Bhanu,
Thank you for that comment. Yes, I concur with that caution. Which is why raise the question about what test vehicles to use (are being used) for CAF on uVia designs.
Are folks using custom design specific CAF coupons for specific pwbs/applications?
Or are folks just staying in between the lines and relying on the standard thru via IPC coupons?
Or are folks working with uVias just taking the Alfred E. Neuman approach to CAF? <What? Me worry?>
-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Bhanu Sood
Sent: Thursday, September 5, 2019 7:48 PM
To: [log in to unmask]
Subject: [EXT] Re: [TN] CAF in a uVia world
Voltage is just one factor in a half dozen or so contributors to CAF.
For example, you’re not out of the CAF woods with laser ablated microvia holes, a poorly designed or executed siloxane process will still rear it’s ugly head leading to glass/polymeric separation, mechanical drilling or not.
On Thursday, September 5, 2019, Dwight Mattix <[log in to unmask]>
wrote:
>
> Anyone here running uVia CAF test vehicles?
>
>
> Bev,
> Thanks for that prompt reply/acknowledgement.
>
> In our uVia area it has mostly been in shorter life, lower voltage
> apps (e.g. high end consumer, engineering ref designs etc) as compared
> to the days when we both played Base Station games (has it really been
> that long?). Those applications allowed room to be casual
> (dismissive?) of CAF concerns in the uVia pwb.
>
> Now these uVia apps are finding their way into critical use case, and
> long term high availability, higher sustained temp/duty cycle
> applications that call for IMHO more attention to CAF now.
> (Automotive, infrastructure)
>
> CAF risks in uVias has the advantage of laser ablated vias vs.
> mechanical drilling disruption of the laminate. But the uvia drill
> edge to drill edge spaces run much tighter than in a mechanically
> drilled pwb. So… Then there's the voltages involved which tend to be
> lower and lower and would it seems work to reduce the CAF risks than
> in our bad old days with PTH only designs for infrastructure on BUTS pwbs (big ugly thick suckers).
>
> re: Certainly for the materials, construction and suppliers used in
> those two projects, stacked microvias were not as robust as staggered.
> Yeah I/we have a bit more experience than the average bear with
> respect to uVia stacking (and uVia stacking on core vias). We were
> early, very early, adopters -- some would say pioneered even. Living
> on the leading node of pitch and pin count (and frequency/radio complexity) will do that to you.
> :) In any case, have a pretty good understanding of that Z-axis part of
> it; where to put limits in design; and how to
> test/qualify/demonstrate reliability for our use case.
>
>
> -----Original Message-----
> From: [log in to unmask] <[log in to unmask]>
> Sent: Wednesday, September 4, 2019 3:43 PM
> To: 'TechNet E-Mail Forum' <[log in to unmask]>; Dwight Mattix <
> [log in to unmask]>
> Cc: [log in to unmask]
> Subject: [EXT] RE: [TN] CAF in a uVia world
>
> Dwight,
> Thx.
>
> After BlackBerry ceased making devices and sold off my lab by auction
> ☹, I went to run the CALCE Lab at the University of Maryland, but for
> a variety of reasons I was not happy there and resigned after four
> months and came home to Canada. The last couple of years I have
> worked part time as a project facilitator for the High Density
> Packaging User Group, an electronics industry research consortium of
> about 50 companies. So, I personally or through HDP, have not done
> any CAF testing on what you label ELIC. HDP does have two CAF
> projects, one looking at developing a new standard coupon that will be
> offered to the industry and another project looking to develop a new CAF equation.
>
> With regards to stacked microvias, HDP has completed two other
> projects (presented at SMTAI in 2017), is trying to start a third and
> is keeping a toe in the pool of the microvia turmoil that the IPC is trying to corral.
> Certainly for the materials, construction and suppliers used in those
> two projects, stacked microvias were not as robust as staggered.
>
> Regards,
> Bev Christian
> Project facilitator
> HDPUG
>
>
> -----Original Message-----
> From: TechNet <[log in to unmask]<mailto:[log in to unmask]>> On Behalf Of
> Dwight Mattix
> Sent: September 4, 2019 4:42 PM
> To: [log in to unmask]<mailto:[log in to unmask]>
> Subject: [TN] CAF in a uVia world
>
> Nice to see Bev back in the mix so I admit this post is mostly a bit
> of trolling for his input. :) But I know there are other veterans of
> the CAF wars so...
>
> For those of you working with full stacked uVia designs (aka ELIC:
> Every Layer Interstitial Connection) what have you done in terms of CAF testing?
>
> Use one or more of the standard IPC CAF thru via coupons with the hole
> edge/hole edge spacings down to ~10mils and call it good enough?
> Or do you go to custom CAF test vehicle designs that reflect the uVia
> stack and (tighter) spacing that is typical of uVia designs?
>
>
>
--
Bhanu Sood
Tel: (202) 468-8449
|
