Hi Rainer,

I agree with Dave but you might try contacting Edmund Optics and see if they will custom cut some specific glass to the size you are looking for.  In a former life, I remember we tried something along the same lines of thought.  The glass would always spread more than the actual components.

Phil

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Monday, July 21, 2014 8:14 AM
To: [log in to unmask]
Subject: Re: [TN] Dummy Glass QFN

Hi Rainer - my experience using 'glass components' has been that the solder paste wetting is different that what you will get with a real laminate component. However, the testing results were still useful for the investigation we were conducting, we just had to keep in mind that what we observed on the glass components wasn't going to be exactly replicated with the real components. Good Luck with the testing.

Dave


On Mon, Jul 21, 2014 at 9:53 AM, Rainer Taube <[log in to unmask]>
wrote:

> 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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