Hi Siggi,
I have answered this question a number of times before.
No standards on shear/pull testing exist—nor should they exist. And there are 
good reasons none exists.
First, there cannot be such thing as a true shear/pull test;' while you are 
of course stressing the solder joint, what you are doing to the solder joint in 
most cases is primarily peeling it—the proper reference would be a 'peeling' 
test. 
Second, the solder joint strength, as determined by a lead peeling test, has 
no bearing on the reliability of the solder joint, provided the peeling test 
does not reveal inadequate wetting or poor metallization, e.g., 'Black Pad.’
Third, in a peeling test you always need to observe the whole peel-load 
history for the whole peeling process; e.g., with a leaded solder joint the largest 
load will be at the initial portion of peeling through the heel fillet, with 
lower loads subsequently depending on whether or not (or to what extent) side 
fillets are present. 
Fourth, the fracture surface of the peeled solder joints give typically more 
information than do the peel-load histories, because the ONLY really important 
finding is whether or not adequate wetting has taken place, i.e. the 
separation is mostly in the solder vs. being interfacial; or whether or not the 
metallization is the 'weakest' link, i.e. the separation is between metallization 
layers. Good quality solder joints frequently cause failure between the 
soldering pad and the component/PCB resin matrix.
Fifth, for leaded solder joints, the reliability in actual use does to a 
large extent depend on the heel fillet and the 'bottom flat' wetting; if the foot 
length is <3W, than also on the presence of a toe fillet, because short feet 
'rock' during thermal cycling. Side fillets are less important, unless you have 
wetting problems.

Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com


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