[PCB_FORUM] Re: Via-In-Pad

Alexis,
        The best answer to your question will come from your PCB 
        supplier. Ask them about their preferred process, and it's
        pros and cons.

        Another way to handle via in pad is to plate the via solid.
        Solid vias have the advantage that they can conduct more 
        current and more heat, especially good under QFN type devices.

        Also ask you supplier about the finished flatness of the pad
        for each process.
         
Regards,
       Mike Finczak
       CopperCAD Design
       www.CopperCAD.com
       905-488-8958



 

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Phil Treen
Sent: Thursday, January 29, 2009 7:08 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Via-In-Pad



Hi Alexis,

 

I have used via-in-pad quite a bit.  We epoxy fill the via and then
plate over.  It is important that the Tg of the epoxy be near equivalent
to the Tg of the FR4 so that expansion and contraction are similar so as
not to pop the pad during the reflow process.

 

                                    Phil

 

 

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of
ameehan@xxxxxxxxxxxxxx
Sent: Wednesday, January 28, 2009 8:23 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Via-In-Pad

 

One of our engineers has asked if we can implement via-in-pad on a
handful of 0603 pads to facilitate routing of critical lines. We've
never done it here before, and I know that it increases both fab and
assembly costs. I'm also concerned about the risks involved (trapped
solvents, rising via plugs, etc). Has anyone out there used this
technology on only a few components with success (and minimal problems)?
I'm not sure if we should be doing this on a layout spin that needs to
be our production version. Thanks in advance for any feedback.

Alexis Meehan

Opnext Subsystems, Inc.

Desk: 408-385-3040

 

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