or later. Some screw up most
of the time.




--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors
On Tue, 02 Jun 2015 08:54:17 -0700, John Larkin

Quoted text here. Click to load it

https://dl.dropboxusercontent.com/u/53724080/PCBs/Bubble_Board.jpg

https://dl.dropboxusercontent.com/u/53724080/PCBs/Bad_Plating.jpg

https://dl.dropboxusercontent.com/u/53724080/PCBs/BadVia2.jpg






--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

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

Quoted text here. Click to load it

--  

John Devereux

Re: Out-of-tolerance zero ohm resistors
On Tue, 02 Jun 2015 08:06:33 +0100, John Devereux

Quoted text here. Click to load it

There's barely any solder on most of those pads.


--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors
On Mon, 01 Jun 2015 12:28:11 -0700, John Larkin

Quoted text here. Click to load it

Again, it's not necessary if the line is set up properly.

Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it


  You are beyond stupid.

Re: Out-of-tolerance zero ohm resistors
On Tue, 02 Jun 2015 09:23:36 -0400, DecadentLinuxUserNumeroUno

Quoted text here. Click to load it

No, AlwaysWrong, you have that market cornered.

Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

My production people want it, so they get it. PCB cost averages about
1% of the price of our products, so the gold flash must be ballpark
0.1%.

Besides, the gold looks cool.


--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors
Den tirsdag den 2. juni 2015 kl. 16.21.50 UTC+2 skrev John Larkin:
Quoted text here. Click to load it

I've seen the "massive" number $1 per square feet

-Lasse

Re: Out-of-tolerance zero ohm resistors
On Tuesday, June 2, 2015 at 12:27:07 PM UTC-4, Lasse Langwadt Christensen wrote:
Quoted text here. Click to load it


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

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

Cheers,
James Arthur

Re: Out-of-tolerance zero ohm resistors
Den onsdag den 3. juni 2015 kl. 14.38.37 UTC+2 skrev snipped-for-privacy@yahoo.com:
Quoted text here. Click to load it

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


Re: Out-of-tolerance zero ohm resistors
On Wed, 3 Jun 2015 09:22:33 -0700 (PDT), Lasse Langwadt Christensen

Quoted text here. Click to load it

There is on mine! Both sides!

https://dl.dropboxusercontent.com/u/53724080/Protos/Gold_FR4.JPG


I bought two pieces, 1 square foot each, $100 each. I think the board
house just made up those prices. We are a good customer, and
purchasing said "The President wants these...."

What she actually said was probably "This in stupid crazy, but the
President wants these."



--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors
On Tue, 02 Jun 2015 07:21:46 -0700, John Larkin

Quoted text here. Click to load it

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.

Quoted text here. Click to load it

;-)

Re: Out-of-tolerance zero ohm resistors
On 5/31/2015 9:05 PM, krw wrote:
Quoted text here. Click to load it

The contract assemblers I use wanted me to switch to gold plating to  
make their assembly easier.  I got them to agree to it not costing me  
more, but each batch is quoted so I'd have no way to verify that, lol.
Still, they had a strong preference.  My runs are typically 100 boards,  
so still not large production.

--  

Rick

Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

It's electroless nickel and microinches of gold immersion, not much
gold. The gold dissolves in the solder.

ROHS sucks, but sucks a little less on ENIG boards.


--  

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

We've slightly trimmed the long signature. Click to see the full one.
Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

Right.  Small lots.  Ask them about 50K a month.

Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

  Most PCB houses are keyed toward it, and it does not add that much to
cost and DOES improve reliability as the boards are simply better, AND
if you want to sell in Europe, you have to use lead-free, and that means
gold on nickel.

  Nice try though.

Re: Out-of-tolerance zero ohm resistors

Quoted text here. Click to load it

It is a significant extra cost, it is used a lot on small runs and
prototypes but HASL is the usual finish for mass production I believe.

Quoted text here. Click to load it

No it does not it means lead-free HASL.

nickel-gold also works of course but it costs extra.



--  

John Devereux

Re: Out-of-tolerance zero ohm resistors
On Monday, 1 June 2015 04:42:23 UTC+1, DecadentLinuxUserNumeroUno  wrote:

Quoted text here. Click to load it

No it doesn't.  One of the very big contract manufacturers in the UK
prefers to use bare copper with a protective organic coating for
lead-free.  They have no problems with this.

Too much gold is a bad thing, as it forms a brittle inter-metallic
compound with tin which can reduce the reliability of the solder joint.

See for example
http://www.dfrsolutions.com/wp-content/uploads/2013/12/Gold-Embrittlement-in-Leadfree-Solder.pdf
or
http://www.circuitinsight.com/pdf/solder_joint_embrittlement_mechanisms_solutions_standards_ipc.pdf

John




Re: Out-of-tolerance zero ohm resistors
Den mandag den 1. juni 2015 kl. 23.28.56 UTC+2 skrev snipped-for-privacy@gmail.com:
Quoted text here. Click to load it

all the coatings have pros and cons  

http://dcchapters.ipc.org/assets/pnw/presentations/20030925_finishes.pdf

-Lasse

Site Timeline