Thank you all for the comments. I´m not looking for the wetting 
characteristics but for the paste spreading in a capillary as we have under 
BTCs like QFNs, especially the parts with pitches <= 500µm. I have not 
seen any research on this issue.

From videos with little glass slides on the paste deposites with nearly the 
size and weight of a qfn we saw that the spreading of the paste sometimes 
is very critical. This may cause shorts and solderballs under the 
components. To verify this observation it would be nice to have glass 
components with wettable terminations, because the wetting of glass slides 
with terminations may be more realistic compared to a slide without 
terminations, but in general, there may be a risk with the behaviour of solder 
past under BTCs especially if the paste hight/stencil thickness is very low.

Regards

Rainer


Am 21 Jul 2014 um 10:13 hat Steven Creswick geschrieben:

> Rainer,
> 
> I understand what you are looking for, as we did it ourselves.
> 
> You need to find a thin film house that can deposit NiC [or Ti], Ni
> [or Cu], Au [flash] in the pattern you desire onto the glass
> substrate.  
> 
> My experience has been that this works well for cleaning evaluations
> and underfill flow evaluations [but the wetting characteristics are
> not exactly the same as a laminate...], but I would not put any
> merit in mechanical test results [such as temp cycle, etc.] as the
> pads are much more likely to lift off the glass than your solder is
> to fail.
> 
> Once the array of patterns is deposited on the glass, just dice them
> apart and pick & place as if they were normal parts.
> 
> When I get back later today, I will see if I can dig up any possible
> sources for you.  In the mean time, I suggest looking for those that
> have thin film capability, or those that sputter [or evaporate] on
> glass routinely, such as optical filter manufacturers, etc.
> 
> 
> Steve Creswick
> Sr Associate - Balanced Enterprise Solutions
> http://www.linkedin.com/in/stevencreswick
>                          616 834 1883
> 
> 
> 
> 
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