I agree.
Many of these materials expand during the curing process and completely
fill the barrel while releasing all volatiles. Consequently after
leveling and plating they become benign.
Lee
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mcmaster, Michael
Sent: Tuesday, June 29, 2004 8:33 PM
To: [log in to unmask]
Subject: Re: [TN] VIA in Pad
Reuven - I disagree with your assertion that VIP is not 100% safe. With
proper selection of via fill material and a reasonable hole aspect
ratio,
you should have neither solderability or void issues.
Mike McMaster
RF Product Engineer
Merix Corporation
503-992-4263
> ----------
> From: Reuven ROKAH[SMTP:[log in to unmask]]
> Reply To: TechNet E-Mail Forum.;[log in to unmask]
> Sent: Monday, June 28, 2004 10:08 PM
> To: [log in to unmask]
> Subject: Re: [TN] VIA in Pad
>
> I recommend to try as a first priority to layout the via out of the
BGA
> pad
> (bump) to adjacent special micro via hole pad.
> Up to 0.5 mils pitch it can be done.
> The filling VIP is not 100% safe (solderability and voids aspects).
>
>
> Best Regards
>
> Reuven ROKAH
>
>
>
>
> "Macko, Joe @
> IEC" <joe.macko To:
[log in to unmask]
> Sent by: TechNet cc:
> <[log in to unmask] Subject: Re: [TN] VIA
in
> Pad
> >
>
>
> 28/06/2004 17:35
> Please respond
> to "TechNet
> E-Mail Forum.";
> Please respond
> to "Macko, Joe @
> IEC"
>
>
>
>
>
> Tom,
>
> My experience has been that their generally a direct correlation
between
> voiding and VIP locations. Of course, the size of VIP has a direct
> bearing
> on the potential size of the void in the solder ball ..... Our
current
> policy is to fill all VIPs to preclude any voiding problems or
> insufficient
> solder conditions in leaded parts.
>
> I would sensitize your customer to the potential for voiding which may
not
> meet IPC guidelines, and the need for rework with VIPs for leaded
parts.
> Good luck.
>
> joe
>
> -----Original Message-----
> From: Tom Parkinson [mailto:[log in to unmask]]
> Sent: Friday, June 25, 2004 8:20 AM
> To: [log in to unmask]
> Subject: [TN] 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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