[SI-LIST] What is the difference between "non dry circuit test" and

Zhangkun-
 

Sometimes "dry test" refers to the nature of the physical contact. If the
probes making the electrical contact are just touching the circuit element,
it is called a "dry contact". There is a lot of physics associated with
making reliable dry contacts in electrical test. This is the nature of
testing all semiconductor packages and bare die. Needle and Form Factor MEMs
probes make a dry contact to the pads on the die. Spring probes make a dry
contact to the pads or balls on the package. 

 

In dry contacts, contact resistance can play a dominate role. With gold on
gold and more than 40 gm of force, the dry contact resistance can be a few
milliOhms. But with Tungsten on Al pads, the dry contact resistance can be 2
ohms. With probes tips on solder pads or balls, the dry contact resistance
can be 5-50 mOhms, depending on the oxide at the interface. 

 

Designing the probe tip geometry and metallurgy for reliable, reproducible
dry contacts for hundreds of thousands of tests is a challenge. There's lots
of subtle physics at the interface. 

 

A non dry test would use either a high shear, sliding, pin in box type
connection, typically between gold surfaces, or a solder connection.

 

--eric

 

**************************************

Dr. Eric Bogatin, President

Bogatin Enterprises, LLC

Signal Integrity Online Training

Next Public class: Oct 11, 12, 2006, San Jose, CA

Mastering Signal Integrity Characterization Techniques

26235 w 110th terr

Olathe, KS 66061

v: 913-393-1305

f: 913-393-0929

c:913-424-4333

e:eric@xxxxxxxxxxxxxxx

 <http://www.BeTheSignal.com> www.BeTheSignal.com

****************************************

Msg: #1 in digest

Date: Sat, 26 Aug 2006 14:47:59 +0800

From: Zhangkun <zhang_kun@xxxxxxxxxx>

Subject: [SI-LIST] What is the difference between "non dry circuit test" and

 

Dear all

Currently, I am using MICRO-OHMMETER of Keithly. There are two elements,
"non dry circuit test" and "dry circuit test". What is the difference
between these two elements?

 

Best Regards

 

Zhangkun

2006.8.26

 



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