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April 2001

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Subject:
From:
"Hiteshew, Michael" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 19 Apr 2001 13:08:31 -0400
Content-Type:
text/plain
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text/plain (58 lines)
Rick,
 We've been using BGA's for about 3 years. When we started, we queried other
divisions advanced packaging groups for guidelines. They suggested tenting
vias on the top to prevent bridging. We left the vias untented on the bottom
to allow test folks to probe them. Our boards are IR. reflowed. We've never
experienced any problems as far as I know.

Michael Hiteshew
Lockheed Martin NE&SS Marine Systems
410-682-1259

> ----------
> From:         Rick Thompson[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Rick Thompson
> Sent:         Thursday, April 19, 2001 10:46 AM
> To:   [log in to unmask]
> Subject:      [TN] Vias under BGA's - Tented or Not??
>
> Hi,
>
> We're running several designs from a new customer with multiple BGA's. The
> boards are laid out such that the vias under the BGA's are not soldermask
> tented on either side.  Our experience with this type of layout is for a
> greater tendency to bridge as well as requiring the bottom side to be
> masked
> prior to any wave solder operation.  The customer is resistant to changing
> this layout but I'd like to get some other opinions.
>
> My questions are: What are others doing in terms of PCB layout of BGA's?
> Is
> the above layout common? What if any trends are there in the industry for
> these types of layout?
>
> Thanks in advance for any insights.
>
>
>
> Rick Thompson
> Ventura Electronics Assembly
> 2655 Park Center Dr.
> Simi Valley, CA 93065
>
> +1 (805) 584-9858   x-304  voice
> +1 (805) 584-1529 fax
> [log in to unmask]
>
>

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