Hi Tom,
Is for high volumn fab and assy? For fab it's not a problem. With Assy it
could turn into a very large problem depending upon what steps you're
taking to ensure "flatness" of the BGA pad with the via-in-pad design. The
company I work for is seeing not a lot, but enough fallout with the BGA
assy (opens) to completely eliminate VIP designs. One way we're doing it
is to stay away from 'less than 1mm' BGA packages. One way we've also
experimented is to 'stagger' the uVia slightly off the BGA pad. That way
the majority of the BGA pad will be completely flat even if the VIP area
is not. (Yes, we've also experimented with solderpaste volumn too, but
that's again just a cludge work-around to solve a fallout anomaly)
Again, this is High Volumn only. There are many, many, many companies
where it's not a concern, or have solved the issue to their satisfaction
(maybe they have better assy equipment/manufacturers)
Good day.
Mitch
>
> If "Via in Pad" refers to laser microvias, this is a fairly common
> practice,
> and likely everyone owns a product (digital camera, cell phone, camcorder)
> than uses this type of design. If properly designed and fabricated you
> should have no problems manufacturing the assembly.
>
> Check the DC archives, as there's probably a wealth of information on the
> subject.
>
> Dave
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Tom
> Parkinson
> Sent: Friday, June 25, 2004 10:14 AM
> To: [log in to unmask]
> Subject: [DC] VIA in Pad
>
> We're a CM. One of our customers is asking us to build a board assembly
> that will be using BGAs with VIAs in pads. They are in the design stages
> at
> this point, and we have some concerns with having a Via in the middle of a
> BGA pad. Anyone have suggestions and/or experience with this??
>
> Thanks
>
>
> Tom Parkinson - Quality System Manager - CIT
> WinTronics, Inc.
> Ph: 724-981-5770 Ext. 235
> Fax: 724-981-1772
>
>
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