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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Gold Embrittlement

johnwnz

#28840

Gold Embrittlement | 31 May, 2004

Hey there, trying to get soem useful data on joints that suffer from gold embrittlement. Anyone got any data on effects ont he electrical conductivity of the joints over time? does it degrade quicker than a normal good joint? (let's all ignore the fact that the joints are weaker sor a 2nd shall we)

reply »

#28848

Gold Embrittlement | 1 June, 2004

Intermetallic growth is a diffusion process, the thickness of the intermetallic is given by: z^2 = (Do)(t)exp[-Q/RT] Where Do (m2 s-1) is the diffusion coefficient, T(�K) is the temperature, Q (J mol-1) is the activation energy and R (8.314 J mol-1 �K-1) is the gas constant. From previous work at CALCE, recommended values for the activation energy for 60Sn40Pb solder is 78 kJ and the diffusion coefficient was empirically calibrated as 1.5 x 10-5 m2 s-1 . If you plug and chug, you will find that at 80*C (353*K), Time||IMC Thicknss micron 10 sec||0.02 1000 sec (~15 min)||0.2 100000 sec (~1 day)||2 10000000 sec (~100 days)||20

While CALCE reports are usually numbingly expensive, what do you loose?

Cemal Basaran has talked on SMTnet about measuring the thickness of IMC in good / bad connections. So that may be someone else to check with: Cemal Basaran, Dr Associate Professor SUNY Buffalo Electronic Packaging Laboratory

Work: 716-645-2114 X2429 Fax: 716-645-3773 E-Mail: cjb@eng.buffalo.edu

243 Ketler Hall North Campus SUNY at Buffalo Buffalo, NY 14215

reply »

#28855

Gold Embrittlement | 1 June, 2004

To maybe simplify, contact David Sbiroli(Apps. Engineer) @ Indium corporation. I have worked with Dave on this issue before. He can most likely get you the info you need.

1-800-4 INDIUM

PS: Dave F. : My plasma arc accumulator has unusual carbon scoring on and around the dylithium chamber plenum. Any ideas ?

reply »

#28863

Gold Embrittlement | 1 June, 2004

Se�or Tech: Would you believe it!!! We had the same thing about a week ago. The carbon layer is real thin, almost a brownish color, correct? Couldn�t figure it out for nuthin�. We were all just standing around like dupes, without a clue. We ended-up bringing in a consultant [Jim Doohan from Vancover BC]]. Turns-out, it had something to do with the Spallation Neutron Source. Go figure.

reply »

Ken

#28877

Gold Embrittlement | 1 June, 2004

There are studies out there that looked at gold embrittlement. The overall consensus is to not exceed 5% by weight. As far as the conductivity question, as themo/mechanical creep fatigue sets in, your conductivity will be affected as the joint is separating until 100% fracture. Thermal cyles, of course, will augment the difusion process (and embrittlement) as Dave (so eloquently) described. I gotta run, oddly, the gamma ray alarm just sounded and I'm getting very ANGRY right now!

reply »

#28881

Gold Embrittlement | 2 June, 2004

dave,

let me just go on record as saying your a scary individual if you knew all that off the top of your head!

John

reply »

#28891

Gold Embrittlement | 2 June, 2004

It has been our experience that Spallation Neutron Source units are definitely a problematic area. But...we have just recently found that if you tweak the trim characteristics on the hydrogen assimilation unit, ion pacification can truly be achieved with minimal effort.

Note: This information is accurate and true to the best of our knowledge.All testing was performed using a V9600 plasma arc accumulator. Specific applications and conditions may require custom system configurations.

reply »

Vahid V

#29074

Datecode & Solderability | 13 June, 2004

Is there a indutry standard on SMT datecode? My last company's guideline was two years but I don't remember seeing any specific studies. Thanks.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

Lead Free Wave Solder - 1 Click SMT

Used PCB Equipment - AdoptSMT