Nick,

A generic methodology can be described as follows-
1. Xsection SJ of interest - This is the most basic of all steps and is
applicable during development, test and production phases. Observations are
made for wetting of substrate surface & component lead, fillet formation,
voids, grain structure and intermetallic growth. A normal SJ will surpass
the pad bond strength and may also surpass the lead strength.
2. Stress Test - This is a classical SJ evaluation, both thermal cycle and
thermal shock. This may also include vibration to see the synergistic
effects of thermal-mechanical stresses. Details depend upon the substrate
material, assembly size, weight  and components types.
3. Tensile and shear tests - You can get some quantitative results by doing
tenisle test on individual lead SJ's and shear test on passive component
SJ's. If you know the wetting area on pad and lead, you can calculate SJ
strength ( an approximation) and compare with your test results.
4. Mechanical Deflection System (MDS) - This is a relatively new test
method. However, it is much faster than thermal cycle/thermal shock and can
be implemented for production runs if required. Again assembly size, weight,
material and components determine the test details. IBM Endicott
 www.ibm.com) can run this test for you and they can provide further
details. A short description of MDS is given on page 304 of  the book
'Failure Modes and Mechanismsin Electronics Packages'  ( www.wkap.nl) with
some reference papers on MDS from IEPS and EE&P.

MDS is applicable to both test vehicle and product while test vehicle is
preferred for stress test. Hope this helps.

----- Original Message -----
From: "Nick.Sanzo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, September 28, 2000 3:06 PM
Subject: [TN] Solder Joints


> Hello all
> I am interested in knowing if anyone is aware of any possible methods or
> information regarding testing of solder joints. What I am looking for
> specifically is a way of determining the strength of a joint and a way of
> determining the properties (ie: thickness) of the intermetallic layer. I
am
> not sure where to find such information. I have attempted internet
searches
> but I have been unsuccessful. Any info would be greatly appreciated.
> Thanks in advance.
>
> Nick Sanzo
>
> Operations Engineering-Leitch Technologies
> 416-445-9640   ext. 3852
> [log in to unmask]
> http://www.leitch.com
>
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