Main advantage as Inge pointed out is at higher frquency. The most
advantageous being that using buried and blind via technology (typically
laser drilled) for high speed signals there is no stub that can cause signal
reflections and so avoids the need to go to back drilling and other
preventive measures necessary on through hole drilled boards at high
frequency.
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
Sent: Thursday, April 01, 2010 2:06 AM
To: [log in to unmask]
Subject: Re: [TN] FW: Tear drops?
Iain,
we have been doing some prototyping boards with VIP and non-filled. We base
the job on a report that I'll send offline to you. You gain a lot of space
for the fanouts, of course, but at the same time the requirement for
precision is increasing. Our boards are laser drilled, think it was YAG. We
were not satisfied with the first ones, debris problem and uneven centering.
With non-filled vias there is a risk for solder voids. You need a very good
X-ray equipment to judge the solder joint quality. What is the thickness of
your boards and the number of I/Os for your packages. We have not series
produced yet. The design engineers are very eager to get a go, because there
are apparent advantages in terms of shorter transmission ways at GHz
frequencies.
What kind of products do you aim at?
Inge
--------------------------------------------------
From: "Braddock, Iain (UK)" <[log in to unmask]>
Sent: den 1 April 2010 01:13
To: <[log in to unmask]>
Subject: [TN] FW: Tear drops?
> I guess from the lack of responses on this forum either you guy's are
> too busy or don't use them.
>
> Perhaps a slightly shifted question:
>
> Is anyone using µvia in pad for µBGA/CSP & are you filling the via's &
> with what?
>
> Regards,
> Iain.
>
> ________________________________
>
> From: Braddock, Iain (UK)
> Sent: 30 March 2010 10:07
> To: [log in to unmask]
> Subject: Tear drops?
>
>
> Hi everyone,
>
> I'm interested in whether any of you feel there is a benefit of tear
> drop designed pads on your boards to improve x-ray inspection and
> whether you have implemented it and the associated difficulty tracking
> especially <0.8mm pitched devices?
>
> Or perhaps you have implemented a design other than tear drop?
>
> Any comments would be very much appreciated.
>
> Regards,
> Iain.
>
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